JPH0769443B2 - 6 degree of freedom fine movement device - Google Patents

Description

The present invention relates to a degree-of-freedom fine movement device that finely moves in a space with 6 degrees of freedom suitable for positioning a wafer in a semiconductor manufacturing / inspecting apparatus or positioning a sample or a tool in a machine tool.

[Conventional technology]

In the conventional 6-degree-of-freedom fine movement device, as described in JP-A-59-129636, 6 drive mechanisms transmit only each feed direction,
The structure was provided with a conduction mechanism that allowed movement in the other direction.

[Problems to be solved by the invention]

In the above-mentioned conventional technology, mechanical backlash, friction such as rolling and sliding occurs at the joint between the drive mechanism of each axis and the driven portion, so the mechanical rigidity and drive resolution are low, and positioning accuracy is low. There was a problem that it could not be raised.

An object of the present invention is to provide a 6-degree-of-freedom fine movement device capable of performing ultra-precision position control of a sample or a tool independently of each axis with respect to the 6-degree-of-freedom of space.

[Means for solving problems]

In order to achieve the above-mentioned object, the present invention has six driving elements using a piezoelectric element that is elastically driven between the driven portion and the fixed base and has elastic pairs of spherical pairs at both ends. Connected and supported on almost the same plane as the driven part at one location in the X direction, two locations parallel to the Y direction, and three locations in the vertical direction.
Target movement amount D of the driven part in the 6 degrees of freedom (X, Y, Z, ωX, ωY, ωZ) direction and the 6 drive axes (X1, Y1, Y2, Z1, Z2, Z3)
When the target movement amount D of any degree of freedom is determined by defining the relationship between the displacement amount P and the displacement amount P by P = J ⁻¹ · D (where J is a determinant of 6 rows and 6 columns), the displacement amount of the drive shaft A six-degree-of-freedom fine movement device characterized in that P can be controlled with six degrees of freedom by uniquely obtaining P by the above equation and expanding and contracting the driving element based on this.

[Action]

For example, a driven part formed by a chuck or the like for fixing a sample such as a wafer is finely displaced in six degrees of freedom by six driving elements. Each drive element uses a fine motion actuator such as an electrostrictive element, a magnetostrictive element, or a thermal deformable element (shape memory alloy) as a drive source, and elastic supports (joints) of spherical pairs are bonded or fastened to both ends of the actuator. To use. This element is fixed at three points in the horizontal plane of the driven part and three points in the vertical direction. By driving the fine movement actuator, the driven portion makes a link movement via the elastic pair (joint) of the ball pair. Even if the six fine movement actuators are driven at the same time, the fine movement actuators themselves translate and rotate through the elastic supports of the spherical bodies at both ends thereof, so that no slippage or friction occurs between the driven portion and the driving portion. Also, since this elastic support is a lath machined with constrictions so that it has a circular cross section in a part of metal, it has high rigidity in the driving direction, and in the rotation direction around the constriction. Is a structure that is easily deformed. For this reason, a highly rigid drive mechanism with no backlash, slippage, or shavings is provided, and super-precision (resolution of 0.01 μm or less) positioning is possible.

〔Example〕

An embodiment of the present invention will be described below. FIG. 1 is a plan view showing an embodiment of a 6-DOF fine movement device according to the present invention,
FIG. 2 is a front view.

The present embodiment is a fine movement device for precisely positioning a sample 1 such as a semiconductor wafer with 6 degrees of freedom. In this fine movement device, the precisely positioned driven part is a chuck (driven part) 2 for vacuum or mechanically fixing the sample 1. Three driving elements for positioning in the horizontal plane, six ΔX driving elements, are provided on each of the six outer peripheral portions of the chuck (driven portion) 2.
3, ΔY ₁ drive element 4, ΔY ₂ drive element Further, three drive elements for vertical and inclined in-plane positioning, ΔZ ₁ drive element 6, ΔZ ₂ drive element 7, and ΔZ ₃ drive element 8, respectively, are fixed. There is.

Further, as a displacement sensor for measuring the displacement of each fine movement driving element, ΔX sensor 9, ΔY ₁ sensor 10, ΔY ₂ sensor 11, Δ
A Z ₁ sensor 12, a ΔZ ₂ sensor 13, and a ΔZ ₃ sensor 14 are provided with the base 15 as a measurement reference.

Hereinafter, the details of the mechanism of each unit and the operation will be described. First, the fine movement actuator 16 as the drive source of the drive elements 3, 4, 5, 6, 7, 8 is not such that a mechanical backlash or the like like a drive source using a motor and a feed screw is likely to occur. , Electrostrictive elements, magnetostrictive elements, thermal deformable elements (shape memory alloys, etc.) or linear actuators (ultrasonic motors, etc.) to which these are applied are suitable, but are limited to these as long as the same effects can be obtained. It is not something that will be done. At both ends of the fine movement actuator 16, a joint 17 having an elastic support portion 18 that enables the kinematic pair movement is adhered or screwed. The joint 17 is a metal part in which a constricted portion (elastic support portion) 18 having a circular cross-sectional shape is machined by a lathe in the central portion. One end of the integrated unit in which the joint 17, the fine movement actuator 16 and the joint 17 are integrated is attached to the bracket 19 fixed to the base 15, and the other end is fixed to the blocks 20 and 21 fixed to the chuck 2.
It is fixed to. This configuration is the same for the drive elements 3, 4, 5 of ΔX ₁ , ΔY ₁ , ΔY ₂ . Also, ΔZ ₁ , ΔZ ₂ , and ΔZ
The drive elements 6, 7, 8 of ₃ have joints 22
The shape of is different from the joint 17, but the function is the same.

