JPH01137547A - Focused energy beam processing device and processing method - Google Patents

Abstract

PURPOSE:To perform the processing with high position precision and depth precision by providing an optical component provided at the center with a hole physically allowing a focused energy beam to pass through it on the optical axis of the focused energy beam. CONSTITUTION:A radiating system of the focused light and a detecting system of the reflected light and the interference light are provided so that at least part of the optical axis coincides with the optical axis of the focused energy beam. A reflecting mirror 22 provided with a hole at the center is installed on the optical axis of the ion beam below a deflector electrode 8, the ion beam passes through the center hole and is radiated to a sample 10. On the other hand, the light from an observation lighting lamp 33 passes through half mirrors 24 and 19 and a window 20 and enters a vacuum chamber 14 and is collected by an objective lens 21 and is radiated on a sample 10 by a reflecting mirror 22. The reflected light from the sample reversely passes through the same path and is image-formed by a camera 25, the optical microscope image thus obtained is sent to a main controller 30 and displayed on a monitor 32. The processing with high position precision and depth precision can be thereby performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a focused energy beam processing apparatus and method thereof, and is particularly suitable for processing semiconductor devices such as VLSI as a workpiece. The present invention relates to a focused energy beam processing apparatus and method.

[Conventional technology]

As a conventional focused energy beam device, a focused ion beam processing device, IMA (Ion Micro
.

Analyzer) +Electron beam lithography equipment, etc., and the means to observe the workpiece in these was the secondary particle image σ value obtained by detecting secondary particles emitted from the surface of the workpiece. . Here, the secondary particles include secondary electrons, secondary ions, etc. 0 As an example of a conventional device, the configuration of a focused ion beam processing device is shown in Figure N2 f. An ion beam 2 extracted from an ion source 1 is focused by a focusing lens 4 and irradiated onto a sample 10 for processing. Also, ion beam irradiation (!: PI
Once in a while, CVD gas is supplied to the nozzle 35 to perform local film formation. At this time, the blanking controller 12ζ turns on and off the ion beam, and the deflector controller 13 controls the deflection of the ion beam. Secondary electrons or secondary ions mainly generated from the sample 10 during ion beam irradiation are detected by a secondary particle detector 9 (e.g. multi-channel grate), and the SIM (
Scanning Ion Microscopy:
(scanning ion microscope) to obtain an image. The sample surface is observed using this SIM image. Incidentally, related to this type of focused ion beam processing apparatus is, for example, Japanese Patent Application Laid-Open No. 61-2
No. 45553 is mentioned.

Further, as an example of an electron beam apparatus in which both a secondary electron image and an optical microscope image can be observed by switching, there is Japanese Utility Model Publication No. 59-10687.

[Problem that the invention seeks to solve]

In the conventional focused energy beam apparatus described above, only secondary particle images are used for sample observation. Here, the secondary particle image is an image that detects secondary particles generated from the sample surface in synchronization with the deflection scanning of a focused beam, and expresses the difference in the generation rate of secondary particles depending on the location as a change in brightness. It is. What can be obtained from a secondary particle image is information about the sample surface ω unevenness and the material, but it is not possible to know, for example, the internal structure of the sample.On the other hand, semiconductor devices such as LSIs are currently becoming highly integrated.

In order to increase functionality, wiring and elements are becoming more multi-layered. When processing a multilayered semiconductor device as a workpiece, the following new requirements have arisen.

(1) Positioning is performed with respect to desired wiring, etc. in the lower layer, and processing is performed while monitoring positional deviation.

(2) Control the machining in the depth direction and complete the machining without damaging the lower layer of the workpiece.

Conventional focused energy beam devices that use secondary particle images as an observation method cannot meet these requirements.In other words, the lower layer cannot be observed using the secondary particle image, making it difficult to position the lower layer for processing. In addition, it is possible to detect secondary ions as secondary particles and obtain information on the direction of the grain, but in the case of high aspect ratio processing for multi-I semiconductor devices, Detection of the next ion itself is difficult, and precise depth control is impossible.

On the other hand, if optical observation means is used, the underlying structure can be observed through the transparent insulating layer of a multilayered semiconductor device. In addition, using optical interference, processing depth,
Vertical information such as the thickness of the insulating layer can be obtained.

Here, as an apparatus capable of viewing both a secondary electron image and an optical microscope image, there is an apparatus described in Japanese Utility Model Publication No. 10687/1987. However, this device uses a system that switches between secondary electron image observation and optical image observation by moving a prism for optical image observation in and out under the optical axis of the electron beam, so observation using both is performed simultaneously. I can't. Therefore, when a focused energy beam device is applied, with this method, it is impossible to simultaneously perform processing by beam irradiation while optically monitoring the positional deviation and processing depth with respect to the underlying layer.

An object of the present invention is to provide a focused energetic beam that can perform processing with high positional accuracy and depth accuracy while monitoring positional deviation and processing depth with respect to the lower layer when processing multilayered semiconductor devices. We provide processing equipment.

