JPH11243053A - Projection exposure device and projection exposure method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the alignment accuracy on a photosensitive substrate of a projection image or the alignment accuracy in overlapped exposure excellent by setting the illumination region for position alignment on a mask with an opening, which is smaller than the opening for setting the illumination region on the mask. SOLUTION: When the image of a circuit pattern is transferred on the specified image forming surface, the illumination region of a mask is set with the first opening. When the positioning pattern provided on the mask is detected, the illumination region including the positioning pattern is set with the second opening, which is smaller than the first opening. At this time, the mark for die-by-alignment provided on a reticle 12 and the inverse projection image by a projection lens 21 of the mark for die-by die alignment are overlapped and observed. A step alignment microscope 11 for this purpose is arranged in the exposed optical path directly over the reticle 12 so that advance and retreat can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for projecting and exposing an image of a pattern formed with a mask on a photosensitive substrate from a projection optical system, for example, an exposure apparatus, a method and a circuit manufacturing method of a step-and-repeat system. .

[0002]

2. Description of the Related Art In recent years, a large number of reduction projection type exposure apparatuses, so-called steppers, have been used in the manufacture of semiconductor devices such as VLSI. The stepper accurately sets a reticle on which a circuit pattern or the like has been drawn at a predetermined position of the apparatus, and moves the stage on which a semiconductor wafer as a photosensitive substrate is mounted in xy
The projection of the circuit pattern is repeatedly performed by stepping the circuit pattern in the direction by a fixed amount. In this case, the exposure image by the projection lens as the projection optical system needs to be precisely aligned with a predetermined position on the wafer. An off-axis alignment method is known as this alignment method.

[0003] The off-axis alignment method is a method in which an alignment mark on a wafer is detected by using a wafer alignment microscope separately provided at a position different from a projection lens, and the wafer is aligned with the microscope. The wafer (stage) is moved by a fixed amount based on the position and is sent below the projection lens, where exposure is performed by a step-and-repeat method. In this case, unless the distance between an arbitrary point on the wafer and the projection position of the reference point on the reticle is determined accurately, overlay exposure with high accuracy cannot be performed. In order to accurately determine the distance, the optical axis position of the off-axis microscope and
An observation system for detecting the position of a reference point (such as an alignment mark) on the reticle, that is, the distance between the optical axis position of a so-called reticle alignment microscope (hereinafter referred to as a baseline measurement value) is correctly measured. It is assumed that
Baseline measurement uses fiducial marks provided on the stage, and the position of the stage when the off-axis wafer alignment microscope detects the fiducial mark, and the reticle alignment microscope uses the fiducial mark through the projection lens. The position of the stage at the time of detection is measured by using a laser light wave interferometer (hereinafter, referred to as a laser interferometer) for measuring the stage position.

In general, a reticle alignment microscope is used when aligning a reticle prior to an exposure operation on a wafer. The reticle alignment microscope irradiates the entire surface of the reticle with illumination light for exposure, and a reference provided near the reticle. This is for observing the image of the reticle alignment mark as a point. At the time of this reticle alignment, placing a wafer on the stage is prohibited. As described above, in the type in which the illumination light for exposure is applied to the entire surface of the reticle at the time of reticle alignment, the illumination light similarly irradiates the reference mark on the stage via the projection lens also at the time of the above-described baseline measurement. Then, the image of the reference mark is observed again by the reticle alignment microscope via the projection lens.

In this type of projection lens, when illumination light for exposure is incident, a part of the light is absorbed as heat, and imaging characteristics such as a focal position and an imaging magnification change. Therefore, when a large amount of illumination light for exposure is incident on the projection lens at the time of baseline measurement or reticle alignment, there is a disadvantage that the accuracy of the measured baseline measurement value or the reticle alignment accuracy deteriorates. .

[0006]

SUMMARY OF THE INVENTION The present invention solves these drawbacks and enhances the accuracy of baseline measurement values and the accuracy of reticle alignment, thereby improving the alignment accuracy of a projection image to be exposed on a photosensitive substrate or superposition. An object of the present invention is to provide a projection exposure apparatus, a method, and a circuit manufacturing method with improved alignment accuracy and the like in exposure.

