KR0163838B1 - Scan type exposure apparatus and exposure method using the same - Google Patents

Abstract

The scanning exposure apparatus of the present invention scans and moves synchronously with respect to a projection optical system a first movable stage equipped with a reticle, a second movable stage equipped with a wafer, and the first and second movable stages with respect to the projection optical system. A projection system for projecting the pattern of the reticle onto the wafer, a first mark formed on the reticle and having a plurality of marks arranged in the scanning direction, and fixedly mounted on the second movable stage in the scanning direction. A reference plate having a second mark in which a plurality of marks are arranged, a third movable stage on which the second movable stage is mounted and moving in a direction different from the moving direction of the second movable stage, and on the third movable stage And a photodetector fixed to it. The reference plate and the photodetector are positioned at positions on the first mark projected by the projection optical system by moving the second and third movable stages, and the first and second movable stages are moved by the projection optical system. The first mark image is detected through the second mark by the photodetector while synchronously moving.

Description

Scanning exposure apparatus and exposure method using the same

1 is a schematic diagram showing a general configuration of a scanning exposure apparatus according to an embodiment of the present invention.

2 is a schematic perspective view of a main part of a scanning exposure apparatus according to an embodiment of the present invention;

3 is an enlarged view of the transmission mark of the reticle.

4 is an enlarged view of a transmission mark of a wafer.

5 is an enlarged view of the light intensity sensor.

6 is a schematic diagram illustrating a method for detecting a position of a reticle.

7 is a schematic diagram illustrating a reticle position detection method similar to that of FIG. 6.

FIG. 8 is a schematic diagram illustrating the detection process. FIG. 8-1 is a schematic diagram of the relative positional relationship between the transmission mark of the reticle and the transmission mark of the wafer, and FIG. 8-2 of FIG. 8 is the time of reticle position measurement. A schematic diagram of the output signal of the light quantity sensor of FIG. 8 (8-3) is a schematic diagram of the output signal of the light quantity sensor at the reticle phase measurement, and (8-4) of FIG. 8 is the output of the light quantity sensor at the reticle magnification error measurement. Schematic diagram of the signal.

9 is a plan view of a scanning exposure apparatus according to an embodiment of the present invention for explaining a positional relationship.

10 is a schematic diagram of an alignment microscope.

11 is a schematic diagram of a reference pattern in an alignment microscope.

12 is a schematic diagram of a scanning exposure apparatus according to an embodiment of the present invention for explaining a positional relationship.

13 is a flowchart of a device manufacturing process.

14 is a flowchart of a wafer process.

* Explanation of symbols for main parts of the drawings

1: excimer laser 2: beam shaping means

3: mirror 4: light sensor

5: condenser lens 6: reticle

7: Reticle Stage 8,23,24: Linear Motor

9: bar mirror 10,21,22: laser interferometer

11: magnification adjusting mechanism 12: motor

13 projection optical system 14 wafer

15 wafer chuck 16 _θ Z tilt stage

17: injection stage 18: Y stage

19: stage base 20: L-shaped mirror

25 Light emitting portion of the focus detection system 26 Light receiving portion of the focus detection system

30: microscope 31: TV camera

32: scanning stage side transmission mark plate 33: stool lens

34: light quantity sensor 35: light quantity sensor unit

100: exposure area of the reticle 101: illumination area

102,121 ~ 124: Reticle side penetration mark

103,125 ~ 128: Injection stage side penetration mark

111 ~ 114: Light quantity detector

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning exposure apparatus for synchronously scanning a reticle and a wafer with respect to a projection optical system and transferring a pattern of a reticle to a wafer, and an exposure method using the same.

FIG. 12 shows an example of a relative positional relationship between a wafer and a lake and an image detection method of a projection optical system in a step-and-repeat exposure apparatus.

In FIG. 12, reference numeral 200 denotes an Hg (mercury) lamp which is a light source of an illumination system, 201 denotes an elliptical mirror that collects light from the Hg lamp 200, and 202 denotes an elliptical mirror on the reticle 6 It is a condenser lens for condensing light from 201). On the reticle 6, alignment marks are formed.

13 denotes a projection optical system, 14 denotes a wafer, 15 denotes a wafer chuck, 203 denotes a transmissive mark on the wafer side corresponding to the transmissive mark of the reticle 6, and 204 denotes a transmissive mark on the wafer side ( A light quantity sensor that detects the amount of light that has passed through 203, which is integrated with the transmission mark 203 on the wafer side. Reference numeral 205 denotes an XYZ stage for moving a wafer in the X, Y, and Z directions, 206 a position detector for detecting the position of the XYZ stage 205, 207 a light quantity measuring instrument of a light intensity sensor, and 208. Is a control system (i.e., a CPU data processing system).

In this conventional exposure apparatus, the transmissive mark 203 mounted on the XYZ stage 205 and the light amount sensor 204 are integrated and moved in the X, Y, and Z directions to detect the position of the maximum light amount. By this, the position of the reticle-to-video image and its upper surface position are detected (Japanese Patent Application Laid-Open No. 2-58766).

The above-described method in the conventional step-and-repeat exposure apparatus is effective when the reticle is stationary with respect to the projection optical system.

