JP2002277399A - Lighting system and inspection device using the same, encoder, and instrument for measuring height - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the resolution of an optical sensor in the radial direction substantially equal to the resolution in the circumferential direction, without increasing the inspection time. SOLUTION: A beam outputting means outputs two light beams f3, f5 of slender elliptic shapes having the same size. The two beams f3, f5 advance in such a manner that the major axes of the elliptic shapes correspond respectively to opposed sides of a rectangle. A condenser lens 4 makes one beam f3 out of the two beams output from the beam output means incident on the vicinity of the center, and makes the other beam f5 incident on the vicinity of an end apart form the center, so as to condense both beams f3, f5 on an inspected sample face 5. The inspected sample face 5 is thereby irradiated with plurality of very small lighting beams discretely arrayed linearly at a prescribed pitch.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a magnetic disk,
The present invention relates to an illumination device for optically inspecting a surface of a semiconductor wafer, a liquid crystal display, a photomask, a magneto-optical storage disk, and the like, and an inspection device, an encoder, and a height measuring device using the same.

[0002]

2. Description of the Related Art When a surface of a magnetic disk, a semiconductor wafer, a liquid crystal display, a photomask, a magneto-optical storage disk, etc. is inspected in a non-contact manner, a laser beam or the like is generally irradiated on the surface of the specimen to be inspected. Light reflected from the surface, scattered light, or transmitted light is received by the optical sensor, and based on the electrical signal detected by the optical sensor, whether the surface of the sample to be inspected is free of scratches or foreign matter is determined. Inspection and measurement of the height of the surface of the sample to be inspected.

In such an optical inspection apparatus, in order to shorten the inspection time, the shape of a laser beam applied to the surface of a magnetic disk or a wafer, which is a sample to be inspected, is shortened in the circumferential direction and the radius is reduced. An elliptical shape that is elongated in the direction, and an optical sensor that is divided in the radial direction according to the elongated elliptical laser light is prepared, and the magnetic disk or wafer is rotated, and light reflected from the surface or scattered light is prepared. Inspection of whether or not there is a flaw or foreign matter on the surface is performed by receiving light. In an apparatus for optically measuring a height using a confocal point, a point-like illumination is applied to the surface of a sample to be inspected, and reflected light is received by an optical sensor via a pinhole. At this time, by moving the objective lens, the output of the optical sensor at the confocal position is maximized. As described above, the height measuring device measures the height of the minute area on the surface of the sample to be inspected based on the output of the optical sensor. Note that horizontal scanning is required to know the three-dimensional shape of the entire surface of the sample to be inspected. Conventionally, such horizontal scanning is performed using a polygon mirror or the like.

[0004]

However, information corresponding to the shape of the laser light to be irradiated enters the pixels of the optical sensor divided in the radial direction of the sample to be inspected. That is, the optical sensor includes information (reflected light and scattered light) corresponding to a laser beam having a minute illumination width along the circumferential direction of the sample to be inspected, and an elongated illumination width along the radial direction of the sample to be inspected. The incident light is mixed with information (reflected light and scattered light) corresponding to the laser light. Therefore, it is well known that the resolution of the optical sensor is significantly lower in the radial direction than in the circumferential direction. This is because, in the radial direction of the optical sensor, information corresponding to illumination light corresponding to an adjacent pixel is likely to be mixed. That is, in the radial direction of the optical sensor, stray light scattered from the surface of the test sample other than defects such as foreign particles is mixed into adjacent pixels. In order to reduce the occurrence of such stray light, if the illumination width in the radial direction is set to be substantially the same as the illumination width in the circumferential direction, there is no risk of mixing due to stray light as described above. It takes a lot of time to inspect the entire surface of the sample to be inspected by the amount of illumination, and it is not practical to use an elliptical laser beam for shortening the inspection time. On the other hand, the light receiving area of the optical sensor has been reduced, but at present, it cannot be sufficiently reduced due to the limitation of the resolution of the imaging system. In the case of height measurement, when scanning in the horizontal direction is performed by a polygon mirror or the like, the entire apparatus is complicated and expensive, and it is difficult to further reduce the size.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and provides an illumination that can make the resolution of an optical sensor in the radial direction substantially the same as the resolution in the circumferential direction without increasing the inspection time. It is an object to provide an apparatus and an inspection apparatus using the same.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an encoder capable of performing accurate position measurement with high resolution without being affected by a change in the amount of light.

An object of the present invention is to provide a height measuring apparatus which can easily measure a three-dimensional shape of a surface of a sample to be inspected with a simple configuration.

[0008]

According to a first aspect of the present invention, there is provided an illuminating device comprising at least two elongated elliptical light beams of the same size, wherein the major axis of each of the light beams is elliptical. A beam output unit that outputs the light beam so as to travel while maintaining a parallel relationship, and the light beam is output to the surface of the sample to be inspected so that the major axis of the light beam output from the beam output unit matches each other. And irradiating means for irradiating a plurality of minute illumination lights discretely arranged at a predetermined pitch in a linear manner on the surface of the sample to be inspected by irradiating the specimen at different angles. By irradiating two elongated, elliptical beams of the same size output from the beam output means under the above conditions, the two light beams are superimposed on the surface of the sample to be inspected. As a result, a small illumination light group showing an illumination intensity distribution in which a peak appears at positions separated by a predetermined pitch BP as shown in FIG. 3 is generated. This minute illumination light group is a group of a plurality of small discrete circles arranged linearly. By using such a plurality of small illumination light groups, it is possible to realize a very high horizontal resolution near the wavelength of the laser light.

According to a second aspect of the present invention, in the first aspect, the beam output means is deformed by the beam deforming means for deforming a circular light beam into an elongated elliptical shape, and the beam deforming means. Beam splitting means for splitting an elliptical light beam into a transmitted light beam and a reflected light beam,
Beam reflecting means for reflecting the reflected light beam so as to become a parallel light beam traveling in the same direction with a predetermined distance from the transmitted light beam, and the irradiating means comprises: A collector that is incident near the center, reflects the reflected light beam reflected by the beam reflecting means near an end distant from the center, and condenses the transmitted light beam and the reflected light beam on the surface of the sample to be inspected. It is configured to include optical lens means. This is a specific configuration of the beam output means and the irradiation means,
One light beam is branched to generate two light beams. Since the beam output means only needs to output a light beam under the conditions as described in claim 1,
The two output light beams may be deformed into elliptical shapes.

According to a third aspect of the present invention, in the illumination device according to the second aspect, the beam output unit outputs three light beams, and the irradiation unit outputs one of the light beams to the condenser lens unit. In the vicinity of the center of the condensing lens means, and the other two near the ends located equidistant from the center of the condensing lens means, and irradiate these three light beams to the surface of the sample to be inspected. It is composed. The two light beams are made to enter the symmetrical positions of the condenser lens means to flatten the phase within the illumination point on the surface of the sample to be inspected. Thus, an intensity interferometer or a phase interferometer can be configured using the linear minute illumination light.

According to a fourth aspect of the present invention, in the illuminating apparatus according to the third aspect, the beam output means is deformed by a beam deforming means for deforming a circular light beam into an elongated ellipse, and the beam deforming means. Elliptical light beam first
A first beam splitting means for splitting the transmitted light beam into a first reflected light beam and a parallel light beam traveling in the same direction at the same distance as the first transmitted light beam. First beam reflecting means for reflecting the first reflected light beam and entering near one end of the condensing lens means, and converting the first transmitted light beam into a second transmitted light beam and a second reflected light beam A second beam splitting unit that splits the light into a light beam and makes the second transmitted light beam incident near the center of the condenser lens unit, and in the same direction at the same distance as the second transmitted light beam. And a second beam reflecting means for reflecting the second reflected light beam so as to become a traveling parallel light beam and making the reflected light beam incident near the other end of the condenser lens means. . This is a specific example of the configuration of the beam output unit and the irradiation unit according to the third aspect, in which one light beam is branched and reflected to generate three light beams.

A lighting device according to a fifth aspect of the present invention is the lighting device according to the first, second, third, or fourth aspect, further comprising optical element means for changing an optical path length of at least one of the light beams. The position of the minute illumination light depends on the phase difference between the two converged light beams. Therefore, when the surface of the sample to be inspected fluctuates, the phase difference between the two light beams and the focus position fluctuate, and the minute illumination light is shifted as a whole, so that accurate measurement cannot be performed. Therefore, in the illumination device of this embodiment, the optical path length of at least one of the two light beams is changed using the optical element means, and the phase of the light beam irradiated on the surface of the sample to be inspected is slightly changed. The minute illumination light can be shifted as a whole in a minute range equal to or smaller than the wavelength of the minute illumination light. Therefore, even when the surface of the sample to be inspected fluctuates and the minute illumination light is shifted as a whole, the position of the minute illumination light is corrected by using the optical element means in accordance with the amount of the shift, so that the shift is caused by the shift. The effects can be counteracted.

