JPH09213771A - Wafer direction setter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To orient the wafer supported on a suction pad in a prescribed direction of crystallization while removing the pollution of the wafer, with simple configuration. SOLUTION: This device has a suction pad 1 which sucks and supports a roughly disclike wafer 3 having a cut for positioning at the periphery and is driven with a drive motor 2, and a laser beam transmitter 4 and a laser beam receiver 5 arranged to catch the region of the periphery or its vicinity of a wafer 2, and a sequencer 6 obtained by the operation of the positional data corresponding to the above cut, based on the output of light reception of the laser beam receiver 5. According to the operation result, an encoder 7 controls the stop position of the drive motor 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer orientation setting device for aligning a crystallographic direction of a wafer in a fixed direction to perform processing.

[0002]

2. Description of the Related Art In the production process of silicon wafers, it is sometimes necessary to orient the silicon crystal in a fixed direction. Therefore, conventionally, when a wafer is produced, a smooth notch surface called an orientation flat is provided on the outer periphery, or V notches or small holes which are V-shaped notches are formed to form these notch surfaces, V notches, and small holes. The silicon crystal direction is used as a reference.

When processing such wafers one by one, each wafer is held by a suction pad,
It is necessary to gently rotate the suction pad, detect whether the orientation flat, V-notch, or small hole that serves as the reference is on the wafer, and stop the suction pad at a fixed position (angle).

Therefore, hitherto, a sensor is mechanically brought into contact with the outer periphery of the wafer to gently rotate the wafer from an arbitrary position, and the sensor output detects a position such as the orientation flat or V notch. Judging this as the predetermined crystallographic direction of the wafer during the above processing,
It enables processing and processing.

[0005]

However, in such a conventional wafer orientation setting method, the sensor itself comes into direct mechanical contact with the outer peripheral edge of the wafer, so that the wafer itself is contaminated by the dirt attached to the sensor. Therefore, it is necessary to completely clean the dirt attached to the sensor before positioning the wafer, which complicates the work process and the system and increases the cost of the entire system. There were challenges. Further, if there is misalignment, it is impossible to detect it, and it is necessary to install a centering mechanism in the device.

The present invention has been made in order to solve the above-mentioned conventional problems, and it is supported on a suction pad during processing while eliminating contamination of the wafer due to mechanical contact of a conventional sensor. It is an object of the present invention to provide a wafer orientation setting device capable of aligning a wafer in a predetermined crystal orientation and realizing this with a simple configuration.

[0007]

According to a first aspect of the present invention, there is provided a wafer orientation setting device for adsorbing and supporting a substantially disk-shaped wafer having a notch for positioning on its periphery and rotating the wafer by a drive motor. Based on a pad, a laser light transmitter and a laser light receiver arranged so as to sandwich a region near the outer periphery of the wafer on the suction pad, and a light reception output of the laser light receiver according to the amount of passing light of the laser light. A sequencer for calculating position data corresponding to the cutout is provided, and the stop position of the drive motor is controlled according to the calculation result by the sequencer.

Further, in the wafer direction setting device according to the invention of claim 2, when the notch is a V notch or a small hole in the sequencer, the amount of light passing through the laser beam at a set angle due to the rotation of the wafer and a minute amount. The absolute value of the difference from the passing light amount at the time of the next cycle after a fixed time is obtained, and the position where this absolute value is maximum is controlled as the position data corresponding to the V notch or the small hole to control the motor. It was done.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a conceptual diagram showing a wafer orientation setting device of the present invention. In FIG. 1, reference numeral 1 denotes a suction pad which is rotationally driven by a drive motor 2, and a wafer at a prepositioned position on the suction pad 1. 3 can be held by suction.

The wafer 3 is provided with an orientation flat or V so that the crystal direction of silicon is displayed.
Notches such as notches and small holes are formed at the production stage.

Reference numerals 4 and 5 are a laser light transmitter and a laser light receiver, respectively, which are the above-mentioned suction pad 1
The upper wafer 3 is arranged so as to be sandwiched from above and below around the outer periphery thereof with a predetermined interval.

Further, 6 is a sequencer, which is an orientation flat of the wafer 3 or a V notch,
A signal obtained by voltage-converting the amount of passing light from the laser light transmitter 4 which changes according to the small hole by the laser light receiver 5 is quantized into a digital signal through an analog / digital converter (not shown), and this digital signal is quantized. Process
The amount of passing light corresponding to the position data corresponding to the cutout is stored.

Reference numeral 7 denotes an encoder for controlling the drive motor 2 for stopping and controlling the rotation of the drive motor with a rotation amount according to the result of position data calculation by the sequencer 6.

Next, the operation will be described. First, when the notch provided on the wafer 3 is an orientation flat 3a formed on the outer periphery as shown in FIG. 2, the wafer 3 captured by the suction pad 1 is placed on the bonding surface thereof. Then, the laser light is radiated from the laser light transmitter 4 to a predetermined area (a fixed area) near the outer periphery of the wafer 3 by gently rotating the wafer.

Therefore, a part of the irradiated laser light is blocked by the outer periphery of the wafer 3, and the other laser light reaches the laser light receiver 5.

