JPH048441A - Locking mechanism - Google Patents

Abstract

PURPOSE:To generate sufficiently high power without entailing any problem on pollution and heat generation by exciting a piezoelectric actuator attached to one side of the paired members relatively movable, making a contact member contact with the other side of the paired members, and locking them through frictional force. CONSTITUTION:A first wedge 3 is moved by a screw 8 in a vertical direction with the shaft of a piezoelectric actuator 1, transmitting the force to a second wedge 4, and the second wedge 4 is moved in the axial direction of the piezoelectric actuator 1, thereby giving the specified preload to the actuator 1, and a semiconductor wafer is charged to a wafer chuck on a plate base 7. After positioning is over, is a driving source of the actuator 1 is turned ON, this actuator 1 is extended and this extension is transmitted to an elastic hinge 2, whereby a shoe 5 clamped to this elastic hinge 2 reaches the inner wall of a housing 6, and a contact point is immobilized by means of friction force, through which two directions of theta and z are locked up.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a locking mechanism, and more particularly to a locking mechanism suitable for locking a movable member at a position where the movable member is positioned.

In a positioning mechanism that is not restrictive or has a fine movement mechanism, a lock suitable for use in a medium-sized motion machine tank, which is suitable for locking after moving an object within the adjustable range of the fine movement mechanism. It is a mechanism.

[Prior art] In precision processing equipment, etc., after receiving and receiving the workpiece,
You may want to adjust and fix its position. In such cases a locking device is used.

For example, in the manufacture of semiconductor devices, when mounting a semiconductor wafer on an exposure device, the semiconductor wafer is transported by air pressure, placed on a wafer chuck, and then fixed to the wafer chuck using a vacuum chuck, etc. . However, during transportation and mounting on the semiconductor device, it is unavoidable that the semiconductor wafer deviates from its desired position to some extent, for example, a rotational error of less than ±1 degree occurs. If the exposure apparatus has extremely high positioning accuracy, the fine adjustment device may not be able to correct such deviations. For example, it would be impossible to make a rotation mechanism with a precision of less than a second perform many rotations. Therefore, it is desirable to preliminarily adjust the position of the wafer chuck on which the semiconductor wafer is placed using a somewhat rough adjusting device and to lock the wafer chuck at that position. Further, the thickness of a semiconductor wafer varies from about 400 μm to about 800 μm depending on its standard. In order to adjust the surface to a predetermined height with semiconductor wafers having different thicknesses mounted thereon, adjustment of approximately several hundred μm is required, and it is preferable to lock the wafer after adjustment.

It is convenient to provide a locking mechanism because once such positional adjustment is performed, it can be fixed until the end of the exposure process.

Possible types of such a locking mechanism include those that utilize pneumatic pressure or hydraulic pressure, and those that utilize electromagnetic force. However, for those that use air pressure, the legal pressure range that can be handled is as low as 10 kg/cj or less, and the resulting force is small at 10 kr or less for 1-, whereas for those that use hydraulic pressure, it is sufficient at several hundred kK for 1 d. Although high forces can be generated, they require liquid piping and the associated potential for leakage. In the manufacturing process of semiconductor devices,
Pollution caused by oil, etc. must be strictly controlled, so
Hydraulic drive locking devices are difficult to use, but there are devices that use magnetic force, such as voice coil motors, but while generating force, it is necessary to pass current through the coil, etc. Placing a heat source in a highly accurate positioning device that generates heat will cause temperature changes. When the temperature changes, the positioning accuracy changes due to thermal expansion.

In other words, if a temperature change occurs, it becomes difficult to obtain the desired accuracy.

[Problem to be solved by the invention] As explained above, according to the conventional technology, a sufficiently high force can be generated without worrying about contaminating the atmosphere.
Moreover, a highly accurate locking device that does not generate substantial heat has not been obtained.

The object of the invention is to provide a locking device that is capable of generating sufficiently high forces without causing problems with contamination or heat generation.

[Means for Solving the Problems] A locking device of the present invention includes a pair of members that are fitted into each other and are movable relative to each other, and a piezoelectric actuator that is fixed to one of the pair of members and that expands and contracts in response to an electrical signal. and a contact member that is attached to the piezoelectric actuator and comes into contact with the other of the pair of members when the piezoelectric actuator is excited to lock the relative movement of the pair of members by friction.