[0007]

In order to solve the above-mentioned problems, the present invention provides a projection optical system for forming an image of a pattern formed on a mask on a substrate; A projection exposure apparatus comprising: an illumination optical system for illuminating light; and a detection optical system for optically detecting an alignment pattern provided on a mask or an alignment pattern formed on a substrate. , An energy adjusting means for adjusting the energy incident on the projection optical system is provided, and the energy adjusting means is operated while the detection optical system is detecting the alignment pattern.

[0008] Further, an illumination area adjusting means for changing an area on the mask including the positioning pattern is provided.

[0009]

FIG. 1 is a diagram showing a schematic configuration of a reduction projection type exposure apparatus according to an embodiment of the present invention. Light from a mercury lamp 1 as a light source is collected by an elliptical mirror 2 and reflected by a dichroic mirror 3 before reaching a rotary shutter having four blades. The luminous flux passing through the shutter 4 is an optical beam including a fly-eye lens and the like.
The light enters the integrator 5 and forms a number of secondary light source images. The light emitted from the optical integrator 5 is
The light is reflected by the dichroic mirror 6 and enters the main condenser lens 7. Below the condenser lens 7, a reticle blind 8 as an illumination field stop having four independently movable blades is provided.

The light from the condenser lens 7 uniformly illuminates the reticle 12 as a mask with uniform light intensity.
A reticle alignment microscope (hereinafter, referred to as R-Mic) 9 as a detection optical system for aligning the reticle 12 with respect to the apparatus main body is provided between the condenser lens 7 and the reticle blind 8. FIG.
Although only the R-Mic 9 is shown in the figure, a two-dimensional displacement between the x direction of the reticle 12 and the y direction orthogonal to the reticle 12 is actually detected by the microscope Rxy- for detecting the cross mark of the reticle 12. Two microscopes are provided: a Mic 9a and a microscope Rθ-Mic 9b for detecting a linear mark provided at a position different from the cross-shaped mark and calculating a displacement in the rotation direction of the reticle 12.

An image of a circuit pattern or the like drawn on the reticle 12 is formed by a reduction projection lens 21 on a predetermined image plane. The wafer 16 located in the image plane is x,
The stage 17 is held on a stage 17 that moves two-dimensionally in the y direction, and the stage 17 is driven by a motor 19. The coordinate position of the stage 17 is always measured by the laser interferometer 18. A mark plate 15 having a reference mark FM used for measuring a baseline between various alignment microscopes is fixed on the stage 17. The mark plate 15 is formed by forming a light-reflective layer of chrome or the like on the surface of a glass substrate and etching a part of the layer to provide a reference mark FM. At the time of baseline measurement, the surface of the mark plate 15 is adjusted in the height direction so as to coincide with the image plane of the projection lens 21.

Further, the apparatus according to the present embodiment has a reticle 12
The die-by-die alignment mark provided on the wafer 16 and the die-by-die alignment mark provided on the wafer 16 are provided.
A step alignment microscope (hereinafter, referred to as S-Mic) 11 for superimposing and observing a back projection image (enlarged image) of the alignment mark by the projection lens 21.
Are disposed in the exposure optical path immediately above the reticle 12 so as to be able to advance and retreat. Although only one S-MiCII is shown in FIG. 1, each of the x-direction spup mark and the y-direction step mark provided at two different positions on the reticle 12 is separately detected. , Microscope Sx-Mi
Two are provided, c11a and microscope Sy-Mic11b.

The projection lens 2 is located below the reticle 12.
1 forms a sheet-like spot light in the image forming plane of the projection lens 21 by irradiating the laser light flux 29 into the laser light flux 1, and optical information generated when the spot light irradiates a mark on the wafer 16 ( A laser step alignment system (hereinafter, referred to as LS) 35 that receives diffracted light, scattered light, and the like via the projection lens 21 and detects the position of the wafer 16 is provided. The LS system 35 also actually generates a spot light extending in the x direction, and
It comprises two sets of a Y-LS system 35a for detecting the position in the direction and an x-LS system 35b for generating a spot light extending in the y direction and detecting the position of the wafer 16 in the x direction. The wavelength of the laser beam 29 of the LS system 35 is set so as not to expose the photoresist applied to the wafer 16.

Now, three wafer alignment microscopes (hereinafter referred to as W-Mic) 13 are provided around the projection lens 21 for off-axis wafer alignment.
a, 13b and 13c are provided at predetermined intervals. However, the W-Mic 13c is not shown in FIG. The arrangement of the three W-Mics 13a, 13b, 13c is disclosed in detail in Japanese Patent Application Laid-Open No. 56-102823, and will not be described here.