According to a sixth aspect of the present invention, in the illuminating apparatus according to the fifth aspect, the optical element means is composed of two identical wedge-shaped optical elements, and the light is moved by moving at least one of the optical elements. It is configured to change the optical path length of at least one of the beams. This restricts the configuration of the optical element means. By arranging the same wedge-shaped optical element at a point symmetric position and moving one of them, the optical path of the light beam passing through the two optical elements is moved. The length is changed.

According to a seventh aspect of the present invention, in the illuminating apparatus according to the fifth or sixth aspect, a variation detecting means for detecting a variation in a position of the minute illumination light applied to the surface of the sample to be inspected; Light path length control means for controlling at least one of the optical elements in accordance with the fluctuation amount detected by the amount detection means to control the optical path length. Even when the surface of the sample to be inspected fluctuates and the minute illumination light is shifted as a whole, when the position of the minute illumination light is corrected using the optical element means according to the shift amount, the shift amount is small. You have to detect how much. The fluctuation amount detecting means detects the shift amount, and the optical path length control means moves the optical element according to the shift amount detected by the fluctuation amount detecting means,
Negative shift effects.

According to an eighth aspect of the present invention, in the illuminating apparatus according to the seventh aspect, the fluctuation amount detecting means passes only a linearly polarized component of the light beam reflected from the surface of the sample to be inspected. Means, a polarizing beam splitter means for reflecting the light beam passing through the quarter-wave plate means,
Light-receiving element means having pixels divided at substantially the same pitch as the pitch of the minute reflected light so as to correspond to at least one location of the minute reflected light formed by the light beam reflected by the polarizing beam splitter means. It is configured to include. This is a specific limitation of the fluctuation amount detecting means described in claim 7, and the light reflected on the surface of the sample to be inspected is transmitted to the light receiving element means by using a quarter-wave plate and a polarizing beam splitter. By irradiating the micro-reflection light having the same shape as the micro-illumination light formed on the sample surface to be inspected on the light receiving element means, the light is irradiated to the sample surface according to the output from the light receiving element means. A variation amount (shift amount) of the position of the minute illumination light is detected.

According to a ninth aspect of the present invention, there is provided an inspection apparatus comprising at least two elongated elliptical light beams of the same size, wherein the major axes of the respective elliptical light beams maintain a parallel relationship. Beam output means for outputting the light beam so as to travel while irradiating the light beam at different angles to the surface of the sample to be inspected so that the major axis of the light beam output from the beam output means respectively coincides with each other. Irradiating means for irradiating a plurality of minute illumination light discretely arranged at a predetermined pitch linearly on the surface of the sample to be inspected, an illuminating device including the beam output means and the irradiating means, Position control means for controlling the irradiation position of the minute illumination light on the surface of the sample to be inspected by relatively moving the surface of the sample to be inspected. This means that the illumination device composed of the beam output means and the irradiation means according to claim 1 is entirely moved by using the position control means, so that the minute illumination light required for the inspection is changed to the sample to be inspected. The surface is irradiated to perform a desired inspection.

According to a tenth aspect of the present invention, in the inspection apparatus according to the ninth aspect, the position control means sets the number BP / n of the minute illumination light to a value BP / n obtained by dividing a pitch BP of the minute illumination light by a division number n. The illuminating device is configured to move along a straight line on which the minute illumination light is arranged, with a value m × BP / n obtained by multiplying m as a moving distance SS. Since the minute illumination light is discretely arranged at a predetermined pitch in a linear manner, it is necessary to move the position control means in a predetermined manner in order to perform scanning between the minute illumination light without omission. Thus, by determining the moving distance SS of the lighting device moved by the position control means as described above, the position control means can easily move between the minute illuminating lights simply by sequentially moving the lighting device by the predetermined distance SS. It will be possible to scan. The method of moving by a predetermined distance SS as in the position control means is most suitable when the surface of the disk is inspected in a spiral shape.

According to an eleventh aspect of the present invention, in the inspection apparatus according to the tenth aspect, the position control means subtracts 1 from a value n × z−1 obtained by multiplying the number of divisions n by an integer z.
Is set to be equal to the number m of the minute illumination light. By setting the value of several m of the minute illumination light to the value n × z−1, the same portion is not scanned a plurality of times, and the entire surface of the disk is scanned by each minute illumination light without excess or shortage. Will be able to By setting the number m of the minute illumination light to be different from the value n × z−1, it is also possible to set an area where a plurality of scans are performed. By allocating the scanning of the region where the plurality of scans are performed to the data processing time and the like, the inspection processing time and the like can be effectively used.

According to a twelfth aspect of the present invention, in the inspection apparatus according to the ninth aspect, the beam output means is deformed by a beam deforming means for deforming a circular light beam into an elongated ellipse, and the beam deforming means. Beam splitting means for splitting the elliptical light beam into a transmitted light beam and a reflected light beam, and reflecting the reflected light beam so as to become a parallel light beam traveling in the same direction with a predetermined distance from the transmitted light beam Beam irradiating means, and the irradiating means makes the transmitted light beam enter near the center, and makes the reflected light beam reflected by the beam reflecting means enter near the end distant from the center. And condensing lens means for condensing the transmitted light beam and the reflected light beam on the surface of the sample to be inspected. This is a specific example of the configuration of the beam output means and the irradiation means, similar to the second aspect.
A light beam of a book is generated.

According to a thirteenth aspect of the present invention, in the inspection apparatus according to the ninth aspect, the beam output means outputs three light beams, and the irradiation means outputs one of the light beams to the condenser lens means. In the vicinity of the center of the condensing lens means, and the other two near the ends located equidistant from the center of the condensing lens means, and irradiate these three light beams to the surface of the sample to be inspected. It is composed. As in the third aspect, the two light beams are respectively incident on symmetrical positions of the condenser lens means to flatten the phase in the illumination point on the surface of the sample to be inspected.

In the inspection apparatus described in claim 14, in claim 13, the beam output means is deformed by a beam deformation means for deforming a circular light beam into an elongated ellipse, and the beam deformation means. First beam splitting means for splitting the elliptical light beam into a first transmitted light beam and a first reflected light beam; and a parallel beam traveling in the same direction at the same distance as the first transmitted light beam. A first beam reflecting means for reflecting the first reflected light beam so as to be incident on one end of the condensing lens means so that the first reflected light beam becomes a second light beam; A second beam splitting unit that splits the transmitted light beam and the second reflected light beam, and makes the second transmitted light beam incident near the center of the condenser lens unit; Same person with equal distance And a second beam reflecting means for reflecting the second reflected light beam so as to become a parallel light beam traveling toward the other end of the condensing lens means and making it incident near the other end of the condensing lens means. is there. This corresponds to claim 13
Specifically, the configuration of the beam output means and the irradiation means is described, and one light beam is branched and reflected to generate three light beams.

According to a fifteenth aspect of the present invention, in the inspection apparatus according to any one of the ninth to fourteenth aspects, there is provided an optical element means for changing an optical path length of at least one of the light beams. This is achieved by changing the optical path length of at least one of the two light beams by using the optical element means and finely changing the phase of the light beam irradiating the sample surface to be inspected, as in the fifth aspect. The illumination light can be shifted as a whole in a minute range equal to or smaller than the wavelength of the minute illumination light.

According to a sixteenth aspect of the present invention, in the inspection apparatus according to the fifteenth aspect, the optical element means is composed of two identical wedge-shaped optical elements, and the optical element is moved by moving at least one of the optical elements. It is configured to change the optical path length of at least one of the beams. This limits the configuration of the optical element means of claim 15 as in claim 6.

According to a seventeenth aspect of the present invention, in the inspection apparatus according to the fifteenth or sixteenth aspect, a variation detecting means for detecting a variation in a position of the minute illumination light applied to the surface of the sample to be inspected; Light path length control means for controlling at least one of the optical element means to control the light path length in accordance with the fluctuation amount detected by the amount detection means. In this case, the shift amount is detected by the fluctuation amount detecting means, and the optical element is moved according to the shift amount by the optical path length control means to cancel the influence of the shift.

[0025] In the inspection apparatus according to the eighteenth aspect, the quarter-wave plate according to the seventeenth aspect, wherein the variation detection means passes only a linearly polarized component of the light beam reflected from the surface of the sample to be inspected. Means, a polarizing beam splitter means for reflecting the light beam passing through the quarter-wave plate means, and at least one portion of minute reflected light formed by the light beam reflected by the polarizing beam splitter means. And light receiving element means having pixels divided at substantially the same pitch as the pitch of the minute reflected light. This is similar to claim 6,
The variation detecting means described in claim 12 is specifically limited.

