JPH03120712A - Exposure device - Google Patents

Abstract

PURPOSE:To reduce an error in registration for improving transfer accuracy by providing an exposure value controlling means for making the exposure value uniform in an exposure range and a position reference controlling means for moving a one-dimensional position reference of the exposure value controlling means with respect to an exposure device frame. CONSTITUTION:A shutter controller 64 controls a position or a moving speed of shutter apertures 36 and 37 at each time point based on a shutter driving table. Thus position references of the shutter apertures 36, 37 are shifted corresponding to a shift y of a current profile 2i with respect to a reference profile 1i due to a y fluctuation of a posture of an aligner 40, and the tip 1a of the shutter aperture is shifted by y to 2a and the rear end 1b is shifted to 2b. Therefore a time required since the tip 2a of the shutter aperture passes by until the rear end 2b passes by is shifted according to a shift amount of the profile 2i to make an exposure value over an entire exposure range uniform.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an exposure apparatus that prints and transfers an image of an original plate such as a mask onto a substrate to be exposed such as a semiconductor device C with high precision.

[Prior Art] In recent years, semiconductor integrated circuits have become more and more highly integrated, and the exposure apparatus (aligner) used to manufacture them is also required to have higher transfer precision. For example, 2
In 56 megabit DRAM class integrated circuits, the line width is 0.
．． An exposure device that can print patterns of about 25 microns is required.

As an exposure apparatus for printing such ultrafine patterns, an apparatus that performs so-called proximity exposure using orbital synchrotron radiation (SOR-X-rays) has been proposed.

This orbital synchrotron radiation is in the form of a sheet beam that is uniform in the horizontal direction, so in order to expose the surface, the mask and wafer are moved vertically 8 times to scan the surface with horizontal sheet beam X-rays. Scanning exposure method, ■ Scanning mirror exposure method in which sheet beam-shaped X-rays are reflected by a swinging mirror and scanned vertically over the mask and wafer, and ■ Horizontally by an X-ray mirror with a convex reflecting surface. A batch exposure method has been proposed in which sheet beam-shaped X-rays are diverged in the vertical direction and the entire exposure area is irradiated simultaneously.

The inventors of the present invention proposed an X-ray exposure apparatus based on this blanket exposure method and previously filed an application as Japanese Patent Application No. 1983-710W-0.

In the X-ray exposure apparatus of this prior application, the intensity (illuminance) of the X-rays as exposure light is uniform in the horizontal direction (hereinafter referred to as the X direction), but in the vertical direction (hereinafter referred to as the Y direction). For example, as shown in the illuminance distribution curve of FIG. 2A, the intensity is uneven, being high at the center and decreasing as you move away from the center. In the prior application, two shielding plates each having a rectangular opening (shutter aperture) are used, and their moving speeds in the Y direction are independently controlled as shown in FIG. 2B. As shown in the figure, the exposure amount in each part of the exposure area is controlled. That is, for each portion in the Y direction, the leading edge 1a of the opening of the shielding plate on the side that advances later passes through and the exposure light (X-rays)
Trailing edge 1 of the aperture of the shielding plate on the preceding side after starting to pass through
By controlling the time it takes for the exposure light to pass through and block the exposure light, the entire exposure area is exposed properly and uniformly. In this case, the exposure amount control is based on the 6th A measured within the exposure area.
This is performed based on the X-ray intensity distribution curve (hereinafter referred to as profile) in the Y direction as shown in the figure.

[Problems to be Solved by the Invention] As a result of further studies on the X-ray exposure device of the prior application in order to further improve the transfer accuracy, the present inventors found that the relative positional fluctuation between the exposure area and the X-ray flux It was found that the effect on transfer accuracy cannot be ignored.

For example, the X-ray flux changes by Δy, and the profile becomes 2A.
When Δy changes from the position indicated by the solid line to the position indicated by the dotted line in the figure, the intensity ■ of the X-ray at position y changes. Therefore, in order to keep the variation in the intensity I to 0.1% or less, it must be y y . Specifically, the angle of view in the Y direction of the exposure area is 30 mm, the profile shown by the solid line in Figure 2A is expressed as a quadratic function vertically symmetrical about the center line, and the lowest intensity is equal to the highest intensity. Assuming that it is 80%, then in order to suppress the X-ray intensity unevenness to 0.1% or less, the relative positional variation Δy of the X-ray flux with respect to the exposure area should be set to 40%.
This means that it has to be less than μm.

