JPH11307436A - Projection aligner, reticle and reticle aligning method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure high-precision pattern transfer without lowering the throughput. SOLUTION: A projection exposure apparatus comprises a reticle stage 33 on which a reticle 31 on whose side walls reflection plates 50X-1 , 50X-2 , 50Y-1 and 50Y-2 for a reticle are provided is mounted, an X-Y stage 44 on which a wafer 45 is mounted, motors 47 and 48 for moving the X-Y stage 44 in a planar direction, a reduction lens 40, reticle dimension measuring units 52X-1 , 52X-2 , 52Y-1 and 52Y-2 for detecting the amount of displacement of the reticle 31 by emitting laser beams toward the reflection plates 50X-1 , 50X-2 , 50Y-1 and 50Y-2 and receiving the laser beams therefrom, and a control unit 60 which positions the reticle 31 and the wafer 45 after displacement based on the amount of displacement of the reticle 31 acquired by the reticle dimension measuring units 52X-1 , 52X-2 , 52Y-1 and 52Y-2 . The positional correction of the wafer and transfer pattern is possible in real time when the reticle is displaced or deformed. It is therefore possible to carry out high-precision projection exposure without lowering the throughput.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection exposure apparatus, a reticle, and a reticle positioning method, and more particularly to a projection exposure apparatus for forming a predetermined pattern on a wafer using a reticle, a reticle, and a reticle positioning method. As one of the projection exposure apparatuses, a reduction projection exposure apparatus used for manufacturing a semiconductor device is known. The reduction projection exposure apparatus is configured to transfer a predetermined transfer pattern onto a wafer by optically reducing and projecting a predetermined transfer pattern (original pattern) formed on a reticle onto a wafer. I have.

2. Description of the Related Art In recent years, high density and high integration of semiconductor devices have been achieved, and accordingly, a projection exposure apparatus capable of forming a fine pattern with high precision has been desired.

[0003]

FIG. 1 shows a conventional projection exposure apparatus 1.
FIG. FIG. 2 is an enlarged view of the vicinity of the mounting position of the reticle 11 and the wafer 25 in the projection exposure apparatus 10. The reticle 11 is provided with an alignment mark 12 for positioning on the upper surface thereof. A reticle microscope 29 for observing the alignment mark 12 is provided above the reticle 11.

The reticle 11 is a reticle stage 1
3 is attached. The reticle stage 13 is formed with a suction hole that does not appear in the drawing, and the reticle 11 is fixed to the reticle stage 13 by sucking the reticle 11 by the suction hole. An X-direction reflector 17 and a Y-direction reflector 18 are formed on the outer peripheral side wall of the reticle stage 13. Also,
An X-direction stage length meter 22 is provided at a position facing the X-direction reflector 17, and a Y-direction stage length meter 23 is provided at a position facing the Y-direction reflector 18.

[0005] Each of the stage length meters 22 and 23 irradiates a laser beam to each of the reflecting plates 17 and 18 and receives the reflected light.
The directional displacement and the Y-directional displacement, that is, the displacement of the reticle 11, can be measured. Also, reticle stage 1
A reticle stage driving device 14 is disposed below the lower part 3. This reticle stage driving device 14 is
X-direction drive motor 15 and first Y-direction drive motor 1
The reticle stage 13 is moved in the X direction and the Y direction by driving the motors 15 and 16.

An opening is formed at the center of the reticle stage 13 and the reticle stage driving device 14. Projection light emitted from a light source (not shown) and passed through the reticle 11 is used for the reticle stage 13 and the reticle stage driving device. 14. Further, below the reticle stage driving device 14, a reduction lens 20 constituting the optical system of the projection exposure apparatus 10 is provided. The reduction lens 20 is configured so that the transfer magnification (reduction ratio) can be changed by a lens controller 21 connected thereto.

Further, below the reticle stage driving device 14, an XY stage 24 is provided. This X
The -Y stage 24 is configured to mount the wafer 25 on its upper part. Further, on the upper surface of the XY stage 24, a reference mark 26 serving as a positioning reference when positioning the reticle 11 is provided. Further, the XY stage 24 has a second X-direction drive motor 27 and a second
, A Y-direction drive motor 28 is provided.
When the XY stage 24 is moved to the X-
It is configured to be movable in the direction and the Y direction.

In the projection exposure apparatus 10 having the above configuration,
Light emitted from a light source (not shown) is applied to the wafer 25 via the reticle 11 and the reduction lens 20. On the reticle 11, a predetermined pattern to be transferred to the wafer 25 is formed in a large pattern. Therefore, reticle 11
Is incident on the reduction lens 20, and the pattern formed on the reticle 11 is reduced by the reduction lens 20 and irradiated onto the wafer 25.

