JPS622553A - Trimming unit - Google Patents

Abstract

PURPOSE:To accomplish high-precision positioning by a method wherein a displacement gauge accurately determines the position of a trimming mechanism and the difference between the actual position signals and target position signals is fed back into a controlling unit for the actuating of driving members. CONSTITUTION:A closed loop servo is constructed for the actuation of a trimming mechanism. The attitude of the trimming mechanism is determined by an eddy current type non-contact displacement gauge 41 detecting the positions of the X, Y and theta axes of the trimming mechanism. The detected signals are amplified by a pre-amplifier 42 and then digitized in an AD converter, whereafter they are applied to a comparator 44. Target position signals yielded by a computer 45 are also applied to the comparator 44. A controlling circuit 46 goes into operation and actuates driving members 6-9, which continues until the difference is small enough to fall within the range of tolerance outputted by the computer 45. This neutralizes the interference with each other of the three axes in a trimming mechanism, and allows the trimming mechanism to accomplish its inherent long-stroke movement and high-precision positioning.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a fine movement device for rotating and rectilinearly moving an object position with high precision.

[Technical background of the invention and its problems]

In recent years, electron beam lithography equipment, reduction projection type transcription equipment, X-ray transcription equipment, etc. have been developed to form fine patterns on samples such as semiconductor wafers and mask substrates. In order to maintain accuracy, a fine movement mechanism is required to drive minute displacements. Further, a fine movement mechanism with high precision is required not only in the above-mentioned apparatus but also in fields where precise measurements are performed using measuring instruments.

Fine movement mechanisms include those that move in the -axial direction and those that perform rotational movement, but conventional rotary fine movement mechanisms that perform rotational movement have the following problems. In other words, fine movement drive is difficult with long strokes;
Those capable of fine movement had problems such as not being able to lengthen the stroke.

Furthermore, there is a demand for a fine movement mechanism that can perform both rotational and linear movements, but no such mechanism has been reported that is capable of fine movement and has a long stroke.

In order to solve the above problem, the present inventors have recently developed the third
As shown in the figure, we have developed a fine movement mechanism using piezoelectric elements (
JP 58-190079).

In this system, a plurality of drive members 6. . . . , 9 and a plurality of fixing members 12 . . . , 15, and the fixing action of the movable members 1. to 15 by the same driving source. ~, 4 rotational movement and linear movement are possible. Further, there is no disadvantage that the stroke becomes extremely small when fine movement is performed, and a sufficiently long stroke can be obtained with fine movement, and in principle, infinite rotation and straight movement are possible.

However, this type of micro-motion mechanism has the following problems. That is, the movable member is in a state where it can move in any desired direction, and due to its structure, mutual interference between the respective axes cannot be avoided. In other words, the fine movement mechanism (moving member)
For example, even if the fine movement mechanism is moved in the X-axis direction, the fine movement mechanism will move slightly in the Y-axis and θ-axis directions, as shown in FIG. This positional deviation becomes a big problem in devices that require highly accurate positioning, such as electron beam lithography devices.

In addition, in FIG. 6, the upper plot point ○ is the detected position of point A of the movable member in the Y direction when the fine movement mechanism is moved forward in the X direction as shown in FIG. Plot point ・ is the detected position of point A in the Y direction when moving in the opposite direction to the X direction.

Similarly, the lower plot point O. detects the positions of 8 points of the moving member. And the straight line in the center is A.

It shows the moving position of the midpoint of B.

[Purpose of the invention]

The present invention has been made in consideration of the above circumstances, and its purpose is to be able to perform rotational and linear fine movement using the same drive source, and to make the stroke sufficiently long. The object of the present invention is to provide a fine movement device that can perform positioning with extremely high accuracy.

(Summary of the Invention) The gist of the present invention is to accurately measure the position of the fine movement mechanism using a displacement meter, and feed back the difference between the position signal and the target position signal to the control circuit to drive the drive member. The purpose is to perform accurate positioning.

