JPH0722099B2 - Accuracy inspection method and exposure apparatus having the inspection function - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an exposure apparatus for transferring a pattern image of a mask, a reticle or the like onto a photosensitive substrate by a step-and-repeat method, a so-called stepper accuracy inspection method. And an exposure apparatus having a self-diagnosis (self-check) function by the method.

(Background of the Invention) In recent years, a large number of reduction projection type exposure apparatuses, so-called steppers, have been used in VLSI manufacturing lines. The role of the stepper is to create a resist pattern with a defined line width at a defined position on the silicon wafer. High-precision alignment technology is required to achieve this "defined position," and a high-resolution reduction projection lens is required to achieve the "defined line width." It In the case of a stepper, as elements related to alignment, alignment of an exposure image with respect to a coordinate system in an exposure field (shot) of a projection optical system, a step feed mechanism of a wafer stage, and a shot (chip) array formed by an alignment system The exposure image can be roughly aligned with the coordinate system of The image alignment error with respect to the coordinate system in the exposure field includes factors such as a magnification error of the projection optical system, distortion (image distortion) of the optical system, and a rotation error when the reticle is mounted. The positioning error with respect to the coordinate system of the chip array is due to stage stepping error, alignment error, wafer stage rotation error, etc.When global wafer alignment is performed, the stage scaling error, orthogonality, straightness, etc. Errors such as degrees are also included. Any alignment error causes a decrease in accuracy of overlay exposure for forming a plurality of layers on a wafer in an overlapping manner. Therefore, conventionally, in order to inspect the overlay accuracy of an exposure apparatus, overlay exposure is performed on a wafer for trial baking using two reticles having an actual circuit pattern or reference marks, and the wafer is exposed. After developing the resist pattern remaining on the wafer, another highly accurate inspection device,
(Line width measuring device, etc.) was used to measure the overlay accuracy. In this case, it is essential to use a highly accurate inspection device. Such an inspection device is expensive, and unlike a manufacturing device such as a stepper, it is not always operated. However, when a semiconductor element manufacturing line using a stepper is created, an inspection device is required to be attached to the line, resulting in high cost. Further, when trying to control the accuracy at the time of overlay exposure based on the overlay error measured by the inspection device, it becomes very troublesome, and not only the accuracy of the stepper but also the inspection device has to be managed. Therefore, a simpler method of inspection has been desired.

Furthermore, when overlay exposure is performed by trial baking, two reticles are required, and the patterns (reference marks, etc.) formed on each of the two reticles have an alignment error and line width error, and reticle replacement. Since the reticle alignment error and the like accompanying the above are included in the overlay accuracy, there is also a problem that the overlay accuracy inherent in the exposure apparatus cannot be accurately inspected.

(Object of the Invention) The present invention provides a method for accurately inspecting overlay accuracy, that is, alignment accuracy and stepping accuracy of a step-and-repeat type exposure apparatus, and a sensor for alignment provided in the exposure apparatus itself. It is an object of the present invention to obtain an exposure apparatus having a function capable of easily performing an accuracy inspection using only the above.

(Summary of the Invention) The present invention provides a two-dimensionally movable stage and an alignment sensor (X-LSA system, which detects an alignment mark formed on a photosensitive substrate held on the stage.
Y-LSA system) and a method for inspecting the accuracy of an apparatus (stepper) that sequentially exposes a pattern image of a mask on a photosensitive substrate in the first exposure step of exposing alignment marks on the mask on the photosensitive substrate. (Steps 100; 110), and the alignment mark of the mask and the photosensitive substrate by a predetermined amount (Δx, Δy) with respect to the exposed position on the photosensitive substrate of the arc image formed by the first exposure process. Exposure step (steps 103, 10)
4; 111,112) and alignment sensor (X-LSA system,
Y-LSA system) for measuring a positional error between the mark images formed in the first exposure process and the second exposure process (steps 106; 114), and alignment accuracy according to the measured positional error. Storing in the exposure apparatus (step 107;
115) is included as a technical point.