However, the scanning type exposure apparatus that has been recently noticed has the following problems.

(1) Speckle:

In a scanning exposure apparatus, in order to improve the resolution and productivity, an extra-ultraviolet laser (for example, a KrF excimer laser or an ArF excimer laser) is often used as a high power and short wavelength light source.

Such ultraviolet lasers are generally highly coherent and generate interference patterns (speckles) on the wafer surface.

In the scanning exposure apparatus, during the actual exposure process, the reticle and the wafer are scanned and moved with respect to the illumination light (or projection system), so the influence of such speckle is remarkably reduced. If such a scanning exposure apparatus employs a method or configuration for stopping the reticle to detect the position or the top position of the reticle-to-image, the detection is performed in a substantially stationary state (i.e., it does not take advantage of the scanning exposure apparatus. ), Detection is greatly affected by the speckle. As a result, accurate light quantity measurement is impossible.

(2) effective light source difference

In the scanning exposure apparatus, compared with the step-and-repeat exposure apparatus, it is necessary to make higher the optical energy density of the exposure light irradiation area in order to secure the throughput. To this end, special attention must be paid to the durability of the optical component in design. As a countermeasure, it is effective to form an effective light source during the scanning operation in consideration of the scanning direction (the shape of the effective light source is different in the exposure area in the scanning direction of the projection optical system). This makes it possible to separate the condensing position of the light energy between the scanning direction and the direction perpendicular to the scanning direction in the projection optical system, thereby preventing the concentration of the light energy on the elements constituting the projection optical system.

However, when the above countermeasures are taken, the effective light source is different in the scanning state and the stationary state.

That is, in the method or apparatus for detecting the position or the upper surface of the reticle-to-image in the almost stationary state, it is difficult to accurately detect the position of the reticle-to-image or the upper surface in the scanning state due to the difference of the effective light source in the exposure area.

(3) Posture of the injection stage:

In the scanning exposure apparatus, the posture of the reticle stage for scanning movement of the reticle and the posture of the scanning stage for scanning movement of the wafer are controlled to maintain an ideal position during the scanning movement, but how the posture changes between the scanning state and the stationary state. There is no specific means to detect. That is, in the method of measuring in the almost stationary state, since the influence of the posture of the scanning stage is not included, it is difficult to accurately detect the position and the upper surface of the reticle-to-image in the scanning state.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method and / or an apparatus capable of accurately measuring the position, top position, and / or magnification error of a reticle-to-image in a scanning exposure apparatus.

According to one aspect of the present invention, there is provided an apparatus comprising: a first movable stage for mounting a first object and moving in a predetermined one-dimensional direction; A second movable stage which mounts a second object and moves in a predetermined one-dimensional direction; A projection system which scan-moves the first and second movable stages in synchronization with the projection optical system and projects the pattern of the first object onto the second object through the projection optical system; A first mark formed on said first object and having a plurality of masks arranged in a scanning direction; A reference plate having a second mark fixedly mounted on said second movable stage and having a plurality of marks arranged in a scanning direction; A third movable stage which mounts the second movable stage and moves in a direction different from a moving direction of the second movable stage; A photodetector fixedly mounted on said third movable stage; A first function of moving the second and third movable stages to position the reference plate and the photodetector at a position on the first mark projected by the projection optical system, and the first and second movable stages A scanning type exposure apparatus is obtained, comprising: control means having a second function of synchronously moving with respect to the projection optical system and detecting the first mark image through the second mark by the photodetector. .

In a preferred embodiment according to the aspect of the present invention, the second movable stage has optical axis direction moving means for moving in the optical axis direction of the projection optical system, and the control means drives the optical axis direction moving means for the reference plate. It is characterized in that the photodetector detects the first mark image through the second mark by changing the position in the optical axis direction.

In another preferred form according to the aspect of the present invention, the first and second marks are marks in which a plurality of marks are periodically arranged.

In still another preferred form of the aspect of the present invention, the first and second marks are marks in which a plurality of marks having different inclinations are arranged.

In still another preferred form of the aspect of the present invention, the first and second marks are marks in which a plurality of marks having different inclinations are arranged. The control means controls the projection optical system based on the signal detected by the photodetector via the second mark and the positions of the first and second movable stages when the signal is detected. The position of the first mark is projected onto the second mark is determined through.

In still another preferred form of the aspect of the present invention, the control means includes a signal for detecting the first mark image through the second mark by the photodetector, and the second at the time of detecting the signal. Based on the position of the movable stage, the position in the optical axis direction of the projection optical system in which the first mark is formed through the projection optical system is determined.

According to another aspect of the present invention, a scanning exposure apparatus for scanning a first object and a second object in synchronization with a projection optical system and simultaneously projecting a pattern of the first object onto the second object through the projection optical system. An exposure method comprising: forming a first mark on the first object in which a plurality of marks are arranged in a scanning direction; Fixing a reference plate having a second mark having a plurality of marks arranged in a scanning direction on a movable stage on which the second object is mounted; Positioning a photodetector at a position on the first mark to be projected or projected by the projection optical system; And scanning the first object and the reference plate synchronously with respect to the projection optical system and detecting the first mark image through the second mark by the photodetector. Is obtained.