Furthermore, in the proximity exposure method, variations in the incident angle of illumination light cause deterioration in overlay accuracy.

For example, the proximity gap G between the mask and the wafer
is 50 μm, and the overlay error Δ due to the variation of the incident angle is
In order to make δ 0.002 μm or less, the amount of incident angle variation 〇 is Δθ=Δδ/G <0.002150=4xl 0-5rad, that is, 4
Must be less than or equal to XIQ-5rad.

Further, when the illumination light has a divergence angle, the angle of incidence of the X-rays with respect to the exposure area varies with the relative position variation Δy. This incident angle variation amount Δθ is calculated by setting the distance between the divergence point (for example, the X-ray incident position on the divergence convex mirror) and the exposure surface to 5 m.
Then, Δθ=Δy<4X10-'rad 000. The above-mentioned overlay error Δδ occurs due to this incident angle variation 〇. In this case, the overlay error Δδ appears as a run-out error in which a different transfer rate is distributed on each part of the exposure surface.

According to the above equation, the relative position variation Δy must be 0.2 mm or less.

It should be noted that the factors causing the variation in Δy are those caused by the attitude variation of the exposure apparatus due to the movement of the wafer stage.
About μm, relative displacement due to temperature fluctuation is about 10 μm,
The relative displacement due to floor vibration is expected to be approximately 2 μm.

An object of the present invention is to provide an exposure apparatus capable of further improving transfer accuracy by reducing the overlay error Δδ caused by the incident angle variation 〇 and the relative position variation Δy.

[Means for Solving the Problems] In order to achieve the above object, the present invention attempts to make the exposure amount uniform within the exposure area by setting the exposure time distribution corresponding to the one-dimensional intensity unevenness of the illumination light. An exposure amount control means and a position reference control means for moving the position reference of the exposure amount control means in the one-dimensional direction with respect to the exposure apparatus frame are provided.

In one aspect of the invention, the exposure amount control means includes a shutter means having a light shielding plate and a drive means for driving the light shielding plate according to a drive curve corresponding to the intensity unevenness, and the position reference control means includes a shutter means having a light shielding plate and a drive means for driving the light shielding plate according to a drive curve corresponding to the intensity unevenness. It uses a method that moves the standard of.

In another aspect, a portion of the shutter means including a light shielding plate is formed into a unit, and the shutter unit is moved in the one-dimensional direction with respect to the exposure device frame or rotated around the optical axis of the illumination light. .

These positional references are, for example, detected by detecting the relative posture change between the exposure apparatus main body including the exposure apparatus frame and the floor on which the illumination system including the SOR device as the exposure light source is installed, and adjusted according to this detection signal. be done.

[Operations and Effects] In the above configuration, when the position reference control means moves the position reference of the exposure amount control means with respect to the exposure apparatus frame, the exposure time distribution of illumination light within the exposure area is shifted. Therefore, by detecting the relative positional variation Δy between the illumination light and the exposure area, and moving the positional reference in response to this detection signal to shift the exposure time distribution, it is possible to compensate for the exposure unevenness caused by the positional variation Δy. I can do it.

Furthermore, in a method in which the positional reference is moved by relatively moving the exposure apparatus main body and the illumination system, it is possible to further reduce the overlay error caused by the positional variation Δy.

[Example] FIG. 1 shows the configuration of an X-ray aligner according to an example of the present invention. In the same figure, 11 is an SOR device;
It is placed on a device stand 12, and X-rays 1 are emitted from a light emitting point 13.
Emit 4. 21 is a first mirror whose reflecting surface is processed to have a convex shape in order to magnify the sheet beam-shaped SORX ray 14 elongated in the X (horizontal) direction in the Y (vertical) direction; 22 is the X that is diverged by the first mirror 21; This is a second mirror that reflects the beam 15 so that its central axis is horizontal.

The X-ray flux reflected by the second mirror 22 is the illumination light 1 for exposure.
6 into the aligner body 40.

23 is a mirror chamber for creating a desired vacuum atmosphere around the first mirror 21 and the second mirror 22; 24 is a first mirror drive device used to adjust the attitude of the first mirror 21; 25 is a second mirror chamber; A second mirror drive device 26 used to adjust the attitude of the mirror 22 is a mirror mount on which the mirror unit 20 consisting of the first mirror 21 to the second mirror drive device 25 is placed.