That is, the amount of laser light passing through the arc portion 3b of the wafer 3 is constant, while the amount of laser light passing through the orientation flat 3a gradually increases and gradually as the wafer 3 rotates. Decrease.

Therefore, the laser light receiver 5 outputs a voltage signal corresponding to the passing light amount which changes in this way, and the sequencer outputs the maximum passing light amount when the wafer 3 makes one rotation based on the voltage signal. Then, the position at which the voltage signal reaches the maximum level is obtained and stored.

Next, the encoder 7 rotates the drive motor 2 to that position and stops it according to the stored position. That is, all the wafers 3 have the silicon crystal directions aligned on the adsorption pad 1 in a certain direction, and the predetermined process in the wafer manufacturing process is performed in that direction.

On the other hand, when the notch provided on the outer periphery of the wafer 3 is a V notch (or a small hole (not shown)) 3c as shown in FIG. 3, as in the case of the orientation flat 3a, the laser is used. The amount of passing light that can be detected by the laser light receiver 5 does not have a pattern of gradually increasing and decreasing.

Therefore, in this case, the sequencer 6
The position detection calculation is performed according to the predetermined program in.

That is, in this sequencer 6, first,
Let Vn be the amount of light (digital amount) of the laser light passing through the wafer 3 at a certain rotation angle, and let Vn + 1 be the amount of light (digital amount) in the next cycle after a minute fixed time has elapsed. Is calculated by the following equation,
This is stored.

[0022]

[Equation 1]

That is, the V notch 3 is located at a position where the absolute value of the difference in the amount of light passing through the wafer 3 when the wafer 3 makes one revolution becomes maximum.
Since there are c and small holes, the position is memorized. Then, according to the stored position, the encoder 7 rotates the drive motor 2 to that position and stops it.

In this way, all the wafers 3 adsorbed on the adsorption pad 1 have their silicon crystal directions aligned in a fixed direction, and according to this orientation, each wafer 3 adsorbed on this adsorption pad 1 Predetermined processing can be added.

The diameter of the wafer 3 is, for example, 8 inches, the rotation speed of the wafer 3 is 8 sec / 1 rotation, the calculation interval (sampling interval) is 10 msec, and the V notch 3 is formed.
When one side of c is 2 mm, the above calculation is performed twice between the V notches 3c.

[0026]

As described above, according to the first aspect of the present invention, a suction pad that sucks and supports a substantially disk-shaped wafer having a positioning notch on the periphery and that is rotated by a drive motor is provided. Laser light transmitter and laser light receiver arranged so as to sandwich the area on the suction pad near the outer periphery of the wafer, and the above notch is supported based on the received light output of the laser light receiver according to the amount of passing light of the laser light. Since the encoder is configured to control the stop position of the drive motor in accordance with the calculation result of the sequencer, the wafer can be detected by the conventional mechanical contact sensor. While eliminating contamination, the wafer supported on the suction pad can be aligned in a predetermined crystallographic direction during processing.
There is an effect that it is possible to realize this easily and at low cost with a simple configuration.

According to the invention of claim 2, in the sequencer, when the notch is a V notch or a small hole,
The absolute value of the difference between the passing light amount of the laser light at the set angle due to the rotation of the wafer and the passing light amount in the next cycle after a minute fixed time is obtained, and the position where this absolute value becomes maximum is the V notch. Alternatively, since the position data corresponding to the small hole is output to the encoder, regardless of the size of the wafer, the V notch, and the size of the small hole, the calculation processing of the passing light amount under the predetermined program processing is performed. The effect that the detection and setting of the wafer direction can be realized accurately is obtained.

Further, according to the second aspect of the present invention, even if there is a misalignment, the orientation flat, the V notch, etc. can be detected, so that a device having a centering function is unnecessary and the cost for constructing the device is low. Since no centering is required, the movement (tact time) is faster and therefore the throughput is increased.
Of course, since it is a non-contact type, it does not stain the wafer.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a wafer orientation setting device according to an embodiment of the present invention.

FIG. 2 is a plan view showing an example of a wafer.

FIG. 3 is a plan view showing another wafer.

[Explanation of symbols]

 1 Adsorption Pad 2 Drive Motor 3 Wafer 4 Laser Light Transmitter 5 Laser Light Receiver 6 Sequence 7 Encoder

Claims (2)

[Claims] 1. A substantially disk-shaped wafer having a notch for positioning on its periphery is suction-supported, and a suction pad rotated by a drive motor and an area near the outer periphery of the wafer on the suction pad are sandwiched. A laser light transmitter and a laser light receiver that are arranged, a sequencer that calculates position data corresponding to the notch based on the received light output of the laser light receiver according to the amount of passing light of the laser light, and the sequencer. A wafer orientation setting device comprising: an encoder that controls a stop position of the drive motor according to a calculation result. 2. The sequencer, when the notch is a V notch or a small hole, sets the amount of laser light passing through the wafer at a set angle by the rotation of the wafer and the amount of passing light in the next cycle after a minute fixed time. 2. The wafer orientation setting apparatus according to claim 1, wherein the motor is controlled by obtaining an absolute value of a difference between the two, and using the position where the absolute value becomes maximum as position data corresponding to the V notch or the small hole. .