JPS63155634A - Alignment of wafer - Google Patents

Abstract

PURPOSE:To shorten the time required to position a wafer by a method wherein the wafer is positioned during the period to transfer the wafer from an accommodation case to a wafer chuck. CONSTITUTION:A wafer 14 on a transfer wafer-chuck 2 leaves an accommodation case 1 and rolls toward the direction A. When an orientation flat OF formed of the wafer 14 becomes in parallel with the transfer direction A during this transfer period, a sensor 3 detects this situation and stops a turning operation of the chuck 2 for turning the wafer. Because the positioning accuracy is not high in this case, the wafer 14 is turned a little at a position B for correction of the positioning discrepancy by a correction sensor 5. Then, the wafer 14 is sucked by an arm 4 and is transferred to a wafer chuck 6.

Description

[Detailed Description of the Invention] [Summary] When positioning a circular wafer having a handle, the wafer is positioned during the period of movement from the wafer storage case to the wafer chuck, thereby reducing the time required for positioning. Wafer alignment method made possible.

[Industrial application field]

The present invention relates to a positioning method, and more particularly to an improved method for positioning a circular wafer having a handle, such as a wafer forming a semiconductor device.

In the manufacturing process of semiconductor devices, the wafer to be processed has a handle called an orientation flat, and the wafer is positioned using this as a reference. An alignment method is desired.

[Conventional technology]

In the conventional wafer alignment method, wafer alignment is performed using a positioning mechanism having a structure as shown in FIGS. 4 to 6.

The mechanism shown in FIG. 4 takes out a wafer 14 from a wafer storage case 1 by a transport mechanism 20 using a belt or the like, transports it to an intermediate stage 21 for positioning, and aligns the wafer on this intermediate stage 21. Is going.

Positioning in this case involves installing a set of two detection sensors 22 on the intermediate stage 21 at fixed positions on the orientation flat of the wafer 14, rotating the wafer 14 at a very low speed, and rotating the wafer 14 at a very low speed. When the wafers are operated at the same time, they stop rotating and perform wafer alignment. Wafer 14 positioned at a fixed position
is transported to the wafer chuck 6 by the transport arm 19.

The mechanism shown in FIG. 5 has substantially the same way of taking out and transporting the wafer 14, but the method of aligning the wafer on the intermediate stage 21 is different.

In this case, a detection sensor 23 similar to that shown in FIG. 4 is provided, and after the wafer 14 is rotated once at high speed to detect the position of the orientation flat, the position is memorized and the second Rotate the wafer 14 to that position
The wafer is aligned using three positioning rollers 24 and a punch 25, as shown in FIG.

[Problem that the invention seeks to solve]

The problem with the conventional wafer alignment method described above is that in the case of FIG. 4, the rotation is stopped at the same time as the orientation flat is detected by the detection sensor 22.
In order to align the wafer, the wafer must be rotated at a very low speed, which takes time, and in the case of Figure 5, the final positioning is done mechanically, so the required Although the time is short, the precision is not good, and the wafer alignment is performed using rollers and punches, which can cause damage to the wafer.

The present invention aims to provide a wafer alignment method that can be performed easily and inexpensively in view of the above-mentioned circumstances.

[Means for solving problems]

The above problems are solved by the wafer alignment method according to the present invention, which positions the wafer during the movement period from the wafer storage case to the wafer chuck.

[Effect]

That is, in the present invention, the orientation flat is detected by the sensor without rotating the wafer while the wafer is taken out from the storage case and transported, and the wafer is positioned. Therefore, the wafer can be aligned in a short time. It becomes possible.

〔Example〕

One embodiment and other embodiments of the present invention will be described below with reference to FIGS. 1 to 3.

In FIG. 1, the wafer 14 taken out from the storage case 1 by being placed on the transport wafer chuck 2 is moving while rotating in the direction A shown in the figure.

The sensor 3 provided on a line parallel to this moving direction is the second
As shown in the figure, there are 3b which is shielded by the wafer 14 when the orientation flat is parallel to the moving direction, and 3a which is shielded only by the circular arc portion of the wafer 14, and the state shown by the dotted line in Figure 1. Ya second
When the state shown on the right side of the figure is reached, the two adjacent sensors 3a are not shielded and only sensor 3b is shielded, so the rotation of the transfer wafer chuck 2 is stopped and the orientation flat is set in the next process. It rotates 90 degrees counterclockwise according to the position, continues moving in direction A, and stops at position B as shown in the figure.