30 is a shutter unit, which includes a shutter stay 31 and shutter shafts 32 and 33 attached to the shutter stay 31.
It is also constituted by shirtter membranes 34 and 35 stretched between each shirtter shaft 3232 and 33.33. The shutter films 34 and 35 are endless shutter films (SU) having rectangular openings (shutter apertures) 36 and 37, each side of which is longer than the dimension of the exposure area.
S) Consists of a belt.

40 is the aligner body, 41 is a mask having a transfer pattern formed from an X-ray opaque material such as gold, and 42 is the mask 41.
43 is a movable mask stage equipped with a mask 4
1 on a mask stage 42; 44, a wafer to which the image of the mask 41 is to be transferred; 45, a movable wafer stage on which the wafer 44 is mounted; 46, a wafer 44 on the wafer stage 45; 47 is an aligner frame for mounting the mask stage 42, wafer stage 45, etc., 48 is an aligner base on which the aligner frame 47 is placed, 49 is for supporting the aligner base 48 on the floor 1. The air spring 61 is a non-contact displacement meter for detecting positional fluctuations of the aligner body 40 with respect to the floor 1.

The aligner base 48 is supported at three locations by at least three air springs 49. In addition, the non-contact displacement 1 2 position 61 measures the displacement of at least three locations on the aligner base 48 to detect the variation in the height of the aligner body 40 with respect to the floor 1.

50 is a helium chamber for creating a desired helium atmosphere around the shutter unit 30, the mask 41 on the mask stage 42, and the wafer 44 on the wafer stage 45. Further, 51 and 52 are the mirror chamber 2
3 and the helium chamber 50, i.e., the aligner body 40, to maintain their respective atmospheres; 53, a bellows to flexibly connect the mirror chamber 23 and the aligner body 40; 54, the illumination light 16; This is a beryllium window that is transparent and insulates the vacuum atmosphere in the mirror chamber 23 from the helium atmosphere in the helium chamber 5o.

Reference numeral 62 denotes a posture detection section that detects the posture of the aligner main body 40 based on the outputs of the plurality of non-contact displacement meters 61, and 63 shifts a shutter drive table (not shown) based on the output of the posture detection section 62. The correcting drive table shift units 63 and 65 are shutter control units that control the positions or moving speeds of the shutter apertures 36 and 37 at each time based on the drive table.

In the aligner shown in FIG. 1, first, an X-ray illumination meter (not shown) mounted on a carriage (not shown) is scanned in the Y direction within the exposure area to create a profile (
(illumination light intensity distribution curve). When creating this profile, the posture detection section 62 takes in the output of each non-contact displacement meter 61 and stores the posture of the aligner main body 40 at that time. In addition, in this profile creation operation, drive data for each of the shutter apertures 36 and 37 is calculated so that the exposure amount is uniform within the exposure area in accordance with the created profile, and is stored in the shutter drive table. Ru.

During the exposure process, the posture detection unit 62 captures the output of the non-contact displacement meter 61 as necessary, such as immediately before the first shot exposure of one wafer, compares it with the above-mentioned stored content, and compares it with the above-mentioned stored content.
Detects the change in attitude Δy. Drive table shift section 6
3 corrects the shutter drive table based on the attitude change Δy detected by the attitude detection unit 62. This correction is performed by shifting the shutter drive table.

The shutter control section 65 controls the position or moving speed of the shutter apertures 36 and 37 at each time point based on the shutter drive table.

As a result, as shown in FIG. 2A, the shutter aperture 36 is adjusted in response to the deviation Δy of the current profile 21 (broken line) from the reference profile 11 (solid line) due to a Δy change in the attitude (height) of the aligner main body 40.
and 37 are shifted so that the leading edge 1a of the shutter aperture is shifted to 28 and the trailing edge 1b is shifted, as shown in FIG. 2B.
is shifted by Δy to 2b. Therefore, the time from when the leading edge 2a of the shutter aperture passes until when the trailing edge 2b passes is shifted in accordance with the shift amount of the profile 21, as shown in FIG. Efforts will be made to equalize the situation.

FIG. 3 shows the configuration of an X-ray aligner according to a second embodiment of the invention. The aligner shown in FIG. 1 has a posture control section 367 and an air spring air amount adjustment mechanism 368 added to the aligner shown in FIG.
In addition to the attitude variation Δy in the vertical) direction, the structure is configured to detect variation Δω2 around the Z axis (illumination optical axis), variation Δω8 around the x axis, and variation Δω7 around the Y axis, and detects Δω8, Δω
Correction of 7 and Δω2 and coarse correction of Δy are performed by controlling the attitude of the aligner main body 40 using the attitude control unit 367 and air spring air amount adjustment mechanism 368. Similarly, this is done by shifting the shutter drive table.