In a preferred form according to the aspect of the present invention, the detecting step changes the position of the reference plate with respect to the optical axis direction of the projection optical system to detect the first mark image through the second mark by the photodetector. Characterized in that.

In another preferable aspect according to the aspect of the present invention, the exposure method is based on the positions of the first and second marks when the first mark image is detected through the second mark by the photodetector. And determining, by the projection optical system, the position at which the first mark is to be projected or projected onto the second mark.

In still another preferred form of the aspect of the present invention, the exposure method includes a signal in which the first mark image is detected through the second mark by the photodetector, and the optical axis direction when the signal is detected. And determining the position in the optical axis direction in which the first mark is imaged through the projection optical system, based on the position of the reference plate of.

According to still another aspect of the present invention, there is provided a device manufacturing method using a scanning exposure apparatus for scanning a reticle and a wafer in synchronization with a projection optical system and simultaneously projecting the pattern of the reticle onto the wafer through the projection optical system. A method comprising: forming a reticle mark on the reticle, in which a plurality of marks are arranged in a scanning direction; Fixing a reference plate having a wafer mark having a plurality of marks arranged in a scanning direction on a movable stage on which the wafer is mounted; Positioning a photodetector at a location on the reticle mark to be projected or projected by the projection optical system; And a step of scanning the reticle and the reference plate in synchronization with the projection optical system and detecting the reticle mark image through the wafer mark by the photodetector. .

Other objects, features and advantages of the present invention will become more apparent upon consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.

Hereinafter, the present invention will be described in detail with reference to the drawings.

In FIG. 1 showing a scanning exposure apparatus according to an embodiment of the present invention, (1) an excimer laser for generating pulsed light, and (2) a light beam shaping for shaping light from an excimer laser to a predetermined size. Means (3) is a mirror, (4) is an optical sensor for detecting illuminance on the reticle plane, (5) is a condenser lens, (6) is a reticle, and (7) is a reticle (6) during the exposure process. A reticle stage for scanning operation, (8) a linear motor for scanning movement of the reticle stage (7) in the direction shown, (9) a bar mirror fixed to the reticle stage (7), (10) a reticle stage A laser interferometer for detecting the speed or position of (7), (11) a magnification adjusting mechanism for slightly changing the magnification of the projection system, (12) a motor for driving the magnification adjusting mechanism (11), and (13) a reticle Is a projection optical system for projecting a pattern of? To the wafer 14.

15 is a wafer chuck holding a wafer 14, 16 is a _θZ tilt stage for rotating, tilting and tilting the wafer chuck 15, 17 is a _θZ tilt stage 16 At the same time, the scanning stage which performs the scanning operation during the exposure operation, 18 is a Y stage for moving the scanning stage 17 in a direction perpendicular to the scanning direction, 19 is a stage base on which the Y stage 18 is mounted, ( 20 is an L-shaped bar mirror fixedly mounted on the wafer chuck 15, 21 is a laser interferometer for detecting the speed or position of the wafer chuck 15 in the scanning direction, and 22 is a scan of the wafer chuck 15 A laser interferometer for detecting a speed or position in a direction perpendicular to the direction, 23 is a linear motor for driving the scanning stage 17 in the scanning direction, and 24 a Y stage 18 in a direction perpendicular to the scanning direction. It is a linear motor to drive.

Reference numeral 25 denotes a light emitting portion of the tilt focus detection system for projecting a light beam onto the wafer surface, and 26 denotes a position of the light from the light emitting portion 25 reflected from the surface of the wafer 14 to measure the inclination and position of the wafer surface. In the light receiving portion of the tilt focus detection system for measuring, the elements (25) and (26) cooperate to form a tilt focus detection system.

Reference numeral 30 denotes an alignment microscope for measuring the position of the alignment mark on the wafer 14, 31 a TV camera mounted on the alignment microscope 30, 32 a fixed reticle mounted on the wafer chuck 15, and the like. The scanning stage side transmissive mark plate on which the side transmissive mark is imaged, 33 is an imaging lens for projecting light from the reticle side transmissive mark onto the light quantity sensor 34, and 34 is a light quantity sensor having four light quantity detection units. And 35 are light amount sensor units fixedly mounted on the Y stage, in which the imaging lens 33 and the light amount sensor 34 are integrated.

40 is a light emission control unit operable to output and apply a light emission command signal to the excimer laser 1 when the scan stage 17 becomes a predetermined positional relationship in response to the input of the position information of the scanning stage 17, (41) Is a current voltage converter for converting an optical current signal from the optical sensor 4 for detecting illuminance on the reticle surface into a voltage signal, 42 is an integrator for integrating the voltage output signal of the current voltage converter 41, An analog digital (A / D) converter for converting analog data of the integrator 42 into digital data, 44 is a memory for setting the position of the relay lens in response to the central processing unit (CPU) 70, 45 is A digital analog (D / A) converter for converting digital data from the memory 44 into analog data, 46 activates the relay lens driving motor 12 by position data from the D / A converter 45. It is a driver.

