JPS61251028A - Exposing apparatus - Google Patents

Abstract

PURPOSE:To improve the precision in shifting stage by a method wherein the gradient of score to detect shifting distance of stage on stage shifting axis is detected in case of supplying power or as necessary. CONSTITUTION:A score 43 is shifted from X0 and Xn while the displacements DELTAY1, DELTAY2,...,DELTAYn in Y direction of square 43 on each point X1, X2,...,Xn measured by receives 61 or 62 are calculated by measured values by the other receiver 63. Next the gradient theta of square 43 is calculated by method of least squares. After detecting the gradient theta of square 43, a substrate stage with corrected theta added thereto is step-shifted. The gradient theta can be corrected by offsetting the feed (Lx, Ly) respectively by DELTAX=Ly tantheta and DELTAY=Lx tantheta.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to an exposure apparatus that prints a pattern image on an original plate, such as a semiconductor circuit, onto an exposed object, and particularly relates to an exposure apparatus suitable as a divided exposure type for printing a large screen in parts. Regarding equipment.

[Description of Prior Art] In a mirror projection type semiconductor printing apparatus, a mask and a substrate (or wafer) are placed on a carriage, and the entire screen is exposed by scanning and moving the carriage onto an exposure surface.

However, as recent trends have shown that screens have become larger due to larger diameter wafers to reduce chip costs and the manufacture of large liquid crystal display panels for LCD TVs, the exposure range has become larger. In addition, there is a problem in that the apparatus becomes larger due to the need to increase the scan length.

As a countermeasure to this problem, a step-and-scan printing method has been considered in which the screen is divided and scan printing is performed multiple times.

FIG. 3 shows the configuration of such a step-and-scan type exposure apparatus previously proposed by the present inventors. In the figure, 1 is a photomask on which a printed pattern is formed, and 2 is a mask stage on which the mask 1 is mounted and is movable in the X, Y, and θ directions. 3 is a glass substrate on which a large number of pixels and switching transistors for controlling on/off of these pixels are formed by normal photolithography procedures in order to manufacture a liquid crystal display board, and the length of the diagonal line is is about 14 inches square. 4
is a substrate stage that can hold the substrate 3 and move in the X, Y, and θ directions. The step movement of the substrate stage 4 is controlled by a precision length measurement system using a laser interferometer (not shown). Reference numeral 5 denotes a well-known mirror projection system consisting of a combination of a concave mirror and a convex mirror, which projects a pattern image of the mask 1 aligned at a predetermined position by the mask stage 2 onto the substrate 3 at the same magnification. Reference numeral 6 denotes an illumination optical system that illuminates the mask 1 at the exposure position with light of a specific wavelength from a light source (not shown), and by exposing the photosensitive layer on the substrate 3 through the pattern on the mask, This is to enable the pattern to be transferred onto the substrate 3. Note that the optical axis of the projection system 5 is made to coincide with the optical axis of the illumination system 6.

7 is a LAB (linear air bearing) that can be moved along two guide rails 8 provided in the Y direction (perpendicular to the page), one of which is movable in the X direction (horizontal direction of the page) and Z direction (direction perpendicular to the page). The other type is a Z-direction restraint type. 9 is a holder (carriage) that holds the mask stage 2 and substrate stage 4 in a fixed relationship;
7, the mask 1 on the mask stage 2 and the substrate 3 on the substrate stage 4 can be integrally transferred.

11 is a mask transport device for sequentially transporting each mask 1 to the mask stage 2; 12 is a gap sensor for detecting the distance between the focal plane of the projection system 5 and the surface of the substrate 3;
For example, an air microsensor or a photoelectric type sensor that detects the distance using reflected light from the substrate 3 is used. Reference numeral 13 denotes a base on which the projection system 5, illumination system 6, and guide rail 8 are mounted in a fixed relationship.

In the apparatus shown in the figure, the surface of the substrate 3 is divided into, for example, four exposed areas, and these exposed areas are placed on the substrate stage 4.
By step movement, the mask 1 and the projection optical system 5 are sequentially fed into the exposure area under the mask 1 and the projection optical system 5, and the mask pattern is exposed four times, thereby printing a pattern for the LCD panel on the entire surface of the substrate 3. A substrate stage 4 is mounted on the carriage 9 in order to perform this step-and-scan printing at higher speed and with higher precision. Furthermore, as shown in FIG. 2, by placing a scoyer 43 on the θ table 42 and measuring the distance to this scoyer 43 with a laser interferometer (not shown), the substrate stage is set when the substrate 3 is fed in steps. 4 and the XY coordinates of the substrate 3.

