JPH029550A - Driving device for six-degree-freedom fine moving stage - Google Patents

Abstract

PURPOSE:To improve positioning rigidity and to improve controllability by a method wherein six sets of feed mechanisms are independently formed so that fine movement in the directions of an X-axis, a Y-axis, and a Z-axis of a fine moving state, and fine rotation around the Z-axis, the Z-axis, and the U-axis are controllable. CONSTITUTION:A stage 42 is pressed through the force of a spring 47 and a nut member 44 is pressed through a floating pad 43 with the aid of a single pulse motor 46 to perform positioning in a direction X. Similarly, a nut member 58 is pressed through a floating pad 57 through the force of a spring 61 with the aid of two pulse motors 60 to perform positioning in a direction Y. A feed mechanism in the direction of the X-axis is formed with three pulse motors 52. A wafer 4 is vacuum-adsorbed on the upper surface of a stage 42, and a displacement amount of the surface of the wafer 4 from the focus point surface of a reflection projection optical system 7 is detected in relation to nine detecting points 56 by means of an electrostatic volume type proximity sensor 54. From the displacement amount, displacement and inclination between the similar plane of the surface of the wafer 4 and the focus point surface of the optical system 7 are determined, the three motors 52 are run, and a stage 42 is moved vertically and inclined for correction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a driving device for a six-degree-of-freedom fine movement stage that enables precise fine-movement control of the stage with six degrees of freedom. In particular, the present invention is suitable as a substrate positioning mechanism for a projection type exposure apparatus.

[Prior art]

The fine movement stage drive device having six degrees of freedom mentioned above is
It is also used in projection exposure equipment that prints mask patterns onto the wafer surface. In the operating procedure of the device, 1.
It is necessary to project and image the mask pattern onto the wafer surface using a projection optical system. The range in which the high-resolution mask pattern required for the projection optical system is imaged is the range near the focal plane of the projection optical system, and the imaging condition deteriorates rapidly as the distance from the focal plane increases. In practice, the allowable amount of deviation from the focal plane of the projection optical system on the entire wafer surface is ±6 μm, and in order to obtain stable resolution, it is necessary to position the entire wafer surface at the focal plane of the projection optical system with high precision. is required. After the above positioning (focusing), the mask pattern and the pattern formed on the wafer surface are moved with high precision (
±025 μm) is required. Therefore, the wafer mounting apparatus requires a position constraint function with a total of six degrees of freedom.

In normal cases, the above six degrees of freedom control is performed on the two horizontal orthogonal axes X, Y and the vertical axis Z, and is performed on parallel movements in these 5 directions and rotation around the three axes. , whereby the position and orientation of the rigid body in the five-dimensional space are determined. However, the above-mentioned five axes are not limited to the horizontal and vertical orthogonal s-axes, and it is also possible to set oblique diagonal axes to perform six degrees of freedom control.

FIG. 1 shows a schematic front view of a conventional 1:1 reflection projection exposure apparatus.

Stone surface plate Iij is finished with high precision and has a thread angle of 2 degrees.
performs a linear movement left and right on the stone surface plate 1 with high precision (±0.08 μm). A wafer mounting device [5] and a mask mounting device 5 are provided on the sled 2, and are capable of mounting a wafer 4 and a mask 6, respectively. Further, a reflection projection optical system 7 and an alignment scope 8 are fixed on the stone surface plate 1, and a height reference plate 9 is fixed below the reflection projection optical system 7. The mask pattern of the mask 6 illuminated in the shape of an arcuate slit by an illumination optical system (not shown) located below the stone surface plate 1 is projected and imaged onto the surface of the wafer 4 by the reflection projection optical system 7, and the entire thread 2 is projected onto the surface of the wafer 4. By moving it left and right, a mask pattern can be laid and exposed over the entire surface of the wafer 4. The alignment scope 8 has a function of detecting the overlapping state of the alignment mark on the wafer 4 and the alignment mark in the mask pattern.