(50), (53) and (56) are memories for holding scan rate command signals for the reticle stage (7), the scanning stage (17) and the Y stage (18), (51), (54) and Reference numeral 57 denotes a D / A converter for converting digital data from the memories 50, 53, and 56 into analog data, and reference numerals 52, 55, and 58 denote D / A conversion circuits 51. ), (60), (61), and (62) drivers that amplify the analog signals from (54), (57) to activate linear motors (8), (23), (24), respectively. The position counters of the stage 7, the scanning stage 17 and the Y stage 18, 63, 64, 65 and 66 are analog signals inputted from a light quantity sensor having four light quantity detection units. A / D converter for converting digital data into digital data, 70 is a central processing unit (CPU) which operates to control the entire exposure apparatus, and 71 is a read storing various programs and control data of the CPU 70. Dedicated memory (ROM), 72 is used by the CPU for temporary storage Constant velocity extraction memory (RAM).

The operation of this embodiment will be described with reference to the following items:

[1] reticle settings

[2] reticle position detection

[3] face detection, reticle

[4] detection of magnification errors over the entire surface of the reticle

[5] rough focusing, alignment microscope

[6] detection of reference pattern positions, alignment microscope

[7] loading of wafers

[8] detection of wafer location

[9] scanning exposure

[10] taking out wafers

[1] Setting the reticle:

After the reticle 6 is loaded on the reticle stage 7, the reticle 6 is positioned at a predetermined position on the reticle stage 7 by a reticle-only microscope (not shown) and a reticle driving mechanism (not shown). .

[2] Detect position of reticle:

After positioning of the reticle 6 is completed, the optical sensor unit 35 on the Y stage 18 moves to the exposure area of the projection optical system 13 by the movement of the Y stage 18. In addition, when the scanning stage side transmissive mark plate 32 also moves to the exposure area in response to the movement of the scanning stage 17, the scanning stage side transmissive mark plate 32 causes the light amount sensor unit ( 35) Move to the above position. This is shown in FIG. In FIG. 2, reference numeral 100 denotes an exposure target area of the reticle 6, 101 denotes an illumination area defined in the illumination system, 102 denotes a reticle side transmission mark disposed on the reticle 6, and 103 ) Are transmission marks formed on the scanning stage side transmission mark plate, and 111 to 114 are four light quantity detection units in the light intensity sensor 34.

After the above operation, the specific mark image in the center portion of the scanning direction of the reticle side transmission marks 121 to 124 (FIG. 3) formed through the projection optical system 13 is the scanning stage side transmission marks 125 to 128 ( The reticle stage 7 and the scanning stage 17 are positioned so as to coincide with the specific mark in the center of the scanning direction of FIG. Next, the scanning operation is started at the same scanning speed as in the wafer exposure process.

Here, when the reticle stage 7 and the scanning stage 17 are driven by the relative positions which completely coincide with each other, the relative position deviation occurs between the reticle side transmission mark 102 and the scanning stage side transmission mark 103 during the scanning operation. Note that the amount of light incident on the light amount detectors 111 to 114 (FIG. 5) does not change. In view of this, in this embodiment, the relative position between the reticle side penetration mark 102 and the scanning stage side penetration mark 103 is specifically set so as to deviate from the ideal relative position other than the specific mark in the center. This is shown in Fig. 8-1.

In Fig. 8-1, the solid line is an ideal relative position and the actual relative position at the time of measurement by a dotted line.

In Fig. 8 (8-1), the origin 0 is the position of the reticle stage 7 and the scanning stage 17 where the reticle side penetration mark 102 and the specific mark at the center of the scanning stage side penetration mark must coincide with each other. to be. Specific points A and B are positions where the period of the reticle side transmission mark 102 and the period of the scanning stage side transmission mark 103 are shifted by one period (Lp).

Therefore, the specific mark at the center of the reticle side transmission mark 102 and the scanning stage side transmission mark 103 at the origin 0 completely coincide with each other, and the period and the scanning stage of the reticle side transmission mark 102 at the specific points A and B When the period of the side penetration mark 103 is shifted completely by one period Lp, as indicated by the solid line of (8-2) in FIG. 8, the light quantity detecting units 111 to (at the origin 0 and the specific points A and B). All outputs of 114) are maximum.

Here, if the specific mark at the center of the reticle side transmission mark 102 and the scanning stage side transmission mark 103 at the origin 0 does not coincide with each other completely, as indicated by the dotted line in (8-2) in FIG. The point at which the output of any or all of (111) to (114) becomes the maximum deviates from the origin zero.

6, the dotted line is the center line of the reticle side transmission marks 121 and 122, and the solid line is the center line of the scanning stage side penetration marks 125 and 126. In FIG.

FIG. 7 is an enlarged view of a portion of FIG. 6 showing the case where the reticle side transmission mark deviates by the amount of Xeou, Yeou from the ideal relative position with respect to the scanning stage side transmission mark. In this case, the relative positions at which the outputs of the upper light quantity sensors 111 and 112 are maximized deviate from the ideal relative positions by L1 and L2, respectively.

