JPS6344493B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a moving table, and particularly to an improvement in a fine moving table that requires a minute movement on the order of submicrons.

Conventionally, fine movement tables used for high-precision positioning of LSIs and other high-density electronic components have been used to perform fine movement mechanically using screws such as ball screws, or by using elastic deformation or other types of piezoelectric This was done using elements such as magnetostrictive elements. However, with the above-mentioned screws, smooth micro-movement is difficult due to the influence of solid friction. Furthermore, when using elastic deformation, it is difficult to move the stage on which the workpiece is placed while maintaining the flatness accuracy, especially as the amount of movement increases. Furthermore, it has been difficult to maintain accuracy in piezoelectric elements and magnetostrictive elements due to the heat generated.

This invention provides a table on which a workpiece is placed,
To provide a table that floats on fluid and can be moved minutely while ignoring heat generation and friction by unbalancing the pressure of the fluid applied from each side of the table.

Hereinafter, the present invention will be explained based on drawings showing embodiments.

1 to 3, reference numeral 1 denotes a disk-shaped stage on which a wafer or other object to be measured or a workpiece is placed;
Fillets 3a, 3b, 3c and 3d are protruded at equal intervals (among these, fillets 3c and 3d are longer than fillets 3a and 3b). 4 is a base that is a fixed table or forms part of an XY table that moves together with stage 1.
A circular recess 5 is formed which is slightly larger (approximately 20 to 30 μm) than the outer diameter of the fillet 3a.
The lower end surface of the stage 1 except 3d is fitted. The recessed portion 5 is provided with a large number of air holes 7 that open at its bottom 6 as part of the first fluid ejection mechanism A that levitates the stage 1. These air holes 7 communicate with a fluid passage 8 formed inside the base 4, and serve as an outlet for processing fluid such as compressed air sent through this passage 8. On the other hand, in order to rotate and move the stage 1 in the horizontal direction, L-shaped blocks 9a to 9h are installed on the base 4 as a second fluid ejection mechanism B. Each of the fillets 3a to 3d is sandwiched between a pair of L-shaped blocks 9a to 9h with a small gap (about 10 to 15 μm). Each of the L-shaped blocks 9a to 9h has fluid ejection holes 10a to 10h that eject fluid such as compressed air toward the side surfaces of the fillets 3a to 3d. Further, the first and second fluid ejection mechanisms A and B
are fluidly connected to a pressure regulating mechanism C that controls the pressure of each fluid, as shown in FIG. The pressure adjustment mechanism C includes fluid ejection holes 10a to 1
Pressure regulating valves 30 that are individually fluidly connected to 0h and adjust fluid pressure by opening and closing the valves by electromagnetic drive.
It consists of a pressure regulating valve 31 which is fluidly connected to a to 30h and the fluid passage 8 and adjusts the fluid pressure by opening and closing the valve by electromagnetic driving. These pressure regulating valves 30a to 30h, 31 are connected to an arithmetic control unit D such as a microcomputer and apply control signals SA, . . . , SI to perform pressure regulation as described below. . Further, the calculation control section D is electrically connected to the displacement detection mechanism E. This displacement detection mechanism E is based on the fillet 3.
A capacitive type X displacement detection sensor 40 is mounted on the base 4 facing the end surface of the fillet 3b and outputs a detection signal SJ indicating the amount of displacement of the stage 1 in the X direction. A capacitive Y displacement detection sensor 41 is attached to the base 4 and outputs a detection signal SK indicating the amount of displacement of the stage 1 in the Y direction, and a first Y displacement detection sensor 41 is attached to the base 4 opposite to one side 50 of the fillet 3c. The rotation angle detection unit is composed of a displacement detection sensor 42 and a second displacement detection sensor 43 mounted on the base 4 facing one side 51 of the fillet 3d, and outputs detection signals SL and SM indicating rotation of the stage 1 in the θ direction. It consists of part 44.

