JPH04337621A - Alignment stage device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positioning stage device for rotation, up/down, and leveling, and is particularly used in semiconductor manufacturing equipment to position a wafer at the focal position of a reduction projection lens and at a position in the rotational direction. This invention relates to improvement of the stage drive mechanism.

0002

[Prior Art] In semiconductor manufacturing equipment, when lithography processing is performed on a wafer, one direction (X
The wafer is placed on a mounting table above an XY stage that can be driven in the other direction (Y direction) and the other direction (Y direction) perpendicular to this direction. Furthermore, this XY stage is adjusted and moved in the rotational direction within the horizontal plane (Θ direction) and the mark on the wafer in the direction perpendicular to this horizontal plane (Z direction) using a certain reference mark. ,
Perform lithography processing.

Generally, a lithography processing apparatus is shown in FIG.
As shown in the figure, a ΘZ stage 54 is installed at the upper center of an X stage 52 and a Y stage 53 whose positions are controlled by an L-shaped mirror 50 and a laser interferometer 51. The wafer is then properly aligned and exposed. In this case, the drive mechanism in the Θ direction is for removing rotational component errors, and coarse movement (resolution 10
(equivalent to 1 μrad) and microtremor (equivalent to 1 μrad resolution)
This is done by making adjustments. Further, the drive mechanism in the Z direction is for positioning the projection lens 54 in the height direction, which is also performed by coarse movement (resolution 1 to 2 μm) and fine movement (resolution 0.01 μm) adjustment. Note that exposure in the lithography process is performed by transmitting light from a light source 56 having a reflecting mirror 55 through a condenser lens 57, a reticle 58, and a projection lens 54.

[0004] The table on which the wafer is placed is placed in the horizontal plane of X, Y,
The amount of movement in the Θ direction is determined by the amount of movement during wafer loading and the loading accuracy. When operating in the Z direction, the distance between the projection lens 54 and the wafer is detected by an autofocus detector, and the amount of drive is adjusted by feeding back based on the detection signal. Note that a description of the specific configuration of these positioning means will be omitted. After setting the wafer in the proper position as described above, lithography processing begins.
Each chip is sequentially processed while repeating movement operations in the X and Y directions.

What is shown in FIG. 13 and subsequent figures are conventional examples of the above-mentioned positioning means for adjusting the movement in the Θ direction and the Z direction. This is based on the publication “Automation Technology” (1987,
Vol. 19, No. 9). Figure 1
3 is a longitudinal sectional view of the Θ, Z stage, and FIG. 14 is a plan view. The Q rotary plate 59 is rotated by a cylindrical rotary shaft 60, and in order to prevent the rotary shaft 60 from tilting, a member is provided to support the rotary shaft 60 so that it rubs against the outer peripheral surface from three directions. (3-line friction method where the joint is linear). Further, the supporting member from one of the directions has a spring property, and is preloaded by a screw attached to this supporting member so as to prevent tilting and play in the radial direction. Further, at three locations on the outer circumference of the Θ rotary plate 59, there are flat receiving pins 62 for holding a plane parallel to the base 61.
is provided, and the upper surface of the Θ rotary plate 59 is pressed by a spring 63 to prevent it from floating up.

In order to coarsely and finely move the Θ rotary plate 59, a lever portion 64 is formed on a part of the outer periphery of the Θ rotary plate 59, and this lever portion 64 is connected to the feed nut 65 for fine movement. This is done while moving forward and backward through the PZT66. and,
Coarse movement is done by stepping motor 67 and high precision lead screw 68
The fine movement is performed by the movement of a fine movement PZT 66 provided in the PZT holder 69.