That is, the present invention provides a drive member comprising at least three moving members movably placed on a base and piezoelectric elements connected between the moving members.

and a fixing member that fixes each movable member on a base, and rotates and moves the movable member in a straight line by the expansion and contraction action of the drive member and the fixing action of the fixed member, wherein the actual position of the movable member is determined. A measuring means for measuring in the X, Y, and θ directions; a comparing means for comparing the measured position obtained by the measuring means with a set position that the moving member should actually be; and a positional deviation obtained by the comparing means. A control means is provided for controlling the amount of movement of the movable member by the drive member in accordance with the information.

〔Effect of the invention〕

According to the present invention, each expansion and contraction action by one or more drive members,
By appropriately combining the fixing actions of the plurality of fixing members, rotational movement and linear movement of the movable member by the same driving source are possible.

In addition, there is no disadvantage that the stroke becomes extremely small when fine movement is performed as in the conventional mechanism, and a sufficiently long stroke can be obtained with fine movement, and in principle, infinite rotation and straight movement are possible. This eliminates the need for drive and fine movement mechanisms. In addition, since the movable member is directly driven by a drive member made of a piezoelectric element as a drive source, for example, an applied voltage of 1[
Ultra-fine movement of 0.005 [μm] can be reliably performed at [V]. Furthermore, the piezoelectric effect of members varies from several hundred [Kg] to several [Kg] depending on the magnitude of the applied voltage.
1], and it is possible to provide a fine movement mechanism that generates a large torque.

In addition, the present invention eliminates interference between each axis of the fine movement mechanism by performing closed loop control, making it possible to achieve extremely accurate positioning using the inherent long stroke and fine movement. Its range of applications expands as a drive mechanism.

[Embodiments of the invention]

First, before explaining embodiments, the structure and operation of the fine movement mechanism, which is the basis of the present invention, will be explained.

Figures 3 (a) to (C) each show a schematic configuration of a conventional fine movement device (a> is a plan view, (b) is a sectional view taken along arrow A-A in (a), and (C) is a It is a sectional view taken along arrow B-B in (a). In the figure, reference numerals 1, 2, 3, and 4 are rectangular plate-shaped moving members, and these moving members 1. to .4 are attached to a conductive base 5. Adjacent movable members 1.-.4 are connected by drive members 6, 7, 8, and 9, respectively.

That is, the driving member 6 is disposed between the moving members 1 and 2, and the driving member 6 is disposed between the moving members 1 and 2.
．． A driving member 7 is disposed between the movable member 3. ．． A driving member 8 is provided between the moving members 4 and 1, and a driving member 9 is provided between the moving members 4 and 1. Drive member 6. ~.

Reference numeral 9 denotes a piezoelectric element, for example, made of lead zirconate titanate, which expands and contracts depending on the applied voltage, and the movable member 1. ~． 4
are each attached and fixed.

Note that this fixing may be done by adhesion, screwing, press-fitting, or the like. Further, the drive member 6 includes a switch 10a.
Similarly, the drive member 7 is connected to a power supply 11b via a switch 10b, the drive member 8 is connected to a power supply 11c via a switch 10C, and the drive member 9 is connected to a power supply 11c via a switch 10d. The power source 11d is connected to the power source 11d.

On the other hand, an electrostatic chuck (fixed member) 12 consisting of an electrode 12a and insulating layers 12b and 12G is disposed under the movable member 1.
Similarly, a moving member 2. is provided. ~． Electrostatic chucks 13, 14, and 15 are provided at the bottom of 4, respectively. These moving members 1. ~． 4. For example, the movable member 1 is fixed to the base 5 by suction by connecting a power source 17a between the electrode 12a and the base 5 via the switch 16a. In addition, in the figure, 13a, 15a are mills, and 13b, 15a are mills.

15b, 13c, ~15c are insulating layers; 16b, ~.

16d represents a switch, and 17b to 17d represent power supplies, respectively.

