JPH07181277A - Driving device - Google Patents

Abstract

PURPOSE:To provide an X-Y stage capable of switching between automatic control and manual control. CONSTITUTION:Controllers 16x and 16y drive ultrasonic linear motors 6x and 6y following the first command signal (count value from counters 20x and 20y based on sensors 14x and 14y) until photoelectric sensors 8x and 8y detect origin sensors 14x and 14y. If the origin sensors 14x and 14y are detected, relative position relation between scales 10x and 10y and the wafers on the X-Y stage is determined for the detected origin. When the count values of the counters 20x and 20y coincide with the position coordinates of the chip to be inspected on the wafer, the controllers 16x and 16y stop the driving of the linear motors 6x and 6y based on the first command signal. Then, an inspector drives the ultrasonic linear motors 6x and 6y following the second command signal (command signal based on manual operation of manual input device 22) and visually inspects the chip.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive device using an ultrasonic linear motor as a drive source, and is particularly suitable for an XY stage of a semiconductor inspection microscope for screen inspection of chips on a semiconductor wafer. Drive device.

[0002]

2. Description of the Related Art Microscopic inspection of a chip printed on a semiconductor wafer is performed by placing the wafer on an XY stage attached to a microscope and allowing an inspector to manually operate the XY stage. The method of visual inspection is common. However, the use of motorized stages rather than manual stages is desirable to perform efficient inspection.

As a conventional electric XY stage of this type, a stepping motor or a servo motor with a rotary encoder is used as a driving source, and its rotational movement is performed by a ball screw or a precision sliding screw. There are many types that convert to linear motion by a motion conversion mechanism using a feed screw such as a child.

The control method is such that the controller calculates a positioning command unit determined from the rotational resolution of the stepping motor or the detection resolution of the rotary encoder and the pitch of the feed screw, and based on the numerical value. This is executed by sending a predetermined number of pulse signals from the controller to the motor.

By the way, in the actual inspection process, not all the chips burned on the wafer are inspected, but the specific chips with a certain mark are inspected.

Specifically, a predetermined chip to be inspected is detected by a position sensor, and the predetermined chip is moved into the field of view of the microscope by operating the stage, and then the inspector examines the chip. Carefully carry out defect inspection by visual observation.

Here, the electric stage needs the following two functions. First, the predetermined tip is moved into the field of view of the microscope, and secondly, the movement is smooth. However, in order to realize the above-mentioned function, the drive source and sensor of the conventional electric stage are not necessarily suitable. This is because the driving source and the sensor are required to have high resolution in order to realize the above-mentioned functions, but they are not required to have high precision. Generally, a high-resolution drive source and a sensor are expensive because of their high accuracy. However, in the inspection process of semiconductors, high resolution is required, but it is not necessary to have high precision. Therefore, if an expensive drive source or sensor with high resolution and high precision is used, the manufacturing cost of the electric stage is high. Becomes unnecessarily expensive.

In order to move the visual field onto a predetermined chip, the accuracy of the drive source of the electric stage is hardly required.
Because the size of the chip is a few mm square, the accuracy for moving a given chip within the field of view is sufficient on the order of submillimeters.

After a given chip has been moved into the field of view,
Regardless of the accuracy of the drive source of the electric stage, it suffices if the stage can be moved finely and smoothly by a position input device such as a joystick.

[0010]

The object of the present invention is not to have a relationship of "high resolution is naturally high precision" as in the conventional art, but to have a characteristic of "high resolution but not high precision". It is possible to provide a driving device that can be manufactured at a low cost and is particularly suitable for semiconductor inspection.

[0011]

According to one aspect of the present invention, there is provided an apparatus for driving a driven body that moves in at least one dimension. This driving device is an ultrasonic linear motor for driving a driven body in at least one-dimensional direction.
Controller, control means for controlling the driving of the driven body by the ultrasonic linear motor, detection means for detecting the drive amount of the driven body from a predetermined position, and the drive amount detected by the detection means. Based on the first command signal to the control means,
The first command signal causes the control unit to control the driving of the driven body, and the second command signal is given to the control unit by manual input, and the second command signal causes the control unit. Second command means for controlling the driving of the driven body, and switching means for selectively switching the first command signal and the second command signal to be given to the control means.