[Means to eliminate the problem]

The above purpose is to simultaneously irradiate focused light extremely close to the focused energy beam (within the diameter of the focused energy beam or several times the diameter of the focused energy beam), process the workpiece with the focused energy beam, and at the same time optically This is achieved by observing and measuring ζ.

[Effect]

An irradiation system for focused light and a detection system for reflected light, interference light, etc. are provided so that at least a part of their optical axes coincide with the optical axis of the focused energy beam. Specifically, an optical component (an anti-9A mirror, an objective lens, etc.) having a hole in the center through which the focused energy beam physically passes is provided on the optical axis of the focused energy beam. Thereby, while processing is performed using a focused beam that has passed through the hole in the optical component, it is possible to simultaneously use these optical components to condense and irradiate light, and to detect reflected light and the like. Therefore, processing using a focused energy beam and optical observation and measurement using focused light can be performed simultaneously.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a focused ion beam processing apparatus will be described below with reference to the drawings.

<Embodiment 1> FIG. 1 shows an apparatus configuration of a first embodiment of the present invention. The ion beam 2 extracted from the ion source 1 is focused by a focusing lens 4.
The beam is focused and irradiated onto the sample 10 for processing. Further, at the same time as the ion beam irradiation, CVD gas is supplied from the nozzle 35 to perform local film formation. At this time, the blanking controller 12 controls on/off of the ion beam, and the deflector controller 16 controls the deflection of the ion beam. Further, the flow rate of the CVD gas from the CvD gas cylinder 53 is controlled using the flow rate adjusting pulp 34. Secondary electrons or secondary ions generated from the sample 10 upon irradiation with the ion beam are detected by the secondary particle detector 9 to obtain SIM@. SIM image is main controller 6
0 (transfer, display on monitor 511).

Here, in the present invention, since the sample is irradiated with focused light at the same time as the ion beam, reflected light, scattered light, etc. are generated. Therefore, as the secondary particle detector 9, one that uses light for detection (such as a combination of a scintillator and a photomultiplier) is inappropriate, and one that directly multiplies secondary particles as electrons (a multi-channel plate, a channel tron, etc.) is inappropriate. etc.).

A reflecting mirror 22 having a hole in the center is installed on the optical axis of the ion beam below the deflector electrode 8 . The ion beam passes through this central hole and irradiates the sample 10. On the other hand, the light from the lamp 25 for observation illumination is transmitted to the half mirrors 24 and 1.
9 and into the vacuum chamber 14 through the window 20;
The light is focused by the objective lens 21 and irradiated onto the sample 10 by the reflecting mirror 22. The CIJ reflected light from the sample passes through the same path in the reverse direction and forms an image on the camera 25, and the obtained optical microscope image is sent to the main controller 30 and sent to the monitor 32 (
Display this.

Here, regarding the objective condensing system for illumination light, etc., see Figures 5 to 5.
This will be explained using figures. The objective condensing system shown in WJ561 is similar to that shown in FIG. irradiate. In this case, since the distance between the objective lens 21 and the sample 1o becomes long, it is necessary to use a long focus objective lens 21, and the magnification of the optical microscope image cannot be very high. The objective condensing system shown in FIG. 4 uses an objective concave mirror 49 in place of the reflecting mirror 221, and when the illumination light from the side is bent by the objective concave mirror 49, the optical path is simultaneously condensed onto the sample 10. irradiated. In this case as well, since the objective concave mirror 49 has a long focal point, the magnification of the optical microscope image cannot be very high. The objective condensing system shown in FIG. 5 uses an objective lens 21 with a hole in the center, and after the illumination light has its optical path bent by reflection @I22,
The light is focused through the objective lens 211 and irradiated onto the sample 10. In this case, the objective lens 21 has a complicated structure, but a short focus lens can be used, and an optical microscope image can be obtained at high magnification.

In the present invention, by simultaneously irradiating the sample with an ion beam and focused light, it is possible to simultaneously detect the SIM image of a desired location on the sample and the optical microscope 1j+2.

Therefore, a method for processing a multilayer sample using simultaneous observation of a SIM image and an optical microscope will be described with reference to FIG. Here, an example is shown in which a window opening is processed to expose the lowest layer wiring 50 in an LSI having a three-layer wiring structure. When the interlayer insulating film is flattened to form a multilayer wiring, the unevenness information indicating the position (t) of the wiring below it no longer appears on the LSI surface. Therefore, in the SIM image in FIG. The position of the wiring 50 cannot be detected and positioning at the start of processing is impossible.On the other hand, in the optical microscope image detected at the same time, since light passes through the interlayer insulating film, the position of the wiring 50 cannot be detected.
The digit t can be detected. Therefore, processing positioning to the lowest opening wMSO becomes possible by the following procedure.