A photosensitive resist is applied to the wafer 25 in advance, so that the reticle 11 and the reduction lens 2
In addition, by performing a projection process through a mask 0, and then performing a photolithography process such as predetermined etching, resist stripping, and cleaning, a fine pattern can be formed on the wafer 25. In order to form a fine pattern on the wafer 25 with high precision as described above, the wafer 25 (that is, X-
It is necessary that the reticle 11 be positioned with respect to the Y stage 24) with high accuracy. Subsequently, a conventional method of positioning the reticle 11 will be described.

For positioning of the reticle 11, the reticle 1
A reticle microscope 29 disposed opposite to the reticle 1 is used. The reticle microscope 29 is positioned with high precision with respect to a reference mark 26 provided on the XY stage 24 in advance. The position of the reticle microscope 29 with respect to the reference mark 26 is set to a position facing the alignment mark 12 formed on the reticle 11 when the reticle 11 is positioned at a predetermined position.

Accordingly, the reticle 11 is displaced by using the reticle stage driving device 14, and the position is controlled so that the center position of the alignment mark 12 formed on the reticle 11 is observed at the center position of the reticle microscope 29. The reticle 11 can be positioned at a predetermined position. In this positioning process, the displacement of the reticle stage 13 to which the reticle 11 is fixed is
2 and 23, and each motor 1
The reticle 11 is positioned by controlling 5 and 16. Thus, reticle stage 1 on which reticle 11 is fixed
Since the positioning process is performed while directly measuring the displacement of No. 3, the reticle 11 can be positioned with respect to the reference mark 26 with an accuracy of 0.01 to 0.02 μm.

[0012]

By the way, the reticle 1
1 receives a large exposure energy from a light source during the exposure processing, and the higher the exposure energy, the greater the thermal effect on the reticle 11. The following two problems are caused in the reticle 11 by receiving the exposure energy.

One problem is that the heat generated by receiving the exposure energy causes an overall thermal expansion of the reticle 11, which changes the transfer magnification to the wafer 25. That is, when thermal expansion occurs in the reticle 11, if the transfer magnification of the reduction lens 20 is constant, the projection pattern on the wafer 25 also becomes large, making it impossible to perform proper transfer.

Second, when the reticle 11 thermally expands as described above, the reticle 11 expands without centering on the center position of the reticle stage 13 to which the reticle 11 is adsorbed, so that the reticle 11 is unbalanced vertically and horizontally. This is a problem that a suction displacement occurs in the device. The cause of the imbalanced suction displacement is due to the transfer pattern formed on the reticle 11. That is, the reticle 11 has a structure in which a transfer pattern made of chromium (Cr) is formed on a substrate usually made of quartz. Quartz transmits light and generates a small amount of heat. However, a transfer pattern made of chromium (Cr) does not transmit light and therefore receives a large exposure energy. Therefore, a difference occurs in the amount of thermal expansion between the position where the transfer pattern is formed and the position where the transfer pattern is not formed, thereby causing an unbalanced suction displacement of the reticle 11.

This phenomenon has been known in the past. Therefore, conventionally, the alignment mark 12 on the reticle 11 is measured at intervals by using the reticle microscope 29,
The transfer magnification of the reduction lens 20 is changed using the lens controller 21 based on the measurement result,
The reticle 11 and the wafer 25 are moved by moving the stage 24.
Alignment with was performed.

FIG. 2 shows a conventional projection exposure apparatus 10 in which each time five wafers 25 are exposed, the reticle 11 is exposed.
7 shows a positioning result when repositioning between the wafer and the wafer 25 (hereinafter, this is referred to as an interval check). In the figure, the vertical axis indicates the amount of displacement of the reticle 11, and the horizontal axis indicates the exposed wafer 25.
Are shown.

As shown in FIG. 1, in the conventional method, a wave is generated in the alignment result of the wafer 25, and a good result cannot be obtained. More specifically, if it is desired to suppress the amount of misalignment to 30 nm or less, it is necessary to perform interval checking every two or three sheets, which causes a problem of lowering the throughput. At present, about 30 seconds are required for one interval check. Therefore, if the interval check is performed every two sheets, a loss of about 13 minutes occurs for 50 sheets.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has as its object to provide a projection exposure apparatus, a reticle, and a reticle positioning method capable of transferring a pattern with high accuracy without lowering the throughput.