In this case, the detecting means includes a scale attached to the driven body and a photoelectric sensor for reading the scale. The scale may be a reflective scale having reflective portions and non-reflective portions that are alternately arranged along the moving direction of the driven body, or may be alternately arranged along the moving direction of the driven body. A reflective scale having a transmissive portion and a non-transmissive portion may be used.

Preferably, a plurality of types of the scales can be attached to the driven body in a replaceable manner. According to an embodiment of the present invention, a semiconductor wafer is mounted on a driven body, and the scale has a pitch that is an integral multiple of the pitch of the chips printed on the semiconductor wafer.

[0014]

According to the drive device of the present invention, an ultrasonic linear motor is used as a drive source. This ultrasonic linear motor is based on the drive amount detected by the detecting means.
And the control by the second command signal based on the manual input are selectively switched and driven. Since this ultrasonic linear motor is not highly accurate, it can also be controlled by manual input.

[0015]

1 to 3 show an embodiment of the present invention. In this embodiment, the present invention is applied to an electric XY stage 2 of a semiconductor inspection microscope. On the XY stage 2,
A semiconductor wafer 4 is placed.

In the following description, the X axis 2 of the XY stage 2
The components related to the x and Y axes 2y are indicated by the reference numerals with subscripts x and y, respectively. Ultrasonic linear motors 6x and 6y shown in FIG. 4 are used as a drive source for the XY stage 2. The ultrasonic linear motors 6x and 6y will be described later.

In FIG. 1, the relative displacement between the origin on the X and Y axes of the stage 2 and the semiconductor wafer 4 on the stage 2 is detected by an XY displacement detection sensor. The displacement detection sensor is composed of photoelectric sensors 8x and 8y having a light receiving portion and a light emitting portion, and reflective scales 10x and 10y that reflect light from the photoelectric sensors 8x and 8y.

The reflective scales 10x and 10y are marked at an integral multiple of the arrangement pitch of the chips 4a on the semiconductor wafer 4. That is, reflective scales 10x, 10y
The reflective portions and the non-reflective portions are alternately arranged along the extending direction so that they have an integral multiple of the chip pitch on the wafer 4. These scales 10x and 10y are
Positioning pins 12x, 1 at fixed points on the coordinates of stage 2
It is arranged by 2y. Further scale 10x, 10
The y is fixed to the stage 2 by a fixing means (not shown) such as a screw so as not to move undesirably.

Since the scales 10x and 10y are marked with an integral multiple of the chip pitch as described above,
If the position of the wafer 4 on the stage 2 is known, the coordinate position where the chip 4a is printed and the photoelectric sensor 8x,
The relationship of the number of signals of 8y can be easily calculated.

The origins of the stage 2 on the X and Y axes are determined by detecting the origin sensors 14x, 14y arranged near the stage 2 by photoelectric sensors 8x, 8y.

As shown in FIG. 3, the ultrasonic linear motor 6
x and 6y are driven through the drivers 18x and 18y by the drive signals output from the controllers 16x and 16y.

Counters 20x and 20y for counting output signals from the photoelectric sensors 8x and 8y are connected to the controllers 16x and 16y. Further controller 1
A manual input device 22 such as a joystick is also connected to 6x and 16y. That is, the controller 16x, 1
6y is selectively controlled by either a first command signal as a count value input from the counters 20x, 20y or a second command signal as a manual input command signal input from the manual input device 22. To be done.

The manual input device is provided with a manual switch (not shown) for transmitting the end of the second command signal to the controllers 16x and 16y. Next, the ultrasonic linear mode
The data 6x and 6y will be described. However, this linear mode
Since this is a known one disclosed in Japanese Patent Application No. 4-321096 by the applicant of the present application, only a brief description will be given here. Further, since the linear motors 6x and 6y have the same structure, the linear motor 6x will be representatively described.