The ΔX sensor 9, the ΔY ₁ sensor 10, and the ΔY ₂ sensor 11 are coaxially opposed to the corresponding drive elements 3, 4 and 5, and the bracket 2
It is fixed at 3. The displacement sensors 9, 10 and 11 are preferably formed by a capacitance type displacement meter or the like and have a resolution of 0.005 μm or less. Since the fine movement element constituted by the driving elements 3, 4, 5 and the displacement sensors 9, 10, 11 is intended for positioning control of ± 0.01 μm or less,
The displacement sensor also needs to be able to guarantee at least a resolution of 0.01 μm.

On the other hand, the ΔZ ₁ , ΔZ ₂ and ΔZ ₃ sensors, 12, 13 and 14 are provided symmetrically with respect to the center of the chuck 2. Sensor used here
An electric micrometer or a differential transformer is used for 12,13,14. Since the chuck 2 moves in a plane and tilts, if a normal contact-type electric micrometer is used, the tip of the probe is worn and the measurement accuracy deteriorates. Therefore, the core (iron core) 23 is fixed to the chuck 2, and the coil 24 is fixed to the base 15 via the bracket 25. As a result, the displacement can be measured without contact, and the measurement accuracy is improved.

The displacement sensors 9, 10, 11, 12, 13, 14 are determined in relation to the target positioning accuracy, and are not limited to the sensors shown in this embodiment.

here, Is a Jacobian matrix determined by the geometrical arrangement of each driving element.

For example, when the drive elements are arranged as shown in FIG. 3, Is expressed by the following equation (4).

That is, in the present fine movement device, the movement amount (axial displacement, axial rotation angle) of each degree of freedom is uniquely determined from the displacement of each drive element.

On the other hand, the target value for each degree of freedom , The positioning control amount of each drive element Is calculated by the following equation (5). here, Is the inverse Jacobian matrix of.

Therefore, as shown in FIG. 4, the target value is set in the driver (driving circuit) 30. Is given, and the driven parts 2 are driven by controlling the fine movement actuators of the drive elements 3 to 8 until the displacement outputs of the driven parts 2 detected by the displacement sensors 9 to 14 match.
Will be positioned at the desired target position.

FIG. 3 shows the modeled layout of the six drive elements 3, 4, 5, 6, 7, 8 of the 6-DOF fine movement mechanism described above. That is, the joint portion between each drive element and the wafer chuck 2 is at substantially the same height, and the constricted portion (center of the elastic support link of the ball pair) of the ΔX drive element 3 and the ΔY ₁ drive element 4 is in the X direction. At almost the same position, 6 degrees of freedom, that is, the amount of movement for ωx, ωy, ωz, X, Y, Z Is the displacement of each drive element It is given by the following equations (1) to (3).

That is, the positioning of the driven part 2 is performed by the positioning control amount (target value) obtained by the equation (5). Until the output of each displacement sensor and the output of each displacement sensor match, the fine movement actuator is controlled by the driver (driving circuit) 30 by the closed loop control.

According to the above-described embodiment, the coupling position (driving point) of each driving element and the driven portion is arranged in the same plane, so that mechanical displacement interference of each axis is eliminated, and each shaft is displaced. Highly independent positioning control is possible.

As described above, when the above embodiment is applied to the wafer stage of the X-ray exposure apparatus and the reduction projection exposure apparatus, a mask (reticle) is obtained.
It is possible to realize parallelization with respect to and alignment in the XY plane with high accuracy.

〔The invention's effect〕

According to the present invention, a sample or a tool can be finely positioned independently and with ultra-precision (resolution of 0.01 μm or less) in 6 degrees of freedom in space. For example, by applying it to a wafer fine movement stage for a semiconductor exposure apparatus, etc. The accuracy can be improved, which enables transfer of a fine pattern of 0.5 μm or less.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of the 6-DOF fine movement device of the present invention, FIG. 2 is a front partial sectional view of FIG. 1, and FIG. 3 is a motion model of the 6-DOF fine movement device of the present invention. Explanatory drawing which shows, 4th
The figure is a block diagram showing the positioning control of the six-degree-of-freedom fine movement device of the present invention. 2 …… Chuck (driven part) 3,4,5,6,7,8 …… Drive element 9,10,11,12,13,14 …… Displacement sensor 15 …… Base 18 …… Constriction (elastic support) Part)

Claims (1)

[Claims] 1. Driving elements using piezoelectric elements having elastic pairs of spherical pairs at both ends between a driven portion and a fixed base and driven to expand and contract, that is, six driving elements, that is, substantially flush with the driven portion. The above is connected and supported at 1 place in the X direction, 2 places in parallel to the Y direction, and 3 places in the up-and-down direction. To the displacement amount P of the six drive shafts (X1, Y1, Y2, Z1, Z2, Z3), P = J ^-1 · D (where J is 6 lines 6 When the target movement amount D with an arbitrary degree of freedom is determined, the displacement amount P of the drive shaft is uniquely obtained by the above formula, and the driven element is expanded / contracted based on this A 6-degree-of-freedom fine-moving device characterized in that it can be controlled with 6-degrees of freedom.