JPH0466895A - Fine adjustment stage with six degrees of freedom - Google Patents

Abstract

PURPOSE:To attain high response and high accuracy by fastening each actuator to a stage member through hinges having high rigidity to mono-axis direction and enabling elastic deformation to other directions. CONSTITUTION:For a stage member 10 having enough high rigidity, main axes of inertia are coordinates XYZ and gravity center is the original point of the coordinates. 6 actuators 1 to 6 are provided to drive the member 10 and are fastened to P1(alpha1,beta1,gamma1) to P6(alpha6,beta6,gamma6), respectively. An X actuator 1 lets X directional force work to the member 10 at a fastening point P1. Two Y actuators 2 and 3 let Y directional force work to the member 10 at points P2 and P3, respectively. Also, three Z actuators 4 to 6 let Z directional force work to the member 10 at points P4 to P6, respectively. By these 6 forces, the member 10 undergoes a displacement with 6 degrees of freedom, x to z, and phix to phiz. This stage with multiple degrees of freedom can satisfy all the equations.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a stage device, and particularly to a stage device with high precision and multiple degrees of freedom.

"Prior Art" Conventionally, many stage devices with multiple degrees of freedom have been constructed by stacking stages with low degrees of freedom.

For example, an XYθ2 stage device is configured by placing a Y stage on an X stage and further placing a θ2 stage on top of the Y stage. When adding the degree of freedom of Z-θX-θy to this, for example, the X stage is held at three locations by actuators in two directions.

Each of these stages is driven by, for example, an actuator that is a combination of a DC motor and a pole screw.

In recent years, for example, in the field of semiconductor devices, as the degree of integration has improved, higher processing precision has been required. for example,
The stage of a semiconductor exposure apparatus is now required to have an accuracy of about 0.1 μm or more.

It is extremely difficult to realize such a high-precision stage with the stage configuration described above.If a power transmission mechanism is used, it is difficult to avoid force and backlash.
Approximately 0.1 μm becomes the accuracy limit.

For example, to achieve ultra-high precision of 0.01 μm or more, it is necessary to improve the accuracy of the heavy hm-movement stage by placing a fine-movement stage on top of the coarse-movement stage.

Even with such a fine movement stage, if a stacked structure as described above is used, backlash may occur between each stage or distortion due to friction may occur.

One configuration that can easily achieve high accuracy as a fine movement stage is a parallel link stage in which a large number of actuators are directly coupled to the stage.

For example, six actuators are connected to one sufficiently rigid stage to perform movement with six degrees of freedom. By directly coupling each actuator to the stage, the position of the stage can be controlled with high precision by monitoring the movement of the stage and providing feedback to each actuator.6 εProblems to be Solved by the Invention] However, When driving one stage with multiple actuators, interference between degrees of freedom becomes a problem. For example, when the stage is driven in the X direction, the stage is also displaced in the Y direction. Since the drive is in the X direction, even if only the X direction position is monitored and feedback is provided to the X direction actuator, displacement or vibration in the Y direction may not be completely eliminated. This kind of interference may not be a big problem in the low frequency range, as it is easy to correct it using control means, but it becomes a problem in the high frequency range, making it difficult to stabilize the stage itself. , which leads to deterioration of accuracy. When attempting to move the stage at high speed, it is impossible to avoid using a high frequency region, and it becomes necessary to solve interference between multiple modes. An object of the present invention is to provide a multi-degree-of-freedom fine movement stage with high response and high precision.

"Means for Solving the Problems" The present invention reduces interference between vibration modes of a multi-degree-of-freedom stage device.

The stage of the present invention is a 6-degree-of-freedom fine movement stage in which 6 sets of actuators are directly connected to and driven by a 6-degree-of-freedom stage member, and each actuator has machinability in one axis direction and machinability in the other direction. is connected to the stage member via a hinge that can be elastically deformed, and when the principal axes of inertia of the stage member are X, Y, and Z, one actuator has a displacement in the X direction of (α1, β1, γ1). The two actuators apply displacement in the Y direction to the stage member through the arranged hinges (α2, β2, γ2), -(α3, β3, γ
3) applied to the stage member via a hinge disposed in;
The displacement of three actuators in two directions (α4-β4,
γ4), (α5, β5, γ5), (α6, β6, γ6)
is applied to the stage member via a hinge located at , and satisfies the following: γ1=γ2=γ3=0 β1=0 α2+α3=0 (α5+α6)(β5+β6) (α6β5+α5β6)/2.

