JPH05235146A - Method for conveying wafer - Google Patents

Abstract

PURPOSE:To provide a method for conveying a wafer which can accurately position the wafer without generating dusts. CONSTITUTION:The method for conveying a wafer comprises the steps of placing a wafer 1 removed from a wafer carrier 2 on a stage 4, then picking up the image of the wafer 1 by a CCD camera 6a, position-detecting the wafer 1 from the image in a rotating direction and a surface direction, and then moving a wafer conveyor 5 to a position of the wafer 1 based on a result of the detected position. Further, the wafer 1 may be positioned in its rotating direction by rotating the stage 4 based on a result of the detected position of the rotating direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer transfer method in which the position of a wafer taken out from a wafer carrier is detected and then transferred to the next apparatus by using a wafer transfer machine.

[0002]

2. Description of the Related Art A semiconductor device such as an integrated circuit formed on a wafer is manufactured through a number of manufacturing processes. In each of the manufacturing processes, a plurality of wafers, which have been subjected to the respective processes, are housed in a wafer carrier, and the wafer carriers are delivered to the next manufacturing process. In all of these manufacturing processes, since the manufacturing is performed based on the orientation flat (hereinafter referred to as the orientation flat) that indicates the crystal orientation of the wafer, the manufacturing equipment pulls out the necessary wafer from the wafer carrier and then uses the orientation flat as the reference. Need to be positioned. However, the wafers stored in the wafer carrier often have different orientation flat positions. Therefore, in the wafer transfer method in each manufacturing process, first, a required wafer is taken out from the wafer carrier, the wafer is positioned in the rotation direction and the surface direction, and then transferred to each device.

Used in such a transportation method,
A wafer positioning method will be described with reference to FIGS. FIG. 3 is a perspective view (No. 1) for explaining a conventional wafer positioning method. Guides 41 are provided on both sides of the wafer 1 so as to match the curvature of the outer periphery of the wafer 1. Wafer 1
This is for positioning in the plane direction of.

As another positioning method, FIG. 4 is a perspective view (No. 2) for explaining a conventional wafer positioning method.
Is. In this positioning method, after mounting the wafer 1 in the guide groove 44, the wafer 1 is pressed against the two guide rollers 43 by the pusher roller 42. And
By rotating the wafer 1 and bringing the orientation flat 11 of the wafer 1 into contact with the two guide rollers 43, positioning in the rotation direction and the surface direction is performed. Then, after the positioning of the wafer 1 is completed by using any of these positioning methods, the wafer 1 is transferred to the next apparatus.

[0005]

However, the wafer transfer method using these positioning methods has the following problems. That is, when the positioning method as shown in FIG. 3 is used, when the wafer 1 is sandwiched by the guides 41 from both sides, dust is generated from the wafer 1 due to contact between the end surface of the guide 41 and the side end surface of the wafer 1. Even when the positioning method shown in FIG. 4 is used, dust is generated from the wafer 1 due to the contact between the side end surface of the wafer 1 and the guide roller 43 and the pusher roller 42. This dust generation greatly affects the characteristics of the semiconductor element and the productivity such as yield. Further, in any of the wafer transfer methods using any of the positioning methods, the wafer 1 is mechanically sandwiched to perform the positioning, which is not sufficient for the wafer transfer that requires highly accurate positioning. Therefore, the present invention provides a wafer transfer method that does not generate dust and can perform highly accurate positioning.

[0006]

SUMMARY OF THE INVENTION The present invention is a wafer transfer method which has been made to solve the above problems. That is, in the wafer transfer method of transferring the wafer taken out from the wafer carrier to the next device by using the wafer transfer machine, first, the wafer taken out from the wafer carrier is mounted on the stage, and then the optical reading device is used. The image of the wafer is captured, the position of the wafer in the rotational direction and the surface direction are detected from the captured image, and then the wafer transfer machine is moved to the position of the wafer based on the result of the position detection. Further, by rotating the stage based on the result of the position detection in the rotation direction of the wafer, positioning of the wafer in the rotation direction is performed, and then based on the result of the position detection in the plane direction, the wafer carrier is moved to position the wafer. Is to move to.