FIG. 2 shows an enlarged cross-sectional view of the wafer mounting device 5 described above. A base 11 of the wafer mounting device is fixed to the aforementioned sled 2, and an XY stage 12 is placed on the wafer mounting device base 11 via a steel ball 16. The XY stage 12Vi can move freely within a horizontal plane along the upper surface of the base 11, and has two degrees of freedom. This XY stage 12 is a feeding mechanism (not shown)
The position is controlled within the range of ±5+w+ in the sled running direction (X direction) and in the direction perpendicular thereto (X direction) within the horizontal plane. This XY stage 1
2 is rotatably provided with a θ stage 13 via a ball bearing 17, and this θ stage B is further provided with a vertical shaft 14. This vertical shaft 14, nut 19, feed
It has a structure that is driven up and down by a Z stage 18 and a pulse motor 20, and acts as a Z stage. This Z
A θ stage 15 with 14 vertical shafts, which is a stage, is locked in a pair so as not to rotate, and is supported so as to be vertically slidable.

A wafer mounting table 15 is placed above the vertical shaft 14.
The conical recess at the upper end of the vertical shaft 14 and the wafer f”t
bl and the lower spherical seat of the table 15 are engaged, so that the wafer mounting table 15 can be tilted freely.

In this way, the conventional wafer mounting device has XY, x, f-
The XY stage 12 supports the θ stage 15, and the θ stage 15 supports the vertical axis 14.
It had a triple structure in which the wafer mounting table 15 and the wafer 4 were supported.

Next, the operation of this conventional wafer mounting apparatus will be explained. First, in the state shown in FIG. 2, the wafer 4 is vacuum suctioned onto the wafer mounting table 15 using the suction hole 22ft. Next, raise the vertical axis 14 and
0.Press the surface of the wafer 4 to 0.

Then, the inclination is corrected by the reaction force from the wafer mounting table 15 and the wafer pad 10, and the wafer mounting table 15 assumes a horizontal position. The pad 10 described above is arranged at the apex of an equilateral triangle whose center of gravity is the center of the wafer 4,
The specified height (0,5
m), the surface of the wafer 4 is positioned at a position higher than the focal plane of the catoptric projection optical system 7 by the specified height. In this state, the vacuum chamber 21 is evacuated and the entire wafer mounting table 15 is suctioned and fixed to the vertical shaft 14, and the vertical shaft 14 is further lowered together with the wafer 4 and the wafer mounting table 15 by the above-mentioned specified height, and the wafer surface is exposed to the reflection projection optical system. It was moved in parallel to within the depth of focus of 7.

After the above-described operation, the XY stage 12 is moved and the θ stage 15 is rotated to match the alignment mark placed on the sea urchin/14 with the alignment mark on the mask pattern. In this state, the sled 2 was once moved to the forward side, and then while returning at a constant speed on the return path, the mask pattern 41 was emitted onto the entire surface of the wafer 4, and the mask pattern was printed on the surface of the sea urchin/X4.

[Problem that the invention seeks to solve]

The above-mentioned conventional technology had the following drawbacks: 1. After pressing the surface of the wafer 4 against the pad 10 to make it parallel to the focal plane of the reflection projection optical system 7, the vertical axis 14 (Z Since movement or rotation is performed at five locations: the stage), theta stage 15, and the Parallelism and height positioning f with respect to the focal plane of 7
＃Easy to lose strength.

2 The XY stage 12 is placed on the wafer mounting device base 11.
, a θ stage 15 and a second stage 14 are provided, and the wafer mounting table 15 is placed on top of them, so the overall positioning rigidity from the wafer mounting device base 11 to the Urchin I/mounting stand 15 is low, and the Urchin/1 mounting stand is 15 has poor positional stability.

3. XY stage 12ij #stage 15, upper and lower 4
1114 and these driving means,
The total weight tFi of this XY stage 12 is large. Therefore, X
The feed mechanism of the Y stage carries the entire weight of the 9X
The Y stage 12 must be driven and controlled, reducing the controllability of fine movement feed.

The purpose of the present invention is to solve the above-mentioned problems of the prior art by making it possible to finely control each of the six degrees of freedom of the stage with high precision, to increase positioning rigidity, and to provide six degrees of freedom with improved controllability. It is an object of the present invention to provide a fine movement stage driving device.

[Rounding method to solve problems]

That is, in order to achieve the above object, the present invention includes a stage on which a substrate is placed and has six degrees of freedom, and a set of X-feeding mechanisms that apply force directly to the stage to slightly move it in the X direction.
Two sets of Y feed mechanisms that apply direct force to the fine movement stage at two locations to slightly move it in the Y direction, and five sets of two feed mechanisms that apply direct force to the stage at six locations to make it slightly move in the Z direction. The six sets of feed mechanisms are configured to be able to independently control fine movement of the fine movement stage in the X-axis, Y-axis, and two-axis directions, and fine rotation around the Z-axis, X-axis, and Y-axis. This is a driving device for a six-degree-of-freedom fine movement stage.

