JPH03265118A - Aligner - Google Patents

Abstract

PURPOSE:To correct the slippage of an alignment axis to an exposure light axis so as to improve transcription accuracy by detecting the rotational slippage around a Y axis of the alignment light axis, and rotating the alignment light axis around the Y axis through an actuator. CONSTITUTION:The X-ray beam 14 from a track emitted light (SOR) device 10 becomes an exposure X-ray beam 18 by formation or the like, and is applied to the thick plate and the board to be exposed being held in the vertical direction by the aligner 20 freely capable of fine rotation around the Y axis, being suspended by a twist removing system 27 such as a pneumatic bearing, etc. The rotational slippage between the alignment light axis of this device 20 and the exposure light axis of the beam 18 is detected by a secondary sensor, etc., and according to the detection results, two sets of pneumatic springs 33 constituting an actuator correct the rotational slippage, and it becomes an aligner where transcription accuracy is elevated.

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 wafer with high precision.

[Prior Art] Semiconductor integrated circuits have become increasingly highly integrated in recent years, and exposure devices (aligners) used to manufacture them are also required to have higher transfer precision. For example, 2
A 56 megabit DRAM class integrated circuit requires an exposure device that can print a pattern with #J width of about 0.25 microns.

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.

Since this orbital synchrotron radiation is in the form of a sheet beam that is uniform in the horizontal direction, in order to expose the surface, ■ scan the surface by moving the mask and query in the vertical direction and scanning the surface with horizontal sheet beam X-rays. Exposure method: ■ scan mirror exposure method in which a sheet beam of X-rays is reflected by a swinging mirror and scanned over the mask and wafer in the vertical direction, and ■ X-ray mirror with a convex reflecting surface allows horizontal scanning 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 previously filed an application for an exposure apparatus according to this blanket exposure method as Japanese Patent Application No. 1983-71040.

[Problems to be Solved by the Invention] Incidentally, in such a 5OR-X-ray exposure apparatus, the SOR device, which is the light source of the exposure illumination light, and the exposure apparatus main body, in which the mask and wafer are set, are separated. Therefore, the exposure area (mask and wafer) and the
The relative positional variation (posture variation) with the OR-X-ray flux (SOR beam) occurs to a greater extent than in a conventional exposure apparatus having a light source inside the main body. In the exposure apparatus of the prior application, such posture fluctuations cause deterioration of transfer accuracy.

That is, in the proximity exposure method, if the angle of incidence of illumination light on the exposure area changes, the overlay accuracy deteriorates. For example, when the proximity gap G between the mask and the wafer is 50 μm, in order to make the overlay error Δδ due to the incident angle variation 1/100 of the pattern #JI width, that is, 0.002 μm or less, the incident angle variation Δ
θ as Δθ=Δδ/G <0.002150=4xlO-5rad or 4X
Must be less than 10-Srad.

In addition, in the exposure apparatus of the prior application, since the SOR beam that is the exposure illumination light has a divergence angle, the incident angle of the illumination light on the mask and wafer due to the relative positional variation Δy between the mask and query and the illumination light. changes. This incident angle variation Δθ is uniform in the vertical direction (hereinafter referred to as Y It has a one-dimensional intensity distribution (profile) in which the intensity is high at the center and decreases as it moves upwards or downwards. In the above-mentioned prior application, by setting an exposure time distribution corresponding to the profile of illumination light in this -dimensional direction, the amount of exposure within the exposure area is made uniform. However, for example, if the profile curve and the exposure time distribution curve corresponding to this profile are shifted by Δy, the X-ray intensity I at position y becomes. This incident angle variation Δθ causes the above-mentioned overlay error Δδ. The overlay error Δδ in this case appears as a run-out error in which different transfer magnifications are distributed in different parts of the surface of the sea urchin. According to the above equation, the relative position variation Δy must be 0.2 mm or less.

In addition, in the exposure apparatus of the earlier application, the illumination light S
The OR beam fluctuates in the horizontal direction (hereinafter, the Assuming that the angular dimension is 30 mm, the profile is expressed by a quadratic function that is vertically symmetrical about the center line, and the minimum intensity is 80% of the maximum intensity, then the X-ray intensity unevenness is 0.1 % or less, the relative positional variation Δy of the SOR beam with respect to the exposure area must be
must be 40 μm 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,
It is estimated that the relative displacement due to the vibration of the floor is approximately 2 μm.

As described above, in the exposure apparatus of the prior application, when the postures of the SOR beam, which is illumination light for exposure, and the mask and wafer change, the transfer accuracy deteriorates. Therefore, S
It is necessary to control the orientations of the OR beam, mask, and wafer to be constant.