The above R-Mic 9a, 9b, S-Mic1
1a, 11b, LS system 35, and W-Mic13a,
Each of the alignment sensors 13b and 13c includes a photoelectric element for outputting a photoelectric signal corresponding to the mark detected by each of the alignment sensors.
Enter 0. The unit 20 detects a position shift of the mark detected by each alignment sensor, and controls the motor 19 and the like so that the position shift is corrected or the stage 7 is positioned at a predetermined position. The unit 20 controls opening and closing of the shutter 4 and also inputs coordinate position information from the laser interferometer 18.

FIG. 2 is a plan view schematically showing the relationship between the arrangement of the alignment sensors on the image plane and the projected image of the reticle 12. As shown in FIG. In FIG. 2, a circular area indicated by a broken line is an image field If of the projection lens 21.
, And a square area having substantially the same size is the outer shape of the reticle 12. Pattern area PA of reticle 12
Is determined so as to fit within the image field If. The coordinate system x is set so that the center of the image field If, that is, the optical axis of the projection lens 21 is the origin CC.
When y is determined, the detection center 90a of the Rxy-Mic 9a is located on the x axis, and the detection center 90b of the Rθ-Mic 9b is located on the y axis.

The detection center 90a is a two-dimensional center of the index mark in the Rxy-Mic 9a sandwiching the cross mark on the reticle 12, and the detection center 90b is a line extending in the x direction on the reticle 12. It is the center of the index mark in Rθ-Mic 9b that sandwiches the shape mark.
However, an optical axis correction mechanism for displacing the detection center 90b by a small amount in the y direction and adjusting the distance Y1 in the y direction from the detection center 90a is incorporated in the Rθ-Mic 9b. Further, Sx-Mic 11a is located on the y-axis on the opposite side of the origin CC of Rθ-Mic 9b, and Rxy-Mic 9b
On the opposite side of the origin CC of Mic9a, Sy-Mic
11b is located on the x-axis. Further, in the image field If and on the x-axis outside the pattern area PA, a sheet-like spot light S by the Y-LS system 35a is provided.
Py is positioned to be elongated in the x direction, and similarly, on the y axis outside the pattern area PA, the spot light SPx by the X-LS system 35b is positioned to be elongated in the y direction.
The W-Mic 13a has a detection center 130y for detecting the position of the mark extending in the x direction on the wafer 16 or the mark plate 15 in the y direction. Are located only on the y-axis at a distance. Similarly, the W-Mic 13b has a detection center 130 for detecting the position of the mark extending in the y direction.
The center 130x is located on the x-axis separated from the detection center 90a by Wx in the x-direction.

The W-Mic 13c is a W-Mic 13a.
W-Mic
In cooperation with 13a, two distant marks on the wafer 16 are simultaneously observed to detect a rotation error of the wafer 16. A cross-shaped reference mark FM as shown in FIG. 2 is provided on the surface of the mark plate 15 on the stage 17, and linear marks extending in the y direction are denoted by FMx and x.
A linear mark extending in the direction is defined as FMy. The fiducial mark FM has a detection center 90a of each alignment sensor,
90b, 130y, 130x, 130θ and spot light S
Px, SPy, Sx-Mic11a, Sy-Mic
11b, it moves around as detected by each alignment sensor during baseline measurement.

FIG. 3 is an optical arrangement diagram showing a specific configuration of the reticle alignment microscope R-Mic9 in the above-described apparatus. A prism block G0 is provided at the tip of the R-Mic 9, and illumination light LB from the condenser lens 7 is provided.
Is transmitted through the prism block G0 and the reticle 1
Illuminate 2. The light from the mark on the pattern surface PT of the reticle 12 is reflected by the inclined surface g of the prism block G0, then enters the first objective lens G1 to become parallel light, and is formed into a predetermined image plane FP by the second objective lens G2. Converges to
An enlarged image of the mark is formed. A glass plate waiting for an index mark representing the detection center 90a or 90b as shown in FIG. 2 is disposed on the image forming plane FP, and further behind the index plate and the index mark (not shown) on the reticle 12 are arranged. An eyepiece (TV camera) for superimposing and observing marks and the like, a photoelectric element for photoelectrically detecting a shift between the index mark and the reticle mark, and the like are provided.