Further, in the drive device for the 6-degree-of-freedom fine movement stage, the present invention provides that each of the five sets of Z feed mechanisms is engaged with the stage at one end in a ball-to-coupled manner, and the other end is engaged with the fixed member in a ball-to-coupled manner. 6 characterized in that it is formed of piezo elements that are combined
This is a drive device for a fine movement stage with degrees of freedom.

[Effect]

According to the above configuration, a very compact and highly rigid 6
A fine movement stage with a degree of freedom can be obtained. In particular, it is possible to control the focusing point on the substrate at high speed.

〔Example〕

Next, an outline of an embodiment of the present invention will be explained with reference to FIGS. 5 and 4.

The fifth prisoner is a vertical sectional view of the stage control device of the present invention;
The figure is a plan view of the same.

This embodiment is configured to control the position of the stage 42 holding the wafer 4 by suction in two horizontal orthogonal axes X and Y and the vertical 411Z direction, as well as to control the rotational posture around the five axes. When implementing the present invention, it is also possible to perform control not only on five orthogonal axes but also on five axes in arbitrary directions.

41 is the base of the wafer mounting device. This base 41
1 pulse motor 46 for configuring one set of X-direction feeding mechanisms; 2 pulse motors 46 for configuring two sets of Y-direction feeding mechanisms.
5 pulse motors 60 (Fig. 4) and 5 sets of Z-direction feeders! Three Hares motors 52 to configure III
(Fig. 3) Fully secure. These pulse motors 46.6
0.52 shaft, lead screw 45.59.511 respectively
f! : Sticks. The nut members 44, 58, and 50 that are threadedly engaged with the feed screws 45, 59, and 51 are locked against rotation relative to the wafer mounting device base 41, and are fitted so as to be slidable in the axial direction.

As described above, this embodiment includes one set of feeding mechanisms provided in the X direction, two sets of feeding mechanisms provided in the X direction, and five sets of feeding mechanisms provided in the Z direction.

A cavity 55 for vacuum suction is provided on the upper surface of the stage 42 to provide a wafer mounting function. The weight of this stage 42 is due to the weight of the floating pad 49 and steel balls 48, which will be described later with reference to FIG.
It is supported by five nut members 50 via. This is a spring that is biased by its own weight.

The stage 42 is pushed against the nut member 44 by a spring 47 provided in the X direction and through a floating pad 45, which will be described in detail later with reference to FIG. 5, to loosen the stage 42 in the X direction. Similarly, a spring 61 provided in the %YX direction presses against the nut member 5 via a floating pad 57, which will be described later, to achieve positioning in the X direction.

Nine capacitive proximity sensors 54 are fixed to the bottom surface of the reflective projection optical system 7 to detect the surface position of the wafer 4 and increase the deviation between the top surface of the wafer 4 and the focal plane of the optical system 7. accuracy(
±0.2 μm) so that it can be detected in a non-contact manner. Nine X marks 5 shown on the surface of the wafer 4 in the fourth factor
6 represents a detection point of the sensor 54.

Details of the above-mentioned floating pads 49 and 45 will be explained with reference to the wcs diagram. Although the floating pad 57 provided in the X-direction feeding device does not appear in this cross section, it is a component similar to the floating pad 45 of the X-direction feeding device shown in this figure. The floating pad 45 has its left end spherical surface held by the spherical seat of the nut 440, and its right end flat surface abuts against the side surface of the stage 42 to transmit the feed amount of the feed mechanism to the stage 42. Furthermore, since the spherical and flat surfaces at both ends of the floating pad 45 serve as air bearings, the stage 42 can be moved up and down, forward and backward, and in X and Y directions.

There is no resistance to tilting around the Z axis. Therefore, the floating pad 45 has a free leg that does not resist movement of the stage by other feed mechanisms, while at the same time being able to transmit a corresponding feed amount in the X-axis direction.

The upper surface of the nut member 50 of the Z direction feeding mechanism is made to be precisely parallel to the focal plane of the reflection projection optical system 7. Floating pad 4 that comes into contact with the upper surface of this nut member 50
The lower surface of the floating pad 9 has an air bearing, so that the floating pad 49 can move horizontally on the upper surface of the nut 50 with almost no resistance. The frictional force with the conical surface can be almost ignored. Therefore, the 'A steel ball 8 and the floating pad 49 transmit the feeding and landing in the Z direction to all the stages 42, and at the same time do not act as resistance to the movement and inclination of the stage 42 in the horizontal plane by other feeding mechanisms. 62 is floating pad 4
5.49 is a tube that supplies air.