In FIG. 4, only the ultrasonic transducer 24x of the ultrasonic linear linear motor 6x for driving the X axis of the stage 2 is shown. The ultrasonic transducer 24x has a main vibrating body 26x made of an elastic body (for example, brass).
Three sub-vibrators 28x are fixed to the lower surface of the main vibrating body 26x along the extending direction (X-axis direction) of the main vibrating body 26x. The three sub-vibrators 28x are the main vibrators 26x.
Are located at both ends and in the center, which are positions corresponding to the nodes of the secondary bending vibration of the main vibrating body 26x. A piezoelectric body 32x is engaged and held in the two recesses 30x formed between the three sub-vibration bodies 28x so as not to directly contact the main vibration body 26x. The piezoelectric body 32x is a laminated piezoelectric element in which a plurality of piezoelectric elements are laminated along the X-axis direction. Here, the phase when a voltage is applied to the piezoelectric body 32x is the A phase for the left piezoelectric body 32x and the right piezoelectric body 32x.
x is referred to as phase B.

Sliding members 34x mainly made of polyimide are fixed to both ends of the upper surface of the main vibrating body 26x. The X drive shaft 2x of the stage 2 can be pressed onto the sliding member 34x.

In such an ultrasonic transducer 24x,
Piezoelectric body 32x by applying a predetermined DC voltage to A phase and B phase
It is assumed that a compressive preload is applied to and then an alternating voltage having a predetermined frequency and a predetermined amplitude is applied to the A phase and the B phase. in this case,
If the A phase and the B phase have the same phase, the primary resonant longitudinal vibration is excited, and if the A phase and the B phase have opposite phases,
A secondary resonant bending vibration is excited.

On the other hand, when the phases of the A phase and the B phase are shifted by 90 degrees, the ultrasonic elliptical circular vibration 36 in which the longitudinal vibration and the bending vibration are combined can be excited in the vicinity of the sliding member 34x.
Therefore, the phase difference between the A phase and the B phase is 90 degrees (or −
90 degrees), the elliptic vibrations 36 excited near the sliding member 34x generate a thrust force that moves the X axis 2x of the stage 2 pressed against the sliding member 34x in the X direction. The moving resolution by that is possible to the order of nanometer.

The operation of the driving apparatus of the present invention will be described with reference to FIGS. 1 to 3 again. Controller 16x, 1
6y is a chip (screening chip) to be inspected (screening chip) 4a1, 4a2, 4a of all the chips 4a by an input means (not shown) such as a keyboard attached thereto.
It is assumed that the position coordinates of 3 ... (Chips filled in black in FIG. 1) have been input in advance. Further, it is assumed that the controllers 16x and 16y have been given a program of an operation sequence in advance.

First of all, the controllers 16x and 16y have a first command signal (X and Y axis sensors 14x and 1) until the photoelectric sensors 8x and 8y detect the origin sensors 14x and 14y.
(Count value from counter 20x, 20y by 4y)
Accordingly, the ultrasonic linear motors 6x, 6y are driven via the drivers 18x, 18y.

When the origin sensors 14x and 14y are detected, the relative position relationship between the scales 10x and 10y and the wafer 4 at this time is determined with the detected position as the origin.

Next, when the count values from the counters 20x and 20y coincide with the position coordinates of the screening tip, the controllers 16x and 16y cause the ultrasonic linear motors 6x and 6y to respond to the first command signal. Stop driving. This state is shown in FIG. Therefore, controller 16
x and 16y are not controlled by the concept of so-called servo or feedback, but continue to output drive signals until the count values from the counters 20x and 20y reach a predetermined value.

When the driving of the ultrasonic linear motors 6x, 6y by the first command signal is stopped, the chip to be inspected is
It is within the field of view 40 of the microscope. Where the inspector is
By the second command signal (command signal by the manual operation of the manual input device 22), the ultrasonic linear motors 6x, 16x, 16y and the drivers 18x, 18y
While driving 6y, every corner of the chip is visually inspected.

Since the moving resolution of the ultrasonic linear motors 6x and 6y, which is the driving source of the stage 2, can be of the order of nanometers, the stage 2 can be smoothly operated during visual inspection. The stage 2 can be accurately stopped at the desired position. Therefore, it is possible to perform the same inspection as that of the conventional stage that employs a high resolution and high precision mechanical element.

When the visual inspection of one screening chip 4a1 is completed, the inspector uses the above-mentioned manual switch attached to the manual input device 22 to terminate the driving by the second command signal, the controllers 16x and 16y. Tell to. Then, the controllers 16x and 16y are controlled again by the first command signal according to the program, and the X of the stage 2 is moved toward the next screening chip 4a2.
Drives the axis and Y axis. In this way, the screening inspection of the chips is sequentially continued.