According to a twelfth aspect of the present invention, there is provided an illuminating device, comprising: a beam output means for outputting at least two circular light beams having substantially the same size traveling in the same direction at a predetermined distance; The light beam is incident near an end where a perpendicular passing through a midpoint of a line connecting the optical axes of the outputted light beams substantially intersects the center, and both light beams are focused on the surface of the sample to be inspected. Accordingly, there is provided an irradiating means for irradiating a plurality of minute illumination light discretely arranged at a predetermined pitch on the surface of the sample to be inspected. By passing two small circular beams of the same size output from the beam output means through the condenser lens as the irradiation means under the above conditions, the two light beams are superimposed on the surface of the sample to be inspected. Then, the inverse Fourier transform is performed, and a group of minute illumination light showing an illumination intensity distribution in which a peak appears at a position separated by a predetermined pitch BP as shown in FIG. 9 is generated in a form arranged in a plane (lattice form). Is done. By using such a planar small illuminating light group, a very high resolution in the vicinity of the wavelength of the light beam can be realized in the vertical and horizontal directions.

According to a twentieth aspect of the present invention, in the illuminating device according to the nineteenth aspect, the beam output means outputs four light beams, and the irradiating means outputs two of the light beams to respective optical axes. Are incident near the end where the perpendicular passing through the midpoint of the line connecting the two points substantially intersects the center, and are incident near the end where the other two of the light beams have the center as the point symmetric center. One light beam is focused on the surface of the sample to be inspected. In this case, as in the third aspect, the phase in the illumination point on the surface of the sample to be inspected is flattened by making the light beam incident on the symmetric position of the condenser lens means. Thus, an intensity interferometer or a phase interferometer can be configured using the planar minute illumination light.

According to a twenty-first aspect of the present invention, there is provided an inspection apparatus, comprising: a beam output means for outputting at least two circular light beams having substantially the same size and traveling in the same direction at a predetermined distance; The two light beams are incident near the end where a perpendicular passing through the midpoint of the output line connecting the two light beams substantially intersects the center, and both light beams are collected on the sample surface to be inspected. An illuminating unit configured to irradiate a plurality of micro-illumination lights discretely arranged at a predetermined pitch on the surface of the sample to be inspected by illuminating, and an illumination device including the beam output unit and the irradiating unit And a position control means for controlling the irradiation position of the minute illumination light on the surface of the sample to be inspected by relatively moving the surface of the sample to be inspected and the surface of the sample to be inspected. This is necessary for the inspection by moving the illumination device composed of the beam output means and the irradiation means described in claim 19 and the surface of the sample to be inspected relatively using the position control means as a whole. A minute inspection light is irradiated on the surface of the sample to be inspected to perform a desired inspection.

According to a twenty-second aspect of the present invention, in the inspection apparatus according to the twenty-first aspect, the beam output means outputs four light beams, and the irradiating means outputs two of the light beams to respective optical axes. Are incident near the end where the perpendicular passing through the midpoint of the line connecting the two points substantially intersects the center, and are incident near the end where the other two of the light beams have the center as the point symmetric center. In this configuration, two light beams are focused on the surface of the sample to be inspected. This corresponds to the twentieth aspect, wherein a light beam is incident on a symmetrical position of the condenser lens means to flatten the phase in the illumination point on the surface of the sample to be inspected.

According to a twenty-third aspect of the present invention, in the twenty-first aspect, the relative movement direction between the illumination device and the sample surface to be inspected and each grid line of the minute illumination light are at a predetermined angle. It is configured to intersect. Since the minute illumination light is discretely arranged at a predetermined pitch on a plane,
In order to scan between the minute illumination lights without omission, it is necessary to move the position control means by a predetermined method. When moving, when the relative movement direction of the illumination device or the sample surface to be inspected and each grid line of the minute illumination light are in the same direction, for example, when the illumination device is moved in the horizontal direction, the minute illumination light Since it is not possible to scan the vertical gap,
There is a need to move vertically. Therefore, by making the moving direction of the illuminating device moved by the position control means and each grid line of the minute illumination light intersect at a predetermined angle, the illuminating device can be moved in any one direction (horizontal direction or vertical direction). By moving, it is possible to scan the gap between the minute illumination light in the horizontal direction and the vertical direction without omission.

The encoder according to claim 24, wherein at least two elongated elliptical light beams of the same size, wherein the major axes of the respective elliptical light beams maintain a parallel relationship. A beam output unit that outputs the light beam as it travels, and by irradiating the light beam output from the beam output unit so that the major axis of the light beam coincides, discretely at a predetermined pitch at the irradiation position. Irradiating means for forming a plurality of arranged minute illuminating lights, and relatively moving along the major axis direction of the light beam with respect to the irradiating means, receiving the minute illuminating light and outputting a detection signal thereof Optical sensor means, and position detecting means for detecting a relative positional relationship between the irradiation means and the optical sensor means based on the detection signal output from the optical sensor means. It is those with a. This relates to an encoder configured to detect a relative positional relationship between minute illumination light and optical sensor means using the illumination device according to the first aspect. Since the illuminating device emits a plurality of minutely arranged illuminating light discretely, when the illuminating device receives the illuminating light by the optical sensor, the output of the optical sensor changes stepwise. By counting the number of output steps that change stepwise, an accurate position can be measured without being affected by a change in the amount of light.

The height measuring device according to claim 25 is
A beam output means for outputting four circular light beams having substantially the same size and traveling in the same direction at a predetermined distance; and two light beams output from the beam output means being connected to each other by their respective optical axes. Are incident near the end where the perpendicular passing through the midpoint of the line connecting the two points substantially intersects the center, and are incident near the end where the other two of the light beams have the center as the point symmetric center. Irradiating means for irradiating a plurality of minute illumination light discretely arranged at a predetermined pitch on the surface of the sample to be inspected by condensing two light beams on the surface of the sample to be inspected; and A light receiving means for receiving a part of the light beam reflected from the surface; and a control means for obtaining height information on the surface of the sample to be inspected based on a detection signal output from the light receiving means. It is. This relates to a height measuring device configured using the lighting device described in claim 20 as lighting means. The illuminating means irradiates planar minute illumination light having a flattened phase based on the four light beams to the surface of the sample to be inspected. A part of each reflected light of the planar minute illumination light applied to the surface of the test sample is received by the light receiving unit as planar minute reflected light. When the surface height of the surface of the sample to be inspected fluctuates variously, the radius of the point-like illumination of the planar micro-illumination light increases accordingly, and the radius of the planar micro-reflection light that is the reflected light also increases. , The output of each pixel of the light receiving means changes.
The height of the sample surface to be inspected can be measured based on the output from the light receiving means corresponding to all the point-like reflected light of the planar minute reflected light in the measurement area.

The height measuring device according to claim 26 is
26. The quarter wave plate means according to claim 25, wherein said light receiving means passes only a linearly polarized light component of the light beam reflected from said sample surface to be inspected, and the light beam passing through said quarter wave plate means. And light receiving element means for receiving minute reflected light formed by the light beam reflected by the polarizing beam splitter means. This means that the light receiving means
It comprises a one-wave plate means, a polarizing beam splitter means and a light receiving element means, and the reflected light from the surface of the sample to be inspected is incident on the light receiving element means by using these.

The height measuring device according to claim 27 is
26. The minute illumination light on the inspection sample surface according to claim 25, wherein an optical system including the beam output unit, the irradiation unit, and the light receiving unit and the inspection sample surface are relatively moved. Is provided with position control means for controlling the irradiation position. This is claimed in claim 2
By moving the optical system composed of the beam output unit, the irradiation unit, and the light receiving unit described in 5 and the surface of the sample to be inspected relatively using the position control unit,
The microscopic illumination light is applied to the surface of the sample to be inspected to perform a desired inspection. When moving, the relative movement direction between the optical system and the surface of the sample to be inspected may intersect each grid line of the planar minute illumination light at a predetermined angle. . In addition, it is preferable to move by a method as described in claim 10 or claim 11.

The height measuring device according to claim 28 is:
The control device according to claim 25, 26 or 27,
The converging position of the illuminating unit is changed by relatively moving the irradiation unit and the surface of the sample to be inspected, and the sample to be inspected is changed based on a detection signal output from the light receiving element unit during the movement. It is configured to obtain height information on a surface. This is a specific example of the height measuring method performed by the control means. For example, while moving the objective lens constituting the illuminating means up and down, and changing the focal position (condensing position) thereof, The lens position where the output of each pixel of the light receiving element means corresponding to the shape illumination becomes maximum is recorded. Since the recorded lens position corresponds to the height on the surface of the sample to be inspected, the height measuring device can measure the height information of the surface of the sample to be inspected based on the lens position.

[0036]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a diagram showing a schematic configuration of the illumination method of the present invention. The cylindrical lens 1 emits a laser beam f1 having a circular cross section emitted from a beam output unit (not shown), for example, a laser device, into an elongated ellipse such that the vertical direction in the drawing is the minor axis direction and the depth direction is the major axis direction. It is transformed into a laser beam f2 having a shape. The half mirror 2 allows the laser beam f3, which is approximately half the amount of the elliptical laser beam f2 deformed by the cylindrical lens 1, to pass through as it is, and reflects the other half of the laser beam f4 toward the mirror 3 in the upward direction. Mirror 3 is half mirror 2
The laser beam f4 reflected by the laser beam f4 is reflected so as to become a parallel light beam f5 traveling in the same direction as the laser beam f3.
Therefore, the laser beams f3 and f5 have a relationship of parallel light beams traveling in the same direction with a predetermined distance L. The cross-sectional shape of each of the laser beams f3 and f5 is an elongated elliptical shape whose major axis is in the depth direction of the drawing. Laser light f3
The major axis of the elongate elliptical shape of f5 advances while corresponding to the opposing sides of the rectangle.