Next, coarse movement in the Z direction is performed using an inchworm motor 70. FIGS. 15A and 15B are a schematic diagram and an operation explanatory diagram of the inchworm. In this way, the inchworm motor 70 includes a piezoelectric actuator holder part 71 in which two upper and lower cylindrical parts are connected by an elastic hinge spring, a holding lever 72,
It has a movable part 74 which presses and holds the cylindrical part of the holder at 73, and a piezoelectric actuator which drives the holder and the holding lever. As shown in FIG. 15B, by sequentially switching the voltage application to each piezoelectric actuator, the cylindrical portion is repeatedly displaced up and down like an inchworm. In this case, the average upward and downward displacements are 2.5 μm/
It is a step. As described above, the wafer 75
This allows for proper positioning.

[0008]

[Problems to be Solved by the Invention] In the above conventional example, when the Θ rotary plate 59 is slightly moved, a piezoelectric element (with a stroke of 10 μm) is used.
m), the rotating shaft 60
It is necessary to eliminate as much of the backlash component in the thrust direction as possible (tilt and radial) and backlash of the high-precision lead screw 68, and the preload pressure on the rotating shaft 60 must be set high. Then, the rotational load on the stepping motor 67 becomes large, and the stepping motor 67
may cause fever. This heat generation causes the peripheral parts of the device to expand, displacing the wafer several micrometers upward, and far exceeding the depth of focus of the projection lens, making it impossible to perform proper lithography processing. There was a problem.

[0009] Furthermore, the inchworm motor configured to move in the Z direction has a three-way structure consisting of the PZT holder 71a of the piezoelectric actuator holder part 71 and the movable part 74.
There was a problem in that wear occurred at the contact portions (three-wire contact portions) and a sliding phenomenon occurred during operation, making it impossible to obtain a constant amount of displacement. Furthermore, the holding lever 72 of the movable part 74
, 73 is not strong enough, or the upper and lower holding levers
If the pressure balance is different, the Z axis will tilt during the XY operation, resulting in a so-called oscillation phenomenon. This oscillation has an extremely large effect on the accuracy of wafer alignment.

The present invention has been proposed to solve the above-mentioned problems, and provides a positioning stage device that can properly position, for example, a wafer with respect to a reticle and perform highly accurate processing by operating a ΘZ stage. It is intended for this purpose.

[0011]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a positioning stage device which is rotatable in a horizontal plane and movable up and down in a direction perpendicular to the rotating plane. A rotation mechanism in a horizontal plane that has a bearing that can adjust the preload on the outer periphery of the stage support shaft in the rotation direction that supports the stage, a ball member attached to the circumferential side of the stage, and a a plurality of coarse adjustment tools, each of which has a cam member fixed to a rotary member and has a sloped surface, and which moves the stage in the vertical direction by bringing a ball member into contact with the sloped surface of the cam member; The positioning stage device is characterized in that it is provided with a vertical adjustment mechanism having a fine movement adjustment tool disposed between the movement adjustment tools.

0012

[Operation] As described above, the stage support shaft fitted into the bearing rotates via the bearing, so compared to friction sliding, the rotational load is reduced and the heat generation of the motor is prevented. can be achieved. In addition, since the positioning stage is moved up and down by the action of the ball and the inclined surface of the cam that are in contact with it, a large preload can be applied, preventing the stage from falling and ensuring proper positioning. - can be moved.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings. FIG. 1 is an overall schematic diagram of an apparatus according to the present invention, and FIG. 2 and subsequent figures show each component. Although not shown in FIG. 1, the wafer 1 is set on a wafer chuck 2 as shown in FIG. The wafer chuck 2
is fixed to the top plate 3 with screws or the like. As shown in the plan view of FIG. 3, the top plate 3 is movable in the Z direction (vertical direction) relative to the Θ rotary plate 16 by means of a restraining member 5 attached to the Z plate 7; ) is provided in a fixed state.