In FIG. 3, the dashed line 11 is RM
represents the optical axis of ic9, and the solid line 12 represents the principal ray. The principal ray 12 is determined so as to pass through the center of the entrance pupil of the projection lens 21. The R-Mic 9 is configured to focus on the pattern surface PT of the reticle 12. Therefore, when the reference mark FM is located in the image plane of the projection lens 21, the image is transmitted through the projection lens 21 to the pattern plane P
As a result, the image of the reference mark FM is formed in focus on the imaging plane FP of the R-Mic 9.
In the system shown in FIG. 3, the optical axis of the Rxy-Mic 9a is fixed to the device, but the Rθ-Mic 9a
For b, the optical axis correction mechanism as described above is incorporated.

Next, a series of flows of the baseline measurement of this embodiment will be described. In the present embodiment, it is assumed that the shutter 4 is used as a dimming unit when the reticle alignment microscope is used. In the apparatus shown in FIGS. 1 to 3, the management of the baseline measurement value is performed by the Rxy-Mic shown in FIG.
The detection center 90a of 9a serves as a reference. First, reticle 12
Is set on the device. At this time, the reticle 12 is positioned so that the cross mark RM for reticle alignment on the reticle 12 deviates from the index mark indicating the detection center 90a of the Rxy-Mic 9a in a predetermined direction as shown in FIG. Next, the four blades of the reticle blind 8 are almost fully opened as shown in FIG. 3, and the Rxy-Mic 9a and the Rθ-M
Both the ic 9b allow the reticle alignment mark to be observed. Then, as shown in FIG. 5, the shutter 4 is opened halfway.

Conventionally, the shutter 4 is fully opened to allow all of the illumination light beam LB 'to pass therethrough, so that almost the entire surface of the reticle 21 is given the same amount of light as during exposure. However, in this embodiment, the shutter 4 is opened halfway, and the illumination light flux L
Since a part of B 'is made to pass and the rest is shielded from light, the amount of light for illuminating the reticle 21, that is, the amount of light incident on the projection lens 21, is significantly lower than the amount of light at the time of exposure. Here, the half opening of the shutter 4 is not necessarily limited to the meaning that half of the illumination light beam LB ′ passes. The extent to which the light amount (intensity) for illuminating the reticle 12 can be reduced depends on the sensitivity of the photoelectric element in the R-Mic 9. That is, when the mark is detected, the shutter 4 is controlled so that the signal-to-noise (S / N) ratio of the photoelectric signal decreases the illumination light intensity within a necessary range.
Is determined.

Next, the stage 17 is moved and positioned so that the reference mark FM coincides with the detection center 90a of the Rxy-Mic 9a as shown in FIG. The control unit 20 determines the coordinate value (X0, Y
0) is read from the laser interferometer 18 and stored. The coordinate value (X0, Y0) is the projection position of the Rxy-Mic 9a (center 90a) on the moving plane (xy coordinate system) of the stage 17. At this time, the Rxy-Mic 9a detects a back-projected image of the reference mark FM by the projection lens 12 through the transparent portion of the reticle 12. This is R-Mi
This is because c9 is configured to focus on the pattern surface PT on the back surface of the reticle 12.

Next, the control unit 20 moves the stage 17 and places the reference mark FM at a position where the detection center 90b of the Rθ-Mic 9b should be located in design. This is based only on the coordinate values read by the laser interferometer 18,
This is performed by controlling the motor 19. The position of the reference mark FM at this time is determined by the previous coordinate value (X0, Y
0), as shown in FIG. 2, a design interval (X1, Y1) between the detection center 90b and the detection center 90a is added, and is a coordinate value (X0 + X1, Y0 + Y1). When the reference mark FM is positioned, Rθ-Mic
The above-described optical axis correction mechanism is adjusted so that the detection center 90b of the reference mark 9b and the linear mark FMy extending in the x direction of the reference mark FM match in the y direction. As a result, the two reticle alignment microscopes are accurately aligned with respect to the coordinate system of the stage 17.