In this embodiment, the entire transmission mark has an inclination of 45 degrees with respect to the scanning direction. As such:

From this it becomes:

At the same time, measurement is performed on the other pair of reticle side penetration marks 123 and 124 and the other pair of scanning stage side penetration marks 127 and 128. If the reticle side penetration mark is cut by L3 and L4, respectively, from the ideal relative position to the scanning stage side transmission mark, the following relation is obtained:

Here, the distance in the Y direction between the upper transmission mark 125 (126) and the lower transmission mark 127 (128) is D, the deviation from the ideal position on the reticle (Xeo, Yeo), the angle deviation is eeo, the center If the magnification error is Meo, it is as follows from Xeou, Yeou, Xeod and Yeod equation:

By the measurement and association, the angle deviation (Xeo, Yeo) as well as the deviation from the ideal position on the reticle ( eo) and the center magnification error (Meo) become clear.

Note that the L1 to L4 are easily determined from the relative position at which the light quantity detecting units 111 to 114 become maximum levels.

The L1 determination method will now be described with reference to (8-1) and (8-2) in FIG.

In (8-2) of FIG. 8, Loo 'is the distance to the point where the light quantity detection part 111 is maximum. If the distance on the reticle side where one cycle of the pattern is shifted is La and the interval of one cycle of the pattern is Lp,

By the same method as described above, L2 to L4 can be easily obtained by measurement and calculation.

In this embodiment, the relative position between the reticle side penetration mark 102 and the scanning stage side penetration mark 103 is specifically set so as to deviate from the above-described ideal relative position except for the specific mark in the center portion. Here, the distances from the origin 0 to the specific points A and B are La and Lb, respectively, which are each about 10 mm. In contrast, one cycle of the scanning stage permeation mark is about several micrometers. Therefore, it can be considered that the speckle, the effective light source, and the posture are all the same between the reticle position detecting operation and the actual exposure operation.

[3] Detect top position of reticle:

Deviation from the ideal position on the reticle (Xeo, Yeo), angular deviation ( eo) and correction of magnification error Meo. Deviations from the ideal relative position (Xeo, Yeo) are corrected by changing the relative position on the scanning stage 17 side. Angle deviation eo) corrects by rotating the reticle on the side of the reticle stage 7 by _θ , and the center magnification error Meo using the magnification adjusting mechanism 11.

Thereafter, a plurality of times the reticle stage side penetration mark 102 and the scanning stage side penetration mark 103 are made to perform a scanning operation, and the outputs of the respective light quantity detection units 111 to 114 are detected. However, every scanning operation, and changes the position of the scanning stage side transmission mark 103 in the focus direction of a projection system 13 by the Z-tilt _θ stage 16.

When the position of the scanning stage side penetration mark 103 is changed in the focusing direction of the projection system 13, the output of the light amount detecting portions 111 to 114 changes as shown in (8-3) of FIG. .

Here, the Z-direction position of the scanning stage side penetration mark at which the outputs of the weight loss detection units 111 to 114 is maximum is the upper surface position of the reticle. From the Z direction position at which the output of the light quantity detectors 111 and 112 is maximum and the Z direction position at which the outputs of the light quantity detection units 113 and 114 are maximum, The position and inclination, ie the ideal top surface, can be determined.

This ideal upper surface needs to be reproduced with respect to the wafer surface in synchronism with the scanning operation in the next wafer exposure process. After the measurement, the scanning stage side mark plate 32 is moved below the projection system 13, In synchronization with the scanning operation, the ideal upper surface is reproduced using the scanning stage side transmissive mark plate 32. At this time, the ideal upper surface position measured based on the tilt focus detection system 25 is stored in the memory.

[4] Detecting magnification errors on the entire surface of the reticle:

After measurement and correction of deviations (Xeo, Yeo), angular deviations (eeo) and magnification error (Meo) from the ideal position of the reticle 6 and after measurement of the ideal upper surface for the dice of the reticle, all errors are corrected The reticle stage side transmission mark 102 and the scanning stage side transmission mark 103 are again associated with each other so as to perform a scanning operation and measure the output of the light quantity detecting units 111 to 114.

Here, it is checked whether the correction is completed with respect to the specific mark position of the center portion of the transmission mark, and at the same time, it is checked whether the output of the light quantity detecting units 111 to 114 becomes the maximum.

At the specific points A and B, if any of the outputs of the light quantity detection units 111 to 114 becomes the maximum at a point other than the specific points A and B, the same as in the case of the position detection of the reticle (item [2]) In the same way the following procedure is obtained: deviation from the ideal position on the reticle on position A (Xea, Yea), angle deviation ( ea) and magnification error Mea, and deviation from the ideal position of the reticle at the B position (Xeb, Yeb), angle deviation (eeb), and magnification error are detected. The result and the deviation at origin zero Xeo, Yeo, Based on eo and Meo, the positional deviation, the angle deviation, and the magnification error in the section from the origin 0 to the A position and the section from the origin 0 to the B position are approximated by the position r in the columnar direction of the reticle side transmission mark. As Xe (r), Ye (r), The values of e (r) and Me (r) are obtained. For Xe (r), correction is made by changing the relative position of the transmission mark in synchronization with the scanning operation. For Ye (r), Y is synchronized with the scanning operation. By changing the stage position, By rotating the wafer side in synchronism with the scanning operation for e (r), all deviations can be corrected by performing correction by the magnification adjusting mechanism 11 in synchronism with the scanning operation for Me (r).