Furthermore, the top plate 3 is connected to a Z plate 7 having a substantially triangular main body and legs located at the apexes of the triangle as shown in the plan view of FIG. Fixed. The legs of the Z plate 7 are provided with the aforementioned PZTs 6 for fine Z movement so that the top plate 3 can be moved up and down. PZT6 for Z fine movement is
As shown in the front view of FIG. 5, it is composed of a PZT 8 and an internal PZT element 9, and is adapted to expand and contract in the direction of the arrow by applying a voltage to the PZT element 9. The inclination of the top plate 3 with respect to the base 4 can be adjusted by extending and contracting the Z fine movement PZTs 6 provided at three locations on the Z plate 7. Further, by simultaneously displacing the three Z fine movement PZTs 9, the top plate 3 can be translated in the vertical direction.

Further, as shown in the cross-sectional view of the bearing part in FIG. 6A, a shaft 10 is vertically installed at the center of the Z plate 7 with a screw. This shaft 10 has a bearing (linear bush) 1
1 is fitted. The bearing 11 has a warp 12 formed in the longitudinal direction as shown in the plan view of FIG. 6B, and is tightened by a linear bush receiver 13 as shown in the plan view of FIG. 6C. In other words, the linear bush receiver 13 has a slit 14 formed therein, and the screw 1
By tightening 5, the radial play with the shaft 10 is minimized, and it becomes possible to slide in the vertical direction.

Further, a Θ rotary plate 16 is fixed to the bearing 11 with screws via a rising portion 17 formed in the center. A cam ring 19 is provided on the outer periphery of the rising portion 17 via a preloaded ball bearing 18 . Flanges are formed at equal intervals on three sides of the outer periphery of the cam ring 19, and cams 20 are provided on the upper surface of each flange. A pin 40 is provided on the lower surface of the flange, and slides on a pin 41 provided on the Θ rotary plate 16 and having a surface parallel to the rotation surface, thereby regulating the movement of the cam ring. FIG. 7 shows an enlarged side view of the vicinity of the cam 20, and the upper surface of the cam 20 is formed into an inclined surface. Further, above the cam 20, a cam shaft plate 21 and a Z plate 22 are overlapped with fixing screws 23,
An adjusting body having a coarse movement ball screw 24 and a fine movement ball screw 25 is provided. FIG. 8 is a side view of the cam 20 and its surroundings, showing that the ball formed at the tip of the coarse movement ball screw 24 is in contact with the inclined surface of the cam 20.
As the cam 20 moves together with the cam ring 19, the Z plate 7 moves up and down. That is, when the ball comes into contact with the high part of the slope of the cam 20, the Z plate 7 rises, and when it comes into contact with the low part of the slope, it descends. The ball portion of the coarse movement ball screw 24 that slides on the cam 20 may be a non-rotating member having a substantially spherical contact portion.

As shown in FIG. 4, an arm portion 26 is formed protruding from one of the flanges of the cam ring 19, and this arm portion 26 is connected to a screw mechanism provided on the output shaft of the Z-direction actuator 27. The cam ring 19 having the cam 20 rotates around the ball bearing 18 by driving the Z-direction actuator 27 . Due to this rotation, the Z plate 7
This makes it possible to move up and down.

Further, as shown in FIG. 6A, the Θ rotary plate 16 is formed with a rotary plate leg portion 29 at its lower part, and this rotary plate leg portion 29 is rotated through a preloaded large diameter ball bearing 30. It is rotatably attached to a base support 31 which is fixed to the base 4 with screws. Further, as shown in the plan view of FIG. 9, an arm 31 is formed protruding from the Θ rotary plate 16, and this arm 31 is connected to a ball 33 provided on the PZT receiver 32 as shown in the side view of FIG. is in contact with. PZT3
5 is fixed to a screw nut 36 via a PZT receiver 34. A coil spring 37 is connected to the nut 36 to reduce backlash, and the Θ rotation drive motor 4 is connected to the nut 36 via a coupling 38 and a reduction gear 39.
0 is connected and driven. The Θ rotary plate 16 is regulated by a plunger screw 41 with a ball provided on the Θ retainer 5, as shown in FIGS. 1 and 11.