[0019]

Means for Solving the Problems In order to solve the above problems, the present invention is characterized by taking the following means. In the projection exposure apparatus according to the first aspect of the present invention, a reticle stage on which a transfer pattern is formed and a reticle provided with a reflecting member on an outer peripheral side wall portion is mounted, and the transfer pattern formed on the reticle is transferred. A wafer mounting stage on which a wafer is mounted, and
A wafer mounting stage driving device for moving the wafer mounting stage in the plane direction, an optical system for projecting the transfer pattern onto the wafer at a predetermined transfer magnification, and transmitting and receiving light toward the reflecting member, A reticle length measuring device for detecting the amount of displacement of the reticle, and the drive control of the wafer mounting stage drive device is performed based on the amount of displacement of the reticle obtained by the reticle length measuring device, and the positioning of the reticle and the wafer after the displacement is performed. And positioning means for performing the positioning.

According to a second aspect of the present invention, in the projection exposure apparatus according to the first aspect, the optical system includes a projection lens configured to change a transfer magnification of the transfer pattern with respect to the wafer; A lens controller that controls a transfer magnification of the projection lens, and performs drive control of the lens controller based on a displacement amount of the reticle obtained by the reticle length meter, and the transfer that changes due to deformation of the reticle. And a transfer magnification control means for correcting the magnification to a predetermined magnification.

According to a third aspect of the present invention, in the projection exposure apparatus according to the first or second aspect, a laser interferometer is used as the reticle length measuring device. According to a fourth aspect of the present invention, in a rectangular reticle in which a transfer pattern to a wafer is formed on a transparent substrate, a reflecting member is provided on an outer peripheral side wall of the transparent substrate. .

According to a fifth aspect of the present invention, in the reticle according to the fourth aspect, a concave portion is formed in the outer peripheral side wall portion at a position where the reflective member is disposed, and the reflective member is disposed in the concave portion. It is characterized by the following. According to a sixth aspect of the present invention, there is provided the method for positioning a reticle in the projection exposure apparatus according to any one of the first to third aspects, wherein a transfer pattern is formed and a reflective member is provided on an outer peripheral side wall portion. Mounting the reticle on the reticle stage by sucking the reticle, and mounting the wafer on which the transfer pattern formed on the reticle is transferred onto the wafer mounting stage; and a reference mark provided on the wafer mounting stage. A first positioning step of positioning the reticle at a predetermined reference position based on an alignment mark provided on the reticle;
The displacement of the reticle is detected by a reticle length meter,
A second positioning step of positioning the wafer at a position corresponding to the displacement of the reticle based on the displacement of the reticle.

According to a seventh aspect of the present invention, in the reticle positioning method according to the sixth aspect, the second reticle positioning method comprises:
Simultaneously with the positioning step, a transfer magnification changing step of controlling an optical system configured to be able to change the transfer magnification based on the displacement amount of the reticle, and changing the transfer magnification of the optical system to a magnification corresponding to the displacement of the reticle. Is carried out.

Each of the above means operates as follows. According to the first aspect of the present invention, the reticle length measuring device directly detects the displacement of the reticle by projecting and receiving, for example, a laser beam toward a reflecting member provided on the outer peripheral side wall of the reticle. Thus, even if the reticle is displaced with respect to the reticle stage, this displacement can be directly detected by the reticle length meter.

Further, the positioning means controls the driving of the wafer mounting stage driving device based on the amount of displacement of the reticle obtained by the reticle length measuring device, and performs positioning or positioning of the reticle and the wafer after the displacement. When the deformation occurs, the position of the wafer and the transfer pattern can be corrected in real time. Therefore, high-precision projection exposure processing can be performed without lowering the throughput.

According to the second aspect of the present invention, the optical system includes a projection lens configured to change a transfer magnification of a transfer pattern to a wafer, and a lens controller for controlling the transfer magnification of the projection lens. Based on the amount of displacement of the reticle obtained by the reticle length meter, the transfer magnification control means performs drive control of a lens controller that controls the transfer magnification of the projection lens, and sets the transfer magnification that changes due to deformation of the reticle to a predetermined magnification. By performing the correction processing as described above, it becomes possible to perform the transfer magnification correction processing in real time when the reticle is deformed.
Therefore, high-precision projection exposure processing can be performed without lowering the throughput.