[Operation J Piezoelectric actuators basically require current only at the moment of expansion and contraction, and when they are at rest, a small amount of leakage current flows between the laminated layers, but almost no heat is generated.The force generated by piezoelectric actuators is It's large enough so you can securely lock it.

[Embodiment] Figs. 1 and 2 show a rotation/translation locking device according to an embodiment of the present invention. Fig. 1 is a plan view, and Fig. 2 is a sectional view. A disc-shaped plate base 7 including a locking mechanism is disposed within a cylindrical housing 6 having sufficiently high regularity. The plate base 7 has a structure on which an object is placed, and is driven by an actuator (not shown).
As shown more clearly in FIG.
It has a structure that allows it to move in the circumferential direction (theta direction) and the circumferential direction (theta direction). Four piezoelectric actuators 1 are attached to the plate base 7 at 90 degree intervals.

The piezoelectric actuator is, for example, a 6 mm square stacked type and can generate a force of about several dozen. Each piezoelectric actuator 1 has one end fixed to the grate base 7, and the other end can be driven radially outward. An elastic hinge 2 fixed to a plate base 7 is formed at the other end of the piezoelectric actuator 1 .

As shown in a simplified and enlarged view in FIG. 3, the elastic hinge 2 is formed of parallel thin plates 2a and 2b that can be elastically deformed in the thickness direction, and the lengths of two opposing sides are equal. has been done. Therefore, the opposing sides are parallel, and elastic deformation is easily achieved only in one direction indicated by the arrow. Therefore, when the piezoelectric actuator 1 tries to extend in the direction of the arrow, the elastic hinges 2a and 2b are elastically deformed in the direction of the arrow, thereby pushing the shoe 5. It should be noted that the elastic hinge 2 has high machinability in directions other than the direction of the arrow and hardly deforms, thus preventing the application of lateral force to the piezoelectric actuator 1.

In the structure shown in FIG. 1, a pair of wedges 3.4 are provided between the shoe 5 and the piezoelectric actuator 1 for adjusting the distance. That is, a second wedge 4 is connected to the free end of the pressure actuator 1, and a first wedge 3 movable in the right angle direction is engaged thereon by a screw 8. The second wedge 4 is fixed to the movable side of the elastic hinge 2 and is driven in the axial direction by the piezoelectric actuator 1. The long surface of the second wedge 4 is formed to be inclined with respect to a plane perpendicular to the axis. The first wedge 3 has an engagement surface inclined with respect to a plane perpendicular to the axis, and engages the surface of the second wedge 4. The structure is such that when the first wedge is moved by the screw 8, the wedge 4 is pushed in the axial direction of the piezoelectric actuator 1, or moves in the opposite direction. When a laminated piezoelectric element or the like is used as the piezoelectric actuator 1, the characteristics at low voltage often vary due to variations in length, play between the eyebrows, etc. If the first wedge 3 is adjusted to apply an appropriate preload to the piezoelectric actuator 1, play between the eyebrows will be eliminated, and the characteristics can be made linear. Also, the amount of displacement and stress obtained with respect to the applied voltage change are made uniform. The shoe 5 is a member that is pressed against the inner wall of the housing 6, and in a movable state forms a gap of about several tens of μm between the shoe 5 and the inner wall of the housing 6. When locking, the piezoelectric actuator 1 is driven to deform the elastic hinge 2 and press the shoe 5 against the inner wall of the housing 6. Although the absolute value of the voltage required for this operation differs depending on each voltage actuator, if a predetermined pressurization is generated by the wedge 3.4 and then the voltage is driven, variations in characteristics can be homogenized.

The piezoelectric actuator 1 is driven by voltage to generate a sufficiently high force of, for example, several kilotons, and fixes the housing 6 and the plate base 7 by frictional force.

The operation when the rotation/translation lock device shown in FIGS. 1 and 2 constitutes a part of a semiconductor exposure apparatus will be described below. First, the first wedge 3 is moved in a direction perpendicular to the axis of the piezoelectric actuator using the screw 8, and the force is transmitted to the second wedge 4 to move the second wedge 4 in the axial direction of the piezoelectric actuator 1. Apply a predetermined preload to 1.

By keeping the applied pressure within a certain range, the elastic hinge 2 of the parallel link structure also undergoes deformation within a certain range. In this way, the gap between the shoe 5 and the housing 6 is adjusted.