F action] Directly connect multiple actuators to one stage,
Each actuator has one
It has a hinge that is highly rigid in the axial direction and can be elastically deformed in other directions. With such a configuration, even if a large number of actuators are connected to one stage, each actuator can perform a predetermined drive.

Furthermore, the above-mentioned results were obtained by approximating the characteristics of each actuator by elastic characteristics proportional to displacement and damping characteristics proportional to the time derivative of displacement, and finding conditions for reducing interference between actuator displacement and stage displacement. If the condition is satisfied, the equations of motion for each degree of freedom become independent, and interference is prevented.

[Example] FIG. 1 shows a model of the stage according to the invention.

The sufficiently homogeneous stage member 10 has, for example, a rectangular parallelepiped shape as shown in the figure. The center of gravity G of this stage member is taken as shown, and the coordinate form XYZ is taken in the direction of the principal axis of inertia with this center of gravity as the origin. Six actuators 1 to 6 are provided to drive this stage member l, and each actuator is Pl (α1, β1, γ1), P6 (α6
, β6, γ6) to the stage member 10.

The X actuator 1 applies a force in the X direction to the stage member 10 at the coupling point P1. Two Y actuators 2
．． 3 applies a force in the Y direction to the stage member 10 at points P2 and P3, respectively. The three Z actuators 4.5.6 apply forces in the X direction to the stage 10 at points Pa-Ps and P6, respectively. These six forces cause the stage member 10 to move xy, z, φX, φy,
Displacement of φZ with 6 degrees of freedom is performed.

The characteristics of each actuator are approximated by a structure in which the displacement source 11 is connected to a spring 13 and a dashbot 14 in parallel, as shown in FIG. 2(A). That is, the force applied by the actuator is the sum of an amount proportional to the displacement of the spring 13 and an amount proportional to the time derivative of the displacement in the dashbot 14.

Such an actuator model is, for example, shown in Figure 2 (
This is realized by a structural example as shown in B).

That is, spherical hinges 18 are provided at both ends of the laminated piezo element 16.
．． 19 are coupled to transmit the axial displacement given by the laminated piezo element 16 to both sides of the spherical hinge.

The spherical hinges 18, 19 have a structure in which the radius is gradually narrowed from both sides, and have high rigidity in the axial direction, or are hinges that can be elastically deformed in a direction perpendicular to the axial direction, or in bending with respect to the hinge center.

The equation of motion of the stage system in FIG. 1 is expressed as follows.

IM x+ ID x + IK X = IK JT
IA IE + ID JT IA +a where X
is a translational and rotational displacement vector at the center of the stage member 10, and is expressed as: X=(x+y+z+dzx, φy1φ2). Also, dots represent time differentiation.

IE represents the input vector to the actuator, l
E=(e 1 , e 2−e 6 ).

IM is an inertia matrix of the stage member 10, and 1M=d i ag (m, m, m, I x
, I, y, Iz). :i, ID is the attenuation matrix of the actuator and stage system, and IK
is a stiffness matrix of the actuator and stage system, J is a cross-sectional matrix of the actuator displacement amount and stage displacement amount, and IA is a gain matrix of the actuator displacement amount per unit input.

Assuming that the mechanical properties of each actuator 1 to 6, such as rigidity and damping coefficient, are equal for all actuators, IK and ID are respectively expressed by the following equations.

1K = k·IR (2) 1D = d·IR (3) where k is the actuator stiffness and d is the actuator damping coefficient.

IR is a matrix determined by the arrangement position (driving point coordinates) of the actuator, and is expressed by equation (4).

In addition, the point of action Pi of each actuator = 1 to 6)
When the coordinates of are (α1, βi, γ1), the coefficient RI in equation (4) is expressed as follows.