According to the third aspect of the present invention, the displacement of the reticle can be detected with high accuracy by using a laser interferometer as the reticle length measuring device. Also,
According to the fourth aspect of the present invention, since the reflecting member is provided on the outer peripheral side wall of the transparent substrate constituting the reticle, the displacement of the reticle can be measured by the optical length measuring device using the reflecting member. Becomes

According to the fifth aspect of the present invention, since the concave portion is formed in the outer peripheral side wall portion at the position where the reflective member is provided, and the reflective member is disposed in the concave portion, the reflective member is damaged. Can be effectively prevented. According to the sixth aspect of the present invention, after mounting the reticle and the wafer at a predetermined position by performing the mounting process, the first
By performing the positioning step, the reticle is positioned at a predetermined reference position. After that, a second positioning step is performed, and the drive control of the wafer mounting stage driving device is performed based on the amount of displacement of the reticle detected by the reticle length meter, and the wafer is moved to a position corresponding to the displacement of the reticle.

Therefore, even if the reticle is displaced or deformed from the position determined in the first positioning step,
In the second positioning step, the amount of displacement and the amount of deformation are detected by a reticle length meter, and the wafer is moved in real time to a position corresponding to the displacement or deformation of the reticle. Thereby, it is possible to perform the projection exposure processing with high precision without lowering the throughput.

According to the seventh aspect of the present invention, the second
Simultaneously with the positioning step, a transfer magnification changing step of controlling the optical system configured to be able to change the transfer magnification based on the displacement amount of the reticle and changing the transfer magnification of the optical system to a magnification corresponding to the reticle displacement is performed. By doing so, it becomes possible to perform the transfer magnification correction processing in real time when the reticle is deformed. Therefore, high-precision projection exposure processing can be performed without lowering the throughput.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. 3 to 5 show a projection exposure apparatus 30 according to an embodiment of the present invention (a reduced projection exposure apparatus will be described as an example in this embodiment), a reticle 31, and a reticle 3.
FIG. 2 is a diagram for explaining a positioning method of FIG.

FIG. 3 is a configuration diagram of a main part of the projection exposure apparatus 30, FIG. 4 is an enlarged view showing the vicinity of a mounting portion of the reticle 31, and FIG. 5 is a block diagram showing a control system of the projection exposure apparatus 30. It is. In each drawing, a light source for irradiating the reticle 31 with light is omitted for convenience of illustration. The reticle 31 has a configuration in which a light-blocking material such as chrome (Cr) that blocks light is formed in a predetermined transfer pattern on a transparent substrate made of quartz. Therefore, when light is applied to the reticle 31 from a light source such as a mercury lamp, the light is blocked at the position where the transfer pattern is formed, and the light is transmitted at other portions, whereby the transfer pattern is projected on the wafer 25. (Actually, the image is reduced and projected at a predetermined transfer magnification by a reduction lens 40 described later).

The quartz substrate constituting the reticle 31 and the transfer pattern made of chrome or the like have different coefficients of thermal expansion.
Therefore, as described above, when light is emitted from the light source and exposure energy is applied to the reticle 31 to generate heat, unbalanced thermal expansion occurs in the X and Y directions in the drawing. As shown in FIGS. 3 and 4, the reticle 3
A pair of alignment marks 32 for performing a positioning process to be described later are provided on the upper surface of 1. Further, the reticle 31 according to the present embodiment has a reticle reflector 50X-1, 50X-2, 50Y serving as a reflection member on the outer peripheral side wall.
-1, 50Y-2.

The reticle reflectors 50X-1, 50X-
2, 50Y-1 and 50Y-2 are configured to be coated with, for example, an aluminum thin film. The reticle reflectors 50X-1 and 50X-2 are disposed on the outer peripheral side wall of the reticle 31 so as to face in the direction of the arrow X in the figure, and the reticle reflectors 50Y-1 and 50Y-2 are The reticle 31 is disposed on the outer peripheral side wall portion so as to face the middle arrow Y direction.

Further, the reticle reflectors 50X-1, 50X-2, 50Y-1, 50Y are provided on the outer peripheral side wall of the reticle 31.
At the position where -2 is formed, a concave portion 59 is formed.
Then, each reticle reflection plate 50X-1, 50X-2, 50
Y-1 and 50Y-2 are formed in the recess 59. Therefore, each reticle reflector 50X-1,5
The 0X-2, 50Y-1, and 50Y-2 are formed at positions depressed from the outer peripheral side wall portion, so that even a thin aluminum film is not damaged.

Each reticle reflector 50X-1, 50
At positions facing X-2, 50Y-1, and 50Y-2, reticle length meters 52X-1, 52X-2, 52Y-1, and 52Y-2 are provided. Specifically, the reticle reflector 50X-1
The reticle length gauge 52X-1 faces the reticle reflector 50X-2, the reticle length meter 52X-2 faces the reticle reflector 50X-2, and the reticle length meter 52Y-1 faces the reticle reflector 50Y-1. The reticle reflector 50Y-2 has a reticle length meter 5
2Y-2 are configured to face each other.