Furthermore, the present invention comprises a stage (3) capable of two-dimensional movement,
An alignment sensor (X-LSA system and Y-LSA system) for detecting alignment marks formed on the photosensitive substrate (wafer WA) held on the stage is provided, and a mask pattern image is formed on the wafer WA. In a device (stepper) that positions and exposes at a desired position of the mask, a holding unit (reticle holder) that holds a mask (reticle R ₁ ) having an original image pattern (pattern area PA) for forming the mark on the wafer WA. And the pattern area PA
Of the first mark (KX ₁ , KY ₁ , MX,
First exposure control means (step 100) for forming MY),
The first mark (MX, MY) is the alignment sensor (X
-LSA system, Y-LSA system) to detect the exposure position by the first exposure control means (step 100), and the detected exposure position in advance. The images of the pattern area PA of the reticle R ₁ and the wafer WA are shifted relative to each other by a predetermined amount (Δx, Δy), and superimposed exposure is performed, and the second mark (KX ₂ , KY ₂ ) is formed on the wafer WA. Second exposure control means (step 10)
3,104) and alignment sensor (X-LSA system, Y-LS
Interval measuring means (step 106) for measuring the interval (Δx ′, Δy ′) between the second marks (KX ₂ , KY ₂ ) of the first marks (KX ₁ , KY ₁ ) in cooperation with the A system), and Interval (Δx ′, Δ
The technical point is to provide accuracy detection means (step 107) for detecting the difference between y ′) and the shift amount (Δx, Δy) as the alignment accuracy.

Furthermore, the present invention is an apparatus that comprises the stage and an alignment sensor, and sequentially positions and exposes a pattern image of a mask at a desired position on a wafer WA, wherein the reticle holder and the stage are stepped to form an original image pattern. First exposure control means (step 110) for sequentially exposing the images to design positions on the wafer WA to form _first marks (KX ₁ , KX ₂ ), and stepping the stage to the design positions. Predetermined amount (Δ
x, Δy) second exposure in which the original image pattern image of the reticle and the wafer WA are relatively re-exposed to form a _second mark (KX ₂ , KY ₂ ) on the wafer WA. Control means (steps 111 and 112) and alignment sensor (X
-LSA system, Y-LSA system) and an interval measuring means (step 114) for measuring the interval (Δx ', Δy') between the first mark and the second mark, and the interval (Δx ', Δy'). The technical point is to provide accuracy detection means (step 115) for detecting the difference between the shift amount (Δx, Δy) as the positioning accuracy of the stage itself.

(Embodiment) FIG. 1 is a flow chart schematically showing the procedure of a checking method according to an embodiment of the present invention, and FIG. 2 shows a reduction projection type exposure apparatus (stepper) suitable for carrying out the method. FIG. 3 is a perspective view showing a schematic configuration, and FIG. 3 is a plan view showing the arrangement of the alignment sensor of the stepper on the wafer surface (imaging plane of the projection lens).

First, the structure of the stepper of this embodiment will be described with reference to FIG.