Next, the detection center 90a of the Rxy-Mic 9a coincides with the mark RM of the reticle 12, and Rθ−
The reticle 12 is finely moved to perform positioning (reticle alignment) so that the detection center 90b of the Mic 9b and another reticle mark coincide with each other. At this time, specifically, the reflection surface of the mark plate 15 without the reference mark FM is
Stage 17 to be within the field of view of Rxy-Mic9a
Is positioned, the cross mark RM is positioned at the detection center 9
The positions of the reticle 12 in the x direction and the y direction are adjusted so as to match 0a. After that, the reflection surface of the mark plate 15 becomes R
With the stage 17 positioned so as to be within the field of view of the [theta] -Mic 9b, the reticle 12 is centered on the mark RM so that the linear mark coincides with the detection center 90b.
Is slightly rotated. By the above operation, reticle 12
Are accurately aligned with respect to the coordinate system of the stage 17.

When the reticle alignment is completed, the shutter 4 blocks the illumination light beam LB '. Until the shutter 4 closes, the illuminating light continues to enter the projection lens 21 via the reticle 12, but since the shirt star 4 is opened halfway, the incident energy itself is remarkably low. Variations in characteristics (focal position, projection magnification, etc.) are kept sufficiently small. If the imaging characteristics fluctuate, errors will occur during various baseline measurements described below. Next, the projection positions of the step alignment microscopes Sx-Mic11a and Sy-Mic11b are detected using the reference marks FM. At this time, since the reticle 12 is already accurately aligned, the step mark SxM provided around the pattern area PA of the reticle 12 can be observed in the field of view of the Sx-Mic 11a as shown in FIG. Located in.
The step mark SxM is formed in a transparent rectangular window shape. Since the projection position of the step mark SxM is known in advance by design, the control unit 20 moves the stage 17 and, as shown in FIG.
Is positioned so that the linear mark FMx extending in the y direction is sandwiched.

More specifically, when the linear mark FMx is positioned within the window of the step mark SxM, the Sx-Mic
Based on the photoelectric signal from the photoelectric element in 11a, the positional deviation Δx1, Δx2 in the x direction within the window of the linear mark FMx.
And the center of the left / right distribution, that is, Δx1 = Δx
The positioning is completed by slightly moving the stage 17 in the x direction so as to be 2. The control unit 20 reads the position X3 of the stage 17 in the x direction at this time from the laser interferometer 18 and stores it. Similarly, Sy-Mic11
b, the step mark SyM on the reticle 12
(Not shown) and the linear mark FMy extending in the x direction of the reference mark FM are aligned, and the stage 17 at that time is aligned.
Is detected in the y direction. Thereby, the baseline measurement value SX of the step alignment microscope Sx-Mic11a is measured as SX = X3-X0,
The baseline measurement value SY of Sy-Mic11b is SY =
This means that the measurement was made as Y3-YO. Note that Δx1
= Δx2, the center position of the step mark SxM can be obtained without driving in the mark FMx.

Next, a laser step alignment system,
Each spot light S of the Y-LS system 35a and the X-LS system 35b
The projection positions of Py and SPx are detected using the reference mark FM. First, as shown in FIG. 7, after the stage 17 is positioned so that the spot light SPx and the linear mark FMx of the reference mark FM are aligned in parallel, the reference mark FM is moved in the x direction as shown by the arrow. The X-LS system 35b performs photoelectric conversion of the light information from the linear mark FMx with the spot light SPx, and the control unit 20 determines, based on the photoelectric signal, x of the stage 17 when the spot light SPx matches the mark FMx. The position X4 in the direction is detected and stored. Similarly, the control unit 20 runs the linear mark FMy of the reference mark FM in the y direction, and detects and stores the position Y4 of the stage 17 in the y direction when the spot light Sy matches the mark FMy. As a result, the baseline measurement value LSY of the laser step alignment system and the Y-LS system 35a is measured as LSY = Y4-Y0,
The baseline measurement value LSX of the X-LS system 35b is LSX
= X4−X0.

Finally, the projection position of the wafer alignment microscope W-Mic 13a, 13b is set to the reference mark F.
M is used for detection. First, the control unit 20 positions the stage 17 so that the linear mark FMy of the reference mark FM coincides with the detection center 130y of the W-Mic 13a, and detects and stores the position Y5 of the stage 17 in the y direction at that time. I do. Next, the control unit 20 positions the stage 17 so that the linear mark FMx coincides with the detection center 130x of the W-Mic 13b, and detects and stores the position X5 of the stage 17 in the x direction at that time. Thereby, the wafer alignment microscope W-Mic13a
Is measured as Wy = Y5-YO, and the baseline measured value Wx of W-Mic 13b is
Is measured as Wx = X5-XO.