When the inspection of the final screening chip is completed, the controllers 16x and 16y generate a drive signal to move the stage 2 to the origin according to the program.

Further, the size of the screening chip,
When the pitch between chips on the wafer 4 is changed and the change is an integral multiple of the scale of the chips, the position data, that is, the scale pitch given to the controllers 16x and 16y is The program showing the relational expression of the chip pitch may be replaced with a new program corresponding to the above change.

On the other hand, the size of the screening chip,
Changing the pitch between chips on the wafer 4 allows the chip to scale.
If it is not an integral multiple of the scale, scale 10a, 10b,
Replace with a new one that matches the new chip pitch. Scale
Since the rulers 10a and 10b are only fixed by the positioning pins 12x and 12y and screws, their replacement is easy.

Further, the scales 10a and 10b are several mm
Since a submillimeter order of processing accuracy is sufficient to move the corner chip into the field of view, it can be easily manufactured by a user. Therefore, the scale 1 is not highly accurate
Even if 0a and 10b are used, the inspection of the chip 4a on the wafer 4 can be sufficiently carried out, so that the production cost of the stage 2 can be considerably reduced.

The present invention is not limited to the above embodiment, but various changes and modifications can be made. For example,
The rules 10a and 10b are not limited to the reflective type, but may be the transmissive type. That is, a scale in which transparent portions and non-transmissive portions are alternately arranged in an integral multiple of the chip pitch on the wafer 4 may be used.

Also, two controllers for X-axis and Y-axis are used.
Instead of the rollers 16x and 16y, a single controller shared by the X-axis and the Y-axis may be used. In the above embodiment, the present invention is applied to the XY stage 2 that moves two-dimensionally, but the present invention is not limited to the XY stage 2 and the driven body that moves two-dimensionally or the driven body that moves one-dimensionally. It can also be applied to the body.

[0041]

As described above, according to the driving device of the present invention, the ultrasonic linear motor is adopted as the driving source,
The linear motor is driven by selectively switching between the control by the first command signal based on the drive amount detected by the detection means and the control by the second command signal based on the manual input. Therefore, a complicated control system such as servo control or feedback control is not required, and neither a highly precise and expensive servo motor nor stepping motor is required, so that the device configuration can be realized at low cost.

[Brief description of drawings]

FIG. 1 is a top view showing an XY stage of a semiconductor inspection microscope to which a driving device of the present invention is applied.

FIG. 2 is a side view of the XY stage of FIG.

FIG. 3 is a block diagram showing a control system of the XY stage of FIG.

FIG. 4 is a front view schematically showing an ultrasonic linear motor as a drive source of the XY stage of FIG.

5 is a timing chart showing the control timing of the XY stage of FIG. 1. FIG.

[Explanation of symbols]

2 ... XY stage (driven body), 4 ... Semiconductor wafer, 6
x, 6y ... Ultrasonic linear motor, 8x, 8y ... Photoelectric sensor (detection means), 10x, 10y ... Scale (detection means), 16x, 16y ... Controller (control means), 2
0x, 20y ... Counter (first command means, counting means), 22 ... Manual input device (second command means, switching means).

Claims (5)

[Claims] 1. An apparatus for driving a driven body which moves at least one-dimensionally, the ultrasonic linear motor for driving the driven body in at least one-dimensional direction, and the covered by the ultrasonic linear motor. A control means for controlling the driving of the driving body; a detecting means for detecting the driving amount of the driven body from a predetermined position; and a first command signal to the control means based on the driving amount detected by the detecting means. And a first command means for causing the control means to control the driving of the driven body by the first command signal, and a second command signal for the control means by manual input, and the second command signal A driving device comprising: a second command means for causing the control means to control the driving of the driven body; and a switching means for selectively switching between the first command signal and the second command signal to be given to the control means. 2. The drive device according to claim 1, wherein the detection means includes a scale attached to a driven body and a photoelectric sensor for reading the scale. 3. The drive device according to claim 2, wherein the scale is a reflective scale having reflective portions and non-reflective portions that are alternately arranged along the moving direction of the driven body. 4. The drive device according to claim 2, wherein a plurality of types of scales can be attached to a driven body in a replaceable manner. 5. The semiconductor wafer having chips burned thereon is mounted on a driven body, and the scale has a pitch that is an integral multiple of the pitch of the chips. Drive.