The reticle R, which is the projection original plate, is positioned so that its projection center passes through the optical axis of the projection lens 1, and is mounted on a reticle holder (not shown). Projection lens 1 is reticle R
The circuit pattern image drawn in 1 is reduced to 1/5 or 1/10 and projected on the wafer WA. Wafer holder 2 is a wafer
It is provided so as to be capable of minute rotation with respect to the stage 3 which sucks WA in a vacuum and moves two-dimensionally in the x direction and the y direction. The movement of the stage 3 in the x direction is performed by driving the motor 5, and the movement of the stage 3 in the y direction is performed by driving the motor 6. A reflection mirror 7 having a reflection plane extending in the y direction and a reflection mirror 8 having a reflection plane extending in the x direction are fixedly provided on two sides of the stage 3 which are orthogonal to each other. A laser light wave interferometer (hereinafter simply referred to as a laser interferometer) 9 projects laser light onto a reflection mirror 8 to detect the position (or movement amount) of the stage 3 in the y direction, and the laser interferometer 10 reflects the laser light. Laser light is projected onto the mirror 7 to detect the position (or movement amount) of the stage 3 in the x direction. Off-axis type wafer alignment microscopes (hereinafter referred to as WAMs) 20 and 21 are provided on the side of the projection lens 1 in order to detect (or observe) alignment marks on the wafer WA. .
The WAM 21 is located after the projection lens 1 in FIG. 1 and is not shown. WAM20 and 21 are the optical axes of the projection lens 1, respectively
A band-shaped laser spot light YSP, θSP having an optical axis parallel to AX and elongated in the x direction is imaged on the wafer WA. (The spot light YSP is not shown in FIG. 1.) These spot lights YSP and θSP are the photosensitizer (photoresist) on the wafer WA.
Is a light having a wavelength that does not cause the light to be exposed to light. The WAMs 20 and 21 each have a photoelectric element that receives scattered light or diffracted light from the mark and a circuit that synchronously rectifies the photoelectric signal at the oscillation cycle of the spot light, and the spot light θSP (YSP) vibrates in the y direction. An alignment signal corresponding to the amount of deviation of the mark in the y direction from the center is output. Therefore, the WAMs 20 and 21 have the same structure as a so-called spot light vibration scanning type photoelectric microscope.

Now, in this device, laser step alignment (hereinafter referred to as LSA) that detects a mark on the wafer WA via the projection lens 1 is used.
Optical system is provided. A laser beam LB generated from a laser light source (not shown) and passing through an expander (not shown), a cylindrical lens, etc. is a light having a wavelength that does not expose the photoresist to light, and is incident on the beam splitter 30 to be split into two light beams. It One of the laser light fluxes is reflected by a mirror 31, passes through a beam splitter 32, and is converged by an imaging lens group 33 so as to be a spot light having a belt-shaped cross section. Then, the reticle R and the projection lens 1 are converged. And a first folding mirror 34 arranged so as not to block the projection optical path of the circuit pattern. The first folding mirror 34 reflects the laser light beam upward toward the reticle R. The laser beam is provided below the reticle R and has a reflecting plane parallel to the surface of the reticle R.
The light enters the lens 35 and is reflected toward the center of the entrance pupil of the projection lens 1. The laser light flux from the mirror 35 is converged by the projection lens 1 and imaged on the wafer WA as a strip-shaped spot light LYS elongated in the x direction. The spot light LYS is used to relatively scan the diffraction grating-shaped mark extending in the x direction on the wafer WA in the y direction and detect the position of the mark. When the spot light LYS illuminates the mark,
Diffracted light is generated from the mark. The optical information returns to the projection lens 1, the mirror 35, the mirror 34, the imaging lens group 33, and the beam splitter 32, is reflected by the beam splitter 32, and enters the optical element 36 including a condenser lens and a spatial filter. . The optical element 36 transmits the diffracted light (first-order diffracted light or second-order diffracted light) from the mark, blocks the specularly reflected light (zero-order light), and receives the diffracted light through the mirror 37 by the photoelectric element 38. Focus on the surface. The photoelectric element 38 outputs a photoelectric signal according to the amount of condensed diffracted light. Above, the mirror 31, the beam splitter 32, the imaging lens group 33, the mirror
34, 35, optical element 36, mirror 37, and photoelectric element 38 constitute a through-the-lens type alignment optical system (hereinafter referred to as Y-LSA system) that detects the position of the mark on the wafer WA in the y direction. To do.

On the other hand, another laser beam split by the beam splitter 30 is a through-the-lens type alignment optical system (hereinafter, X-LS) for detecting the position of the mark on the wafer WA in the x direction.
It is called A system). The X-LSA system is composed of a mirror 41, a beam splitter 42, an imaging lens group 43, mirrors 44 and 45, an optical element 46, a mirror 47, and a photoelectric element 48, just like the Y-LSA system. A strip-shaped spot light LXS elongated in the y-direction is imaged on.

