JP2964411B2 - Micro rotary table - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a micro rotary table used for a mask aligning device, a micro positioning device and the like for semiconductor manufacturing.

(Prior Art) A minute rotating tape is used in a mask aligning device, a minute positioning device, and the like for semiconductor manufacturing.

FIG. 5 is a diagram showing an example of the structure of a micro rotary table using a conventional piezoelectric element. In FIG. 5, the piezoelectric elements (a), (b), and (c), which extend and contract in the length direction, are respectively positioned at positions where the circumference of the rotatably supported disk-shaped rotating plate is divided into three equal parts. The direction is substantially aligned with the tangential direction of the disk-shaped rotary plate, and the table 100 rotates slightly according to expansion and contraction of the piezoelectric elements (a), (b), and (c).

(Problem to be Solved by the Invention) In the conventional micro rotary table shown in FIG.
It has a structure that supports the rotary table with bearings, and requires high-precision machining to minimize backlash in the bearings.
Furthermore, assembling with a piezoelectric element also requires special attention for positional deviation, and it is very difficult to assemble the piezoelectric element.

Therefore, a technical problem of the present invention is to eliminate the above-mentioned disadvantages of the conventional micro rotary table, and to provide a micro rotary table that has a simple structure and is easy to assemble.

(Means for Solving the Problems) According to the present invention, one end of a hollow cylindrical piezoelectric torsional displacement element is fixed to a fixed base, and the movable table is fixed to the other end. A small rotating table can be obtained. Furthermore, according to the present invention, as a hollow cylindrical piezoelectric torsional displacement element, two fingers are formed by applying cross finger electrodes on the outer peripheral surface of the piezoelectric ceramic hollow cylinder in a direction of 45 ° with respect to the length direction of the piezoelectric ceramic hollow cylinder. A micro-rotary table is obtained by subjecting the piezoelectric ceramic cylinder to polarization processing using the interdigital electrodes.

(Operation) In the hollow cylindrical piezoelectric torsional displacement element constituting the micro rotary table according to the present invention, first, an interdigital electrode is provided on the outer peripheral surface of the piezoelectric ceramic cylinder in a direction of 45 ° with respect to the length direction of the cylinder. When the piezoelectric ceramic cylinder is subjected to polarization using the interdigital electrodes, the polarization direction is perpendicular to the length direction of the interdigital electrodes.

When a voltage is applied to the interdigital electrode in this state, when the polarity of the voltage is the same as the polarity of the voltage at the time of polarization, stretching strain occurs in the direction of the polarization, and the polarity of the voltage is opposite to the characteristic of the voltage at the time of polarization. In such a case, shrinkage distortion occurs in the direction of polarization. When an elongation or contraction distortion occurs in the polarization direction, a contraction distortion or an elongation distortion occurs in the direction perpendicular to the polarization direction, respectively. As a result, torsional displacement occurs in the piezoelectric ceramic cylinder.

Therefore, the movable table provided on the end face of the torsional displacement vibrator performs minute rotation according to the torsional displacement.

(Example) Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view showing an example of the structure of a micro rotary table according to the present invention.

In FIG. 1, a minute table 1 is fixed to one end surface of a cylindrical torsional displacement element 2, and the other end face of the torsional displacement element 2 is joined to a fixed bail (not shown).

The torsional displacement element 2 is formed by press-forming piezoelectric ceramics. On the cylindrical surface 3 of the ceramic, a plurality of electrode groups are provided which are inclined with respect to the central axis.

FIGS. 2 (a), (b), (c) and (d) are views for explaining the operation principle of the torsional displacement element of the present invention.

In FIG. 2 (a), a plurality of interdigitated electrodes 21 and 22 are formed on one surface of a piezoelectric ceramic plate 20 so as to intersect each other.
1 ', 22'.

In FIG. 2 (b), the dashed arrow 23 indicates the interdigital electrodes 21,2.
2 (c) and 2 (d) are side views schematically showing the direction of polarization when the polarization process is performed using FIG. 2, and FIGS. 2 (c) and 2 (d) show the piezoelectric ceramic plate subjected to the polarization process as shown in FIG. 2 (b). 9 is a diagram schematically showing a state of distortion generated when a DC voltage is applied to 9, and a solid arrow 24 indicates the direction of an electric field.

As can be seen from FIGS. 2 (c) and 2 (d), when the polarity of the voltage is the same as the polarity of the voltage at the time of polarization, (c), an elongation strain occurs in the direction of polarization, and the polarity of the voltage at the time of polarization is changed. In the case of (d), which is opposite to the polarity of the voltage, contraction distortion occurs in the direction of polarization.