First, the magnifications of the SIM image and the optical microscope image are made to match in advance. This is easily possible by adjusting the pressure in the ion beam (I direction) with a deflector controller and finely adjusting the magnification of the SIM image.Next, the area including the part to be processed is observed using the SIM image and the optical microscope image. Then, the positional coordinates of both images are made to correspond using a reference that does not cause any positional deviation (for example, the center position of the through hole 53 in Fig. 6). The position of the processed hole 52 is set with respect to the lowermost layer wiring 50, and the set position is made to correspond to the position on the BS IM image, and the processed hole position on the 5IRa image is irradiated with an ion beam to start processing.

Machining is started as described above, but according to the present invention, simultaneously with the machining, the machining position #L can be constantly observed using an optical microscope image and the machining state can be monitored. Here, in the conventional ion beam machining apparatus, the observation means is only a SIM image, and only a SIM image of the inside of the machined hole can be obtained during processing, so that positional deviation etc. due to charge-up of the machined hole itself cannot be detected. Although it is conceivable to intermittently detect a SIM image of a wide area in order to observe the position of the machined hole, it is impossible to detect positional deviation in real time with this method. On the other hand, according to the present invention, during processing t
Since this optical microscope image can be observed in real time, it is possible to perform machining with high positional accuracy while monitoring the positional deviation of the machined hole.

Furthermore, in the conventional apparatus, there was no effective means for monitoring the completion of processing for opening the window to the intended A wiring.

For example, even if the machined part is observed using a SIM image, as the process progresses, secondary particles become difficult to come out from the bottom of the machined hole.
As shown in the figure, the processed hole 52 only appears dark, and it is not possible to determine whether or not the lowest layer wiring 50 is exposed. On the other hand, if the processed part is observed using an optical microscope image, A! Wiring exposure can be determined. That is, while the interlayer 5i02 film etc. remains on the An wiring, the intensity of reflected light is weak due to multiple interference and refraction due to the thin film, and A! When the wiring is exposed, the reflected light intensity becomes stronger due to the high reflectance of Al, and this change in reflected light intensity is detected as a change in the brightness of the machined hole.
7 Wiring exposure can be determined. Therefore, according to the present invention, observation using an optical microscope image can be performed in real time during processing, so that A! It is possible to monitor the exposure of the wiring and start processing from scratch, making it possible to process the window openings with accuracy without excess or deficiency.

Next, a laser interferometer, which is another optical monitoring means for processing in this embodiment, will be explained. In FIG. 1, a laser beam oscillated from a laser oscillator 15 passes through a shutter 16, has its beam diameter expanded by an optical path expander 17, and then passes through a variable transmittance filter 18. Here, the shutter 16 turns on and off the laser beam, and the variable transmittance filter 18 adjusts the intensity of the laser beam. The beam splitter 28 splits the laser beam into two optical paths, and one of the beams passes through the window 20 and enters the vacuum chamber 14 . The incident laser beam is focused by the objective lens 21, the optical path is bent by the reflecting mirror 22, and the sample 10 is irradiated with the laser beam.

At this time, the beam diameter is expanded by the optical path expander 17 in order to reduce the percentage of laser light intensity lost due to the hole in the center of the reflection@22. The reflected light from the sample 10 passes through the same path in the opposite direction, has its optical path bent by the beam sinter 28, and enters the photomultiplex 29. The other laser beam, whose optical path was first split by the beam splitter 28, is reflected by the reflection plate 26, passes through the beam splitter 28, and enters the photomultiplier 29. As described above, the two lights reflected by the sample 10 and the reflecting mirror 26 interfere, and the intensity of the interference light is measured by the 7-meter 29. At this time, according to instructions from the main controller 60, the piezo element 27 is used to slightly move the reflecting mirror 26,
Performs fine adjustment of the optical path difference between two lights. A method for measuring the machining depth using the Michael interferometer configured as described above will be explained with reference to FIGS. 7 to 10.

First, FIG. 7 shows a schematic diagram of an interferometer using a laser with a single wavelength λ. The laser beam irradiated onto the sample 10 is shown in Fig. 7ζ
As shown here, it is always reflected back from the machining center.

As the reflective surface of the processed material recedes during processing, the optical path difference between the two lights changes, and the intensity of the interference light changes. Therefore, by measuring the change in the interference light intensity using the photomultiplier 29 and multiplying the optical path difference between the two lights by 72, the depth of the machining process can be determined. Here, if a material with equal transmittance and reflectance is selected for the beam sinter 28, the photomultiplier 28
The amplitudes of the two lights incident on 9 are proportional to the reflectances of sample 10 and reflector 26, respectively. For example, if the reflectance of the sample 107 reflecting mirror 26 is set to r and 1, respectively, the amplitude of the two lights will be rao at the time of incidence on the photomultiplier 29.
It can be expressed as l ao. Therefore, if the phase difference between the two lights is δ, the amplitude a1 of the interference light is aloao +r age'
...(ri).Here, at the start of machining, the position of the reflecting mirror 26 is finely adjusted so that the interference light intensity becomes maximum (i.e., δ = 0).Then, the phase difference δ becomes as follows depending on the machining depth d. It can be expressed by a formula.

d δ=1 lower・2π...(2
) (1 From equation (2), the interference light intensity Il is determined as follows.