The main controller 50 uses the photoelectric signals from the photoelectric elements 38 and 48, WAM2
The alignment signals from 0 and 21 and the position information from the laser interferometers 9 and 10 are input to perform various arithmetic processes for alignment and output commands for driving the motors 5 and 6. . The main control device 50 includes an arithmetic processing unit such as a microcomputer or a minicomputer, and the arithmetic processing unit includes software for controlling the device for measuring overlay accuracy (positioning accuracy) and accuracy calculation. Software, etc. are included.

Mark position detection by the LSA system is disclosed in, for example, JP-A-59-18720.
The DC photometric method as disclosed in Japanese Patent No. 8 is used. This is to sample the photoelectric signal according to the intensity of the diffracted light from the photoelectric elements 38 and 48 with the pulse for measuring the distance that is output from the laser interferometers 9 and 10 each time the unit movement of the stage 3 (for example 0.02 μm) , Its sampling value (light intensity)
Are sequentially stored in the memory. Then, the center position of the mark is detected by calculation from the data of the intensity distribution waveform of the diffracted light stored in the memory. In this detection method, it is not necessary to position and stop the stage 3 so that the spot lights LYS and LXS coincide with the mark, but simply move the stage 3 so that the mark is relatively scanned once by the spot lights LYS and LXS. The position of the mark (the position of the stage 3 when the spot light and the mark match) can be detected only by itself.

FIG. 3 shows the positional relationship between the WAMs 20 and 21 and the spot lights θSP, YSP, LYS, and LXS of the Y-LSA system and the X-LSA system on the image plane (the same as the surface of the wafer WA) of the projection lens 1. It is a top view. In Fig. 3, the coordinate system with the optical axis AX as the origin
When xy is defined, the x-axis and the y-axis represent the moving direction of the stage 3, respectively. In FIG. 3, a circular area centered on the optical axis AX is an image field if, and a rectangular area inside thereof is a projected image Pr of the effective pattern area of the reticle R. The spot light LYS is projected image P in the image field if.
The spot light LXS is formed so as to coincide with the x-axis at a position outside r, and the spot light LXS is also projected within the image field if.
It is formed so as to coincide with the y-axis at a position outside r. On the other hand, the vibration centers of the two spot lights θSP, YSP are aligned on a line segment (parallel to the x-axis) l that is separated from the x-axis by the distance Yo in the y-direction, and the distance Dx in the x-direction is equal to the wafer WA
It is set to be smaller than the diameter of. In this device, the spot lights θSP, YSP are arranged symmetrically with respect to the y-axis, and the main control device 50 stores information on each position of the spot lights θSP, YSP with respect to the projection point of the optical axis AX. The main controller 50 also stores information about the center position of the spot light LYS in the x direction (distance X1) and the center position of the spot light LXS in the y direction (distance Y1) with respect to the projection point of the optical axis AX.

These pieces of position information serve as reference values for controlling the moving position of the stage 3 during the inspection of overlay accuracy.

Next, a method for checking the overlay accuracy of the apparatus using the apparatus shown in FIG. 2 will be described with reference to FIG. Each step of the flowchart of FIG. 1 is executed by main controller 50. Prior to inspection, prepare reticle R ₁ as shown in FIG. When the coordinate system xy is defined with the center of the pattern area PA of the reticle R ₁ as the origin, the wafer is attached to the x-axis and the y-axis around the pattern area PA, respectively.
Diffraction grating marks RY and RX that are projected and exposed on the WA are formed. Further, diffraction grating marks KY and KX are similarly formed on the x-axis and y-axis at the center of the pattern area PA. The diffraction grating marks KY and KX have exactly the same shape and dimensions as the marks RY and RX. Such a reticle R ₁ is attached to a reticle holder (not shown) of a stepper as shown in FIG. 1, and an optical axis AX of the projection lens 1 passes through the center of the pattern area PA using a reticle alignment sensor (not shown). Position the reticle R ₁ .