[0007]

The position of the wafer can be detected in a non-contact manner by detecting the position in the rotation direction and the surface direction of the wafer from the image captured by the optical reading device. Further, by obtaining the difference between the result of this position detection and the reference position of the wafer, and controlling the wafer carrier and the stage based on this,
It is possible to always pick up a fixed position on the wafer.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A wafer transfer method of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram for explaining the wafer transfer method of the present invention. First, in explaining the wafer transfer method of the present invention, the configuration of the apparatus will be briefly described. That is, a wafer carrier 2 for accommodating a plurality of wafers 1, a wafer extractor 3 for extracting a necessary wafer 1 from the wafer carrier 2, a stage 4 for mounting the wafer 1 extracted by the wafer extractor 3, and A wafer carrier 5 for carrying the wafer 1 mounted on the stage 4 to the manufacturing apparatus is included. Furthermore, above this stage 4, a CCD
An optical reading device including a camera 6a and a CCD linear sensor 6b is provided, and these optical reading devices are connected to a controller 9 via a signal processing unit 7 and an image processing unit 8.

A wafer transfer method using these devices is as follows:
First, a wafer carrier 2 containing a plurality of wafers 1
Then, the wafer 1 to be processed is drawn out by the wafer drawing machine 3. The pull-out method is, for example, by inserting the arm 31 attached to the wafer pull-out machine 3 into the wafer carrier 2,
The desired wafer 1 is lifted and then withdrawn.
In this state, the arm 31 is moved to mount the wafer 1 on the stage 4. At this time, the position of the wafer 1 in the rotation direction,
That is, the positions of orientation flats are different, and the positions in the plane direction are also different.

Next, the wafer 1 mounted on the stage 4
From above, CCD camera 6a and CCD
It is captured by the linear sensor 6b. The CCD camera 6a captures an image of the entire area of the wafer 1, and the CCD linear sensor 6b captures signals of the x area and the y area of the wafer 1. Then, the image of the CCD camera 6a is sent to the image processing unit 8, and the signal of the CCD linear sensor 6b is sent to the signal processing unit 7. The image processing unit 8 compares the position of the orientation flat obtained from the image with the position of the orientation flat stored in advance to detect the positional deviation of the wafer 1 in the rotation direction. In addition, the signal processing unit 7
Thus, the diameter of the wafer 1 in the x-axis direction and the diameter of the wafer 1 in the y-axis direction are calculated, and the center position of the wafer 1 is detected. Then, the central position of the wafer 1 stored in advance is compared with the central position calculated from the fetch signal to detect the positional deviation of the wafer 1 in the surface direction.

Then, information about these positional deviations is sent to the controller 9, and based on this information, an operation command is sent from the controller 9 to the wafer carrier 5. For example, the picked-up position of the wafer 1 stored in advance and the rotation direction,
And an operation command obtained by adding the positional deviation information in the surface direction to the wafer carrier 5. As a result, the wafer carrier 5 can always pick up a fixed position of the wafer 1 no matter what position the wafer 1 is mounted on the stage 4. Therefore, the wafer 1 can be positioned in a non-contact manner without pressing the wafer 1 against a guide or the like.

In addition to the above-mentioned operation command, information on the positional deviation of the wafer 1 in the rotational direction is sent to the stage 4, and the stage 4 is rotated by the amount of positional deviation in the rotational direction.
There is also a method of sending only the positional deviation information in the surface direction to the wafer transfer device 5.

The wafer carrier 5, which has completed handling of the wafer 1, carries the wafer 1 to the manufacturing apparatus and sets the wafer 1 at a predetermined position. After this transportation is completed,
The controller 9 sends a command to the wafer extractor 3 to extract a new wafer 1 from the wafer carrier 2. By repeating these operations, the wafer 1 in the wafer carrier 2
Are sequentially transported.