When only the positional references of the shutter apertures 36 and 37 are shifted, as in the aligner shown in FIG. 1, the influence of the attitude change Δy in the Y direction on the exposure distribution in the figure is corrected. However, the variation of the angle of incidence of illumination light on the exposed area Δ
Since θ is not corrected, the overlay error Δδ is not improved. On the other hand, in the aligner shown in Fig. 3, there are two Δω and Δω7
Since correction of Δω7 is also performed, the overlay error Δδ is also improved, which helps improve transfer accuracy.

FIG. 4 shows a third embodiment of the invention.

The aligner shown in FIG. 1 is different from the one shown in FIG.
and Δω2, and a shutter posture calculation section 463 that calculates the shutter posture based on aligner body posture information from the posture detection section 62 instead of the drive table shift section 63 and shutter control section 65, and based on this information. A shutter attitude control section 465 is used to drive the shutter attitude control device.

The aligner in Figure 4 is roughly Δω compared to the aligner in Figure 1.
Since the second correction is also performed, the uniformity of the exposure amount and the overlay accuracy are good. However, for the one in Figure 1, △ω8
Since correction of Δω7 and Δω7 is not performed, the uniformity of the exposure amount and the overlay accuracy are inferior. However, since it is sufficient to move the shutter unit 30, which weighs at most several tens of kilograms, instead of the aligner body, which weighs several hundred kilograms to several tons, it is expected that the device will be lighter and simpler.

FIG. 5 shows a fourth embodiment of the invention. The aligner shown in the figure is different from the aligner shown in FIG.
A shirt cod control section 564 that performs position reference control of the shutter apertures 36 and 37 based on the shutter posture variation information Δy from 3 is added, and the shutter posture variation Δω2 is replaced by the shutter posture control section 465.
This uses a shutter attitude control section 565 that corrects only the above.

In the aligner of FIG. 5, the y-direction movement mechanism in the shutter attitude control device 431 of FIG. 4 is not necessary.

[Brief Description of the Drawings] Figure 1 is a configuration diagram of an X-ray aligner according to an embodiment of the present invention, and Figures 2A to 20 are illumination intensity distributions (profiles) for explaining the operation of the aligner in Figure 1. ), a shutter drive curve, an exposure time distribution diagram, and FIGS. 3 to 5 are configuration diagrams of X-ray aligners according to second to fourth embodiments of the present invention, respectively. 16: illumination light 30: shutter unit 34. 35: shutter film 36 37: shutter aperture 40 near aligner body 47-aligner frame 61: non-contact displacement meter 62: posture detection section 63: drive table shift section 65/shutter control section 367 : Posture control section 368: Air spring air amount adjustment mechanism 9 31 63 65 64 65: Shutter posture control device Shutter posture calculation section Shutter posture control section: Shutter control section: Shutter posture control section.

Claims (5)

[Claims] (1) An exposure amount control means that aims to equalize the exposure amount within the exposure area by setting an exposure time distribution corresponding to one-dimensional intensity unevenness of illumination light, and a control unit for the exposure device frame of the exposure amount control means An exposure apparatus comprising: position reference control means for moving the position reference in the one-dimensional direction. (2) The exposure amount control means includes a shutter means having a light shielding plate and a light shielding plate driving means for driving the light shielding plate in the one-dimensional direction within the exposure area according to a drive curve corresponding to the intensity unevenness, and 2. The exposure apparatus according to claim 1, wherein the reference control means moves the reference of the drive curve. (3) The exposure amount control means includes a shutter unit movable with respect to the exposure apparatus frame, and the position reference control means includes shutter attitude control means for driving the shutter unit in the one-dimensional direction. The exposure apparatus described. (4) The exposure apparatus according to claim 3, wherein the shutter attitude control means further rotates the shutter unit around the optical axis of the illumination light. (5) The position reference control means includes an attitude change detection means for detecting a relative attitude change between the exposure apparatus main body including the exposure apparatus frame and the floor on which the illumination system including the SOR device as the exposure light source is installed. The exposure apparatus according to any one of claims 1 to 4, wherein the exposure apparatus has a positional reference position according to the detection signal.