In FIG. 3, each reticle length meter 52X-1, 52X-2, 52Y-1, 52Y-2 is shown as a block for convenience of illustration, but the actual configuration is as shown in FIG. In addition, reticle length meter 52X-1, 52X-2, 52Y-1,
52Y-2 is a reticle reflector 50X-1, 50X-2,5.
Reticle laser irradiation device 57 for irradiating laser light toward 0Y-1, 50Y-2, and reticle reflection plates 50X-1, 50X radiated from reticle laser irradiation device 57
-2, 50Y-1, reticle interferometers 58X-1, 58X- for performing interferometry with laser light reflected by 50Y-1, 50Y-2
2, 58Y-1, 58Y-2.

The reticle interferometers 58X-1, 58X
-2, 58Y-1 and 58Y-2 are reticle reflectors 50X
The displacement of the reticle 31 is directly measured based on the interference characteristics of the laser light reflected by the -1, 50X-2, 50Y-1, and 50Y-2. As described above, by adopting a configuration in which the length of the displacement of the reticle 31 is measured based on the interference characteristics of the laser beam, a high resolution of, for example, 0.02 μm can be realized.

Each reticle interferometer 58X-1, 58
The outputs from X-2, 58Y-1, 58Y-2 are output as count values in units of the above resolution. In the drawing, reference numerals 62 and 63 denote prisms or mirrors for forming a predetermined optical path of laser light. The reticle 31 having the above-described configuration includes a reticle stage 33.
Attached to. A suction hole 54 is formed in the reticle stage 33, and a suction device (not shown) is connected to the suction hole 54. Therefore, the reticle 31 is fixed to the reticle stage 33 by driving the suction device and sucking the reticle 31 into the suction hole 54.

A reticle microscope 49 for observing the alignment mark 32 is provided above the reticle 31 when mounted on the reticle stage 33. The reticle microscope 49 is provided with a solid-state imaging device, and is configured to detect a center position of the alignment mark 32 by processing a captured image by an image processing device (not shown).

On the outer peripheral side wall of the reticle stage 33, stage reflecting plates 37X and 37Y are formed. The stage reflectors 37X and 37Y are also coated with, for example, a thin film of aluminum. The stage reflector 37X is on the side of the outer peripheral side wall of the reticle stage 33 in the direction of arrow X in the figure, and the stage reflector 37Y is a reticle. The stage 33 is disposed on the side of the outer peripheral side wall in the direction of the arrow Y in the figure.

An X-direction stage length measuring instrument 4 is provided at a position facing the stage reflector 37X disposed on the X-direction side.
2, and a Y-direction stage length measuring instrument 43 is disposed at a position facing the Y-direction reflector 18. In FIG. 3, for convenience of illustration, each stage length meter 42,
43 is shown in the form of a block.
As shown in the figure, the stage length measuring instruments 42 and 43 include a stage laser irradiator 55 for irradiating the stage reflectors 37X and 37Y with a laser beam, and each stage reflector irradiating from the stage laser irradiator 55. 37X, 3
It is constituted by stage interference receivers 56X and 56Y that receive the laser beam reflected by 7Y and perform interference measurement.

Each stage interference receiver 56X, 5
6Y is configured to directly measure the displacement of the reticle stage 33 based on the interference characteristics of the laser beams reflected by the stage reflecting plates 37X and 37Y. As described above, by measuring the length of the displacement of the reticle stage 33 based on the interference characteristics of the laser beam, a high resolution of, for example, 0.02 μm can be realized. The outputs from the stage interference receivers 56X and 56Y are also output as count values in units of the above resolution.

On the other hand, below the reticle stage 33,
A reticle stage driving device 34 is provided. The reticle stage driving device 34 has a first X-direction driving motor 35 and a first Y-direction driving motor 36, and the reticle stage 33 is driven by the respective motors 35 and 36 in the X and Y directions. It is configured to be moved to.

An opening 64 is formed at a central position between the reticle stage 33 and the reticle stage driving device 34. Light emitted from the light source and passed through the reticle 31 passes through the reticle stage 33 and the reticle stage driving device 34. Then, the light is incident on the reduction lens 40. Further, a reduction lens 40 constituting an optical system is provided below the reticle stage driving device 34. The reduction lens 40 is configured so that the transfer magnification (reduction ratio) can be changed by a lens controller 41 connected thereto.