By the way, the apparatus shown in FIG. 3 has the disadvantage that, especially during the first mask, a difference as shown in FIG. 4 may occur between the patterns printed in sections on the substrate 3. This is because the laser interferometer measures a relative distance from a certain reference position, and the position of the scorer 43 when the power is turned on is usually set as the reference position. In other words, if the scorer 43 is tilted by θ with respect to the XY slide axis of the substrate stage 4 (XY table 45) as shown in FIG. 4 in the X direction, the scorer 43 moves from the solid line position to the dotted line position in the figure, but at this time, the measured value of the receiver 63 changes by ΔY=l-tanθ, and the unillustrated board This is because the stage drive circuit moves the substrate stage 4 in the Y direction by ΔY in order to correct the position of the substrate stage 4 that is shifted by ΔY in the Y direction.

[Object of the Invention] In view of the above-mentioned problems, an object of the present invention is to detect the inclination of a scoyer with respect to the xY slide axis of a stage on which a scoya is mounted in an exposure apparatus when the power is turned on or at a desired time. A further object of the present invention is to improve the feeding accuracy of the stage by correcting the moving directions in the X and Y directions according to this inclination when the stage is moved.

[Explanation of Examples] Hereinafter, the present invention will be explained in detail using the drawings.

Note that parts common or corresponding to those of the conventional example are represented by the same reference numerals.

FIG. 1 shows an electric circuit configuration of a mirror projection type exposure apparatus according to an embodiment of the present invention. In the figure, 14 is a central processing unit (CPU) that controls the operation of the entire exposure apparatus, 15 is a read-only memory (ROM) in which a control program for the CPU 14 is stored, and 1G is a CPU 14 that executes the control program. Random access memory (random access memory) that temporarily stores various data generated when
17 is a mask stage driver, 18 is a substrate stage driver, and 19 is a keyboard. The mask stage 2 and the substrate stage 4 are the same as in FIG. 3, and the receivers 61, 62, and 63 of the laser interferometer are the same as in FIG. 5. This exposure apparatus has the same hardware configuration as the apparatus shown in FIG. 3, but its operation is different by changing the control program stored in the ROM 15.

FIG. 2 is a schematic cross-sectional view of the substrate stage in the exposure apparatus of FIG. 1, viewed in the Y direction. In the figure, reference numeral 41 denotes a chuck for holding the substrate 3 on the substrate stage 4;
2 is a θ table for rotating the substrate 3 along with the chuck 41 within the XY plane, and 43 is a Scoya (L-shaped mirror). 44
is an XY table, and the θ table 42 is rotatably attached to this XY table 45 via a ball bearing.

45 is an actuator for moving the substrate 3 in seven directions to perform focus adjustment and tilt adjustment, and is made of a piezoelectric element or the like. 46 is a Y slider which moves along a Y guide 49 formed on the X slider 48 in accordance with the rotation of a ball screw 47 driven by a motor (not shown).

to move in the Y direction. The XY table 44 is fixed to this Y slider 46 via an actuator 45. 50 is a sliding piece for making the Y slider 46 follow the Y guide 49. Further, the X slider 48 moves in the X direction along an X guide 51 formed in the X direction on the upper surface of the base portion 91 of the carriage 9 in accordance with the rotation of a ball screw 52 driven by a motor (not shown). In addition, the first
In the figure, from the lower half of the X slider 48 to the carriage base 9
The part extending to 1 shows a cross section as seen from the X direction.

Next, the operation of the exposure apparatus having the above configuration will be explained.

In this apparatus, the following score position confirmation operation is started as part of initializing when the power is turned on or when a score position confirmation command is input from the keyboard 19.

That is, while moving the score 43 from xO in FIG. ．． ..., Δy
n (see FIG. 6) is determined from the measured value of the receiver 63.

Subsequently, the slope θ of the score 43 is calculated by the least squares method. That is, θ that minimizes Σ0(ktanθ−ΔYk)2 is determined, and this is determined as the slope of the score 43.

Here, the reason for finding the above-mentioned inclination θ by the least squares method is that when the substrate stage 4 yaws, the inclination θ is simply calculated by θ=t
This is because if the value is calculated as an-'ΔYk/Xk, there will be large variations from measurement point to measurement point.

In addition, in cases where θ itself is extremely small and the above-mentioned variations do not pose a problem, or when the mechanical precision of the moving mechanism of the substrate stage 4 and the rigidity of the constituent members are high and yawing is extremely small, the slope θ of score 43 is determined by only one point. Depending on the measurement value,
For example, it goes without saying that it may be determined as θ=tan-'ΔYn/Xn.