In this embodiment, as described above, only the force in the feeding direction of each feeding mechanism is transmitted between each of the nut members of the six sets of feeding mechanisms and the stage 42, and movement in directions other than the feeding direction is permitted. A transmission member is interposed so that the six sets of feeding mechanisms can drive the stage 42 independently.

Next, a method of using the stage control device configured as described above will be explained. In this embodiment, an automatic control device (not shown) is provided to electrically and automatically operate the sensors and actuating devices as follows.

If, the wafer 4 is vacuum-adsorbed onto the upper surface of the stage 42.

Next, the capacitance type proximity sensor 54 detects the wafer 4.
The amount of deviation of the surface from the focal plane of the reflection projection optical system 7 is detected at nine detection points 56 arranged in a grid without contacting the surface. Then, from these nine deviations 1, the deviation and inclination between the approximate plane of the surface of the wafer 4 and the focal plane of the catoptric projection optical system 7 are determined. Next, the five pulse motors 52 are rotated to move the nut member 50 up and down as appropriate.
The stage 42 is moved up and down and tilted to correct the shift and inclination. At this time, as mentioned above, the floating pad 45.57id has a spherical surface and a flat surface at both ends as air bearing surfaces, so it does not create resistance to the vertical movement and tilting of the 2nd stage 42. Since it is small, there is no resistance to the tilting of the stage 42.

Thereafter, the sensor 54 again detects the amount of deviation of the surface of the wafer 4 from the focal plane, and an operation is performed to confirm that the approximate plane of the surface of the wafer 4 coincides with the focal plane with sufficiently high precision. Here, if the approximate plane of the surface of the wafer 4 does not match the focal plane, the correction of the height and inclination of the stage 42 and the detection of the amount of deviation are repeated again. As described above, the height and inclination of the wafer 4 are positioned so that its approximate plane coincides with the focal plane of the catoptric projection optical system 7. That is, the position of parallel movement in the Z-axis direction,
Five degrees of freedom with rotational posture around the X and Y axes are positioned. At this time, the plane determined by the center points of the three steel balls 48 becomes a correction plane for correcting the inclination of the surface of the wafer 4.

Subsequently, the nut members 44 and 58 are appropriately fed by the pulse motors 46 and 60 to match the alignment marks provided on the wafer 4 and the alignment marks in the mask pattern. At this time, since the lower surface of the floating pad 49Fi is an air bearing surface, it does not act as a resistance to the movement of the stage 42, and the floating pads 45 and 57 also have spherical and flat surfaces at both ends as air bearing surfaces, so the stage 42 moves one rotation. The resistance is a woman. In addition, the steel ball 48ij supporting the stage 42, the floating bat 49, or the conical surface of the stage 42, do not swing or rotate (but are supported by the floating pad 49 together with the stage 42 in a fixed state, Nut member 50 precisely parallel to the focal plane of the reflection projection optical system 7
moving on the upper surface - in this case, strictly speaking, the nut member 5
A vertical deviation occurs due to a deviation in the parallelism between the top surface of the nut member 50 and the focal plane, but if the top surface of the nut member 50 is finished parallel to the focal plane with high precision as in this embodiment, it can be realized on the submicron order. Regarding positioning, the above-mentioned vertical deviation is so small that it can be ignored.

In this way, the stage 42 is positioned in the X direction by the pulse motor 46 that makes up the entire set of feeding mechanisms, and
Two pulse motors 60 forming two sets of feeding mechanisms
The stage 42 is positioned in the Y direction by synchronous rotation. In parallel with this operation, the stage 42 is rotated about two axes by the differential operation of the two pulse motors 60.

As explained above, the six sets of feed mechanisms independently and directly push the stage 42 to control the six degrees of freedom, so positioning rigidity is high.

Furthermore, since the stage 42 does not carry a feeding mechanism, it is lightweight and therefore does not interfere with controllability.

Moreover, since this embodiment performs position detection on the wafer surface in a non-contact manner, there is no risk of damaging or staining the wafer surface.

In the embodiment shown in FIG. 5, the steel ball 4 is used for horizontal positioning.
Exactly the same effect as described above can be obtained by using a transmission mechanism consisting of a floating pad 49 and a vertically floating pad 45.