The correction values Xe (r), Ye (r), Based on e (r) and Me (r), it is determined how the relative position of the scanning stage, the Y stage position, the rotation on the wafer side, the magnification adjusting mechanism and the upper surface position should be corrected or driven.

The data used for such correction and driving is correction data for the reticle viewed from the scanning stage side penetration mark. Therefore, hereinafter referred to as large reticle correction data. At this time, the reticle correction data is a function of the scanning direction position of the reticle.

[5] approximate focusing of alignment microscopes:

The scanning stage side penetration mark 103 is positioned below the alignment microscope using the origin focus switch obtained above.

Here, the objective lens of the alignment microscope is moved in the optical axis direction so that the transmission mark is formed on the TV camera 31. This object is to make the movement in the focus direction as small as possible after moving the wafer after alignment down the projection optical system.

[6] Detection of reference pattern positions in alignment microscopes:

In the exposure apparatus of this embodiment, the projection system 13, the alignment microscope 30 and the light amount sensor unit 35 are arranged on the same Y axis as shown in FIG. Therefore, the light quantity sensor unit 35 is positioned below the alignment microscope by the movement of the Y stage 18, and the scanning stage side transmission mark plate 32 is moved by the light quantity sensor unit (by the movement of the scanning stage 17). It is possible to position above.

The alignment microscope 30 has the configuration shown in FIG. 10, where 150 is a reference pattern in the alignment microscope 30, 151 is an objective lens, and 152 to 155 are optical lenses, 156 and 157 are half mirrors, and 158 and 159 are optical fibers for guiding light for illumination from a light source (not shown).

As shown in FIG. 11, reticle corresponding marks 161 and 162 serving as the positional reference of the alignment microscope are arranged in the reference mark 150. As shown in FIG.

The projection stage side transmissive mark plate 32 is formed such that the projection images of the reticle-corresponding marks 161 and 162 coincide with specific marks of the transmissive marks 125 and 126 on the scan stage side transmissive mark plate 32. Positioning in the scanning direction is performed. Then, the outputs of the light quantity detectors 111 and 112 are detected while changing the position slightly in the scanning direction with respect to this determined position and also changing the position in the focus direction.

By the above operation, the projection image position and image detection of the reticle-corresponding marks 161 and 162 are performed in the same manner as in the case of the detection of the position of the projection image of the reticle side transmission mark 102 and the image detection. All.

This is different from the case of position detection and image detection of the projected image of the reticle side transmission mark 102 in the following two points:

(Iii) Measurement is performed in the stopped state.

(Ii) Only two light quantity detectors are used.

By the above operation, the position of the projection image of the reticle side transmission mark, the position of the projection image of the reticle correspondence marks 161 and 162 with respect to the image surface, and the relative position of the image surface become clear.

This relative position is referred to as the baseline between the projection optical system 13 and the alignment microscope 30.

The above fixing [1] to [6] can be automatically executed by inputting a system calibration command from an operator before the start of wafer processing or during wafer processing.

[7] wafer loading:

Returning to FIG. 1, the exposure apparatus of the present embodiment carries out wafer loading as follows. By input of the wafer processing start command, the wafer is automatically taken out from the wafer carrier in the wafer transfer system (not shown). In the prealignment mechanism in the wafer transfer system, the wafer is mounted on an XY stage, and the wafer end detection function detects not only the outer circumferential shape of the wafer but also its orientation flat portion. Then, the orientation plane of the wafer is oriented in the predetermined direction by the XY _θ stage, and the center position of the wafer is determined. Then, the focus detection function detects the level (height) of the surface of the wafer.

Subsequently, the alignment mark on the wafer is placed under the microscope arranged on the upper portion of the alignment system to measure the position of the alignment mark, and then the pattern position of the wafer becomes a predetermined positional relationship with the specific reference position of the transfer system. The XY _θ stage is driven.

Then, the wafer thickness information found on the basis of wafer level detection is supplied to the central processing unit (CPU) 70 of the exposure apparatus.

Upon receiving this information, the exposure apparatus the CPU (70) is a wafer chuck level to drive the Z drive mechanism of _θ Z tilt stage so that the focus position of the wafer surface is substantially a projection system and the alignment microscope when mounting the wafer (height) Change.

After the above operation, the transfer system moves the wafer from the XY _θ stage of the transfer system onto the wafer chuck of the exposure apparatus by the carrying-in hand.

[8] Detection of wafers:

When the wafer 14 is loaded on the wafer chuck 15, the wafer 14 is moved below the projection system 13 by the Y stage 18 and the scanning stage 17 so that the focus detection system 25, In (26), level measurement of the entire wafer surface is performed.

Then, a plurality of predetermined chip regions on the wafer are sequentially moved below the alignment microscope 30 to perform position measurement of the alignment marks arranged in the respective chip regions.

Position measurement of the alignment mark is performed by projecting the reticle-corresponding marks 161 and 162 and the transmission mark portion 160 in the reference mark 150 in the alignment microscope 30 onto the wafer. In this case, the light passing through the transmission mark unit 160 is used to illuminate the alignment mark of the wafer 14. Therefore, the alignment marks of the reticle correspondence marks 161 and 162 and the wafer 14 are projected on the CCD camera 31.

By this measurement, the relative position of each chip of the wafer with respect to the reticle correspondence marks 161 and 162 in the alignment microscope, and the magnification of the scanning direction and the direction perpendicular to the scanning direction of each chip are determined.

By the above operation, in the exposure process for each chip of the wafer, it is determined how the relative position of the scanning stage, the Y stage position, the magnification adjusting mechanism and the like should be corrected and driven in synchronization with the scanning operation.

The data used for such correction and driving is correction data for the wafer viewed from the reticle corresponding marks 161 and 162 in the alignment microscope 30. Therefore, hereinafter, referred to as large wafer correction data.

[9] scanning exposure:

Based on the above-mentioned large reticle correction data, baseline and large wafer correction data, it is possible to perform focus adjustment by accurately matching the entire surface of each pleat of the reticle and the wafer during the scanning exposure process.

After the measurement of the large wafer correction data is completed, the first chip of the wafer 14 is moved under the projection system 13 based on the large reticle correction data, the baseline and the large wafer correction data, and then the large reticle correction data and the large wafer are adjusted. The reticle stage 7 and the scanning stage 17 start the actual exposure scanning operation while maintaining the ideal relative position and the ideal upper surface position of the reticle and the specific chip by the wafer correction data and performing mutual magnification correction. .

In the exposure apparatus of this embodiment, the exposure amount of the wafer 14 is input in advance. In order to realize this exposure amount, it is necessary to detect the light energy in one pulse of the excimer laser 1 which is a light source.

In this embodiment, before starting the wafer processing, the excimer laser is oscillated and the reticle surface roughness corresponding to the wafer surface roughness is measured by the optical sensor 4. Based on this measurement, the required number of exposure light pulses for the entire area on the wafer is calculated.

The CPU 70 sets the oscillation control unit 40 to the scanning stage position at which the excimer laser is oscillated from the calculated required exposure pulse number before the start of the exposure scan. During the exposure scanning operation, the exposure control unit 40 continuously monitors the position of the scanning stage 17 and excimer laser 1 whenever the scanning stage 17 reaches a preset scanning stage position where the laser should be oscillated. The oscillation command signal is output to the oscillator 1, and the excimer laser 1 is oscillated to generate pulsed light.

By the above operation, exposure of one chip is completed. The same operation is performed on all remaining chips on the same wafer.

[10] Wafer removal:

After the exposure of all the chips is completed, the wafer 14 is moved to the wafer unloading position by the Y stage 18 and the scanning stage 17, and then the wafer 14 is unloaded by the unloading hand (not shown) of the transfer system. It unloads from the wafer chuck 15.

[Modification]

The embodiment of the present invention described above may be modified as follows.

(1) A plurality of wafer-side transmission marks and light quantity sensor:

A plurality of wafer side transmission marks and a plurality of light quantity sensors may be disposed around the wafer chuck. This enables precise correction of the posture difference.

(2) Test Reticle:

It is sometimes impossible to form a plurality of the reticle side transmission marks on the actual reticle to manufacture the actual semiconductor device due to the alignment pattern or the relationship with other patterns. As a countermeasure, strict correction is performed periodically using a test reticle provided with a large number of reticle side penetration marks, so that a small number of reticle side transmission marks may be formed in actual reticles.

(3) Integration of transmission mark and light amount sensor:

On the reticle and the scanning stage, a plurality of inclined transmission marks may be provided as in the above embodiment, and a light quantity sensor may be fixedly mounted below the scanning stage side transmission marks. This makes it possible to image the scanning stage side transmission mark at the same focus state on the light quantity sensor light-receiving surface at all times. It is also possible to detect high precision of the reticle upper surface position. However, in this method, it is necessary to arrange a long light quantity sensor with a uniform detection sensitivity under the scanning stage side transmission mark. Therefore, when a high speed pulse light source such as an excimer laser is used as the light source, the light intensity sensor alone is required for the uniformity of sensitivity. It is generally difficult to be satisfied. This requires calibration of the sensitivity of the light quantity sensor. As an example of this, in the exposure apparatus, while the reticle is in a stationary state, the amount of light incident on the scanning stage side penetration mark is uniformly maintained, and the detection is composed of an integrated structure of the scanning stage side transmission mark and the light quantity sensor while maintaining this state. Move the unit. During this operation, the output change of the light quantity sensor may be stored as calibration data, which may be used for calibration of the output data of the light quantity sensor at the time of actual reticle position detection or image detection. However, if the stability of the light energy from the light source is not so high, it is necessary to calibrate the calibration data by measuring the light energy of the light source using the reticle surface roughness detection system described with reference to the above-described embodiment.

An embodiment of a device manufacturing method using the above-described exposure apparatus will be described below.

FIG. 13 is a flowchart of a manufacturing procedure of a microdevice such as a semiconductor chip (for example, IC or LSI), a liquid crystal panel, a CCD, a thin film magnetic head, or a micromachine. Step 1 is a design step of designing a circuit of a semiconductor device, step 2 is a step of making a mask based on the designed circuit pattern, and step 3 is a step of making a wafer using a material such as silicon.