In the above configuration, the pressure regulating valve 31 is activated by inputting the control signal SI from the arithmetic control unit D, and the stage 1 is moved to the base 4 by the action of the fluid ejected from the air holes 7 in the direction of the arrow T. float from. In this case, by keeping the pressure of the fluid sent through the fluid passage 8 constant, the flying distance from the bottom 6 is kept constant. As described above, while floating from the base 4, the stage 1 makes slight movements in the XY directions as follows. In other words, to move in the X direction in the figure, control signals SE to SH are sent to the pressure regulating valve 3.
By applying signals 0e to 30h, the supply pressure of the fluid from the fluid jet holes 10e to 10h is maintained constant, and the control signals SA to SD are applied to the pressure regulating valves 3.
0a to 30d, a differential pressure is created between the supply pressure of the fluid from the fluid ejection holes 10a and 10c and the supply pressure of the fluid ejection holes 10b and 10d. is moved parallel to the direction. The amount of movement in the X direction at this time is detected by the detection signal SJ from the X displacement detection sensor 40, and the calculation control unit D uses this detection signal.
The stage 1 is positioned in the X direction by stopping the output of the control signals SA to SD in a timely manner based on SJ. On the other hand, when moving in the Y direction, the supply pressure of the fluid ejection holes 10e to 10h may be adjusted in the same way as when moving in the X direction. In addition, when rotating the stage 1 to a predetermined rotation angle, detection signals SL and SM from the first and second displacement detection sensors 42 and 43 are transmitted.
The rotation angle of the stage 1 is calculated by the calculation control unit D based on
0a, 10g, 10d, and 10f are set as one set, and the remaining jet holes 10b, 10h, 10c, and 10e are set as the other set, and a pressure difference is created between the two,
The stage 1 may be rotated to a desired position.

In the above embodiment, the flying height of the stage 1, that is, the Z direction, was slightly moved under a constant condition, but by changing the supply pressure from the fluid passage 8,
It goes without saying that fine movements can be made in synchronization with the movement and rotation in the X and Y directions. In addition, the number of fillets is only one if it is only for rotation.
If the movement is in either the X or Y direction, two may be provided facing each other.

In this way, the stage is moved in a floating state due to the action of the fluid, so it does not generate any stick slip or heat.
As a result of being able to make extremely precise micro-movements, it is possible to perform ultra-precise positioning on the submicron order of objects placed on the stage.

In the above embodiments, the shape of the stage is circular or square, but it is not limited to this, and non-circular shapes such as triangles can also be used, and various shapes may be used without departing from the scope of the invention. It is something that can be transformed.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an embodiment of the present invention with essential parts cut away, FIG. 2 is a sectional view taken along the - line in FIG. 1, and FIG. 3 is a block diagram of the pressure adjustment mechanism. 1: Stage, 3a-3d: Fillet, 4:
Base, 5: Recess, A: First fluid ejection mechanism, B:
Second fluid ejection mechanism, C: Pressure adjustment mechanism, D: Arithmetic control unit, E: Displacement detection mechanism.

Claims (1)

[Claims] 1. A stage having at least one pair of opposing fillets protruding from an outer surface and on which an object is placed; a base having a recess into which the stage is rotatably and loosely fitted; a first fluid jetting mechanism that applies fluid pressure toward the bottom surface of the fillet to levitate the stage; and a second fluid jet mechanism that applies fluid pressure toward the side surface of the fillet to selectively move the stage minutely in the rotational direction or horizontal direction.
a fluid ejection mechanism, a pressure adjustment mechanism that controls the fluid pressure from the first and second fluid ejection mechanisms, a displacement detection mechanism that detects the amount of rotation and horizontal movement of the stage, and this displacement detection mechanism. A fine movement table comprising: an arithmetic control section that outputs a control signal to the pressure adjustment mechanism based on a detection signal output from the mechanism and positions the object by adjusting the fluid pressure.