Il = l at 12 d = ao2 (1 + r2 + 2r (2) = "π) ・
...(3) For example, in LSI processing, AJ wiring and St
When processing a substrate, the reflectance r can be considered to be approximately constant.

At this time, r in equation (3) becomes a constant, and the interference light intensity 11 changes as shown in the graph shown in FIG. 8 as the processing depth d changes. Therefore, by tracking the change in the interference light intensity Is from the start of machining, the machining depth d can be monitored from the relationship shown in FIG.

On the other hand, the reflecting mirror 26 is moved so that the interference intensity factor 1 remains at its maximum value and does not change, that is, so as to cancel out the retreat of the reflecting surface due to processing on the sample 10 side. Then, reflection @26
The machining depth d8 can be directly read from the amount of movement.

At this time, the piezo element used for fine movement of the reflector 26 has a resolution of about 1/1000 of the amount of movement for the entire stroke, and for example, when processing up to a processing depth of 20 μm,
The depth reading accuracy was 0.02 μm, which is sufficient accuracy.

On the other hand, in LSI processing, when processing a 5i02 film as an insulator, the light irradiated onto the sample 104 causes multiple interference from the S t Oz film. At this time, the reflection "4r" is 5tO2
It changes depending on the film thickness, that is, the processing depth, and can no longer be treated as a constant. Therefore, when the above-mentioned depth monitor using interference is applied, the interference light intensity change 1 (/J) becomes complicated,
Monitor accuracy may decrease. In this case, it would be better to measure only the intensity of the reflected light from the sample 10 and monitor the machining depth using changes in the intensity of the reflected light as the machining depth changes, that is, the 5tO2 film thickness, to improve monitoring accuracy. . This monitoring method will be explained in a second embodiment. Note that in the interferometer of this embodiment as well, by blocking the reflected light from the reflecting mirror 26 using a light absorber or the like,
It is possible to easily switch to measuring only the intensity of reflected light from the sample 10. Therefore, in multi#LSI, SiO
When processing the second layer and the AA layer sequentially, the SiO2 layer and the A
By switching and applying depth monitoring based on reflected light intensity measurement and interference light intensity measurement in one layer, it is possible to perform accurate depth monitoring as a whole.

FIG. 9 shows a schematic diagram of an interferometer using lasers of multiple wavelengths. The structure of the interferometer section is the same as that shown in FIG. The oscillation part of the illumination light is a laser oscillator A54°B55,
Each wavelength λ1 oscillated from C56. λ2. Shutter 57. Shutter 58. The shutter 59 is configured to switch between ON and OFF to irradiate each laser beam. Irradiate laser light and measure interference light intensity I
2, but when the reflectance r of the sample 10 is constant (A
Machining 2 with machining depth d4 (when machining l or St)
Figure 10 shows the changes in . Here, laser oscillators A, B,
The interference light intensity when using C is I2A +
I2B + I2C, and are shown in FIG. 10 by a solid line, a -dot-dashed line, and a one-dot line, respectively. Each interference light intensity change is similar to that shown in FIG. 8, and changes at a period of 1/2 of the wavelength. However, the wavelength λ1. Since λ2゜A3 is different, I2A
The value of + I2B + I2C increases as the depth d increases. For example, lasers A and B.

As C, Ar laser blue + Ar laser green, λ1 = 488 nm when using He-Ne laser
.

A2 = 515 nm + λs = 655 nm,
I2A + I2B + I2C match again when the calculated depth d is about 5 my1. Actual processing (
d (several 10 μm), I2A + I2B
+Izc will never match again. Therefore, I
By measuring the five interference light intensities of 2A + I2B + I2C, the depth d at that point can be determined from the relationship shown in FIG.

In depth monitoring using an interferometer as shown in Figure 7, which uses a laser with a single wavelength, the initial value is set so that the intensity of the interference light reaches its maximum at each start of each process, even when multiple processes are performed on the same sample. need to be adjusted.

On the other hand, in depth monitoring using an interferometer as shown in Figure 9, which uses lasers with multiple wavelengths, you need to be at the reference height and adjust only once so that the intensities of the three interference lights are at the maximum. Bye. Each ω at the start of machining is I2A + I2B
+ From the value of I2C, first find the relative height of the machining start surface with respect to the reference height, and then use the relationship shown in Figure 10,
It is sufficient to monitor machining to a desired depth. This depth monitor using a multi-wavelength laser is particularly effective when performing multi-stage processing as shown in FIG.

Next, a local film forming method using the apparatus of this embodiment will be explained. In FIG. 1, the laser beam oscillated from the laser oscillator 15 is irradiated onto the sample 10 through the above-mentioned path.The laser beam intensity is adjusted to a sufficient intensity by the variable transmittance filter 18, and CVD gas to nozzle 5
5, and local film formation is performed by laser CVDfC. In addition, at the same time as the ion beam irradiation (CVD gas is supplied and localized film formation is performed by ion beam CVD (CVD)). niO
N.