FIG. 6 shows a vertical cross-sectional view of an embodiment different from the above, using a shaft 65 fixed to the stage 42 as a guide.

The ball bush 64Vi can be moved in the axial direction. Furthermore, a follower 65 whose outer periphery is spherical is combined with the ball bush 64 to transmit the amount of feed from the nut member 66 and to move forward and backward with no vertical movement.

It constitutes a transmission mechanism that has a degree of freedom that does not cause resistance to the movement of the five stages 42 in rotation and tilt (in two directions).

Instead of using the combination of ball bush 64 and follower 65, the same effect can be obtained by using a follower with a bearing configuration that allows direct axial movement and rotational movement about the axis.

The twisted pad 67, the annular ball row 68, and the inclined pad 69 are similar to the air bearing floating pad 68, which replaces the air bearing floating pad 49 in the previous embodiment with an annular ball row means 68. It is obvious that a transmission mechanism with a degree of freedom is constructed, and has the same operation and effect as the previous example.

FIG. 7 shows a further different embodiment. In this embodiment, a spherical seat 72a is completely formed in the center of a shaft 72 fixed to a stage 42, and a follower 73 is supported so as to be tiltable and rotatable once, thereby freeing relative movement in the vertical direction like the ball bush 64 on the upper side. It is. Also in this example, the outer periphery of the follower 75 is formed into a spherical surface.

Further, in this embodiment, a columnar piezo element 75 is used as a feeding mechanism in the X direction, and is interposed between the stage 42 and the fA adjustment screw 76 via metal fittings 74 at both ends. Even with this configuration, the columnar piezo element 75 allows movement in directions other than the Z direction, expands and contracts in proportion to the applied voltage, and fulfills the feeding function in the Z direction. Works the same as the example.

〔Effect of the invention〕

As detailed above, according to the present invention, the stage on which the substrate is placed can be made very compact, each of the six degrees of freedom can be controlled with high precision, and the rigidity of positioning is high. It has excellent practical effects of good controllability. In particular, there is also the effect of making it easier to control the joining point of the substrates.

[Brief explanation of the drawing]

Figure 1 is a schematic front view of a reflection projection type wafer exposure apparatus.
Fig. 2 is a vertical sectional view of a conventional Ueno mounting device, Figs. , FIG. 5 is a partially enlarged sectional view. FIGS. 6 and 7 are partially enlarged cross-sectional views of embodiments different from those described above. 4... Wafer, 7... Reflective projection optical system, 41...
・Wafer mounting equipment base, 42...stage, 45・
...Floating pad, 44...Nut member, 45...Feed screw, 46...Pulse motor-147...Spring,
48... Steel ball, 49... Floating pad, 50... Nut member, 51... Feed screw, 52... Pulse motor, 55... Spring, 54... Capacitive proximity sensor , 55... Cavity part, 56... Detection point, 57... Floating pad, 58... Nut member, 59... Feed screw, 60... Pulse motor, 61... Spring, 62・・・
・Tube, 65...Shaft, 64...Pole butcher, 65...Follower, 66...Nut, 67...
- Pad, 68... Ball row means, 69... Inclined pad, 70... Steel ball, 71... Nut, 72...
・Shaft, 75...Follower 74...Metal fittings・-7
5... Column piezo element, 76... Adjustment screw. No. 50 2nd Akira 4 Kuniyoshi, 50 Aotsu Niniri

Claims (1)

[Claims] 1. A stage on which a substrate is placed and has 6 degrees of freedom, a set of X feed mechanisms that apply direct force to the stage to cause fine movement in the X direction, and two locations on the fine movement stage. two sets of Y feed mechanisms that apply direct force to the stage to slightly move it in the Y direction; and two sets of Y feed mechanisms that apply direct force to the stage at three locations to move the
and three sets of Z feed mechanisms that finely move the fine movement stage in the X-axis, Y-axis, and Z-axis directions, and the Z-axis, X-axis, and Y-axis. A driving device for a six-degree-of-freedom fine movement stage, characterized in that it is configured to be able to control fine rotation around the stage. 2. A patent claim characterized in that each of the three sets of Z feeding mechanisms is formed by a piezo element having one end engaged with the stage in a ball-to-coupled manner and the other end engaged with the fixed member in a ball-to-coupled manner. A drive device for a six-degree-of-freedom fine movement stage according to item 1.