In this configuration, in order to perform rotational movement, the moving member 3.4 is fixed on the base 5 by the electrostatic chuck 14, 15, and then the driving member 7 is extended as shown in FIG. 4(a). At the same time, the driving member 9 is contracted. This results in
The moving members 1 and 2 rotate slightly in the direction of arrow P. Next, after the movable members 1 and 2 are fixed on the base 5 by the electrostatic chucks 12 and 13, the fixation of the movable members 3 and 4 by the electrostatic chucks 14 and 15 is released. In this state, Figure 4(b)
As shown in FIG.
When extended, the moving member 3.4 rotates slightly in the direction of arrow P. By repeating the above operations: Moving member 1. . . , 4 are rotated in the direction of arrow P.

In order to move in a straight line, the movable member 2.3 is fixed on the base 5 using the electrostatic chucks 13 and 14, and then the movable member 2.3 is
), the drive members 6.8 are extended together. As a result, the moving member 1.4 moves slightly (straight ahead) in the direction of arrow Q. Next, after the movable member 1.4 is fixed on the base 5 by the electrostatic chuck 12.15, the fixation of the movable member 2.3 by the electrostatic chucks 13 and 14 is released. In this state, when the drive members 6.8 are both retracted as shown in FIG. 5(b), the moving member 2.3 moves slightly in the direction of the arrow Q. By repeating the above operations, moving member 1.
. . . , 4 are forced to go straight in the direction of arrow Q.

Thus, moving member 1. . In addition, moving member 1. The direction of movement of the drive member 6. ~.

9 and the electrostatic chuck 12. ~． It can be freely set by appropriately selecting each of the 15 fixing functions.

Next, an embodiment of the present invention using the above fine movement mechanism will be described.

FIG. 1 is a schematic configuration diagram showing a fine movement device according to an embodiment of the present invention. Note that the same parts as in FIG. 3 are given the same reference numerals, and detailed explanation thereof will be omitted. This embodiment differs from the device shown in Fig. 3 in that the fine movement mechanism is driven by a closed-loop servo, and the drive mechanism body
It is similar to the device shown in the figure. That is, the position of the fine movement mechanism (moving member) is determined by the eddy current type non-contact displacement meter 41 (X
.

This detection signal is amplified by a preamplifier 42, digitized by an AD converter 43, and sent to a comparator 44. on the other hand,
The target position is sent from the meter Wi 1145 to the comparator 44, and the control circuit 46 controls the drive member 6. ~,
9 is driven.

Next, the operation of this device configured as described above will be explained.

FIG. 2 is a flowchart showing the driving algorithm. First, the target position and allowable error are read using Reat data. The position in the X direction is measured using a displacement meter using the xdrive, and the fine movement mechanism is driven in the X direction until the difference ΔX between the target position and the measured position becomes less than or equal to the allowable ΔεX. ΔX is △ε
When the value becomes less than or equal to X, the Y-direction position is measured by YdriVe, and the fine movement mechanism is driven in the Y-direction until the difference Δy between the target position and the measured position becomes less than or equal to the allowable error Δεy. However, as described above, since there is interference between the respective axes, when moving in the Y direction, a change also occurs in the X direction. For this reason, ΔX again becomes ΔεX
Check if it is within the range, and if it is, proceed to the next step and return to the X drive if it is not.

Next, with θdrive, the angle in the θ direction is obtained from the displacement meter, and the fine movement mechanism is driven in the θ direction until the difference between the target angle and the measured angle becomes less than or equal to the allowable error Δεθ.

If it is within the allowable error, confirm that ΔX and Δy are within Δε× and Δεy. These △X, Δy are ΔεX, △
If it exceeds εy, the above-described sequence is repeated to perform positioning control to the target position.

Thus, according to the device of this embodiment, the interference between the three axes of the fine movement mechanism can be eliminated, and the long stroke movement and highly accurate positioning that the fine movement mechanism originally has can be performed. Therefore, the present invention can be sufficiently applied to applications that require highly accurate positioning, such as electron beam lithography equipment, and its effects are tremendous.