Step 4 is a so-called pre-process wafer process in which an actual circuit is formed on the wafer by a lithography technique using the prepared mask and wafer, and the next step 5 is a semiconductor process of the wafer processed in step 4 It is an assembly process called post-process which forms into a chip. This process includes an assembly process (dicing and bonding process) and a packaging process (chip sealing). Step 6 is an inspection process for performing the operation check, durability check, and the like of the semiconductor device created in Step 5. By these steps, the semiconductor device is completed and shipped (step 7).

14 is a flowchart showing the details of the wafer process. Step 11 is an oxidizing step of oxidizing the surface of the wafer, step 12 is a CVD step of forming an insulating film on the wafer surface, and step 13 is an electrode forming step of forming an electrode on the wafer by a vapor deposition method. Step 14 is an ion implantation process for implanting ions into the wafer, and step 15 is a resist process for applying a resist (photosensitive material) to the wafer, and step 16 is for exposing the circuit pattern of the mask onto the wafer by the exposure apparatus described above. It is an exposure process to print by. Step 17 is a developing step of developing the exposed wafer, step 18 is an etching step of removing portions other than the developed resist image, and step 19 is a peeling step of peeling the resist remaining on the wafer after the etching step. By repeating these processes, circuit patterns are superimposed on the wafer.

As mentioned above, although this invention was demonstrated with reference to the structure disclosed here, this invention is not limited to this, Comprising: It is a matter of course that all such a deformation | transformation and a correction which fall within the scope of the following claims are included.

Claims (11)

A first movable stage which mounts the first object and moves in a predetermined one-dimensional direction; A second movable stage which mounts a second object and moves in a predetermined one-dimensional direction; A projection system which scan-moves the first and second movable stages in synchronization with the projection optical system and projects the pattern of the first object onto the second object through the projection optical system; A first mark formed on said first object and having a plurality of masks arranged in a scanning direction; A reference plate fixed to the second movable stage and having a second mark in which a plurality of marks are arranged in a scanning direction; A third movable stage which mounts the second movable stage and moves in a direction different from a moving direction of the second movable stage; A photodetector fixedly mounted on said third movable stage; A first function of moving the second and third movable stages to position the reference plate and the photodetector at a position on the first mark projected by the projection optical system, and the first and second movable stages And a control means having a second function of synchronously moving with respect to the projection optical system and detecting the first mark image through the second mark by the photodetector. The optical axis direction moving means of claim 1, wherein the second moving stage has optical axis direction moving means for moving in the optical axis direction of the projection optical system, and the control means drives the optical axis direction moving means to position the reference plate relative to the optical axis direction. And the photodetector detects the first mark image through the second mark. And the first and second marks are marks in which a plurality of marks are arranged periodically. The scanning type exposure apparatus according to claim 1, wherein the first and second marks are marks in which a plurality of marks having different inclinations are arranged. 2. The control apparatus according to claim 1, wherein the control means detects the signal detected by the photodetector through the second mark and the position of the first and second movable stages when the signal is detected. And a position where the first mark is projected onto the second mark through the projection optical cradle. The said control means is based on the signal which detected the said 1st mark image through the said 2nd mark by the said photodetector, and the position of the said 2nd movable stage at the time of detecting the said signal, And the projection optical system determines a position in the optical axis direction of the projection optical system in which the first mark is formed. An exposure method using a scanning exposure apparatus for scanning and moving a first object and a second object in synchronization with a projection optical system and simultaneously projecting a pattern of the first object onto the second object through the projection optical system. Forming a first mark on the first object in which a plurality of marks are arranged in a scanning direction; Fixing a reference plate having a second mark having a plurality of marks arranged in a scanning direction on a movable stage on which the second object is mounted; Positioning a photodetector at a position on the first mark to be projected or projected by the projection optical system; And scanning the first object and the reference plate synchronously with respect to the projection optical system and detecting the first mark image through the second mark by the photodetector. . 8. The exposure method according to claim 7, wherein the detecting step changes the position of the reference plate in the optical axis direction of the projection optical system to detect the first mark image through the second mark by the photodetector. . 9. The method according to claim 8, wherein the first mark is determined by the projection optical system based on the position of the first and second marks when the first mark image is detected through the second mark by the photodetector. And determining a position to be projected or projected onto the second mark. The projection according to claim 8, wherein the projection is based on a signal detected by the photodetector through the second mark and the position of the reference plate in the optical axis direction when the signal is detected. And determining the position in the optical axis direction in which the first mark is imaged through optics. A device manufacturing method using a scanning exposure apparatus which scan-moves a reticle and a wafer in synchronization with a projection optical system and simultaneously projects a pattern of the reticle onto the wafer through the projection optical system, wherein the scanning direction is formed on the reticle in a scanning direction. Forming a reticle mark in which a plurality of marks are arranged; Fixing a reference plate having a wafer mark having a plurality of marks arranged in a scanning direction on a movable stage on which the wafer is mounted; Positioning a photodetector at a location on the reticle mark to be projected or projected by the projection optical system; And scanning the reticle and the reference plate synchronously with respect to the projection optical system and detecting the reticle mark image through the wafer mark by the photodetector.