JPH0192687A - Finely adjusting mechanism - Google Patents

Abstract

PURPOSE: To obtain a mechanism with a high stiffness against outer force by arranging two actuators so that forces in opposite directions can operate. CONSTITUTION: Piezoelectric actuators 71 and 72 are provided at both sides of a central protrusion 51 of a fixed rigid body part 1. The other edges of piezoelectric elements 71 and 72 are connected to protrusions 61 and 62 of each rigid body part 2. The rigid body parts 1 and 2 are connected by elastic flat plates 3 and 4. When voltages V1 and V2 with mutually opposite polarities are applied to the piezoelectric elements 71 and 72, one of the piezoelectric elements 71 and 72 is extended and the other shrinks, thus slightly moving the rigid body part 2 in reference to the rigid body part 1. When either outer force f1 or f2 is applied to the rigid body part 2, it is applied to either the piezoelectric element 71 or 72 as a compression force. The piezoelectric element has a large stiffness against the compression force, thus achieving a mechanism with a large stiffness against both outer forces f1 and f2 .

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fine movement mechanism used in ultra-precision processing, semiconductor manufacturing equipment, electron microscopes, and other devices that require adjustment on the μm order.

[Conventional technology]

In recent years, in various technical fields, there has been a demand for devices capable of fine displacement adjustment on the order of .mu.m. Typical examples are semiconductor manufacturing equipment such as mask aligners and electron beam lithography equipment used in the manufacturing process of LSIs (Large Scale Integrated Circuits) and VLSIs. These devices require fine positioning on the μm order, and as the positioning accuracy improves, the degree of integration also increases.
It is possible to manufacture high-performance products. This kind of fine positioning is necessary not only for semiconductor devices, but also for various high-magnification optical devices such as electron microscopes and ultra-precision processing equipment. It also contributes greatly to the development of advanced technologies such as these. Hereinafter, a fine movement mechanism that performs such fine positioning will be explained with reference to the drawings.

FIG. 6 is a side view of a conventional fine movement mechanism used for ultra-precision machining. In the figure, ■ is a rigid part fixed by appropriate means,
Reference numeral 2 denotes a rigid body portion facing the rigid body portion 1, and numeral 3.4 denotes a flat plate having elasticity that connects the rigid body portions 1.2 at their left and right ends. Each of the flat plates 3.4 is parallel to each other. Reference numeral 5 indicates a protrusion protruding from the rigid body part], 6 a protrusion protruding from the rigid body part 2, and 7 a piezoelectric actuator mounted between the protrusions 5 and 6. The piezoelectric actuator 7 is fixed to the protrusions 5 and 6, for example, with adhesive. 8 indicates a processing tool (bite) fixed to the rigid body part 2.

When a voltage ■ is applied to the piezoelectric actuator 7, the piezoelectric actuator 7 expands and presses the protrusion 6. As a result, the flat plate 3.4 is deformed, the rigid body part 2 is translated to the left in the figure with respect to the rigid body part 1, and the processing tool 8 is also translated at the same time. This amount of displacement can be varied three times on the order of submicrons by the voltage applied to the piezoelectric actuator, and thereby ultra-precision machining can be performed using the machining tool 8. Details of the fine movement mechanism that performs such fine positioning and its operation can be found in Japanese Patent Application Laid-Open No. 61-209846.
It is presented in the publication No.

[Problem that the invention seeks to solve]

However, the piezoelectric actuator used in the above-mentioned fine movement mechanism can withstand compressive force acting on it due to its own rigidity, but its strength is extremely low against tensile force. do. That is, when a force in the direction of the arrow f1, for example a processing reaction force, is applied to the processing tool 8, the piezoelectric actuator 7 has a large strength against the force, but due to some reason, such as vibration or handling error, the force in the direction of the arrow f2 acts. When force is applied, tensile stress is generated in the piezoelectric actuator 7, and if this tensile stress is large, there is a risk that the piezoelectric actuator 7 will be damaged.

An object of the present invention is to solve the problems of the prior art described above and to provide a fine movement mechanism that has extremely high rigidity against external forces.

[Means for solving problems]

In order to achieve the above object, the present invention provides a fine movement mechanism in which a first rigid body part and a second rigid body part are connected by a plurality of elastic members and each rigid body part is relatively displaced. The two actuators are arranged so that their displacement directions are substantially the same, and the end of the first actuator on the first side in the displacement direction is fixed to the first rigid body part, and the second actuator is fixed to the first rigid body part. the first side end in the displacement direction of the second actuator is fixed to the second rigid body; It is characterized in that an end portion of the device is fixed to the first rigid body portion.