R42 = - (γ2 + γ3) R43 - β4 + β5 + β6 R51 = γ 1 R53 = - (αd + αδ + α6) R54 = - (α4β4 + α5β5 + α6β6) R61 =
-β1 R62=α2+α3 R64=-(α2γ2+α3γ3) R65=-β1 γ1 R44=γ22+γ32+β42+β52+β62 R55-γ12+α42+α52+α62R66-β1
2+α22+α32 In equation (1), the Jacobian matrix J is generally a non-diagonal matrix. Therefore, interference exists between each actuator displacement amount and the stage displacement amount. That is, displacement occurs in a degree of freedom different from the displacement given by the actuator. To avoid such interference, first control the input to the actuator as follows.

1E-IA-IJr-1y, r -
(5) Here, xr is the target displacement amount in the oxyz coordinate system. Substituting equation (5) into equation (1), IM father + I
D x + IK X = IKJr IAIA-I Jr -I X r+
ID JT IA IA-1JT -' x r=lK
Xr+lDgr (6)

It is desirable to be able to control the movement of the stage independently for each component in a wide frequency range using equation 0 (6).
The steady-state solution of IKX=lKX r , X=X r as terms that do not include time derivatives
- Contains (7). In a low frequency region that can be regarded as time differential or O, the above equation may be set to satisfy.

However, in a high frequency region, this condition alone is insufficient. In other words, when performing a fast response,
The time derivative of displacement becomes a non-negligible amount. At this time, if there is an influence of the vibration mode due to the presence of inertia, or if there is interference between the motion directions (x-y-z, φX, φy, φZ), it is extremely difficult to perform compensation control that includes that interference. It becomes difficult. Therefore, we will find conditions under which no interference will occur between each degree of freedom.

In equation (6), IM is a diagonal matrix, and K and ID are expressed by equations (2) to (4).

That is, the off-diagonal terms of the IR may be considered, and the necessary and sufficient conditions for the off-diagonal terms to be O are determined as follows.

γ1-γ2-γ3-0... (
8) β 1-0
... (9) α2+α3=0
...(10) (α5+α6) (β5+β6) (α6β5+α5β6)/2 ... (11) When the off-diagonal term is O, the equation written in a matrix can be easily expressed, and equation (6) becomes as follows. can be separated into independent equations.

mm+d 1×=kixr+dI rm9±d
2y+ to 2y=to 2yr+d2yrm2+da之+ka
z=to 3zr+d3之rIxix+d4#x+to4φx
= 4φxr+d4 xr I yiy+d5 #y+ksφ3'=5φyr+a
5 commission Iziz+dsiz+kaφz=kaφzr+a6ゐz
r... (12) That is, in the configuration shown in FIG. 1, when the four conditions shown in the lower part of the figure are satisfied, the six actuators shown in FIG. 1 can be treated as independent actuators without interference.

Equation (8) above indicates that the Z coordinate of each of the X actuator and Y actuator is 0, indicating that the three actuators are arranged on the same X7 plane as the center of gravity, and Equation (9) represents that the Y coordinate of the X actuator is 0, which indicates that the X actuator is arranged on the same axis as the Y axis of the inertial coordinate.Furthermore, equation (10) shows that the X coordinate of the two Y actuators is 0. The opposite sign indicates that the magnitude is equal, and the two Y actuators are arranged at symmetrical positions with respect to the Y axis of the principal axis of inertia.

Equation (11) may not be able to express the geometrical meaning more simply than the above three equations.An example of an arrangement that satisfies this relationship is as shown in the embodiment shown in FIG. This is a configuration in which three X actuators are arranged at the vertices of an equilateral triangle.

FIG. 3 is a perspective view showing a stage device according to an embodiment of the present invention. FIG. 4 shows a side view of the fine movement stage device of FIG. 3 from the Y direction.

The stage member 27 is made of iron or the like and has sufficiently high rigidity. With the position of the center of gravity of this stage member 21 as the origin,
Take the XYZ axes in the direction of the principal axis of inertia.

In the illustrated configuration in which the X actuator 21 is arranged along the Y axis and is coupled to the stage member 21 at a point P1, one end of the spherical hinge is coupled to a fixing member 28 attached to the stage member 21.

The actuator 21 has spherical hinges at both ends.

One Y actuator 23 is coupled to this fixing member 28 . The Y actuator 23 also has spherical hinges at both ends, and the center point P3 of one of the spherical hinges is located on the coupling member 28 side.