It can be OF'F. Therefore, from nozzle 35
The VD supplies the ion beam and laser beam O.
By controlling N and OFF, ion beam CVD
, laser CVD, and simultaneous film formation by both methods can be arbitrarily selected and performed.

FIG. 11 shows an example of local wiring formation using this apparatus.

In laser CVD, a sample is locally heated using a laser beam, and CVD gas molecules near the surface of the sample are decomposed by thermal energy, thereby forming a film. If the laser beam intensity is adjusted to a sufficient level, it has the advantage of being able to form low-resistance wiring with a good crystal structure at high speed, but it has the disadvantage that it is difficult to form thin wiring due to heat diffusion. In addition, in ion beam CVD, the physical energy of irradiated ions - 1
However, the molecules are decomposed and the film is formed. Ion beams have the advantage of being able to form fine patterns because they can be focused finely and have little energy dispersion to the periphery, but the resistivity is high because the crystal structure is difficult to arrange, and the amount of energy is low, making it difficult to form films at high speeds. There are drawbacks that make it difficult. Figure 11 shows both of these C
This is an example of wiring formation that combines the advantages of VD layout. Connect to the lower MAl wiring 65 through the contact hole 66,
While passing through the narrow gap between the Al pad 63 and the AJ pad 64, only the ion beam is irradiated to form a fine ion beam CVD wiring 67. After pulling out the wiring to a position where it will not affect the surrounding area, superimposed laser beam irradiation is performed to create a low-resistance laser CVD layout. Form M68 at high speed.

Next, laser CVD wiring formation on an LSI using the 0-wire device will be explained using FIG. 12. Most of the surface of the LSI is covered with a 5iOz insulating layer and an A7 wiring layer underneath. When a laser beam is irradiated onto an LSI, S
It is transmitted through the iO2 layer, reflected on the surface of the AA layer, and only a portion of the energy of the laser beam is absorbed. Therefore, the LS
When forming laser CVD wiring on the I surface, simply irradiating with laser light would require a very strong laser light intensity, causing problems such as damage to the element. On the other hand, according to the arrangement according to the present embodiment, the ion beam 69 and the laser beam 70 can be superimposed and irradiated simultaneously as shown in the twelfth factor. When CVD wiring is formed using this superimposed beam, an ion beam CVD wiring 67 is first formed, and this wiring efficiently absorbs the laser beam 70 to form a laser CVD wiring 68. At this time, the laser beam 70
Since the strength of can be kept low, problems such as damage to the element can be prevented.

Note that by using this method, it is possible to form a local bottom film by laser CVD not only for LSI but also for materials with considerably high transmittance and reflectance.

<Example 2> FIG. 13 shows the gt configuration of the second embodiment of the present invention.

The lens barrel section of the focused ion beam optical system and the optical microscope image observation section are the same as in the first embodiment. In the non-embodiment, a laser scanning microscope was added as an optical measurement means. The laser beam excavated from the laser oscillator 15 is transmitted to the shutter 16.
．． The light passes through the variable transmittance filter 18 and is once focused by the focusing lens 19, and then enters the XY scanner 67. X
The laser beam that has passed through the Y scanner 37 enters the vacuum chamber 14 through the window 20, and after its optical path is bent by the reflecting mirror 22ζ, it is directed onto the sample 10 by the objective lens 21.
This light is focused.

The reflected light from the sample 10 passes through the same path (1σ) in the opposite direction, is bent by the half mirror 36, and passes through the pinhole 38.
It forms an image and enters the photomultiplier 69. Here, the laser beam focused by the focusing lens 19 is used as a point light source, but the imaging position of this point light source and the reflected light! (Pinhole position) forms a confocal position gc7J relationship, and the laser beam reciprocates through one objective lens 21, making the entire optical system a confocal type. In the manner described above, the reflected light intensity of the spot area 1 of the focused laser beam on the sample 10 is detected by the 7-meter 39. XY scanner TI7
scanning the focused laser beam over the sample 10 using f,2;
In synchronization with the scanning, the reflected light intensity is detected by the 7-meter 39, and a laser scanning microscope image is observed.

Laser scanning microscope images have high resolution, and unnecessary scattered light is removed by pinholes and is not affected by it at all, so a clear image with high contrast can be obtained. Furthermore, even if the same objective lens is used, the focal point closeness as an image becomes deep, so it becomes an optimal optical observation means especially for a deep sample such as a multilayer LSI.

Next, a processing depth monitor using reflected light intensity measurement will be explained. As mentioned in Example 1, when a transparent insulating film (such as a SiCh film) of an LSI is irradiated with light, the light causes multiple interference, and the intensity of the reflected light changes depending on the film thickness. Therefore, when processing a window in the insulating film of a multilayer LSI, a focused laser beam is irradiated onto the processed material at the same time as the processing, and changes in the thickness of the insulating film due to processing are detected as changes in reflected light intensity. and monitor the machining depth.