Note that the present invention is not limited to the embodiments described above. For example, the measuring device that measures the position of the fine movement i-structure includes:
A laser interferometer or an electrostatic container type non-contact measuring device may also be used. Further, the driving algorithm is not limited to the answer shown in FIG. 2, but may be changed as appropriate depending on the situation. Further, in the embodiment, a case has been described in which 41Il of moving members and 41Il of driving members are used, but the number of these may be three or more. In general, the shape, dimensions, etc. of the moving member may be appropriately shaped according to the specifications. Furthermore, it goes without saying that the fixing member is not necessarily limited to an electrostatic chuck, and may be an electromagnetic chuck or other type of chuck. In short, the present invention can be implemented with various modifications without departing from the gist thereof.

[Brief explanation of drawings]

Fig. 1 is a plan view showing a schematic configuration of a fine movement device according to an embodiment of the present invention, Fig. 2 is a flowchart for explaining the operation of the above embodiment device, and Fig. 3 is a fine movement device which is the basis of the present invention. 3(a) is a plan view, FIG. 3(b) is a sectional view taken along arrow A-A in FIG. 3(a), and 3.
Figure (C) is a sectional view taken along arrow B-8 in Figure (a), and Figure 4 (a).
)(b) and FIGS. 5(a) and 5(b) are schematic diagrams for explaining the action of the fine movement mechanism, respectively, FIG. 6 is a characteristic diagram showing an example of interference between each axis of the fine movement mechanism, and FIG. 7 FIG. 2 is a schematic diagram showing the moving direction and position measurement points of the fine movement mechanism. 1, ~. 4... Moving member, 5... Base, 6. ~． 9
... Drive member, 10a, ~, 10d, 16a, ~
. 16 d...switch, 11a, ~, 11d, 1
7a. ~, 17d... power supply, 12. ~． 15... Electrostatic chuck (fixing member), 12a, ~, 14cj-... Electrode, 12a, ~, 14d, 12a, ~, 14cj-
... Insulating layer, 41 ... Non-contact displacement meter, 42 ... Amplifier, 43 ... A/D converter, 44 ... Comparator, 45 ... Computer, 46 ... Control circuit, 47
. . . Drive member control signal, 48 . . . Fixed member control signal. Applicant's agent Patent attorney Takehiko Suzue (a) Figure 4 (a) (b) Figure 5

Claims (7)

[Claims] (1) At least three movable members movably placed on a base, drive members each made of a piezoelectric element connected between these movable members, and each movable member fixed on the base. and a fixing member, the fine movement device rotates and rectilinearly moves the movable member by the expansion and contraction action of the driving member and the fixing action of the fixed member, a measuring means for measuring the actual position of the movable member in the X, Y, and θ directions. and a comparison means for comparing the measured position obtained by the measuring means and the actual set position of the moving member;
A fine movement device characterized by comprising: control means for controlling the amount of movement of the moving member by the drive member in accordance with the positional deviation information obtained by the comparison means. (2) The fine movement device according to claim 1, wherein the measuring means measures the position of the moving member at at least three locations. (3) The fine movement device according to claim 2, wherein an eddy current displacement meter is used as the measuring means. (4) The fine movement device according to claim 2, wherein a capacitive displacement meter is used as the measuring means. (5) The fine movement device according to claim 2, wherein a laser interferometer is used as the measuring means. (6) The fine movement device according to claim 1, wherein the fixed member is formed by forming an electrostatic chuck consisting of an electrode and a dielectric layer on the surface layer of each moving member. . (7) The base and all of the members are made of non-magnetic materials, and lead zirconate titanate is used as the piezoelectric element having the expansion and contraction action, and beryllium copper, aluminum, or titanium is used as other constituent materials. The fine movement device according to claim 1, characterized in that: