JPH04290456A - Positioning method for wafer - Google Patents

Abstract

PURPOSE:To provide a wafer positioning apparatus and a method which carries out the positioning of a wafer having a plurality of orientation flats with reference to a particular orientation flat. CONSTITUTION:A wafer positioning method for realizing positioning with reference to a particular orientation flat 9a of a plurality of orientation flats 9a provided on a wafer detects the position of a particular orientation flat 9a of a plurality of flats 9a using a wafer positioning apparatus, obtains the center of this orientation flat 9a and carries out positioning of the wafer with reference to this center.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a wafer positioning method. A circular wafer is provided with an orientation flat (hereinafter abbreviated as OF) for positioning, and the wafer is positioned based on this OF, but in recent years wafers with two OFs perpendicular to each other are When positioning the
It has become difficult to position the wafer using a specific OF of the two OFs as a reference.

Under the above circumstances, there is a need for a wafer positioning device and a positioning method that can position a wafer based on a specific OF among a plurality of OFs.

0003

2. Description of the Related Art A schematic structure of a mechanism of a wafer positioning apparatus will be explained in detail with reference to FIG. 2, a schematic structure of a wafer positioning apparatus will be explained with reference to FIG. 3, and a conventional wafer positioning method will be explained in detail with reference to FIG.

FIG. 2 is a diagram showing a schematic structure of a mechanism of a wafer positioning device, FIG. 3 is a diagram showing a schematic structure of a wafer positioning device, and FIG. 4 is a diagram illustrating a conventional wafer positioning method.

As shown in FIG. 2, the wafer positioning device mounts a wafer 19 on the surface of a rotary stage 7 rotated by a servo motor 6, with the center of the rotary stage 7 aligned with the center of the rotary stage 7, and rotates the wafer 19 once. It looks like this.

As shown in FIG. 3, the schematic configuration of the wafer positioning device is as follows. The servo motor 6 is rotated.

Wafer 19 above this rotation stage 7
A photosensor 1 is provided at the edge of the sensor 1, and a counter 3 is provided to count the number of pulses at the time when the photosensor 1 starts detecting OF19a and the number of pulses at the time when the photosensor 1 detects that OF19a is no longer present. ing.

To position the wafer 19 using the wafer positioning device having such a configuration, first, the photo sensor 1 detects the OF 19a while the servo motor 6 rotates once in the direction shown by the arrow in FIG. When it started (1
The number of pulses in 1) is counted by the counter 3, and then the number of pulses at the time when the photosensor 1 detects that OF19a is gone (12) is counted, and the average count number of these two counts (13) is calculated. seek.

Next, when the servo motor 6 is rotated in the opposite direction to the position corresponding to this average count number, the center of the OF 19a can be positioned, and the wafer 19 can be positioned with the OF 19a as a reference.

0010

[Problems to be Solved by the Invention] In the conventional wafer positioning method described above, when positioning a wafer having a plurality of OFs, the wafer is positioned based on the OF first detected by the photosensor. Therefore, there was a problem in that the position of the wafers varied.

[0011] In view of the above-mentioned situation, the present invention
It is an object of the present invention to provide a wafer positioning device and a positioning method that enable positioning of a wafer having an OF using a specific OF as a reference.

0012

[Means for Solving the Problems] The wafer positioning method of the present invention includes a photosensor that monitors the presence or absence of an orientation flat provided on a wafer, a servo motor that rotates a rotation stage on which the wafer is mounted, and a servo motor that rotates the rotation stage on which the wafer is mounted. A driver that drives the motor, a pulse oscillator that gives predetermined pulses to this driver, a counter that counts the number of pulses detected by this photo sensor, and a pulse number calculated from this number of pulses that is transmitted to this driver to control the servo. An encoder that drives the motor,
This is a wafer positioning method performed using a wafer positioning device equipped with a central control unit that instructs the pulse oscillator to output pulses and counts activation/deactivation of the photosensor for each pulse. A pulse oscillator is driven by a pulse output instruction, and this pulse oscillator is used to drive a driver to rotate a servo motor to rotate this rotation stage once, and this photo sensor counts the position of the orientation flat in pulse units with a counter. Among the counts of the orientation flats, the central control unit calculates the average of the counts of the desired orientation flat, and by matching the position of this average value with a predetermined position, the desired orientation flat is set. The configuration is such that the wafer is positioned as a reference.

[0013]

[Operation] That is, in the present invention, a pulse oscillator is driven by a pulse output instruction from the central control unit, and this pulse oscillator is used to drive a driver to rotate a servo motor to rotate the rotary stage once, and the photo sensor The position of the orientation flat is counted in pulse units by a counter, the central control unit calculates the average of the counts of the desired orientation flat among the counts of the orientation flat, and the position of this average value is set at a predetermined position. By matching the desired orientation flat, it becomes possible to position the wafer using this desired orientation flat as a reference.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to FIGS. 1 to 3. FIG. 1 is a diagram for explaining a wafer positioning method according to an embodiment of the present invention, FIG. 2 is a diagram showing a schematic structure of a mechanism of a wafer positioning device, and FIG. 3 is a diagram showing a schematic structure of a wafer positioning device.

The schematic structure of the mechanism of the wafer positioning device used in the wafer positioning method of the present invention is the device shown in FIG. 2 used in the conventional wafer positioning method. Although the apparatus having the configuration shown in FIG. 3 is used in the positioning method, since the present invention targets a wafer 9 having a plurality of OF9a, the wafer 9 having a plurality of OF9a
The software used in the central control unit (hereinafter abbreviated as CPU) 2 of the wafer positioning apparatus shown in FIG. Since a function is added to determine the magnitude of the number of pulses, it is possible to position the wafer 9 based on the OF 9a having a predetermined number of pulses.

When positioning is performed using the large OF 9a as a reference using the wafer positioning device having such a configuration, as shown in FIG. Then, count the number of pulses at the time point (2) when the photosensor 1 starts detecting the first OF9a, then count the number of pulses at the time point (2) when the photosensor 1 detects that the first OF9a is gone, Furthermore, the number of pulses at the time point (2) when the detection of the second OF9a starts is counted, and then the number of pulses at the time point (2) when the photosensor 1 detects that the second OF9a is gone is counted.

[0017] Find the difference between the two counts, the count number of ■ and the count number of ■, and then find the difference between the two counts, the count number of ■ and the count number of The CPU 2 determines whether the

[0018] In this case, since the difference between the two counts, the count number of ■ and the count number of ■, is larger, the average ■ of the count number of ■ and the count number of ■ is calculated, and the position of this ■ By adjusting the OF9a to a predetermined position, positioning can be performed using the larger OF9a as a reference.

[0019]

[Effects of the Invention] As is clear from the above explanation, according to the present invention, by extremely simple modification of the software used in the CPU, it is possible to position a wafer having a plurality of OFS using a desired OF as a reference. It is possible to provide a wafer positioning method that is advantageous and can be expected to be significantly economical and improve reliability.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating a wafer positioning method according to an embodiment of the present invention;

[Fig. 2] A diagram showing the schematic structure of the mechanism of the wafer positioning device,

[Fig. 3] A diagram showing a schematic configuration of a wafer positioning device,

[Fig. 4] A diagram illustrating a conventional wafer positioning method,

[Explanation of symbols]

1 is a photo sensor, 2 is the CPU, 3 is a counter, 4 is a pulse oscillator, 5 is the driver, 6 is a servo motor, 7 is a rotating stage, 8 is an encoder, 9 is a wafer, 9a is OF,

Claims (1)

[Claims] 1. A photo sensor (1) that monitors the presence or absence of an orientation flat (9a) provided on a wafer (9), and a servo motor (1) that rotates a rotation stage (7) on which the wafer (9) is mounted. 6
) and a driver (
5), a pulse oscillator (4) that provides a predetermined pulse to the driver (5), and a counter (3) that counts the number of pulses detected by the photosensor (1);
The number of pulses calculated from the number of pulses is applied to the driver (5
) to drive the servo motor (6); and an encoder (8) that instructs the pulse oscillator (4) to output pulses and outputs pulses to the photo sensor (1) for each pulse.
Central control unit (2) that counts activation and inactivation of
A wafer positioning method performed using a wafer positioning device comprising:
) drives the pulse oscillator (4) according to the pulse output instruction, and uses the pulse oscillator (4) to drive the driver (5).
The servo motor (6) is driven to rotate the rotation stage (7) once, and the photo sensor (1) is rotated.
), the position of the orientation flat (9a) is counted in pulse units by a counter (3), and the average of the counts of a desired orientation flat (9a) among the counts of the orientation flat (9a) is calculated by the central control unit. (2) and by matching the position of this average value with a predetermined position, the desired orientation flat (9
a) A wafer positioning method characterized by positioning a wafer (9) using the following as a reference.