A fixing member 29, which is symmetrical to the fixing member 28, is arranged at a position symmetrical to the Y axis, and the center point P2 of the spherical hinge of the actuator 22 is coupled to this fixing member 29. In addition, on the lower surface of the stage member 27, an equilateral triangle is assumed with the projection of the origin 0 placed at the center of gravity, and three
A spherical hinge at one end of the actuator 24, 25, 26 is coupled.

That is, the center points Pa-P5 and P6 of the spherical hinge are Z
It is placed at the vertex of an equilateral triangle with the axis at the center of gravity.

The six actuators used here are shown in Figure 2 (
It can be constructed of a laminated piezo element with spherical hinges provided at both ends, as shown in B).

FIG. 4 shows a side view of the fine movement stage device of FIG. 3 from the Y direction.

When an actuator that expands and contracts in one direction is provided with a structure having low homogeneity in a direction other than the direction of expansion at both ends of the actuator, the amount of displacement of the stage is determined by the combination of the amounts of expansion of each actuator. For example, in the configurations shown in FIGS. 3 and 4, the stage 27 performs a translational movement in the X-axis direction by the expansion and contraction of the X actuator 21, and the two Y actuators 22 and 23 are expanded and contracted by the same amount in the same direction. This allows translation in the Y-axis direction. Also, 2
When the two Y actuators are extended and contracted in opposite directions, a rotational movement θZ is performed around the Z axis, and when the three X actuators 24, 25, and 26 are extended and contracted by the same amount in the same direction, a translational movement in the Z direction is performed. I can do it. Furthermore, by driving the X actuators by different amounts using appropriate combinations, it is possible to perform rotational movements around the -X axis and the Y axis.

By selecting the center of gravity G of the stage member 27 (including parts fixed thereto) and the drive points P1 to P6 of each actuator to meet the above-mentioned conditions, interference between vibration modes is eliminated and each free It is possible to make independent movements occur with respect to degrees. Therefore, effective control can be performed by monitoring each degree of freedom and providing feedback. In this way, a stage device with high precision and high response can be obtained. Since each degree of freedom can be controlled independently, the configuration of the entire control device can be simplified, and accuracy and responsiveness can be ensured.

Although the present invention has been described above in accordance with the embodiments, the present invention is not limited to these. For example, the present invention can be applied not only to semiconductor manufacturing equipment, but also to a wide range of stage equipment that requires precision, such as machine tools. can. A schematic perspective view, and various other changes, improvements, and combinations are possible.
FIG. 4 is a side view of the stage apparatus shown in FIG. 3 as viewed in the Y direction, as will be obvious to those skilled in the art.

[Effects of the Invention] As described above, according to the present invention, interference between vibration modes can be reduced in a parallel link type fine movement stage in which an actuator with six degrees of freedom is directly coupled to a stage device.

Reducing interference can increase the stability of the entire system and improve accuracy.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view showing a model of the stage according to the present invention, FIGS. 2(A) and (B) are diagrams for explaining the actuator, and FIG. 1 to 6 18.19 21 to 26 28.29 Actuator stage Member displacement source Spring Dashpot Laminated piezo element Spherical hinge Actuator Stage Member fixing member Hinge center position Patent applicant Sumitomo Heavy Industries, Ltd. Sub-agent Patent attorney Keishibu Takahashi F=kx+d (dx/dt) (A) Model Pi (αl, β1γ1) γl:γ22γ3=0 β1−0 '2+t! Co=O (α5+α6)・(β5+β6)−(α6β5+α5β
6)/21~6; Actuator 10: Stage member Model of the stage according to the present invention FIG. 1 <Belt example actuator FIG. 2 Side view of the stage device of FIG. 3 FIG.

Claims (1)

[Claims] (1) A 6-degree-of-freedom fine movement stage in which six sets of actuators are directly connected to and driven by a 6-degree-of-freedom stage member, each actuator having high rigidity in one axis direction and elastic deformation in other directions. is connected to the stage member via a hinge that allows
two actuators move the displacement in the X direction (α_1, β_1
, γ_1) to the stage member, and the two actuators apply displacement in the Y direction to (α_2
, β_2, γ_2), (α_3, β_3, γ_3) to the stage member, and the three actuators apply displacement in the Z direction to (α_4, β_4, γ_3).
4), (α_5, β_5, γ_5), (α_6, β_6
, γ_6) to the stage member through hinges placed at .