On the other hand, an XY stage 44 (wafer mounting stage) is provided below the reticle stage driving device 34.
Are arranged. The XY stage 44 is configured to mount a wafer 45 thereon. Also,
On the upper surface of the XY stage 44, a reference mark 46 serving as a positioning reference when positioning the reticle 31 is provided.

Further, the XY stage 44 has a second X
Direction drive motor 47 and second Y direction drive motor 48
(Wafer mounted stage drive)
The XY stage 44 is moved in the X direction and the Y direction by driving the motors 47 and 48. In the projection exposure apparatus 30 having the above configuration, the light emitted from the light source (not shown)
Irradiation is performed on the wafer 45 through 0. A predetermined pattern to be transferred to the wafer 45 is formed in a large pattern on the reticle 31. Therefore, the light transmitted through the reticle 31 enters the reduction lens 40, and the pattern formed on the reticle 31 is reduced by the reduction lens 40 and irradiated onto the wafer 45.

The wafer 45 is coated with a photosensitive resist in advance, so that the reticle 31 and the reduction lens 4
In addition, by performing a projection process through the wafer 45 and then performing a photolithography process such as predetermined etching, resist stripping, and cleaning, a fine pattern can be formed on the wafer 45. FIG. 5 shows a configuration of a control system of the projection exposure apparatus 30. FIG. 2 shows only a control system for controlling the drive of the reduction lens 40 and the XY stage 44 based on the displacement of the reticle 31, which is a main part of the present embodiment.

As shown in the figure, the displacement signals of the reticle 31 detected by the reticle interference receivers 58X-1, 58X-2, 58Y-1, 58Y-2 are transmitted to a control unit 60 constituted by a microcomputer. Is supplied to the system. The control unit 60 calculates the amount of expansion E and the amount of displacement of the reticle 31 (hereinafter, the amount of displacement in the X direction is referred to as an offset amount Lx and the amount of displacement in the Y direction is referred to as an offset amount LY) based on the displacement signal.

Now, the reticle 31 calculated based on the count value detected by the reticle interference receiver 58X-1.
X1, the displacement of the reticle 31 calculated based on the count value detected by the reticle interference receiver 58X-2 is calculated based on the count value detected by the reticle interference receiver 58Y-1. The displacement amount of the reticle 31 is Y1, and the displacement amount of the reticle 31 calculated based on the count value detected by the reticle interference receiver 58Y-2 is Y2.

Then, the expansion amount E, offset amount Lx, and offset amount LY of the reticle 31 can be obtained by the following equations. E = {(X1-X2) + (Y2-Y1)} / 2 (1) Lx = (X1 + X2) / 2 (2) LY = (Y1 + Y2) / 2 (3) As described above. Expansion amount E and offset amount L of reticle 31
When x and the offset amount LY are obtained, the control unit 60 transfers the transfer magnification of the reduction lens 40 that can appropriately perform the transfer process on the wafer 45 using the reticle 31 after thermal expansion based on the obtained expansion amount E. (Hereinafter, referred to as a transfer magnification correction amount), and the obtained offset amount Lx,
And each offset amount L based on the offset amount LY
The amount of movement of the XY stage 44 that can cancel x, LY (hereinafter, referred to as offset correction amount) is calculated.

Subsequently, the control unit 60 controls the drive of the lens controller 41 based on the transfer magnification correction amount calculated as described above, so that the transfer magnification of the reduction lens 40 can be appropriately transferred to the wafer 45. Change to
Further, the control unit 60 controls the driving of the XY stage driving device 61 based on the offset correction amount calculated as described above, and moves the XY stage 44 to the offset amounts Lx, L.
Move Y to a position where it can be canceled.

Subsequently, the projection exposure apparatus 3 having the above configuration
The method of positioning the reticle 31 and the wafer 45 at 0 will be described. In order to perform the positioning process, first, the reticle 31 is placed at a predetermined position on the reticle stage 33, and is mounted on the reticle stage 33 by suctioning through the suction holes 54, and the wafer 45 is mounted on the XY stage 44 by predetermined mounting. Attach to the position (approximate attachment).

Next, a reticle stage drive 34 based on a reference mark 46 provided on the XY stage 44 and an alignment mark 32 provided on the reticle 31.
Is driven to move the reticle stage 33, and the reticle 31 is positioned at a predetermined reference position (first positioning step). When performing the first positioning step, the control unit 60 shown in FIG. 5 performs image processing on a captured image supplied from the reticle microscope 49 by an image processing device (not shown), and adjusts the center position of the reticle microscope 49 and the alignment mark. Distance from 32 to the center position (position shift distance)
Is calculated, and the drive of the reticle stage driving device 34 is controlled so as to eliminate the positional shift distance.