Next, a wafer WA having a photoresist coated on the surface of bare silicon or the like is vacuum-sucked at a predetermined position on the wafer holder 2 and, as shown in step 100, a pattern area of the reticle R ₁ is formed by the step-and-repeat method. The images of PA (marks KY, KX) and marks RY, RX are exposed on wafer WA as a first print (first layer transfer). afterwards,
When the wafer WA is developed, areas PA ′ having a resist pattern corresponding to the pattern area PA are formed in a matrix on the wafer WA. One area PA '
When magnified, the diffraction grating marks MX and MY (transferred images of marks RX and RY) in which minute irregularities due to the resist pattern are gathered
Are formed around the area PA ′, and diffraction grating marks KX ₁ and KY ₁ (transferred images of the marks KX and KY) are formed in the center of the area PA ′, in which fine irregularities due to the resist pattern are gathered. still,
The mark arrangement on the wafer WA is reversed horizontally and vertically with respect to the mark arrangement on the reticle R ₁ because the projection optical system is used.

Next, as shown in step 101, the wafer WA is coated again with photoresist and set at a predetermined position on the wafer holder 2 of the stepper, and each of the marks formed at two distant positions on the wafer WA is removed. , WAM20, 21, position adjustment for adjusting the position of the stage 3 in the xy direction and the rotational position of the holder 2, so-called global alignment, is performed.

Next, step-and-repeat overlay exposure is performed, but the reticle R ₁ is left attached to the stepper in the state of step 100. First, as shown in step 102, prior to the overlay exposure on one pattern area PA ′, the spot light LXS and the mark MX are relatively scanned in the x direction by the X-LSA system, and the spot light LXS and the mark MX are scanned. X in stage 3 when and match
Direction Ax is detected, then the spot light LYS by the Y-LSA system and the mark MY are relatively scanned in the y direction, and the stage 3 when the spot light LYS and the mark MY match
The position Ay in the y direction is detected. This detection position (Ax, Ay)
Are stored in main controller 50.

Next, as shown in step 103, Δx (for example, −20 μm) in the x direction and Δy in the y direction with respect to the detection position (Ax, Ay).
A position (Ax + Δx, Ay + Δy) at which the stage 3 is shifted (offset) by (for example, −20 μm) is calculated.
The shift amounts Δx and Δy may be predetermined minute amounts.
Then, main controller 50 determines that the position of stage 3 measured by laser interferometers 9 and 10 is the calculated position (Ax + Δx, Ay + Δ
y)) to control the motors 5 and 6 to match the stage 3
To position.

Then, at that position, as shown in step 104, the wafer WA
As a second print (second layer transfer) to the reticle
The projected images of R ₁ are overlaid and exposed. Step 102 above,
Step 103 is similarly performed for each area PA ′ of the wafer WA, and exposure is performed by shifting the overlapping position of the projection images of the reticle R ₁ by (Δx, Δy) by the step-and-repeat method.
The exposed wafer WA is developed, and the resist pattern of the reticle R ₁ transferred by the second print is formed. At this time, the mark KX, K of the reticle R ₁ is placed on the wafer WA.
Diffraction grating marks KX ₂ and KY ₂ corresponding to the husband and wife of Y are formed. Here, the mark KX ₂ is displaced from the previously formed mark KX ₁ by Δx ′ in the x direction, and the mark KY ₂ is displaced from the previously formed mark KY ₁ by Δy ′ in the y direction. Shall be located.

The wafer WA on which such a resist pattern is formed is
As shown in step 105, the holder 2 is set again at a predetermined position and global alignment is performed.

Next, as shown in step 106, main controller 50 moves stage 3 to mark X-LSA system spot light LXS and mark.
KX ₁ and KX ₂ are relatively scanned, and the intensity distribution waveform in the x direction of the diffracted light from each of the marks KX ₁ and KX ₂ is captured. Then, the distance Δx ′ between the _two marks KX ₁ and KX _{2 in} the x direction is calculated from this intensity distribution waveform. Similarly, the Y-LSA system is used to calculate the distance Δy ′ in the y direction between the _two marks KY ₁ and KY ₂ .

Next, main controller 50, as shown in step 107, shifts Δx and Δy in design and intervals Δx ′ and Δ as measured values.
The absolute value of the deviation from y'is obtained. This deviation is the overlay accuracy (or alignment accuracy) during overlay exposure.
Is. This accuracy is stored in the main controller 50 and used as management data during actual semiconductor device manufacturing.