Next, the semiconductor wafer is loaded onto the wafer chuck on the plate base 7. At this time, it is assumed that the orientation flat of the semiconductor wafer is displaced by about 1 degree in the circumferential direction. Further, the thickness of a semiconductor wafer differs by several hundred μm depending on its diameter and the like.

The deviation in the circumferential direction and the variation in the thickness direction are adjusted to meet a predetermined standard. This adjustment is performed by a biaxial actuator (not shown) or the like.

After positioning, the drive power for the piezoelectric actuator 1 is turned on. The piezoelectric actuator 1 expands, and the expansion is transmitted to the elastic hinge 2.

The elastic hinge 2 has a parallel link structure, and is restrained from moving in directions other than the axial direction of the piezoelectric actuator, or is elastically deformed in the axial direction of the piezoelectric actuator. Finally, the shoe 5 fixed to the elastic hinge 2 reaches the inner wall of the housing 6, and the friction force makes the contact point immobile and θ
and 2 lock in two directions.

Basically, while a piezoelectric actuator expands and contracts,
Current flows and consumes power, but after the deformation is completed, no current is required other than the leakage current between the laminated layers, so almost no heat is generated.

Piezoelectric actuators can easily achieve high precision because they do not change the temperature of the locking device, and since they generate a large force, they can lock securely through friction.

Although the structure in which a disk-shaped plate base is housed in a cylindrical housing and piezoelectric actuators are provided in four directions has been described above, various other structures can also be adopted.

4(A), (B), and (C) schematically show other embodiments of the present invention.

FIG. 4(A) shows a structure in which a disk-shaped movable member 11 is arranged in a cylindrical housing 12 and a piezoelectric actuator 1 protrudes toward the housing 12 from three directions of the movable member 11. By locking the movable member 11 to the housing 12, the movable member 11 is fixed,
It can be fixed in the θ, Z directions, etc. Stable locking can be achieved if the locking location is in two or more axial directions.

FIG. 4(B) shows a case of a housing and a movable member having a rectangular cross section instead of a circular cross section, in which a movable member 13 on a rectangular plane is housed in a hollow prismatic housing 14,
Piezoelectric actuators are provided on the four sides. x
This structure is suitable for adjusting the y-force direction. The operation is almost the same as that in FIG.

FIG. 4(C) shows a case in which alignment is performed in the in-plane direction without adjustment in the axial direction.The planar movable member 15 adjusts its position in the in-plane direction, and is pressed and locked by the piezoelectric actuator 1. The movement within the plane may be uniaxial or biaxial.

Although a locking device that is not coupled to a stage device that performs minute displacement has been described above, the present invention is not limited to minute displacement; for example, the locking device may be adjusted 360 degrees in the circumferential direction, and may also be applied to linear displacement. The same is true.

Although the present invention has been described above with reference to examples, it will be obvious to those skilled in the art that the present invention is not limited to these examples, and that, for example, various changes, improvements, combinations, etc. can be made.

[Effects of the Invention] As explained above, according to the present invention, there is no heat generation,
To provide a locking device that can be locked with sufficient force and is less likely to pollute the atmosphere.

4A, 4B, and 4C are schematic diagrams showing other embodiments of the present invention.

piezoelectric actuator elastic hinge 1st wedge 2nd wedge shoe housing plate base screw

[Brief explanation of drawings]

Fig. 1 is a plan view showing the rotation/translation locking device, Fig. 2 is a sectional view of the rotation/translation locking device shown in Fig. 1, and Fig. 3 illustrates the piezoelectric actuator and elastic hinge.Patent applicant: Sumitomo Heavy Industries, Ltd. Keishi Takahashi, Patent Attorney, Sub-Agent of Kikai Kogyo Co., Ltd. Rotation translation locking device Figure 2 Piezoelectric actuator and elastic hinge Figure 3

Claims (2)

[Claims] (1) a pair of members that are movable relative to each other in a fitted state; a piezoelectric actuator that is fixed to one of the pair of members and expands and contracts in response to an electrical signal; and a piezoelectric actuator that is attached to the piezoelectric actuator; a contact member that comes into contact with the other of the pair of members when excited, and locks the relative movement of the pair of members by friction. (2) The pair of members is a first member having a cavity and a second member inserted into the cavity, and the relative movement is a translational movement in a predetermined direction and a rotational movement around the predetermined direction. 2. The locking mechanism according to claim 1, wherein the actuator is provided in at least two axial directions.