The condenser lens 4 condenses the laser beam f3 on the sample surface 5 to be inspected and also condenses the laser beam f5 on the sample surface 5 as the laser beam f6. The condenser lens 4 is arranged so as to receive the laser beam f3 near its center and to receive the laser beam f5 near its end portion separated by a predetermined distance L from the center. Therefore, the laser beam f3 that has passed near the center of the condenser lens 4 goes straight and is focused on the sample surface 5 to be inspected, and the laser beam f5 that has passed near the end of the condenser lens 4 has a predetermined distance L It is condensed on the sample surface 5 to be inspected as a laser beam f6 traveling obliquely downward and to the left. Since the sample surface 5 to be inspected is arranged substantially near the focal position of the condenser lens 4,
The two laser beams f3 and f6 are applied to the same position. Note that a plurality of circular shapes shown above the sample surface 5 to be inspected in FIG. 1 schematically show the state of the minute illumination light group formed on the sample surface 5 to be inspected, as shown in the drawing. In the figure, minute illumination light having a substantially circular shape is discretely arranged linearly.

FIG. 2 is a diagram showing a schematic shape of the laser beams f3 and f5 incident on the condenser lens 4. As shown in FIG. FIG. 3 is a diagram schematically showing a small illumination light group realized by the laser beams f3 and f6 converged on the sample surface 5 to be inspected. As is clear from FIG. 2, the cross-sectional shapes of the laser beams f3 and f5 are both elongated elliptical shapes. It can be seen that the light f5 passes. When the elongated elliptical laser beams f3 and f5 as shown in FIG. 2 pass through the condenser lens 4, the laser beams f3 and f6 are superimposed on the surface of the sample surface 5 to be inspected, where Fourier inverse transformation is performed. . By this inverse Fourier transform,
As shown in FIG. 3, a plurality of discrete small circular minute illumination light groups having an illumination intensity distribution having a peak at a position separated by a predetermined pitch BP are generated. When the pitch BP of the minute illumination light group is λ0, where λ0 is the wavelength of the laser light and θ is the elevation angle formed by the laser light f3 and the laser light f6, λ0 =
There is a relationship of BP × sin θ. Therefore, by varying the value of θ, that is, the distance L between the two laser beams f3 and f5, the focal length of the condenser lens 4, and the like, the pitch BP of the minute illumination light can be varied.
In order to change the elevation angle θ, it is easiest and most effective to move the mirror 3 up and down.

By using such a plurality of minute illumination light groups, a very high horizontal resolution near the wavelength of the laser light can be realized, and the number of minute illumination light groups can be 100 in one dimension. Degree can be realized,
By using this illumination method, an inspection device for simultaneous multi-point measurement can be realized. It is also most suitable for realizing an inspection apparatus that performs simultaneous multipoint measurement in which measurement points are discretely present at minute distances. This is possible whether high resolution is required or not. In the embodiment shown in FIG. 1, it is sufficient that the arrangement, shape, and intensity of each beam satisfy the Fourier inverse transform of the desired illumination. It may also be necessary to manipulate the phase between beams or within a beam. Depending on the shape of the illumination, it is also possible to realize this by combining a mirror or the like instead of a lens. For example, the half mirror 2 and the mirror 3 may be formed by adding a film having a desired transmittance (reflectance) to a parallelogram prism, for example. In the example of the one-dimensional arrangement as shown in FIG. 1, the illumination shape can be easily changed by moving the mirror 3 in the vertical direction. When a mirror or the like is used instead of a lens, the illumination shape can be easily changed by moving the mirror or the like.

Next, a case where the inspection apparatus is realized by using the illumination method as shown in FIG. 1 will be described. FIG. 4 is a diagram illustrating an example of a disk disk inspection apparatus. In the figure, the rotation of a disk 41 is controlled by a spindle motor 42. The upper surface of the disk disk 41 is adjusted so that the radial direction of the disk disk 41 and the longitudinal direction (grid line direction) of the linear minute illumination light dispersed discretely in a line as shown in FIG. The illuminating device 43 is arranged. The illumination moving device 44 moves the illumination device 43 in the same arrow direction 45 as the radial direction of the disk 41. The details of how the illumination moving device 44 moves the illumination device 43 will be described later.
By arranging a light receiving element at a position capable of receiving reflected light or scattered light generated in response to the illumination light from the illumination device 43, the inspection device performs the surface inspection of the disk 41. Can be. The disk 41
When the inspection surface is circular as shown in FIG.
By rotating the disk 41 by means of 2 and moving the illuminating device 43 with the illumination moving device 44, the entire surface of the disk 41 can be inspected. Therefore,
When the inspection surface is rectangular, it is necessary to inspect using an XY stage or the like.

Here, when the entire surface of the disk 41 is to be inspected by using linear minute illumination light dispersed linearly as shown in FIG. It is necessary to sequentially move 43 in the arrow direction (radial direction) 45 by a predetermined method. Hereinafter, the lighting moving device 4
4 explains how the illumination device 43 is moved. FIG. 5 is a diagram illustrating the concept of the simplest moving method when moving the lighting device 43. FIG. 6 shows the lighting device 4.
FIG. 10 is a diagram illustrating the concept of an optimal moving method when moving the third moving device;

In FIG. 5, the number m of the linear minute illumination light is a
To h, and each pitch of each minute illumination light a to h is BP
And At this time, between the minute illumination lights a to h, that is, ab, bc, cd, de, ef, fg, g
Since the minute illumination light is not irradiated to each gap portion of −h, it is necessary to perform measurement by irradiating the minute gap light with the minute illumination light. Therefore, in order to measure these gaps, the illumination moving device 44 is appropriately driven, and the illumination device 43 is moved in the radial direction of the circular disc 41 at the measurement interval SP.
Just move. The measurement interval SP is determined by the minute illumination light a to
The value is a value obtained by dividing the pitch BP of h by an integer (n). In the figure, the integer n is set to n = 3, the measurement interval SP is set to 1/3 of the pitch BP (SP = BP / 3), and the gap between the minute illumination light a and the minute illumination light b is set to 2 by the minute illumination light. I will measure twice.

That is, the illumination moving device 44 is arranged as shown in FIG.
When the surface inspection of the disk 41 is completed at the position (A), the illuminating device 43 is moved by the measurement interval SP, and the minute illumination light a to h is moved to the position shown in FIG. In the position shown in FIG.
When the surface inspection of No. 1 is completed, the illuminating device 43 is similarly moved by the measurement interval SP, and the minute illumination light a to h is
Move to the position shown in (C). When the surface inspection of the disk 41 is completed at the position shown in FIG. 5C, the illumination device 43 is turned to a value obtained by adding the distance GP from the minute illumination light a to the minute illumination light h and the measurement distance SP (GP + SP).
To move the minute illumination lights a to h to the positions shown in FIG. FIG. 5E and FIG.
As shown in (F), the illuminating device 43 is moved to
1. Perform a surface inspection. FIG. 5 (G) is similar to FIG.
(F) is shown in order from the top. As apparent from FIG. 5 (G), the entire surface of the disk 41 including the gaps between the minute illumination lights a to h can be completely scanned by the minute illumination lights a to h. However, in this case, the lighting moving device 44 sets the moving distance of the lighting device 43 to SP, SP, GP + SP, SP, SP, GP + SP.
It is necessary to move like. Such movement of the illuminating device 43 is not very preferable when the surface of the disk is inspected in a spiral manner.

Therefore, in this embodiment, when inspecting the entire surface of the disk 41 using linear minute illumination light as shown in FIG. 3, the illumination device 43 is moved as shown in FIG. I made it. In FIG. 6, the number m of linear minute illumination light is eight from a to h, and the pitch of each minute illumination light a to h is BP.
It is. As in the case of FIG. 5, measurement is performed twice between the minute illumination light a and the minute illumination light b, and the division number n is set to n = 3. Then, the measurement interval SP is a value obtained by dividing the pitch BP of the minute illumination lights a to h by the division number (n), that is, SP = BP / 3. At this time, the number m of the minute illumination light is set to a value obtained by multiplying the division number n by the integer z and subtracting 1 from the value (m = n × z−1). In the case of FIG. 6, z = 3 and m = 8 satisfy this condition. Then, when this condition is satisfied, the next scanning position is illuminated by shifting the whole illumination by a predetermined distance SS = SP × m / n from the previous scanning position.