FIG. 14 shows a schematic diagram of multiple interference of light caused by a transparent film.

The sample is an LSI, and transparent insulation rtI is placed on the AJ wiring 72.
A thin film of I71 is then formed. The incident light Lo is repeatedly reflected between the thick insulating layers 71 and passes through the first . 2nd 3rd.・
The reflected light LI HL2 * L3+ . . . is generated. Ll.

L2 + Ll + ...The interference light intensity in which all the reflected lights interfere is detected as the actual reflected light intensity. The transmittance 9 reflectance from the vacuum to the insulating layer 71 is jl+r11 The transmittance 9 reflectance from the insulating layer 71 to the Al wiring 72 is tz
+ r 21 Let the transmittance 9 reflectance from the insulating layer 71 to vacuum be t'l+r'1. Also, the amplitude of the incident light Lo is aO
+The phase difference between adjacent reflected lights (for example, Ll and Lz) is δ,
When the light absorption rate of the insulating layer 71 is α, the amplitude a3 of the repeatedly reflected interference light is obtained by adding all of Ll, L2, Ls... a3=aorl+aot1t'+r2e-2αD
eIδ+aottt'xbi1r22e-4αDeI2δ
+0. .

(Here r'l =-rx + l+t'l=1- r
2s). Moreover, the phase difference δ is insulation, l1j
It can be expressed by the following formula using the film thickness of i71 and the refractive index n.

δ=RiB・2π River (5) (4
) From equation (5), the intensity factor 3 of the repeatedly reflected interference light is determined as follows.

3=la312 (6) Next In this embodiment, FIG. 15 shows a schematic diagram of the device configuration for realizing depth monitoring by measuring the intensity of reflected light. A laser with multiple wavelengths is used as a light source. Laser root generator A73. B74. The respective wavelengths λl, λ2 . The laser beam of λ3 is turned on and off from the shutters 73, 77, and 78J, and each laser beam is switched and irradiated. Laser light is irradiated and reflected light intensity measurement 3 is measured, but when the sample is an LSI (
In equation 6), α becomes 0, and the change in (3) due to film thickness is generally as shown in FIG. 16(f). Here, the reflected light intensities when laser oscillators A, B, and C are used are respectively expressed as +I3B+Isc, and are shown by a solid line and a -dot-dashed line in FIG. 16, respectively. The intensity of each reflected light changes with a period of 1/2n of the wavelength, but since the three wavelengths are different, the intensity of each reflected light shifts with the value of the film thickness.

In the actual LSI film thickness range, I3A + I3B
*Isc will never match, so by measuring the three reflected light intensities, the thickness of the insulating film can be determined from the values. During actual window opening, the bottom of the hole is repeatedly irradiated with these three laser beams at the same time as processing, the film thickness is determined from the intensity of the reflected light, and processing is continued until the value of D becomes zero. Just go.

Next, a method for monitoring the uneven shape of a sample using automatic focusing will be explained using FIGS. 17 and 18. First, the pinhole 38 is aligned with the confocal position for the point light source. In this state, if the laser beam that has passed through the objective lens 21 is focused on the sample 10, the reflected light from the sample 10 will form an image at the position of the pinhole 38, and the intensity of the reflected light detected by the photomultiplier 59 will be at its maximum. become. Conversely, when the focus on the sample 10 is out of focus, the imaging position of the reflected light shifts from the position of the pinhole 38, so the intensity of the reflected light passing through the pinhole 68 decreases rapidly. Therefore, the pinhole 38 is moved back and forth from the confocal position using the piezo element 40, and the objective lens 21 is automatically moved up and down so that the reflected light intensity detected at the front and back becomes equal (so that the amount of blur at the front and back becomes equal). Do focus. At this time, the vertical position of the objective lens 21 is obtained from the voltage applied to the piezo element 89 that drives the objective lens 21. Here, when the laser beam is focused on the sample 10, the distance from the focal plane, that is, the sample surface, to the objective lens 21 is always constant. Therefore, the laser beam is focused on the sample while performing automatic focusing. and objective lens 2 in between.
By monitoring the vertical fluctuations of 1, it is possible to obtain the uneven shape of the sample surface. For example, as shown in FIG. 18, when a laser beam is scanned across the convex portion of the Al metal M82 and the concave portion of the processed hole 83, an uneven profile as shown on the right is obtained. Here, on a steep slope, the reflected light is disturbed and automatic focusing becomes difficult, but this portion is indicated by a dotted line in the figure. Furthermore, by scanning the sample two-dimensionally with a laser beam using the XY scanner 37, it is also possible to monitor the two-dimensional uneven shape of the sample surface.