The various baseline measurement values (SX, SY), (LSX, LSY), (W
(x, Wy), the positioning and exposure of the wafer 16 are performed by the step-and-repeat method.
As described above, according to the present embodiment, when the reticle alignment microscope is used, the shutter 4 is opened halfway to reduce the energy incident on the projection lens 21, so that the projection lens 21 can be measured during various baseline measurements after reticle alignment. The amount by which the position of the projection point at the detection center of the alignment system (detection optical system) intervening in the XY direction fluctuates extremely in the xy directions is reduced. The effect of improving the accuracy of is obtained.

Next, a second embodiment of the present invention will be described with reference to FIG. In this embodiment, a reticle blind 8 is used as a means for reducing illumination light when a reticle alignment microscope is used. The blind 8 comprises four rectangular blades 8a, 8b, 8c, 8d as shown in FIG.
The blades 8a and 8b can move linearly in the y direction, and the blades 8c and 8d move linearly in the x direction. FIG.
As shown in the figure, a reticle alignment microscope Rxy-M
When using ic9a and Rθ-Mic9b, Rθ-M
The blade 8a located on the ic 9b side is almost fully opened,
The blade 8b located on the opposite side of the Rθ-Mic 9b has an R
The xy-Mic 9a is extended to a position where it does not block the field of view, the blade 8d located on the Rxy-Mic 9a side is almost fully opened, and the blade 8c located on the opposite side of the Rxy-Mic 9a does not block the field of view of the Rθ-Mic 9b. It is extended to the position.

In the case of this embodiment, the incident energy to the projection lens 21 when the reticle 12 is illuminated with the shutter 4 fully opened is approximately one unit smaller than the incident energy when the blind 8 is fully opened. By reducing the aperture to / 4, the image quality is reduced by that amount, and the fluctuation of the image forming characteristic of the projection lens 21 becomes extremely small.

In this embodiment, since the shutter 4 may be fully opened, the Rxy-Mic 9a and the Rθ-Mic 9
Of course, the photoelectric signal from the photoelectric element in b has a high S / N ratio,
The detection accuracy of the mark is accordingly improved. However, with the reticle blind 8 squeezed as shown in FIG.
When the shutter 4 is half-opened as in the first embodiment, the energy incident on the projection lens 21 is significantly reduced, which is more effective.

In addition to the embodiments of the present invention, there is provided a configuration in which a dimming filter is inserted in the illumination optical path from the mercury lamp 1 to the reticle 12 only when the reticle alignment microscope is used. The same effect can be obtained.

[0035]

As described above, according to the present invention, the amount of energy incident on the projection optical system can be reduced while alignment is being performed. Can be small. In addition, since errors due to fluctuations in the imaging characteristics of the projection optical system included in the baseline measurement values of various alignment systems (microscopes, etc.) are reduced, the photosensitive substrate (wafer, etc.) based on the baseline measurement values is reduced. The effect is that the positioning of the image becomes more accurate.

[Brief description of the drawings]

FIG. 1 is a diagram showing a competitive configuration of a reduction projection type exposure apparatus according to an embodiment of the present invention;

FIG. 2 is a plan view showing an arrangement relationship of various alignment sensors of the apparatus shown in FIG. 1 in a projection image plane;

FIG. 3 is an optical arrangement diagram showing a configuration of a reticle alignment microscope,

FIG. 4 is a plan view showing an example of alignment by a reticle alignment microscope,

FIG. 5 is a plan view showing a configuration of a shutter as a dimming unit;

FIG. 6 is a plan view showing an alignment state at the time of base line measurement by a top alignment microscope,

FIG. 7 is a plan view showing an alignment state at the time of baseline measurement by a laser step alignment system;

FIG. 8 is a plan view showing a configuration of a reticle blind as a dimming unit according to a second embodiment of the present invention.

[Explanation of symbols]

1 ... mercury lamp, 4 ... shutter, 8 ... reticle blind, 9 ...
..Reticle alignment microscope as detection optical system, 11 ... Step alignment microscope, 1
2. Reticle 13 Wafer alignment microscope ... . Fiducial mark plate, 16
... wafer, 17 ... stagen 1
8 Laser interferometer, 2 Control unit, 35
Laser step alignment system.