That is, the illumination moving device 44 is configured as shown in FIG.
When the surface inspection of the disk 41 is completed at the position (A), the illuminating device 43 is moved by a predetermined distance SS to move the minute illumination light a to h to the position shown in FIG. At the position shown in FIG.
When the surface inspection of FIG. 1 is completed, the illuminating device 43 is similarly moved by a predetermined distance SS, and the minute illuminating lights a to h are
Move to the position shown in (C). FIG.
(D), as shown in FIG.
The surface of the disk 41 is inspected by moving by S. FIG. 6F shows FIGS. 6A to 6E in order from the top. As shown in FIG. 6 (F), the entire surface of the disk 41 can be scanned by the minute illumination lights a to h without excess and deficiency.

It should be noted that several scans at the start and end of the scan need to be performed outside the required scanning range. That is, as is clear from FIG. 6F, the respective intervals when the minute illumination lights a to e in FIG. 6A and the minute illumination lights a and b in FIG. Is different from twice the measurement interval SP or the measurement interval SP. Similarly, the minute illumination light g, h in FIG.
In the case where the minute illumination lights d to h in (E) are arranged in order from the left side, the respective intervals are also different, such as twice the measurement interval SP or the measurement interval SP. On the other hand, the small illumination lights f to h in FIG. 6A, the small illumination lights c to h in FIG. 6B, the small illumination lights a to h in FIG.
The small illumination light a to f of (D) and the small illumination light a of FIG.
The intervals in the case where .about.c are arranged in order from the left are the measurement intervals SP. Therefore, the portion where the interval of the minute illumination light is the measurement interval SP, that is, the minute illumination light f in FIG.
6B, the minute illumination light ah in FIG. 6C, the minute illumination light af in FIG. 6D, and FIG.
The small illumination lights a to c in FIG. 6 (A), the small illumination lights a and b in FIG. 6 (B), and the small illumination lights a and b in FIG. Small illumination light g, h, FIG. 6 (E)
By setting the minute illumination lights d to h outside the scanning range,
As in the case of FIG. 5, the entire surface of the disk 41 can be scanned with the minute illumination light a through h.

As shown in FIG. 6, the moving distance SS of the lighting device 43
Is determined, the illumination moving device 44 only needs to sequentially move the moving distance of the illumination device 43 by the predetermined distance SS, and performs the optimal inspection even when inspecting the surface of the disk 41 in a spiral shape. be able to. Note that the value of the number m of the minute illumination light described above is replaced with the integer z as the number of divisions n.
And the value obtained by subtracting 1 from the value (m = n × z−1)
By setting the area different from the above, it is possible to set an area where a plurality of scans are performed. It can also be used effectively.

Next, when the surface inspection of the disk shown in FIG. 4 is performed using the minute illumination light as shown in FIG. 1, the position of the minute illumination light is determined by the phase difference between the laser light f3 and the laser light f6. Dependent. When the surface of the disk disk fluctuates in the vertical direction, the phase difference between the laser light f3 and the laser light f6 and the focus position fluctuate, and the minute illumination light is shifted in the horizontal direction as a whole. If the phase difference or focus position fluctuates,
The illumination position of the minute illumination light fluctuates accordingly, and accurate measurement cannot be performed. Therefore, in the illumination method according to the present embodiment, it is possible to correct for a change that is equal to or higher than the autofocus following speed.

FIG. 7 is a diagram showing an embodiment of an illumination method capable of correcting a fluctuation exceeding the autofocus following speed. 7, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted. In FIG. 7, the optical elements 6 and 7 change the optical path length of the laser beam f5.
, And the same wedge-shaped object is arranged pointwise. One optical element 6 is a driving means (motor) 8
Is moved in the arrow direction 9 by the laser beam f5.
Can be varied in various ways. When the optical path length of the laser beam f5 is changed by the optical elements 6 and 7, the phase of the laser beam f6 applied to the surface of the sample surface 5 to be inspected is slightly changed. It can be shifted in the following minute range. Therefore, when the surface of the disc fluctuates and the minute illumination light shifts as a whole, the optical element 6 is moved in accordance with the shift amount to correct the position of the minute illumination light. The effect of the shift can be canceled. The wedge-shaped optical element 6 is characterized in that it can be very light in weight as compared with an objective lens, and can easily follow high-speed fluctuations. In addition, although the case where the optical elements 6 and 7 are arranged in the optical path of the laser beam f5 has been described, the invention is not limited to this, and they may be arranged in the optical path of the laser beam f3 or both.

In order to confirm the position of the minute illumination light applied to the surface of the sample surface 5 to be inspected, a polarizing beam splitter 10 and a quarter are provided between the wedge-shaped optical element 6 and the condenser lens 4. The wave plate 11 is disposed, and an image formed by the reflected lights r1 and r2 from the sample surface 5 to be inspected is enlarged via the lens 12 and formed on the optical sensor 13. The polarization beam splitter 10 allows the laser beams f3 and f5 to pass through as it is, and is a reflection beam r of a predetermined linear polarization component that is a reflection beam from the sample surface 5 to be inspected and that has passed through the quarter-wave plate 11.
Only 1 and r2 are reflected to the optical sensor 13 side. The optical sensor 13 is divided corresponding to at least one minute illumination light. The optical sensor 13 when viewed from the lens 12 side is shown as an optical sensor 131. Optical sensor 131
Are divided at a pitch substantially equal to the pitch of the minute illumination light, and one pixel corresponds to one minute illumination light. Therefore, the two laser beams f3 and f5
When the optical path length or focus of the optical sensor 13 fluctuates and the position of the minute illumination light fluctuates, the output of each pixel of the optical sensor 13 becomes unequal, and an output difference occurs between the pixels of the optical sensor 13. Therefore, the optical path length control means 14
Is to control the movement of the wedge-shaped optical element 6 so as not to cause an output difference between the pixels of the optical sensor 13 so that the position of the minute illumination light due to the change in the optical path length of the two laser beams f3 and f5 or the focus. Compensate for fluctuations. Note that the optical path length control means 14 may control the quotient to be 1 using the quotient instead of the output difference between the pixels. It goes without saying that other phase control means may be used instead of the wedge-shaped optical element 6.

In the illumination method described above, the scanning method in the case where the minute illumination light exists in a straight line has been described. Such a scanning method is called a linear discrete illumination scanning method. With the linear discrete illumination scanning method, since surface scanning is realized by relatively large movement of the sample surface to be inspected, it may be difficult to completely connect the surfaces due to vibration of the sample surface to be inspected. Therefore, it is preferable to adopt a surface discrete illumination system in which minute illumination light is scattered in a plane instead of the linear discrete illumination system. FIG. 8 is a diagram showing a positional relationship between two laser beams incident on the condenser lens when performing a planar discrete illumination system in which minute illumination light is scattered in a planar shape. FIG. 9 is a diagram schematically showing the shape of illumination light of the planar discrete illumination system realized by the laser light of FIG. In the on-plane discrete illumination system, as shown in FIG. 8, the condensing lens 4 is irradiated with circular minute beams f8 and f9, thereby obtaining
In this example, a large number of planar minute illumination light arranged at a predetermined pitch as shown in FIG. In order to irradiate the minute beams f8 and f9 as shown in FIG. 8 to the condenser lens 4, the cylindrical lens of FIG. 1 is omitted, and the minute beams f8 and f9 irradiate a position away from the center of the condenser lens 4. The half mirror 2 and the mirror 3 may be arranged as described above. At this time, the minute beams f8 and f9 need to be transformed into beams having a diameter of several times or more the wavelength.

When an inspection apparatus as shown in FIG. 4 is constructed using minute illumination light formed by the above-mentioned planar discrete illumination system, as shown in FIG. Direction 45 (normal line 46 of the disk 41)
And the respective grid lines 51 to 54 of the planar discrete minute illumination light intersect at a small angle φ. FIG.
It is a figure which shows the outline of the irradiation state of planar discrete illumination light on the disk disk surface. In FIG. 10, among the planar discrete minute illumination light as shown in FIG.
The small illumination light located on 54 is used. In this case,
The angle φ is determined by the irradiation position of the minute illumination light 512 one level higher than the lowermost end of the minute illumination light group on the grid line 51 and the grid line 5.
The small illumination light group 4 is set such that the relative positional relationship with the irradiation position of the lowermost minute illumination light 541 in the small illumination light group on the fourth illumination light group 4 has a predetermined overlapping relationship.

That is, the distance O5 between the center O of the disk 41 and the minute illumination light 511 at the lowermost end of the grid line 51
11, the distance O521 between the center O of the disc 41 and the minute illumination light 521 at the lowermost end of the grid line 52;
1 and the distance O between the center O of the disk 41 and the minute illumination light 541 at the lowermost end of the grid line 54.
541, a distance O51 formed between the center O of the disk 41 and the minute illumination light 512 immediately above the lowermost end of the grid line 51;
The distances are increased by a constant value in the order of 2,. This constant value is calculated from the distance O521 to the distance O5.
1/4, ie, (O521-O
511) / 4. As a result, the surface of the disk 41 can be uniformly scanned with a predetermined overlap with no gap using the planar discrete minute illumination light. In addition,
When scanning a wider surface, it is necessary to scan the entire planar discrete minute illumination light in a direction perpendicular to the scanning direction 45. The vibration generated at this time can be scanned without leaking the inspection by overlapping the entire illumination by the vibration amount. For a rectangular inspection target, an XY stage is often used, but the same processing is performed in this case.