In Japanese Patent Application No. 63-252761 filed by the present applicant, during exposure, a vibration isolation system itself equipped with an alignment device that aligns and holds the mask and wafer is used as an actuator to combine the SOR beam with the mask. Controlling the posture of a wafer is disclosed. However, in the system disclosed in Japanese Patent Application No. 63-252761, each actuator means such as an air spring constituting the vibration isolation system drives the alignment device in a substantially vertical direction (Y-axis direction). Substantially vertical deviation Δy and rotational deviation around the exposure optical axis (Z-axis) Δω2
It was only actuating.

An object of the present invention is to further improve transfer accuracy in an exposure apparatus in which an exposure light source and an exposure apparatus main body are separated.

[Means for Solving the Problems] In order to achieve the above object, the present invention includes an alignment device mounted on a vibration isolation system for positionally aligning the original plate and the substrate to be exposed while holding them substantially vertically. An exposure device main body,
In order to transfer and expose the image of the original onto a substrate to be exposed, an exposure apparatus is provided with an exposure light source that generates a beam of light in a substantially horizontal direction and in a direction substantially perpendicular to the original and the substrate to be exposed. a rotary actuator means that rotates around an axis in a substantially vertical direction; an alignment optical axis that is an axis that is substantially perpendicular to the original plate and the substrate to be exposed in the alignment device; and an exposure optical axis that is an optical axis of the exposure light source; The present invention is characterized in that it is provided with means for detecting displacement around an axis in a substantially vertical direction.

In one aspect of the invention, the bearing portion for rotating the alignment device around the substantially vertical axis is the vibration isolating system itself, and the rotary actuator means is an air spring forming the vibration isolating system. It is characterized by certain things.

As a means for detecting the deviation (ΔωY) around the approximately vertical axis (Y-axis), a known method can be used. It is preferable to use an optical system that includes a two-dimensional area sensor disposed at a position with no angle of view, and an optical system that focuses part of the exposure light, particularly a part outside the exposure angle of view, onto the area sensor. Furthermore, even when the exposure light is 5OR-X-rays, the same optical system and two-dimensional area sensor as above can be used by extracting the visible light component in the SOR beam with a radiation-resistant glass filter. I can do it.

[Operation] The alignment optical axis is an axis that serves as a reference for positioning the original and the substrate to be exposed, and ideally should be aligned with the exposure optical axis (Z-axis).

Then, the rotational deviation of the alignment optical axis around the Y axis ΔωY
becomes the incident angle deviation of 80, and the overlay error Δ
It becomes a factor of δ.

In this invention, a means for detecting the rotational deviation ΔωY and an alignment device, that is, an actuator means for rotating the alignment optical axis around the Y axis are provided. Therefore, by manually or automatically operating the actuator means based on the detected rotational deviation Δωa, the rotational deviation Δω7 can be corrected.

[Effect] As described above, according to the present invention, when the alignment optical axis causes a rotational deviation Δωa around the Y axis with respect to the exposure optical axis (Z axis), this can be corrected, and the transfer accuracy can be improved. It is possible to realize an exposure apparatus with higher performance.

[Embodiment] Fig. 1 shows the overall schematic configuration of a 5OR-X-ray exposure apparatus according to an embodiment of the present invention, and Fig. 2 shows one of the pneumatic and electric circuits for attitude control of the vibration isolating mechanism. The system (there are three systems with the same configuration) is shown.

In FIG. 1, 10 is an SOR device, 11 is a storage ring that stores electrons injected from an accelerator (not shown),
12 is a bending magnet, 13 is an SOR frame,
14 is orbital synchrotron radiation (SOR light). 15 is a cylindrical X-ray reflection mirror that shapes the SOR light 14 to the exposure angle of view; 16 is an ultra-high vacuum mirror chamber; 17 is an X-ray mirror mount; and 18 is a shaped exposure beam running in the ultra-high vacuum beam line. Further, 20 is an exposure apparatus main body, and 21
22 is an alignment unit that aligns the X-ray mask 21 and the wafer, 23 is an alignment optical system, 24 is a main frame that supports an exposure stage (not shown), and 25 is an exposure atmosphere. 26 is a vacuum chamber composed of a brightness distribution correction unit for the illumination system, an ultra-high vacuum beam line, and a helium window which is a partition wall of the vacuum chamber 25; 27 is an air spring; 28 is a vacuum chamber 25; 29 is a vibration isolating pedestal, 31 is a Δy adjustment cylinder 32 for adjusting the height of the entire exposure apparatus main body 20, and a Δy adjustment cylinder 32 is for adjusting the relative displacement Δy between the pedestal 30 and the vibration isolating base 28. 33 is an air supply/exhaust system, 34 is a control signal system, and 35 is an air fryer for transporting the apparatus. Air fryer 35 is
When transporting the device main body 20, the device main body 20 is floated on the principle of a hovercraft by blowing out air from the bottom surface, and the movement of the device main body 20 is facilitated. Reference numeral 36 designates an ω-actuate air spring that slightly rotates the entire exposure apparatus main body 20 around the Y axis, 37 a support plate, and 38 a ω-actuate rod.