[Procedure amendment]

[Submission date] January 20, 1999

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Name of invention

[Correction method] Change

[Correction contents]

Patent application title: Projection exposure apparatus and projection exposure method

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0001

[Correction method] Change

[Correction contents]

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an apparatus and method for projecting and exposing an image of a pattern formed with a mask on a photosensitive substrate from a projection optical system, for example, an exposure apparatus and method of a step-and-repeat system.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction contents]

[0006]

SUMMARY OF THE INVENTION The present invention solves these drawbacks and enhances the accuracy of baseline measurement values and the accuracy of reticle alignment, thereby improving the alignment accuracy of a projection image to be exposed on a photosensitive substrate or superposition. It is an object of the present invention to provide a projection exposure apparatus and a method that have improved alignment accuracy and the like in exposure.

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction contents]

[0007]

According to the present invention, there is provided an illumination optical system for illuminating a mask having a circuit pattern formed thereon, and an image of the circuit pattern is transferred to a predetermined image forming surface. In a projection optical system and a projection exposure apparatus including a detection optical system that detects a pattern for alignment provided on the mask, when transferring an image of the circuit pattern to the predetermined image forming surface, When an illumination area is set on the mask with the first opening and the pattern for alignment is detected, the position of the position on the mask is reduced by the second opening having a size smaller than that of the first opening. An illumination area setting unit for setting an illumination area including a pattern for alignment is provided.

[Procedure amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction contents]

Further, a mask on which a circuit pattern is formed is illuminated, and an image of the circuit pattern is projected via a projection optical system.
In the projection exposure method for transferring onto a predetermined image forming surface, when transferring the image of the circuit pattern onto the predetermined image forming surface, an illumination area of the mask is set at a first opening and provided on the mask. When detecting a registered pattern for alignment,
An illumination area including the alignment pattern is set in the second opening having a size smaller than that of the first opening.

[Procedure amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction contents]

Further, the apparatus according to the present embodiment has a reticle 12
The die-by-die alignment mark provided on the wafer 16 and the die-by-die alignment mark provided on the wafer 16 are provided.
A step alignment microscope (hereinafter, referred to as S-Mic) 11 for superimposing and observing a back projection image (enlarged image) of the alignment mark by the projection lens 21.
Are disposed in the exposure optical path immediately above the reticle 12 so as to be able to advance and retreat. Although only one S-MiC 11 is shown in FIG. 1, the S-MiC 11 separately detects the x-direction spoop mark and the y-direction step mark provided at two different places on the reticle 12. , Microscope Sx-Mi
Two are provided, c11a and microscope Sy-Mic11b.

[Procedure amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction contents]

The projection lens 2 is located below the reticle 12.
1, a sheet-like spot light is formed on the image-forming plane of the projection lens 21 by the laser beam 29 incident thereon, and optical information generated when the spot light irradiates the mark on the wafer 16 ( A laser step alignment system (hereinafter, referred to as LS) 35 that receives diffracted light, scattered light, and the like via the projection lens 21 and detects the position of the wafer 16 is provided. The LS system 35 also actually generates a spot light extending in the x direction, and
It comprises two sets of a Y-LS system 35a for detecting the position in the direction and an x-LS system 35b for generating a spot light extending in the y direction and detecting the position of the wafer 16 in the x direction. The wavelength of the laser beam 29 of the LS system 35 is set so as not to expose the photoresist applied to the wafer 16.

[Procedure amendment 9]

[Document name to be amended] Statement

[Correction target item name] 0035

[Correction method] Change

[Correction contents]

[0035]

As described above, according to the present invention, when detecting an alignment pattern, the size of the opening is smaller than the size of the first opening used when transferring the image of the circuit pattern onto a predetermined imaging surface. Since the small second aperture is used, the energy incident on the projection optical system is reduced, and fluctuations in the imaging characteristics of the projection optical system can be reduced.

Claims (2)

[Claims] A projection optical system for forming an image of a pattern formed on a mask on a substrate; an illumination optical system for illuminating the mask with illumination light from a light source; and an illumination optical system provided on the mask. And a detection optical system for optically detecting the alignment pattern formed on the substrate or the alignment pattern formed on the substrate, the energy for adjusting the energy incident on the projection optical system. A projection exposure apparatus comprising an adjusting unit, wherein the energy adjusting unit is operated when the detection optical system detects the alignment pattern. 2. The projection exposure apparatus according to claim 1, further comprising illumination area adjustment means for changing an area on said mask including said alignment pattern.