At this time, the control unit 60 controls the reticle 3
The displacement of the reticle stage 33 to which 1 is fixed is calculated based on the output signals from the stage interference receivers 56X and 56Y, and based on the result, the motors 35 and 36 are controlled to position the reticle 31. When the center position of the reticle microscope 49 and the alignment mark 32 match, the reticle 31 and the wafer 45
It will be in the positioned state.

As described above, by performing the positioning process while directly measuring the displacement of the reticle stage 33 to which the reticle 31 is fixed, the reticle 31 is positioned with respect to the reference mark 46 with an accuracy of 0.01 to 0.02 μm. be able to. By performing the mounting process and the first positioning process described above, it is possible to maintain a state where the reticle 31 and the wafer 45 are positioned with high accuracy before the start of the exposure processing and within a predetermined time after the start of the exposure. it can.
However, when the exposure time becomes longer and the reticle 31 receives a large exposure energy from the light source, overall thermal expansion occurs in the reticle 31, the transfer magnification changes, and the center of the reticle stage 33 on which the reticle 31 is adsorbed. As described above, the suction displacement (offset) occurs unequally due to expansion without centering on the position.

Therefore, the projection exposure apparatus 30 according to the present embodiment
Then, after the first positioning step is performed, the offset amounts Lx, LY (displacement amounts) of the reticle 31 are obtained by the reticle length measuring instruments 52X-1, 52X-2, 52Y-1, 52Y-2. The drive control of the XY stage 45 is performed so as to cancel the amounts Lx and LY, and offset correction for moving the wafer 45 to a position corresponding to the offset (displacement) of the reticle 31 is performed (second positioning step). .

Thus, even if the reticle 31 is displaced with respect to the reticle stage 33 by the exposure energy received from the light source after the first positioning step is performed, this displacement is measured by the reticle length meters 52X-1, 52X-2, 52Y-1, 5
Direct detection by 2Y-2 makes it possible to correct the offset between the reticle 31 and the wafer 45 in real time. Therefore, high-precision projection exposure processing can be performed without lowering the throughput.

In this embodiment, simultaneously with the second positioning step, the reticle length measuring instruments 52X-1, 52X-2,
Reticle 31 obtained from outputs of 52Y-1 and 52Y-2
A process of calculating a transfer magnification correction amount of the reduction lens 40 based on the expansion amount E, and changing the transfer magnification of the reduction lens 40 to a magnification corresponding to the displacement of the reticle 31 via the lens controller 41 (transfer magnification change step). Has also been implemented.

Therefore, even if the reticle 31 is totally deformed due to thermal expansion, the size of the transfer pattern on the wafer 45 is maintained at a predetermined size, so that high-precision projection exposure processing is stabilized. Can be implemented. In the transfer magnification changing step, when the reticle 31 is deformed, the control unit 60 corrects the transfer magnification of the reduction lens 40 in real time, so that highly efficient positioning processing can be performed without lowering the throughput. it can.

FIG. 6 shows a positioning result when the interval check between the reticle 31 and the wafer 45 is performed every time five wafers 45 are exposed in the projection exposure apparatus 30 of the present embodiment. In the figure, the vertical axis indicates the amount of displacement of the reticle 31, and the horizontal axis indicates the number of wafers 45 subjected to the exposure processing. As shown in the figure, according to the projection exposure apparatus 30 and the positioning method of the present embodiment, it can be seen that the deviation amount of the wafer 45 is small and stable even when the exposure processing is advanced.

Further, as in the conventional example described with reference to FIG. 2, if the amount of misalignment is to be suppressed to 30 nm or less, the present embodiment eliminates the need for performing an interval check at all, thereby significantly improving the throughput. Can be planned. Although a change in magnification is not shown, it shows a similar tendency, which can also contribute to an improvement in throughput.

[0063]

As described above, according to the present invention, the following various effects can be realized. According to the first and sixth aspects of the present invention, when displacement or deformation occurs in the reticle, the position of the wafer and the transfer pattern can be corrected in real time in real time. Accurate projection exposure processing can be performed.

According to the second and seventh aspects of the present invention, it is possible to perform the transfer magnification correction processing in real time when the reticle is deformed, thereby achieving high accuracy without lowering the throughput. Can be performed. According to the third aspect of the present invention, the displacement of the reticle can be detected with high accuracy by using the laser interferometer as the reticle length measuring device.