<Embodiment 5> FIG. 19 shows an apparatus configuration of a third embodiment of the present invention. The barrel portion of the focused ion beam optical system is the same as in Example 1, and an oblique illumination laser scanning microscope is provided as an optical measurement means. The laser beam oscillated from the laser oscillator 15 is once focused by the focusing lens 19 as in the second embodiment, and then enters the XY scanner 37. The laser beam that has passed through the XY scanner 67 is sent to the beam splitter 41.
The light is divided into two parts, one of which enters the vacuum chamber 14 through a window 42, is focused by an objective lens 44, and illuminates the sample 10 obliquely. The other laser beam is on window 4
3 and enters the vacuum chamber 14, and after its optical path is bent by reflection @45, it is focused by an objective lens 46 and illuminates the sample 10 obliquely from the opposite direction. Of the reflected light from the sample 10, the reflected light in the direction of the optical axis of the ion beam is focused by the objective lens 47, and the optical path is bent by the reflecting mirror 48.
An image is formed on the pinhole 68 and 7 otomaru 591 are made to enter. Here, an optical system passes from a point light source through the objective lens 44 (or objective lens 46) until an image is formed on a point on the sample 10, and the reflected light from the sample 10 passes through the pinhole 68.
The optical system up to the point where the image is formed constitutes a confocal optical system as a whole. Further, the optical axes of the left and right optical systems are adjusted so that the focal points of the laser beams by the objective lens 44 and the objective lens 46 substantially coincide on the sample 10. In the manner described above, the intensity of reflected light reflected from one point on the sample 10 (the convergence-dispersion point of the two laser beams) in the direction of the optical axis of the ion beam is detected from the photomultiplier 39f. XY scanner 5
7 to scan the sample 10 with a focused laser beam, and in synchronization with the scanning, the reflected light intensity is detected by the photomultiplier 39 to obtain an oblique illumination laser scanning microscope image.

Next, the oblique illumination scanning optical system will be explained using FIG. 20. The optical path when the laser beams are perpendicularly incident on the objective lens 44 and the objective lens 46 and the two laser beams are focused on the same point on the sample 10 is shown by a solid line. Also,
θ with respect to the vertical axis of the lens to scan the laser beam
The dotted line shows the optical path when the incident angle is shifted by . When the angle of incidence shifts by θ on the objective lens 44 side, the objective lens 4
Similarly, on the 6th side, the angle of incidence shifts by θ. Geometrically, it is easy to find f. Therefore, by rubbing the two objective lenses together, the shift of the focal point on the sample 1o The force 1 is proportional to the angle of incidence θ on the lens,
The left and right laser beams always focus on the same point on the sample.

In addition, the focal point of the left and right laser beams is! If the level is off,
The two focal points on the sample will always be offset by a distance l.

Next, observation of an LSI using an oblique illumination laser microscope will be explained using FIG. 21. Observed images when left and right laser illumination lights are irradiated separately are shown in (a) and (b).The irradiation direction of the laser light is indicated by an arrow, and the edge on the irradiation direction side becomes brighter in each case.

In reality, the left and right laser beams are irradiated simultaneously, so the observed image obtained is a superimposition of the two images. It is similar to a scanning microscope image, but because it is obliquely illuminated,
The uneven parts of the sample, especially the edges of the Al wiring, are emphasized, resulting in an image suitable for position detection. For example, when compared with the SIM image shown in (d), it is not possible to clearly detect the edge position of the uneven portion in the SIM image, and in particular, in the bottom layer wiring 86 where no unevenness information appears on the surface, the edge position of the uneven portion cannot be detected. Can not. On the other hand, in the oblique illumination laser scanning microscope image in (c), the edges of the uneven portion can be clearly detected, and the edge position of the lowest layer wiring 86 can be detected with Q] where the laser illumination light passes through the insulating field. .

Here, if the focal points of the left and right laser illumination lights are shifted, the obtained image will be an image obtained by shifting and superimposing the two images (a) and (b). Therefore, by adjusting the optical system while checking the detected image so that the edge positions of the machined holes match on the left and right sides, it is possible to match the focal points of the left and right laser beams.

Further, a shutter or the like is provided on the optical axis of the two laser beams, and the left and right laser beams are switched and irradiated. It is also possible to obtain the image (c) by inputting the two alternately detected images (a) and (a) separately to the image sensor and electrically combining the two images. In this case, it is not necessary to make the focal points of the left and right laser beams completely coincide with each other, and it is sufficient to focus the two laser beams close to each other on the sample.