In FIG. 2, 50 is the equipment installation floor, 51 is an air source, and 5
2 is an air filter, 53 is a regulator, 54 is an air supply solenoid valve, 55 is an exhaust solenoid valve, 5
6 is an electropneumatic proportional valve, 57 is a surge tank for eliminating pressure fluctuations, 58 is an air supply speed controller, 59 is an exhaust speed controller, 60 is a control circuit, and 61 is a drive circuit. .

3A to 3C are a front view, a plan view, and a side view showing the configuration of the exposure apparatus main body 20 in FIG. 1. In the figure, 301 is a wafer to which the image of the mask 21 is to be transferred, 302 is a wafer chuck, 303 is an X-axis guide, and 30
4 is a Y-axis guide, 305 is a main frame support part, 30
6 is a chamber support part.

In the above configuration, a degree of freedom in the ωy (rotation around the Y axis) direction is provided between the vibration isolation system (air spring) 27 and the hanging plate 28, and air is supplied to each of the two air springs 33. By controlling the suspension plate 28, the alignment unit 22 is
This allows for minute rotation around the Y-axis. Thereby, if there is a rotational deviation ΔωY around the Y axis with respect to the two axes of the alignment optical axis, it can be corrected.

4 to 8 show other examples of a rotary actuator that slightly rotates the alignment unit 22 around the Y axis (ω7 rotations).

In FIG. 4, an ωY stage 401 is provided between the floor 50 and the vibration isolation stand 29, and the exposure apparatus main body 20 is mounted on this ω7 stage 401.
01, and the exposure apparatus main body 20 is mounted on the X-2.
An example in which an air spring 402 that can be actuated in a plane is arranged is shown. Note that as the bearing of this ω7 stage 401, an air bearing (air fryer 35) for transporting the exposure apparatus main body 2o shown in FIG. 5 may also be used.

In FIG. 6, an ωY stage 401 is provided between the vibration isolating frame 29 and the vibration isolating system (air spring) 27, and an air spring 402 that can actuate this ω stage 401 in the x-2 plane is arranged. An example is shown in which the decompression chamber 25, together with the suspension plate 28 and the vibration isolation system 27, can be rotated by ωa.

FIG. 7 shows an actuator 70 that gives the main frame support part 305 a degree of freedom in the ωY force direction and drives the main frame 24 in the X-2 plane against the wall of the decompression chamber 25.
1 is provided, and the main frame 24 can be rotated by ω7 relative to the decompression chamber 25.

FIG. 8 shows a structure in which the coupling portion between the alignment frame 22 and the main frame 24 has a degree of freedom in the ω7 direction, and an actuator 801 is provided to drive the alignment frame 22 with respect to the main frame 24 at least within the X-2 plane. An example is shown in which the alignment frame 22 can be rotated by ω7 with respect to the main frame 24.

Note that the present invention is not limited to the above-described embodiments, and can be implemented with appropriate modifications.

For example, alignment scope (alignment optical system)
23 may be given a degree of freedom in the ω-a direction, and only the alignment scope 23 may be driven relative to the alignment frame 22 within the x-2 plane. Alternatively, a mechanism may be provided to drive the optical axis of the alignment scope 23 itself in the ω7 direction.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the overall configuration of an X-ray exposure apparatus according to an embodiment of the present invention, FIG. 2 is an explanatory diagram of the configuration of a control system in the exposure apparatus of FIG. 1, and FIGS. 3A to C are , a front view, a top view, and a side view showing the structure of the exposure apparatus main body portion of the exposure apparatus shown in FIG. 1, and FIGS. 4 to 8 are explanatory diagrams showing modifications of the above embodiment, respectively. 02 7, / 10: SOR device 18: SOR beam 20: Exposure device main body 21: Mask 22: Alignment frame 27; Vibration isolation system 36, 402. 701. 801: Actuator 301: Wafer 401: ωY stage

Claims (2)

[Claims] (1) an exposure apparatus main body having an alignment device for positionally aligning the original and the substrate to be exposed while holding them substantially vertically; and a vibration isolation system equipped with the alignment device; To perform transfer exposure onto the exposed substrate,
an exposure light source that generates a light beam in a substantially horizontal direction and substantially perpendicular to the original plate and the substrate to be exposed; rotation actuator means for rotating the alignment device about the substantially vertical axis; and an original plate in the alignment device; It is characterized by comprising means for detecting a deviation between an alignment optical axis, which is an axis substantially perpendicular to the exposed substrate, and an exposure optical axis, which is an optical axis of the exposure light source, about the substantially vertical axis. Exposure equipment. (2) The exposure according to claim 1, wherein the bearing for rotating the alignment device around the substantially vertical axis is the vibration isolating system itself, and the rotary actuator means is an air spring forming the vibration isolating system. Device.