As described above, in this embodiment, a pair of marks is provided on the central portion of the reticle R _1.
Although only KX and KY are provided, if a pair of marks KX and KY are provided at a plurality of positions in the pattern area PA, the wafer WA
The overlay accuracy can be measured at a large number of points in the upper area PA ′, and the distortion of the projection lens 1 can be detected because the accuracy of each point in the area PA ′ is different. Alternatively, the overlay accuracy may be obtained for each of the plurality of areas PA ′ on the wafer WA, and then the average deviation (δ value) may be obtained.

According to this embodiment, the first print and the second print
Since the reticle is not exchanged with the print and the reticle is still attached to the device, it is caused by the alignment error including the mark position detection error by the X-LSA system and the Y-LSA system and the positioning error of the stage 3. The overlay accuracy can be evaluated.

Further, in this embodiment, the marks MX and MY are detected during the wafer WA alignment at the second point, but the same effect can be obtained by detecting the marks KX ₁ and KY ₁ for accuracy measurement.
However, since the marks MX and MY around the pattern area PA ′ as shown in FIG. 1 are the same as the mark driving arrangement at the time of manufacturing the actual element, the marks MX and MY are detected as in this embodiment. Performing the alignment by performing the alignment means reproducing the alignment state at the time of manufacturing the actual element as it is,
There is an advantage that a more practical accuracy check can be performed.

Further, in this embodiment, as shown in step 103,
Although the shifting directions are the same, different areas on the wafer WA
It is also possible to perform overlay exposure by changing the shift direction or shift amount for each PA ', then obtain the accuracy for each area PA', and obtain the average thereof. The alignment sensor is not limited to the method of this embodiment, and any type of alignment sensor can be used as long as it can be attached to the stepper and can detect the wafer mark. can get. Further, if it is a stepper system, it can be similarly implemented in a proximity system X-ray exposure apparatus.

Next, a stepping accuracy inspection method according to the second embodiment of the present invention will be described with reference to the flow chart shown in FIG. The reticle prepared for this inspection may be exactly the same as that shown in FIG. 1, but a light-shielding area is formed around the marks KX, KY with a predetermined size.

First, as shown in step 110, the main controller 50 steps the stage 3 based on the shot (chip) array data corresponding to the size of the pattern area PA of the reticle R ₁ to step the projected image of the pattern area PA.・ Wafer WA is exposed by the and repeat method. After the exposure is completed, the reticle R ₁ and the wafer WA are left as they are. As a result, latent images of the marks KX and KY are formed in the photoresist.

Then, as shown in step 111, main controller 50 performs a calculation for correcting the position of each shot of the shot array data used in step 110 by Δx and Δy in the x and y directions, respectively. The shift amounts Δx and Δy are predetermined values,
It is stored in the main controller 50.

Next, main controller 50 steps step 3 in accordance with the shot arrangement data modified as shown in step 112 to project the projected image of pattern area PA of reticle R ₁ into the latent image in the photoresist on wafer WA. And re-expose it so that At this time, the periphery of the latent image corresponding to the marks KX, KY exposed in step 110 is an unexposed portion, and the projection image of the marks KX, KY is exposed in this unexposed portion in step 112. become. When the re-exposure to the wafer WA is completed, the wafer WA is unloaded from the stepper and developed. Shot area PA 'on wafer WA after development
In each of the above, the marks KX ₁ and KY ₁ transferred in step 110 and the marks KX ₂ and KY ₂ transferred in step 112 are formed at intervals Δx ′ and Δy ′, respectively.

Next, as shown in step 113, the wafer WA is placed at a predetermined position on the holder 2 and global alignment of the wafer is performed.

Then, as shown in step 114, X-LSA system, Y-LSA system
Using the system, the distance Δx ′ between the marks KX ₁ and KX ₂ and the mark KY
Measure the interval Δy ′ between ₁ and KY ₂ .

Next, main controller 50 determines a predetermined shift amount (Δx, Δy) and the measured interval (Δ
The absolute value of the difference between x ′ and Δy ′) is calculated as the stepping accuracy.