In the above embodiment, the case where the two laser beams f3, f5 or f8, f9 are applied to the condenser lens 4 has been described. However, the number of laser beams is not limited to this. Needless to say, three or more laser beams may be applied to the condenser lens 4 according to a predetermined rule.

In the above embodiment, the case where the inspection is performed using the scattered light of the linear minute illumination light or the planar discrete minute illumination light has been described. Is used for the interferometer, the laser light f3
And the wave front of the laser beam f6 intersect at a predetermined angle, the phase within the illumination point on the sample surface 5 to be inspected is not flat. For this reason, there is a problem that the above-described illumination light cannot be used as the illumination light of the interferometer. Therefore, as shown in FIG. 11, a laser beam f7 symmetrical to the laser beam f6 is applied to the sample surface 5 to be inspected using the half mirror 21 and the mirror 31 with the laser beam f3 as the center line of symmetry. As a result, the laser light f6 and the laser light f7 in the illumination point on the sample surface 5 to be inspected cancel each other out, and the phase in the illumination point is flattened. The small illumination light can be used for both the intensity interferometer and the phase interferometer. In the case of the lighting device of FIG.
The optical path length may be controlled as in the embodiment.

Next, an encoder using the above-described illumination method will be described. 12A and 12B are diagrams illustrating an example of an encoder using linear minute illumination light. FIG. 12A is a diagram illustrating an outline of a lighting device, and FIG. 12B is a diagram illustrating an outline of an encoder unit. In FIG. 12A, a cylindrical lens 1 includes a laser beam f having a circular cross section emitted from a beam output unit (not shown), for example, a laser device.
1 is transformed into an elliptical laser beam f2 such that the vertical direction in the drawing is the minor axis direction and the depth direction is the major axis direction. The deformed prism 61 has a beam splitter 61a inside, and has a reflection mirror 61b at an upper outer edge. The beam splitter 61a allows the laser beam f10, which is about half the light amount of the elliptical laser beam f2 deformed by the cylindrical lens 1, to pass through as it is, and the other half of the laser beam f2
8 is reflected toward the upward reflecting mirror 61b. The reflection mirror 61b further reflects the laser beam f8 reflected by the beam splitter 61a to generate a laser beam f9 directed to the optical sensor 62. The cross-sectional shape of the laser beams f10 and f9 is an elongated elliptical shape whose major axis is in the depth direction of the drawing. The major axes of the elongated elliptical shapes of the laser beams f10 and f9 travel while corresponding to opposing sides of the rectangle. The optical sensor 62 is irradiated with two laser beams f10 and f9, and a group of minute illumination light as shown in FIG.
The minute illumination light group includes a slender elliptical laser beam f10,
f9 is formed by superimposing on the surface of the optical sensor 62 and performing the inverse Fourier transform there. In the case of this illumination device, since it does not pass through the condenser lens 4, the shape of the minute illumination light group on the optical sensor 62 is an elliptical shape elongated in the vertical direction as shown in FIG. In addition, this minute illumination light group is similar to the above-mentioned circular minute illumination light group, and includes a plurality of discrete small elliptical minute illumination light showing an illumination intensity distribution in which peaks appear at positions separated by a predetermined pitch. It is a set.

Such an elliptical minute illumination light is received by the optical sensor 62 and processed by the CPU 65 via the amplifier 63 and the analog-to-digital converter (ADC) 64 so that the optical sensor 62 and the illumination device Can be configured to detect the relative positional relationship between The optical sensor 62 is configured to relatively move in the direction perpendicular to the major axis direction of the elliptical minute illumination light. The optical sensor 62 outputs a signal as shown in FIG. 13 by receiving the elliptical minute illumination light. FIG.
In the graph, the curve shown by the dotted line shows the intensity distribution of the elliptical minute illumination light. The optical sensor 6 according to this intensity distribution
2 outputs a signal that changes stepwise as shown by a curve 131. That is, the signal represented by the curve 131 corresponds to a value obtained by integrating the intensity distribution of the elliptical minute illumination light indicated by the dotted line according to the sensor movement amount. Curve 131 is the optical sensor 6
When the end portion 2 is located between the peaks of the intensity distribution, it shows a substantially flat surface, and when it is located near the peak of the intensity distribution, it shows a gentle slope. The output signals S1 to SA of the optical sensor 62 correspond to the flat portion, and the output signals S1 to SA correspond to the sensor movement amounts P1 to PA, respectively. Therefore, when the output signal is S1, the sensor movement amount is P1, and when the output signal is S5, the sensor movement amount is P5, and the sensor movement amount can be detected based on the output of the optical sensor 62. . Note that the resolution of detecting the movement amount is the same as the pitch of the minute illumination light. In this encoder, since the detection range is limited by the length of the optical sensor 62, the detection range can be expanded by providing a plurality of optical sensors along the moving direction. At this time, adjacent optical sensors are vertically overlapped with each other and are sequentially provided along the moving direction, so that the detection near the boundary between the optical sensors can be performed smoothly. In the above-described embodiment, more accurate position information can be obtained by interpolating between the detected movement amounts P1 to PA. Further, by using a split type sensor as the optical sensor 62 and shifting the mutual phase relationship between the split type sensors, it is possible to improve the resolution of a portion where the inclination of the stairs is gentle. The analog-to-digital converter (ADC) 64 and the CP
Instead of U65, an inflection point of the output signal may be detected by using a differentiating circuit and counted by a counter, or these may be appropriately combined. If the optical sensor 62 is a multi-segment line sensor,
A polyphase general encoder output can also be obtained.

A description will be given of a height measuring apparatus using the above-described illumination method. FIG. 14 is a diagram showing an example of a height measuring device using planar discrete minute illumination light, and FIG.
It is a figure which shows the detail of a part of. This height measuring device
The height of a minute projection such as a liquid crystal spacer is measured by using confocal light by using the minute illumination light as described above.
In the above-described embodiment, as shown in FIG.
By irradiating the condenser lens 4 with f9, planar discrete minute illumination light is formed. However, in this method, when the distance of the surface of the sample to be inspected from the condensing lens 4 changes, the phase difference between the laser light f8 and the laser light f9 and the focus position change, and the planar discrete minute illumination light is totally changed. It will shift. This is the same when measuring the height of the surface of the sample to be inspected. Therefore, in the height measuring apparatus of this embodiment, the condenser lens 4 is irradiated with four minute beams f11 to f14 as shown in FIG. As a result, even when the height of the surface of the sample to be inspected fluctuates, the planar discrete minute illumination light can be prevented from shifting as a whole, and the magnitude of the planar discrete minute illumination light changes according to the height displacement. I will be. By receiving the magnitude of the planar discrete minute illumination light that changes in accordance with the displacement of the height with the optical sensor, the height can be measured.

In FIG. 14 and FIG. 15B, the half mirrors 2, 21, 22 and the mirrors 3, 31, 32, 3
The laser light fa is divided into four small circular beams f11 to f14 by 3, 34. The half mirror 2 is about one-fourth (about 25%) of the light amount of the laser light fa having a small circular shape.
Is reflected toward the mirror 3, and the remaining about three-quarters (about 75%) of the laser light fc is passed as it is. The half mirror 21 reflects the laser light fd of about one third (about 33.3%) of the light quantity of the laser light fc passing through the half mirror 2 toward the mirror 31, and reflects the remaining about 3
Two-half (approximately 66.6%) of the laser light fe is allowed to pass as it is. The half mirror 22 reflects the laser light ff of about half (about 50%) of the light amount of the laser light fe passing through the half mirror 21 toward the mirror 32, and the remaining about 2
One-half (about 50%) of the laser light fg is passed as it is. The mirror 33 reflects the laser light fg passing through the half mirror 22 toward the mirror 34 as it is as the laser light fh. The mirrors 3, 31, 32, and 34 become the parallel light beams f11 to f14 that travel in the same direction on the laser beams fb, fd, ff, and fh reflected by the half mirrors 2, 21, 22, and the mirror 33, respectively. To reflect. Therefore, the laser beams f11 to f14 are generated as shown in FIG.
These are parallel light beams that travel in the same direction with a predetermined distance. The condenser lens 4 is provided with laser beams f11 to f11.
14 is focused on the surface 5 of the sample to be inspected. The condenser lens 4 causes the laser lights f11 to f14 to enter the vicinity of an end where a perpendicular passing through the midpoint of the line connecting the optical axes substantially intersects the center of the condenser lens. Are located. Therefore, the laser beams f11 to f14 that have passed near the end of the condenser lens 4 are the laser beams f1 that travel in the oblique direction.
The light is focused on the sample surface 5 to be inspected as 2 to f15. Since the sample surface 5 to be inspected is disposed substantially near the focal position of the condenser lens 4, the four laser beams f12 to f15 are applied to substantially the same position.