C Effect] By exciting the first actuator and the second actuator in opposite directions, a relative slight displacement occurs between the first rigid body part and the second rigid body part. Also, the first
When an external force acts between the rigid body part and the second rigid body part, this external force acts as a tensile force on one actuator, but as a compressive force on the other actuator, and a compressive force acts on the other actuator. Due to the high rigidity of the actuator on the side, damage to the actuator on the side to which the tensile force is applied can be prevented.

〔Example〕

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

FIGS. 1fa) and 1(b) are side views of a fine movement mechanism according to an embodiment of the present invention. In each figure, parts that are the same as or equivalent to those shown in FIG. 1 are given the same reference numerals and their explanations will be omitted. 5
1 is a projection projecting upward from approximately the center of the rigid body part 1;
61 and 62 are protrusions projecting downward from the rigid body portion 2, respectively. The protrusions 61, 62 are located on opposite sides of the protrusion 51 from each other. 71 is a piezoelectric actuator mounted between the protrusion 51 and the protrusion 61, and 72 is a piezoelectric actuator mounted between the protrusion 51 and the protrusion 62. A strain gauge 9 is attached to the flat plate 4, and its resistance value changes according to the deformation of the flat plate 4. V, , V2 indicate voltages applied to the piezoelectric actuators 71 and 72, respectively.

Now, a positive voltage V is applied to the piezoelectric actuator 71.

(Vl -V.), and when a negative polarity voltage -VO (V2 = Vo) is applied to the piezoelectric actuator 72,
As shown in FIG. 1 (bl), the piezoelectric actuator 71 expands and the piezoelectric actuator 72 contracts by the same amount.

As a result, the projection 61 is pushed to the left, the projection 62 is pulled to the left, the plate 3.4 is deformed as shown, and the rigid part 2 is translated by a distance U relative to the rigid part 1. Note that this deformation and translational displacement are extremely exaggerated. When the voltages V, V2 are set to O, the fine movement mechanism returns to the state shown in FIG. A translational displacement occurs in the opposite direction to the direction shown in bl.

In such a fine movement mechanism, the rigid body part 2 has a
When the force f1 shown in is applied, the piezoelectric actuator 72 receives a tensile force through the protrusion 62, and there is a risk of damage as described above. However, the force f simultaneously applies a compressive force to the piezoelectric actuator 71 via the protrusion 61,
The piezoelectric actuator 71 exhibits extremely high rigidity against such compressive force. Therefore, this rigidity allows the piezoelectric actuator 72 to avoid damage. Similarly, when force f2 acts, a tensile force acts on piezoelectric actuator 71, but at the same time, piezoelectric actuator 72
A compressive force is applied to the piezoelectric actuator 71, and the piezoelectric actuator 71 is not damaged due to its high rigidity.

By the way, the relationship between the voltage applied to a piezoelectric actuator and its displacement shows a hysteresis characteristic as shown in Figure 2, and even if the absolute value of the applied voltage is the same, there are differences in the case of positive polarity and the case of negative polarity. The absolute value of the displacement does not match. On the other hand, the amount of strain in the strain gauge 9 is proportional to the amount of displacement of the piezoelectric actuator. Due to the existence of the characteristics shown in FIG. 2, some kind of control means is required in order to obtain highly accurate displacement. In this embodiment, displacement control is performed using the characteristics of the strain gauge 9 shown in FIG.

FIG. 4 is a block diagram of a control device for a fine movement mechanism according to an embodiment of the present invention. In the figure, 10 is a piezoelectric actuator 7I
1) a sign inverter that inverts the polarity of the signal; 12 a drive amplifier that drives the piezoelectric actuator 72; 13 an amplifier that amplifies a signal according to a change in the resistance value of the strain gauge 9; is a subtracter, and 15 is an adder.

In the state shown in FIG. 1(a), the control device receives a signal U proportional to the target displacement. When input, a voltage is output from the drive amplifier 10 in response to this, and this voltage is applied to the piezoelectric actuator 71, and the piezoelectric amplifier 12 applies a voltage to the piezoelectric actuator 72 to compress it. As a result, the fine movement mechanism undergoes a translational displacement as shown in FIG. 1(b), and the strain gauge 9 produces strain in proportion to this translational displacement. This amount of distortion is converted into an electrical signal, and the amplifier 13
The signal is amplified and input to the subtracter 14. Subtractor 14
outputs a signal proportional to the difference between the target displacement and the actual displacement. In this way, by performing feedback control, the actual translational displacement can be made to match the target displacement.