According to this embodiment, the laser interferometer, 9, 10 and the motor 5, 6
It is possible to easily inspect the alignment accuracy of the stage 3 controlled by the above, that is, the stepping accuracy.

As described above, according to the present invention, the overlay (positioning) accuracy of the exposure apparatus and the stepping accuracy of the stage can be self-checked without requiring an expensive inspection apparatus, and a reticle (mask for accuracy inspection) can be used. Since it is not necessary to prepare two sheets), the cost for inspection can be reduced. Further, since overlay exposure is performed with only one reticle being set, reticle alignment error is not essentially included, and more precise measurement can be performed.

[Brief description of drawings]

FIG. 1 is a flow chart diagram schematically showing the self-checking procedure of an exposure apparatus according to an embodiment of the present invention, and FIG. 2 shows a schematic configuration of a reduction projection type exposure apparatus suitable for the embodiment of the present invention. FIG. 3 is a perspective view, FIG. 3 is a plan view showing the arrangement of spot light as a wafer alignment sensor on a projection image forming plane, and FIG. 4 is a procedure of self-checking stepping accuracy according to a second embodiment of the present invention. It is a flow chart figure showing typically. [Explanation of symbols of main parts] 1 ... Projection lens, 3 ... Stage 50 ... Main controller, R, R ₁ ... Reticle WA ... Wafer RX, RY, KX, KY ... Mark MX on reticle , MY, KX ₁ , KY ₁ …… first mark KX ₂ , KY ₂ …… second mark

Claims (3)

[Claims] 1. A two-dimensionally movable stage, and an alignment sensor for detecting alignment marks formed on a photosensitive substrate held on the stage, and a mask pattern image is sequentially exposed on the photosensitive substrate. In the method for inspecting the accuracy of the device, a first exposure step of exposing an alignment mark on a mask onto a photosensitive substrate; a mark image formed by the first exposure step at an exposed position on the photosensitive substrate. In contrast, a second exposure step in which the alignment mark of the mask and the photosensitive substrate are shifted relative to each other by a predetermined amount and overlapping exposure is performed; a mark image formed in the first exposure step by the alignment sensor. And a step of measuring a positional error between the two mark images by detecting the mark image formed in the second exposure step; And a step of storing the alignment accuracy corresponding to the generated position error in the exposure apparatus. 2. A two-dimensionally movable stage and an alignment sensor for detecting alignment marks formed on a photosensitive substrate held on the stage, and a mask pattern image is sequentially exposed on the photosensitive substrate. Holding means for holding a mask having an original image pattern for forming the marks on the photosensitive substrate; first exposure control for exposing the image of the original image pattern on the photosensitive substrate to form first marks Means for detecting the exposure position by the first exposure control means by detecting the first mark with the alignment sensor; and a predetermined amount for the detected exposure position. A second exposure controller for forming a second mark on the photosensitive substrate by exposing the original image pattern image of the mask and the photosensitive substrate with relative displacement to each other A step; an interval measuring means for measuring an interval between the first mark and the second mark in cooperation with the alignment sensor; an accuracy detection for detecting a difference between the interval and the predetermined shift amount as alignment accuracy. And an exposure apparatus. 3. A two-dimensionally movable stage, and an alignment sensor for detecting alignment marks formed on a photosensitive substrate held on the stage, and a mask pattern image is sequentially exposed on the photosensitive substrate. Holding means for holding a mask having an original pattern for forming the mark on the photosensitive substrate; stepping the stage to sequentially expose the images of the original pattern at designed positions on the photosensitive substrate. First exposure control means for forming a first mark; stepping the stage to relatively shift the original image pattern image of the mask and the photosensitive substrate by a predetermined amount with respect to the design position. Second exposure control means for sequentially re-exposing at different positions to form a second mark on the photosensitive substrate; An interval measuring means for measuring an interval between the first mark and the second mark; and an accuracy detecting means for detecting a difference between the interval and the predetermined shift amount as an alignment accuracy of the stage unit. An exposure apparatus characterized by the above.