Between the half mirrors 2, 21, 22 and the mirrors 3, 31, 32, 33, 34 and the condenser lens 4, at least a linearly polarized light component of the light reflected from the sample surface 5 to be inspected is separated. For example, a polarizing beam splitter 10 and a quarter-wave plate 11 are arranged as a separating unit. The polarization beam splitter 10 and the quarter-wave plate 11 enlarge an image formed by the reflected lights r1 to r4 from the sample surface 5 to be inspected via the lens 12 and form an image on the optical sensor 15. . The polarization beam splitter 10 passes the laser beams f11 to f14 as they are,
Reflected lights r1 to r4 of predetermined linearly polarized light components which are reflected lights from the sample surface 5 to be inspected and which have passed through the quarter-wave plate 11
Only the light is reflected to the optical sensor 15 side. Optical sensor 15
Is a two-dimensional CCD light receiving element having a pixel size capable of receiving an image of planar discrete minute illumination light.
Each pixel of the optical sensor 15 is associated with each point illumination of the planar discrete minute illumination light. Therefore, when the surface height of the sample surface 5 to be inspected fluctuates, the radius of the spot-like illumination of the planar discrete minute illumination light increases, and the output of each pixel of the optical sensor 15 changes. The minute height measurement circuit 16 moves the objective lens 4 up and down with respect to all the point-like illuminations of the planar discrete minute illumination light in the measurement area, and moves each of the optical sensors 14 corresponding to each point-like illumination. Based on the output of the pixel,
The lens position at which the output becomes maximum is recorded. The recorded lens position corresponds to the height of the spacer or the like on the surface 5 of the sample to be inspected. Note that the height may be specified based on the output of each pixel of the optical sensor 15 without moving the objective lens 4. In this case, there is a disadvantage that the ± direction of the height is not known. However, if the surface of the sample to be inspected has no concave portion, there is no problem since the detected height is only the + direction. Note that the quarter-wave plate 11 and the polarization beam splitter 1
Instead of 0, the separating means may be constituted by using a half mirror or the like.

In this height measuring apparatus, the sample surface 5 to be inspected is mounted on a stage, and the stage is moved by a minute distance corresponding to a horizontal pitch in the X direction to measure the height. In addition,
As shown in FIG. 10, the measurement area is installed at a predetermined angle with respect to the moving direction. After the above measurement is repeatedly performed up to the stage end in the X direction, the height is moved in the Y direction by the size of the measurement area, and the above-described height measurement is repeated. Thereby, a three-dimensional shape can be easily obtained over the entire surface of the sample surface 5 to be inspected, and an inspection based on a predetermined inspection standard can be performed. Also,
This height measuring device has an advantage that a minute hole (pinhole) which is indispensable in a conventional height measuring device is not required.

[0062]

According to the illumination device and the inspection device of the present invention, the resolution of the optical sensor in the radial direction can be made substantially the same as the resolution in the circumferential direction without increasing the inspection time. is there.

Further, according to the encoder of the present invention, there is an effect that accurate position measurement with high resolution can be performed without being affected by a change in light amount.

According to the height measuring device of the present invention, there is an effect that the three-dimensional shape of the surface of the sample to be inspected can be easily measured with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a lighting device of the present invention.

FIG. 2 is a diagram illustrating a schematic shape of two laser beams incident on a condenser lens.

FIG. 3 is a diagram schematically illustrating an illumination shape realized by two laser beams converged on a surface of a sample to be inspected.

FIG. 4 is a diagram showing an example of a disk disk inspection apparatus.

FIG. 5 is a diagram showing the concept of the simplest moving method when moving the lighting device.

FIG. 6 is a diagram showing a concept of an optimal moving method when moving the lighting device.

FIG. 7 is a diagram illustrating an embodiment of an illumination method capable of correcting a fluctuation equal to or higher than the autofocus following speed.

FIG. 8 is a diagram showing a positional relationship between two laser beams incident on a condenser lens when performing a planar discrete illumination method in which minute illumination light is scattered in a planar shape.

FIG. 9 is a diagram schematically showing an illumination shape of a planar discrete illumination system realized by the laser light of FIG.

FIG. 10 is a view schematically showing an irradiation state of planar discrete illumination light on the surface of a disk.

FIG. 11 is a diagram showing a modified example of the illumination device when the linear minute illumination light or the planar discrete minute illumination light is used for the intensity interferometer and the phase interferometer.

FIG. 12 is a diagram illustrating an example of an encoder using linear minute illumination light.

13 is a diagram for explaining the operation of the encoder in FIG.

FIG. 14 is a diagram illustrating an example of a height measuring device using planar discrete minute illumination light.

FIG. 15 is a diagram showing details of a part of the height measuring device of FIG. 14;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Cylindrical lens, 2, 21, 22 ... Half mirror 3, 31-33 ... Mirror, 4 ... Condensing lens, 5 ... Sample surface to be inspected 6, 7 ... Optical element, 8 ... Driving means, 9 ... Arrow direction 10 ... polarizing beam splitter, 11 ... quarter wave plate,
DESCRIPTION OF SYMBOLS 12 ... Lens 13,15,62 ... Optical sensor, 14 ... Optical path length control means 16 ... Micro height measuring circuit, 41 ... Disc disk, 61 ...
Deformation prism 63: amplifier, 64: analog-digital converter, 65
... CPU

Continued on the front page F-term (reference) 2F065 AA06 AA09 AA24 BB03 BB16 CC03 DD03 DD06 FF10 FF15 FF42 GG04 HH01 HH06 JJ02 JJ03 JJ25 JJ26 LL00 LL04 LL08 LL12 LL36 LL37 LL46 MM04 A13 Q13 A13 Q13 A13 Q13 A13 A BA11 BB09 BB11 BB20 BC06 CA03 CB01 CB05 DA08 EA11

Claims (28)