In this way, in this example, two piezoelectric actuators are mounted between both open body parts, and when an external force is applied between both open body parts, a tensile force is applied to one piezoelectric actuator, and a tensile force is applied to the other piezoelectric actuator. Since the compressive force is simultaneously applied to the piezoelectric actuator, a fine movement mechanism with high rigidity against external forces can be obtained, and the piezoelectric actuator will not be damaged by external forces. In addition, since a flat plate is used as the elastic member, it has extremely high rigidity against external forces acting within the plane of the flat plate, and as a result, this embodiment has high rigidity against external forces in all directions. It will be held.

Furthermore, by using feed punch control, highly accurate displacement can be obtained.

FIG. 5 is a side view of a fine movement mechanism according to another embodiment of the present invention. In the figure, the parts corresponding to the parts shown in Fig. 1 fal and (bl) are marked with the same reference numerals and the letter R. and the rigid body part 2 are connected by mutually parallel flat plates 3 and 4. In contrast, in this embodiment, the rigid body part IR and the rigid body part 2R are connected to each other by elastic flat plates 3R and 4R extending radially around a point O. It has a configuration in which it is connected with
(The fine movement mechanism shown in bl is a piezoelectric actuator 71.72
In this embodiment, the piezoelectric actuator 71R is excited to generate a relative translational displacement between the rigid body parts 1.2.
, 72R, a relative rotational displacement about point 0 is generated between the rigid body parts IR and 2R.

Details of the fine movement mechanism equipped with radial flat plates 3R and 4R as in this embodiment and its operation are disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 61-2098.
This is described in Japanese Patent No. 46, and the operation of this embodiment also follows this. Furthermore, two piezoelectric actuators x-71R, 7
2R operation is the piezoelectric actuator 71 of the previous embodiment.
The operation is the same as that of 72. It is clear that the control means shown in FIG. 4 is also applied to this embodiment.

In this way, in this embodiment, since two piezoelectric actuators are installed between both open body parts, the same effect as in the previous embodiment is achieved.

In the description of this embodiment, a piezoelectric actuator was used as an example of the actuator, but an actuator consisting of an element that has high rigidity against a force in one direction and low rigidity against a force in the opposite direction, such as an optical displacement element, may also be used. If so, this embodiment can be applied. Further, the actuators are not limited to being arranged in a straight line, but can also be arranged in parallel.

〔Effect of the invention〕

As described above, in the present invention, two actuators are mounted between both open body parts so that a force in the opposite direction to an external force acts, so that a fine movement mechanism with high rigidity against the external force is obtained. Moreover, the actuator will not be damaged by external force.

[Brief explanation of the drawing]

1(a) and (bl) are side views of the fine movement mechanism according to the embodiment of the present invention, FIGS. 2 and 3 are characteristic diagrams of the piezoelectric element and strain gauge, respectively, and FIG. ),
FIG. 5 is a side view of a fine movement mechanism according to another embodiment of the present invention, and FIG. 6 is a side view of a conventional fine movement mechanism. 1, 2. ] R, 2R --- one rigid body part, 3, 4
,3R. 4, R---flat plate, 51.61.62.51R, 61
R, 62#--Protrusion, 71.72.71R, 72R,-
--111-Piezoelectric actuator N ~ ζ, ζ,

Claims (6)

[Claims] (1) In a fine movement mechanism in which a first rigid body part and a second rigid body part are connected by a plurality of elastic members and each of the rigid body parts is relatively displaced, the first actuator and the second actuator are moved in their displacement directions. are arranged so that the first actuator is substantially the same, and the first end of the first actuator in the displacement direction is fixed to the first rigid body part, and the second end of the first actuator is fixed to the second rigid body part. The first side end of the second actuator in the displacement direction is fixed to the second rigid body part, and the second actuator is fixed to the first rigid body part. A fine movement mechanism characterized by being fixed to. (2) The fine movement mechanism according to claim (1), wherein the first actuator and the second actuator are composed of piezoelectric elements. (3) The fine movement mechanism according to claim (2), wherein voltages of opposite polarity are applied to each of the piezoelectric elements when the relative displacement occurs. (4) The fine movement mechanism according to claim (1), wherein each of the elastic members is a flat plate parallel to each other. (5) The fine movement mechanism according to claim (1), wherein each of the elastic members is a flat plate extending radially with respect to a predetermined point. (6) The fine movement mechanism according to claim (1), wherein at least one of the elastic members includes a strain gauge that detects the amount of the relative displacement.