FIG. 3 is a perspective view showing a state of distortion generated on the outer peripheral surface of the cylinder when both end faces of the cylinder 30 are twisted as indicated by arrows 31 in the figure. In FIG. 3, an elongation distortion occurs in a direction at an angle of 45 ° with respect to the axial direction of the cylinder and in the direction of the torsion arrow 32, and the direction indicated by the arrow perpendicular to this direction.
33 has contraction distortion.

Therefore, the interdigital electrodes 21 and 22 as shown in FIG. 2 are formed on the outer peripheral surface of the piezoelectric ceramic cylinder so that the direction of the interdigital finger is at an angle of 45 ° to the length direction of the piezoelectric ceramic cylinder. When a DC voltage is applied to the same interdigital electrode by using the interdigital electrodes 32 and 33, the column is twisted in one direction when the polarity of the voltage is the same as the polarity of the voltage at the time of polarization, and the voltage is applied. If the polarity is opposite to the polarity of the voltage at the time of polarization, it will be twisted in the opposite direction.

FIG. 4 is a perspective view showing an example of the structure of a torsional displacement element used in the micro rotary table according to the embodiment of the present invention.
In FIG. 4, electrodes 41 and 42 which intersect each other are formed on the outer peripheral surface of the hollow cylindrical piezoelectric ceramics 2 at an angle of 45 ° with respect to the length direction.
It is connected to 41 'and 42'. Common electrode 41 'and
Reference numerals 42 'are formed at both ends of the outer peripheral surface of the hollow cylindrical piezoelectric ceramics 2, respectively. In FIG. 4, the common electrode
After applying a DC high voltage between 41 'and 42', that is, between the interdigital electrodes 41 and 42 to perform polarization processing, and then applying a voltage between the same electrodes, as described above, the hollow cylindrical piezoelectric ceramic 41 is formed. ′ Is distorted such that both ends are twisted.

An operation principle of the minute rotary table according to the embodiment of the present invention will be described.

When a DC voltage is applied to the interdigital electrodes of the micro rotary table shown in FIG. 1, a torsional distortion corresponding to the magnitude of the applied voltage is generated on both end faces, and the table is rotated.

As can be seen from FIG. 1, in the micro rotary table 1, the rotary table is joined to the end face of the hollow cylindrical torsion displacement element 2, so that a bearing for rotatably holding the rotary table is unnecessary, and Deterioration of positional accuracy due to backlash can be prevented, and since the structure is simple with few parts used, variations in positional accuracy due to assembly are reduced.

(Effects of the Invention) As described above, according to the present invention, a piezoelectric ceramic hollow cylinder which can be easily manufactured by a generally used press molding technique is used, and the outer peripheral surface thereof is By applying electrode printing, which is a common technique, a piezoelectric torsional displacement element can be obtained, and a micro-rotary table can be constructed simply by fixing a table to the end surface of the hollow cylindrical torsional displacement element thus obtained. As a result, it is possible to obtain a micro rotary table with less variation in positional accuracy due to the bonding process and the complicated assembly process.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a structure of a micro rotary table according to an embodiment of the present invention, and FIGS. 2 (a), (b), (c) and (d).
FIG. 3 is a diagram for explaining the operation principle of the piezoelectric torsional vibrator used for the micro rotary table of FIG. 1, FIG. 3 is a diagram for explaining the torsional displacement of the piezoelectric ceramic cylinder, and FIG. FIG. 5 is a perspective view showing a torsional vibrator used for the table, and FIG. 5 is a perspective view showing an example of the structure of a conventional minute rotary table. In the figure, 1 ... micro rotary table, 2 ... piezoelectric torsional displacement element, 3
…… Cylindrical surface, 100 …… Table, (A), (B), (C)
……Piezoelectric element.

Continuation of front page (56) References JP-A-61-244432 (JP, A) JP-A-63-226710 (JP, A) JP-A-3-50819 (JP, A) JP-A-54-127259 (JP) , A) Japanese Utility Model Hei 1-40088 (JP, U) Japanese Utility Model Sho 58-121423 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01L 21/30 B23Q 1/02

Claims (2)

(57) [Claims] 1. A micro rotary table wherein one end of a hollow cylindrical piezoelectric torsional displacement element is fixed to a fixed base, and a movable table is fixed to the other end. 2. The micro rotary table according to claim 1, wherein said hollow cylindrical piezoelectric torsional displacement element is formed on the outer peripheral surface of the piezoelectric ceramic hollow cylinder by 45 ° with respect to the longitudinal direction of said piezoelectric ceramic hollow cylinder. A micro-rotary table characterized in that two electrodes are provided by applying interdigital electrodes in the direction, and the piezoelectric ceramic cylinder is subjected to a polarization process using the interdigital electrodes.