[Claims] At least two elongated elliptical light beams of the same size, wherein the light beams are arranged such that the major axes of the elliptical shapes of the light beams travel in a parallel relationship. Beam output means for outputting, by irradiating the light beam at different angles to the surface of the sample to be inspected so that the major axis of the light beam output from the beam output unit respectively coincides, to the surface of the sample to be inspected An illuminating device comprising: irradiating means for irradiating a plurality of minute illumination lights discretely arranged at a predetermined pitch in a linear manner. 2. The beam output means according to claim 1, wherein said beam output means transforms the circular light beam into an elongated elliptical shape, and transmits the elliptical light beam transformed by said beam deforming means into a transmitted light beam. Beam splitting means for splitting the reflected light beam and a reflected light beam, and a beam reflecting means for reflecting the reflected light beam so as to become a parallel light beam traveling in the same direction with a predetermined distance from the transmitted light beam. The irradiating means receives the transmitted light beam near the center, and receives the reflected light beam reflected by the beam reflecting means near an end remote from the center, and transmits the transmitted light beam and the reflected light beam. An illuminating device comprising a converging lens means for converging a beam on the surface of the sample to be inspected. 3. The device according to claim 2, wherein the beam output unit outputs three light beams, and the irradiation unit enters one of the light beams near a center of the condenser lens unit, and outputs the other light beam. An illumination device characterized in that the two light beams are incident near the ends located equidistant from the center of the condensing lens means, and these three light beams are irradiated on the surface of the sample to be inspected. apparatus. 4. The apparatus according to claim 3, wherein the beam output means comprises: a beam deforming means for transforming the circular light beam into an elongated elliptical shape; First beam splitting means for splitting into a transmitted light beam and a first reflected light beam, and the first beam splitting means so as to become a parallel light beam traveling in the same direction at the same distance as the first transmitted light beam. A first beam reflecting means for reflecting the first reflected light beam and entering near one end of the condenser lens means; a second transmitted light beam and a second reflected light for the first transmitted light beam Second beam splitting means for splitting the second transmitted light beam into the vicinity of the center of the condensing lens means, and traveling in the same direction at the same distance as the second transmitted light beam Become a parallel light beam Lighting apparatus characterized by being configured to include a second beam reflecting means for reflecting the urchin the second reflected light beam is incident on the vicinity of the other end of said condensing lens means. 5. The lighting device according to claim 1, further comprising an optical element means for changing an optical path length of at least one of the light beams. 6. The optical element means according to claim 5, wherein the optical element means comprises two identical wedge-shaped optical elements, and moving at least one of the optical elements changes the optical path length of at least one of the light beams. A lighting device, characterized in that the lighting device is configured to cause the lighting device to emit light. 7. The fluctuation detecting unit according to claim 5, wherein the fluctuation detecting unit detects a fluctuation in a position of the minute illumination light applied to the surface of the sample to be inspected, and the fluctuation detected by the fluctuation detecting unit. An illuminating device comprising: an optical path length control unit that controls at least one of the optical elements according to an amount to control the optical path length. 8. The quarter-wave plate unit according to claim 7, wherein the fluctuation amount detecting unit includes: a quarter-wave plate unit that passes only a linearly polarized light component of the light beam reflected from the surface of the sample to be inspected; Polarizing beam splitter means for reflecting the light beam that has passed through the plate means; and a pitch of the minute reflected light substantially corresponding to at least one portion of the minute reflected light formed by the light beam reflected by the polarizing beam splitter means. A light receiving device having pixels divided at the same pitch. 9. At least two elongated elliptical light beams of the same size, wherein the light beams are arranged such that the major axes of the respective elliptical light beams travel while maintaining a parallel relationship. Beam output means for outputting, by irradiating the light beam at different angles to the surface of the sample to be inspected so that the major axis of the light beam output from the beam output unit respectively coincides, to the surface of the sample to be inspected Irradiating means for irradiating a plurality of micro-illumination lights discretely arranged at a predetermined pitch in a linear manner; and an illuminating device comprising the beam output means and the irradiating means, and the inspection object surface relatively An inspection apparatus comprising: a position control unit that controls an irradiation position of the minute illumination light on the surface of the sample to be inspected by being moved. 10. The position control unit according to claim 9, wherein the position BP is obtained by dividing a pitch BP of the minute illumination light by a division number n.
/ N is multiplied by the number m of the minute illumination light, and a moving distance SS is a value m × BP / n. Inspection equipment to be characterized. 11. The position control means according to claim 10, wherein a value n × z−1 obtained by subtracting 1 from a value n × z obtained by multiplying the number of divisions n by an integer z is equal to the number m of the minute illumination light. An inspection apparatus characterized by being set to be equal. 12. The beam output means according to claim 9, wherein said beam output means transforms the circular light beam into an elongated elliptical shape, and transmits the elliptical light beam transformed by said beam deforming means to a transmitted light beam. Beam splitting means for splitting the reflected light beam and a reflected light beam, and a beam reflecting means for reflecting the reflected light beam so as to become a parallel light beam traveling in the same direction with a predetermined distance from the transmitted light beam. The irradiating means receives the transmitted light beam near the center, and receives the reflected light beam reflected by the beam reflecting means near an end remote from the center, and transmits the transmitted light beam and the reflected light beam. An inspection apparatus comprising: a condenser lens means for condensing a beam on the surface of the sample to be inspected. 13. The method according to claim 9, wherein the beam output means outputs three light beams, and the irradiation means makes one of the light beams incident near the center of the condensing lens means, and outputs the other light beam. An illumination device characterized in that the two light beams are incident near the ends located equidistant from the center of the condensing lens means, and these three light beams are irradiated on the surface of the sample to be inspected. apparatus. 14. The beam output means according to claim 13, wherein the beam output means comprises: a beam deforming means for transforming the circular light beam into an elongated elliptical shape; First beam splitting means for splitting into a transmitted light beam and a first reflected light beam, and the first beam splitting means so as to become a parallel light beam traveling in the same direction at the same distance as the first transmitted light beam. A first beam reflecting means for reflecting the first reflected light beam and entering near one end of the condenser lens means; a second transmitted light beam and a second reflected light for the first transmitted light beam Second beam splitting means for splitting the second transmitted light beam into the vicinity of the center of the condensing lens means, and traveling in the same direction at the same distance as the second transmitted light beam. With a parallel light beam Inspection apparatus characterized by being configured to include a second beam reflecting means for reflecting said second reflected light beam so that is incident in the vicinity of the other end of said condensing lens means. 15. The inspection apparatus according to claim 9, further comprising an optical element unit that changes an optical path length of at least one of the light beams. 16. The optical element means according to claim 15, wherein the optical element means comprises two identical wedge-shaped optical elements, and moving at least one of the optical elements changes the optical path length of at least one of the light beams. An inspection apparatus characterized by being configured to cause the inspection. 17. The fluctuation amount detection unit according to claim 15, wherein the fluctuation amount detection unit detects a fluctuation amount of a position of the minute illumination light applied to the surface of the sample to be inspected, and the fluctuation detected by the fluctuation amount detection unit. An inspection apparatus comprising: an optical path length control unit that controls at least one of the optical element units according to an amount to control the optical path length. 18. The quarter-wave plate unit according to claim 17, wherein the fluctuation amount detecting unit includes: a quarter-wave plate unit that passes only a linearly polarized light component of the light beam reflected from the surface of the sample to be inspected; Polarizing beam splitter means for reflecting the light beam that has passed through the plate means; and a pitch of the minute reflected light substantially corresponding to at least one portion of the minute reflected light formed by the light beam reflected by the polarizing beam splitter means. A light-receiving element having pixels divided at substantially the same pitch. 19. A beam output means for outputting at least two circular light beams having substantially the same size and traveling in the same direction at a predetermined distance, and an optical axis of the light beam output from the beam output means. By injecting the light beam near the end where a perpendicular passing through the midpoint of the line connecting the two substantially intersects the center and condensing both light beams on the surface of the sample to be inspected, An irradiating means for irradiating a plurality of minute illumination lights discretely arranged at a predetermined pitch in a plane. 20. The beam output unit according to claim 19, wherein the beam output unit outputs four light beams, and the irradiation unit connects two of the light beams with a perpendicular line passing through a midpoint of a line connecting respective optical axes. Are incident near the end where the light beam substantially intersects with the center, and the other two light beams are incident near the end where the center is the point symmetric center.
An illumination device, wherein two light beams are focused on a surface of a sample to be inspected. 21. Beam output means for outputting at least two circular light beams having substantially the same size and traveling in the same direction at a predetermined distance; and the two light beams output from the beam output means. The two light beams are incident near the end where a perpendicular passing through the midpoint of the line connecting the two substantially intersects the center, and both light beams are focused on the surface of the sample to be inspected. Irradiating means for irradiating a plurality of micro-illumination lights discretely arranged at a predetermined pitch in a plane on a surface; and an illuminating device including the beam output means and the irradiating means, and the sample surface to be inspected relative to each other. And a position control means for controlling an irradiation position of the minute illumination light on the surface of the sample to be inspected by moving the inspection device. 22. The light emitting device according to claim 21, wherein said beam output means outputs four light beams, and said irradiating means outputs a perpendicular line passing through a midpoint of a line connecting respective optical axes of said two light beams. Are incident near the end where the light beam substantially intersects the center, and the other two light beams are incident near the end where the center is the point symmetric center.
An inspection apparatus characterized in that two light beams are converged on a surface of a sample to be inspected. 23. The apparatus according to claim 21, wherein a relative moving direction between the illumination device and the surface of the sample to be inspected intersects each grid line of the minute illumination light at a predetermined angle. Inspection equipment. 24. At least two elongated, elliptical light beams of the same size, wherein the major axes of the respective elliptical light beams travel while maintaining a parallel relationship. Beam output means for outputting, and a plurality of minute illumination lights discretely arranged at a predetermined pitch at the irradiation position by irradiating the light beam outputted from the beam output means so that the major axes thereof coincide with each other. Irradiating means for forming the light beam; optical sensor means for moving relatively along the major axis direction of the light beam with respect to the irradiating means, receiving the minute illumination light, and outputting a detection signal thereof; And a position detecting means for detecting a relative positional relationship between said irradiating means and said optical sensor means based on said detection signal output from said means. Order. 25. A beam output means for outputting four circular light beams having substantially the same size and traveling in the same direction at a predetermined distance, and two of the light beams output from the beam output means. A perpendicular line passing through the midpoint of the line connecting the respective optical axes is incident near the end where the center substantially intersects the center, and the other two of the light beams are near the end where the center is the point symmetric center. Irradiating means for irradiating a plurality of minute illumination lights discretely arranged at a predetermined pitch on the surface of the sample to be inspected by converging these four light beams on the surface of the sample to be inspected. A light receiving unit that receives a part of the light beam reflected from the surface of the sample to be inspected; and a control unit that obtains height information on the surface of the sample to be inspected based on a detection signal output from the light receiving unit. Height characterized by comprising measuring device. 26. The quarter wave plate unit according to claim 25, wherein the light receiving unit passes only a linearly polarized component of the light beam reflected from the sample surface to be inspected, and the quarter wave plate unit. A polarizing beam splitter means for reflecting a light beam passing through the light-receiving element, and a light receiving element means for receiving minute reflected light formed by the light beam reflected by the polarizing beam splitter means. Measuring device. 27. The inspection sample surface according to claim 25, wherein an optical system including the beam output unit, the irradiation unit, and the light receiving unit and the inspection sample surface are relatively moved. A height control device comprising a position control means for controlling an irradiation position of the minute illumination light in the above. 28. The control device according to claim 25, 26 or 27, wherein the control means relatively moves the irradiation means and the sample surface to be inspected, based on a detection signal output from the light receiving element means at the time of movement. A height measuring device configured to obtain height information on the surface of the sample to be inspected.