Further, as shown in FIG. 10, a sensor light-shielding plate 42 that rotates coaxially is attached to the cam ring 19, and a photoelectric type sensor for detecting the rotational angle of the cam ring is attached to the fan-shaped opening corner of this sensor light-shielding plate 42. A limit sensor 43 is provided to transmit rotation information of the cam ring 19 to the Θ rotation drive motor 4.
It is controlled by supplying it to 0.

With the above structure, coarse and fine adjustment of the top plate 3 (ie, wafer 1) in the Θ direction and the Z direction is performed as follows. First, for adjustment in the Θ direction, the arm 31 of the Θ rotary plate 16 is moved by the Θ rotation drive motor 40 to perform coarse adjustment. Also,
Fine adjustment is made by driving the PZT35. Next, for adjustment in the Z direction, coarse movement is performed by the Z direction drive motor 45 held in the motor receiver 44 and the cam ring 19, as shown in FIG. Further, as shown in FIG. 5, for fine movement and leveling, the top plate 3 is directly finely adjusted in the vertical direction by three Z fine movement PZTs 6.

[0021]

[Effects of the Invention] As described above, according to the present invention, since the bearing is arranged around the outer circumference of the shaft fixed to the Θ rotary plate,
Since the rotational load is significantly reduced and the motor load for Θ rotation is reduced, heat generation is considerably suppressed. Therefore, obstacles to holding the wafer in a proper position can be eliminated. In addition, as a means for moving in the Z direction (vertical direction),
Since it is configured to operate by a cam having an inclined surface and a ball that abuts the cam, it is possible to efficiently perform the movement while preventing falling, so-called swinging, during XY movement due to insufficient holding force.

[Brief explanation of drawings]

FIG. 1 is an overall schematic diagram of the device.

FIG. 2 is a plan view of a state in which wear is placed.

FIG. 3 is a plan view of the top plate.

FIG. 4 is a plan view of the Z plate.

FIG. 5 is a front view of the PZT for Z fine movement.

FIG. 6 is a cross-sectional view of the vicinity of the bearing, a plan view of the linear bush, and a plan view of the linear receiver.

FIG. 7 is an enlarged cross-sectional view of the cam.

FIG. 8 is a cross-sectional view of the vicinity of the cam.

FIG. 9 is a plan view of the Θ rotary plate.

FIG. 10 is a sectional view of the vicinity of the Θ rotation drive actuator.

FIG. 11 is a cross-sectional view of the vicinity of the Θ suppressor.

FIG. 12 is an overall perspective view of a conventional exposure apparatus.

FIG. 13 is a sectional view of the ΘZ stage.

FIG. 14 is a plan view of the ΘZ stage.

FIG. 15 is a schematic diagram and an operation explanatory diagram of the inchworm.

[Explanation of symbols]

3 Top plate 4 Base 6 PZ for Z fine movement
T7 Z plate 10 Shaft 11 Linear bush 13
Linear receiver 16 Θ rotating plate 17 Cam ring 18
Ball bearing 29 Θ rotating plate leg 30 Large diameter ball bearing

Claims (1)

[Claims] Claim 1: In a positioning stage that is rotatable in a horizontal plane and movable up and down in a direction perpendicular to the rotating plane, preload is adjusted on the outer periphery in the rotational direction of the stage and the stage support shaft that supports the stage. It has a rotation mechanism in a horizontal plane equipped with a rotary bearing, a ball member attached to the circumferential side of the stage, and a cam member fixed to the rotating member disposed near the stage and having an inclined surface. , a plurality of coarse adjustment tools for moving the stage in the vertical direction by bringing the ball member into contact with the sloped surface of the cam member, and a fine adjustment tool disposed between the coarse adjustment tools. A positioning stage characterized by being provided with a vertical direction adjustment mechanism.