The model in which the slope θ of the score 43 is detected as described above is as follows.
The substrate stage 4 is moved step by step after adding this correction for θ. This correction is performed, for example, by the step feed amount (Lx,
The feed amount in the X and Y directions is adjusted according to Δ
It is sufficient to offset by X-Lytanθ and ΔY=lxtanθ. Alternatively, instead of this offset, the θ table 42 may be rotated by the detected inclination θ of the score 43 to align the direction of the score 43 with the XY slide axis before entering the normal operation.

[Example of application of the invention] Note that in 1-description, an example in which the present invention is applied to a mirror projection type exposure apparatus is explained.
The present invention is applicable to other devices that use a batch or divided exposure method, such as a proximity or contact type exposure device, or a so-called stepper that transfers a pattern projected through a reduction projection optical system while stepping the exposed object. It is also possible. For example, when the present invention is applied to a stepper, it is possible to improve the step feed accuracy during so-called glow pal alignment or zone alignment, in which step feed is performed based on the readings of a laser interferometer, even after the first mask printing or the second mask. be able to. Further, in the above description, a case has been described in which the Scoya is mounted on a θ table, but the present invention is also applicable to a case where the Scoya is mounted on an XY table like a conventional stepper.

In addition, in the above embodiment, the × (or Y) of the substrate
Two laser interferometer receivers are used to detect the moving distance in the X direction, but this is to detect yawing when the substrate stage 4 is moved in the X direction. , Y, one receiver each is sufficient.

[Effects of the Invention] As described above, according to the present invention, the inclination of the scorer with respect to the stage movement axis for detecting the stage movement distance is N.
Since the detection is performed when the power source is turned on or when desired, it is possible to know other components when moving the stage (for example, Y, Z, and θ components when moving the stage in the It becomes possible to correct or cancel components other than the above, and it is possible to improve the movement accuracy of the stage. Moreover, this allows each pattern to be better joined when performing divided exposure.

[Brief explanation of drawings]

FIG. 1 is an electric circuit diagram showing the hardware configuration of a semiconductor printing apparatus according to an embodiment of the present invention, FIG. 2 is a schematic cross-sectional view of a substrate stage in the apparatus shown in FIG. 1, and FIG. 4 is a top view of an example of a substrate exposed in parts by the device shown in FIG. 3, and FIG. 5 shows the behavior of the substrate stage when the scanner is tilted. FIG. 6 is a graph showing the displacement in the Y direction when the substrate stage is moved in the X direction when the Scoya is tilted. 1: Photomask, 2: Mask stage, 3: Substrate, 4
: M plate stage, 5: mirror projection system, 9: holder (carriage), 13: base, 14: CPLI. 15: ROM, 1B: Substrate stage driver, 42
: θ table, 43 varnish D set, 44: XY Chi 7/L/
, 61°62.63: Laser interferometer receiver.

Claims (1)

[Claims] 1. Before exposure, in order to move the original plate or the exposed object to the exposure position and positionally align the original plate and the exposed object at the exposure position, the original plate or the exposed object is mounted and placed at a predetermined position. a θ stage that is rotatable within the plane of
In an exposure apparatus equipped with a laser interferometer that measures the distance traveled by the original plate or the exposed object due to the movement of the Y stage, the score for length measurement by the laser interferometer is set to the θ.
a means for placing the XY stage on a stage and moving the XY stage in one direction; and a change in the position coordinate of the XY stage in the X direction whose length is measured by the laser interferometer when the XY stage is moved in one direction. and means for calculating the slope of the score based on the change in the Y direction. 2. The exposure apparatus according to claim 1, wherein the XY stage is moved in one direction when the apparatus is powered on. 3. Pattern printing is performed by dividing the surface of the object to be exposed into a plurality of regions to be exposed, and exposing each region to light by sequentially positioning each region in the projection plane of the image of the original plate. Or the exposure apparatus according to item 2. 4. A patent claim that has a same-magnification projection optical system, and after positionally aligning the original plate and the object to be exposed, the original plate and the object to be exposed are integrally scanned with respect to the projection system for exposure. The exposure apparatus according to the first, second or third item. 5. While stepping the exposed object at predetermined intervals, an image of the original plate is projected and exposed onto the exposed object through a reduction projection optical system, thereby forming a plurality of images of the original plate on the exposed object. An exposure apparatus according to claim 1, 2 or 3, which transfers images. 6. The exposure apparatus according to claim 1, 2 or 3, wherein the original plate and the object to be exposed are exposed in close proximity or close contact with each other in a positionally aligned state.