In this case, the positioning accuracy is not high, so after rotating the wafer 14 a little at position B and correcting the positional deviation using the correction sensor 5, the wafer 14 is sucked by the arm 4.
Highly accurate positioning is performed as shown by the solid line in the figure.

The wafer 14 is transferred onto the wafer chuck 6 by the arm 4 which has adsorbed the wafer 14 which has been positioned by the correction sensor 5 .

When the wafer 14 is transferred between the arm 4 and the wafer chuck 6, the transfer table 6a rises to pick up the wafer 14, and at the same time the arm 4
The vacuum is cut off and arm 4 is retracted. Then, the transfer table 6a lowers and the wafer 14 is attracted to the wafer chuck 6.

In another embodiment shown in FIG. 3, the wafer 14 in the storage case 1 is attracted onto the slightly elevated transport stage 7 and pulled out to position C, where the handler 8 waits at this position. It is inserted in the state shown in FIG. 3(b).

The handler 8 is provided with a detection sensor 10, which rotates clockwise as shown in the figure, and when an orientation flat is detected, the rotation is slowed down to detect the orientation flat with high accuracy.

The rotation angle to this detection position is stored, the transfer stage 7 is lowered, and the wafer 14 is attracted to the handler 8.

The handler 8 rotates counterclockwise by an angle equal to 906 plus the angle to the above-mentioned detection position to bring the wafer 14 to position D as shown in the diagram, and at the same time, the transfer arm 9 rotates to the right and the wafer 14 is rotated counterclockwise. It stops right above the wafer chuck 6 at position D. This position is the transfer arm 9
It is defined by the detection sensor 11 at the position of .

In this case, the position of the orientation flat of the wafer 14 remains unchanged by rotating the handler 8 in the opposite direction by the motor (B) 13 by the rotation angle of the motor (A) 12 that rotates the transfer arm 9.

The center of the wafer chuck 6 is a transfer table 6a, and after receiving the wafer 14 by raising it by the thickness of the part of the handler 8 that supports the wafer 14, the transfer arm 9 is retracted and the transfer table 6a is moved upward. The transfer table 6a is lowered to its original position and the wafer 14 is sucked onto the wafer chuck 6.

According to the wafer alignment method according to the present invention, the wafer 14 is positioned based on the orientation flat while the wafer 14 is taken out from the storage case 1 and adsorbed to the wafer chuck 6, making effective use of the movement period. , it becomes possible to perform highly accurate alignment of the wafer 14 in a short time.

〔Effect of the invention〕

As explained above, according to the present invention, by using a positioning mechanism with an extremely simple structure, the wafer can be positioned in a short time using the orientation flat while the wafer is being transferred from the storage case to the wafer chuck. As a result, the time required for handling wafers in the semiconductor device manufacturing process can be shortened, and the wafer can be transported after holding the wafer and performing alignment, resulting in significant economic and reliability improvements. It is expected to have the effect of improving properties and is extremely useful industrially.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing one embodiment of the present invention, FIG. 2 is a detailed view showing the operating status of the sensor of one embodiment of the present invention, and FIG. 3 is a diagram showing another embodiment of the present invention. Fig. 4 is a plan view showing an alignment method using only a conventional detection sensor, Fig. 5 is a plan view showing an alignment method using a conventional detection sensor and a mechanical method, and Fig. 6 is a plan view showing an alignment method using a conventional detection sensor and a mechanical method. FIG. 2 is a detailed diagram showing the alignment method. In the figure, 1 is a storage case, 2 is a transport wafer chuck, 3 is a sensor, 4 is an arm, 5 is a correction sensor, 6 is a wafer chuck, 6a is a transfer table, 7 is a transport stage, 8 is a handler, 9 is a A transfer arm; 10 is a detection sensor; 11 is a detection sensor; 12 is a motor (A); 13 is a motor (B); 14 is a wafer. FIG. 1 is a plan view showing one embodiment of the present invention. FIG. 2 is a detailed view showing the operating status of the sensor. Fig. 4 A plan view showing the alignment method. Detailed diagram showing the alignment method according to Fig. 6

Claims (1)

[Claims] When positioning a circular wafer with a handle,
From the wafer storage case (1) to the wafer chuck (6)
) A wafer alignment method characterized in that the wafer (14) is positioned during the movement period up to ).