According to the fourth aspect of the present invention, since the reflecting member is provided on the outer peripheral side wall of the transparent substrate constituting the reticle, the displacement of the reticle can be measured by the optical length measuring device using the reflecting member. It becomes possible to measure. According to the fifth aspect of the present invention, the concave portion is formed in the outer peripheral side wall portion at the position where the reflective member is disposed, and the reflective member is disposed in the concave portion, so that the reflective member can be effectively prevented from being damaged. Can be prevented.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a main part of a projection exposure apparatus, which is an example of a related art.

FIG. 2 is a diagram for explaining a conventional problem.

FIG. 3 is a main part configuration diagram of a projection exposure apparatus according to an embodiment of the present invention.

FIG. 4 is an enlarged view showing the vicinity of a reticle arrangement position of a projection exposure apparatus according to an embodiment of the present invention.

FIG. 5 is a block diagram showing a control system of the projection exposure apparatus according to one embodiment of the present invention.

FIG. 6 is a diagram for explaining an effect of the present invention.

[Explanation of symbols]

REFERENCE SIGNS LIST 30 projection exposure device 31 reticle 32 alignment mark 33 reticle stage 34 reticle stage drive device 35 first X-direction drive motor 36 first Y-direction drive motor 37X, 37Y Reflector for stage 40 Reduction lens 41 Lens controller 42Y, 42X Stage Length measuring instrument 44 XY stage 45 Wafer 46 Reference mark 47 Second X-direction drive motor 48 Second Y-direction drive motor 49 Reticle microscope 50X-1, 50X-2, 50Y-1, 50Y-2 Reflector for reticle 52X-1, 52X-2, 52Y-1, 52Y-2 Reticle length measuring device 55 Stage laser irradiation device 56X, 56Y Stage interferometer receiver 56 Reticle laser irradiation device 58X-1, 58X-2, 58Y-1, 58Y-2 Reticle Interferometer Receiver 60 Control Unit 61 YY stage drive

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 21/30 525D

Claims (7)

[Claims] 1. A reticle stage on which a transfer pattern is formed and a reticle provided with a reflection member on an outer peripheral side wall is mounted, and a wafer mount on which a wafer on which the transfer pattern formed on the reticle is transferred is mounted. A stage, a wafer mounting stage driving device that moves the wafer mounting stage in a plane direction, an optical system that projects the transfer pattern onto the wafer at a predetermined transfer magnification, and emits and receives light toward the reflective member. A reticle length measuring device that detects the amount of displacement of the reticle, and the drive control of the wafer mounting stage drive device is performed based on the amount of displacement of the reticle obtained by the reticle length measuring device. A projection exposure apparatus comprising: positioning means for performing positioning. 2. The projection exposure apparatus according to claim 1, wherein the optical system controls a projection lens configured to change a transfer magnification of the transfer pattern to the wafer, and controls a transfer magnification of the projection lens. A lens controller, and performs drive control of the lens controller based on the amount of displacement of the reticle obtained by the reticle length meter, and corrects the transfer magnification that changes due to deformation of the reticle to be a predetermined magnification. A projection exposure apparatus comprising: a transfer magnification control unit. 3. The projection exposure apparatus according to claim 1, wherein a laser interferometer is used as said reticle length measuring device. 4. A reticle, comprising a transparent reticle having a transfer pattern formed on a transparent substrate formed on a transparent substrate, wherein a reflective member is provided on an outer peripheral side wall portion of the transparent substrate. 5. The reticle according to claim 4, wherein a concave portion is formed in the outer peripheral side wall portion at a position where the reflective member is disposed, and the reflective member is disposed in the concave portion. 6. A method for positioning a reticle in the projection exposure apparatus according to claim 1, wherein a transfer pattern is formed and a reticle provided with a reflecting member on an outer peripheral side wall is attracted. By mounting on a reticle stage and mounting a wafer on which a transfer pattern formed on the reticle is transferred onto a wafer mounting stage, a reference mark provided on the wafer mounting stage and the reticle are provided on the reticle. Based on the alignment mark
A first positioning step of positioning the reticle at a predetermined reference position, and detecting a displacement amount of the reticle by a reticle length meter,
A second positioning step of positioning the wafer at a position corresponding to the displacement of the reticle based on the amount of displacement of the reticle. 7. The reticle positioning method according to claim 6, wherein simultaneously with the second positioning step, an optical system configured to change a transfer magnification based on an amount of displacement of the reticle is controlled to control the optical system. A reticle positioning method for performing a transfer magnification changing step of changing a transfer magnification of the system to a magnification corresponding to the displacement of the reticle.