〔Effect of the invention〕

According to the present invention, it is possible to simultaneously perform optical observation and measurement using the focused energy beam f in addition to processing using the focused energy beam f. Machining can be performed while optically monitoring misalignment and machining depth, which has the effect of enabling machining with high positional and depth accuracy.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of the device according to the first embodiment of the present invention, Fig. 2 is a configuration diagram of the conventional device, Figs. Illustration of the statue, No. 7
The figure is a diagram explaining the principle of depth measurement using light interference. Figure 8 is a diagram showing an example of the relationship between depth and interference light intensity. Figure 9 is the principle of depth measurement using light interference using multi-wavelength illumination. Explanatory diagram,
FIG. 10 is a diagram showing an example of the relationship between depth and interference light intensity when using multi-wavelength illumination, FIG. 11 is a schematic diagram of CVD wiring formed according to Example 1, and FIG. 12 is a diagram showing CVD wiring according to Example 1. An explanatory diagram of the wiring formation method, FIG. 13 is a diagram of the device configuration of Example 2, and FIG. 14 is an explanatory diagram of repeated reflection interference.
Figure 5 is a diagram explaining the principle of film thickness measurement using repeatedly reflected interference light (/J), Figure 16 is a diagram showing an example of the relationship between the strength and repulsion of the repeatedly reflected interference light, and Figure 17v is an explanation of the principle of focusing in Example 2. Fig. 18 is an explanatory diagram of a sample uneven shape monitor using focusing, Fig. 12 is an apparatus configuration diagram of LOL M example 3, Fig. 20 is an explanatory diagram of the laser oblique illumination system UJ,
The figure is an explanatory diagram of an oblique illumination laser beam image. 1... Ion source 2... Ion beam 6... Extracting electrode 4... Focusing lens 5... Beam limiting burner 6... Blanking ta 7.
...Blanking aperture 8...Deflector electrode 9...Secondary particle detector 1o...Sample 11.
...Stage 12...Blanking controller
13...Deflector controller 14...Chamber 15...Laser oscillator 16...Shutter 17
... Original path expander 18 ... Transmittance variable filter 19
...Focusing lens 2'0...Window 21...Objective lens 25...Lamp 25...TV camera:) 27.
...Piezo cable 29...Photomaru 30...Main controller 31.32...Monitor 33...C
VD Ganu cylinder 34...flow i x i valve 55
...Nozzle 37...XY scanner 38...Pinhole 39...Photomaru 40...Piezo probe 42.43...Window 44.46.47...Objective lens 49... Objective concave @ 50...A! Wiring 51...Insulating film 52...Processed hole 53...Through hole 54.55.56...Ray f firing m! 57,
58.59...Shutter 63.64...Al pad 65...Al wiring 66...Contact hole 6
7... Ion beam CVD wiring 68... Laser CV
D arrangement 69...Ion beam 7o...Laser light
71... Insulating film 72... Al rice grain arrangement 73.74.7
5...Laser oscillator 76°77, 78...Shutter 84...11th koji distribution 85...2nd~wiring
86... 5th layer wiring 87... Through hole 88.
... Machining hole 89... Piezo element Fig. 7 Fig. 3 side 1 Bottle Fig. 5 Fig. 6 Fig. 8 Eye depth No. 15 Fig. IG Fig. Film thickness D Fig. 17 Fig. 18 Fig. Figure 21

Claims (1)

[Claims] 1. A beam source that generates an ion beam, an electron beam, etc.;
Consists of a focusing optical system, a stage, a secondary particle detector, a CVD gas supply means, and a power supply controller that drives them. It focuses and irradiates an energy beam to process the workpiece, and also irradiates the energy beam in a CVD gas atmosphere. A focused energy beam processing device that performs local film formation is equipped with a light source such as a laser or a lamp, a focused irradiation optical system, a detection optical system for reflected light or interference light, and a power supply controller to drive them. At least a part of the condensing irradiation optical system and the detection optical system of the energy beam are arranged on the optical axis of the condensing optical system of the energy beam, and the condensed energy beam and the condensed light are placed in close proximity (the condensed energy beam diameter or the condensed light diameter). A focused energy beam processing device that is capable of simultaneously irradiating energy (within several times). 2. Claim 1, characterized in that the above-described light source, condensing irradiation optical system, detection optical system, and power supply controller that drives them are means for detecting an optical microscope image.
The focused energy beam processing device described in Section 1. 3. Focused energy beam processing according to claim 1, wherein the light source, the condensing irradiation optical system, the detection optical system, and the power supply controller that drives them are Michelson interferometers. Device. 4. The focusing system according to claim 1, wherein the light source, the condensing irradiation optical system, the detection optical system, and the power supply controller that drives them are means for detecting a laser scanning microscope image. Energy beam processing equipment. 5. Claim 1, characterized in that the above-described light source, condensing irradiation optical system, detection optical system, and power supply controller for driving them are means for detecting an oblique illumination laser scanning microscope image. In the focused energy beam processing device 6 described above, when processing a workpiece by focused irradiation of an energy beam such as an ion beam or an electron beam, focused light is simultaneously irradiated extremely close to the focused energy beam, and this focused light is A focused energy beam processing method characterized by processing a workpiece while optically monitoring processing conditions such as depth and position using a focused energy beam. 7. The focused energy beam processing method according to claim 6, wherein the optical monitoring means for the processing state is an optical microscope. 8. Claim 6, wherein the optical monitoring means for the processing state is a Michelson interferometer.
Focused energy beam processing method described in Section. 9. The focused energy beam processing method according to claim 6, wherein the optical monitoring means for the processing state is a laser scanning microscope. 10. The focused energy beam processing method according to claim 6, wherein the optical monitoring means for the processing state is an oblique illumination laser scanning microscope.