Next, an application example of the wafer transfer method of the present invention is shown in FIG. FIG. 2 is a perspective view illustrating an application example of the present invention, showing a state in which the wafer cleaning apparatus 10 is applied.
The wafer cleaning apparatus 10 removes impurities adhering to the wafer 1 by immersing the wafer 1 in a cleaning liquid such as an organic solvent or pure water in a cleaning tank 16. It is composed of a cleaning tank unit 13, an unloader unit 14, and a control unit 15 for controlling these.
A wafer carrier 2, a wafer extractor 3, a stage 4, and a wafer carrier 5 are arranged in the loader unit 12, respectively. Further, above the stage 4, a CCD camera 6a for capturing the entire image of the wafer 1 and the wafer 1 are provided.
A CCD linear sensor 6b is provided for measuring the diameters of x in the x-axis direction and y-axis direction, respectively.

In the method of transporting the wafer 1, first, the required wafer 1 is pulled out from the wafer carrier 2 by the wafer pull-out machine 3 and mounted on the stage 4. The CCD camera 6a above the stage 4 captures the entire image of the wafer 1, and the CCD linear sensor 6b measures the diameter of the wafer 1 in the x and y directions. As a result, the positional deviation of the wafer 1 in the rotation direction and the surface direction is detected. If it is not necessary to detect the position of the wafer 1 with high accuracy, the CCD linear sensor 6b is not used. At this time, the circumference of the wafer 1 may be measured from the entire image of the CCD camera 6a, and the positional deviations in both the rotation direction and the surface direction may be detected from this. Then, this positional deviation information is sent to the wafer carrier 5 to handle the wafer 1. This wafer carrier 5
Is composed of, for example, a multi-joint robot, and the wafers 1 horizontally mounted on the stage 4 can be vertically arranged on a boat (not shown). Moreover, the orientation flats of the wafers 1 are aligned. After arranging a predetermined number of wafers 1 in this boat, the wafers are directly immersed in the cleaning liquid in the cleaning tank 16. Then, the wafers 1 arranged on the boat are delivered to the unloader unit 14.

When the wafer transfer method of the present invention is applied to the wafer cleaning apparatus as described above, a positioning mechanism for the wafer 1 due to contact is not required, so that dust generation in the wafer cleaning apparatus can be suppressed. Become. The present invention can be applied to a device other than the wafer cleaning device 10, for example, a wafer transfer to a thermal diffusion furnace or a susceptor, and a device such as a coater developer that requires suppression of dust generation and highly accurate positioning. Is a particularly effective method for

[0017]

As described above, the wafer transfer method of the present invention has the following effects. That is, since the wafer position shift is detected from the image captured by the optical reading device and the wafer carrier picks up a fixed position of the wafer based on the detection result, there is no contact between the positioning mechanism and the wafer. Therefore, the wafer can be transferred without causing dusting due to positioning. Further, since the wafer transfer machine is controlled based on the detection result of the positional deviation by the optical reading device, it is possible to carry out the transfer with higher accuracy as compared with the wafer transfer method using the mechanical positioning method.

[Brief description of drawings]

FIG. 1 is a schematic diagram illustrating a wafer transfer method of the present invention.

FIG. 2 is a perspective view illustrating an application example of the present invention.

FIG. 3 is a perspective view (No. 1) for explaining a conventional wafer positioning method.

FIG. 4 is a perspective view (No. 2) for explaining a conventional wafer positioning method.

[Explanation of symbols]

 1 Wafer 2 Wafer Carrier 3 Wafer Drawer 4 Stage 5 Wafer Transfer Machine 6a CCD Camera 6b CCD Linear Sensor 7 Signal Processing Unit 8 Image Processing Unit 9 Controller

Claims (2)

[Claims] 1. A wafer transfer method for transferring a wafer taken out of a wafer carrier to a next apparatus by using a wafer transfer machine, wherein first, the wafer taken out of the wafer carrier is mounted on a stage, and an image of the wafer is displayed. An optical reading device is used to detect the position of the wafer in the rotation direction and the surface direction from the image, and then move the wafer carrier to the position of the wafer based on the result of the position detection. Wafer transfer method. 2. The position of the wafer in the rotation direction is determined by rotating the stage based on the result of the position detection of the wafer in the rotation direction. 2. The wafer transfer method according to claim 1, wherein the wafer transfer device is moved to the position of the wafer based on the above.