JPH10175733A - Wafer transfer mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To confirm presence or absence of a wafer and confirm also the location by detecting weight when the wafer is mounted on a holder. SOLUTION: Before a wafer 1 is mounted on a holder 22, a plate spring 23 is mounted on the holder 22 and a distortion guage 24 is stuck to this plate spring 23. The tip of the plate spring 23 is made to have a structure that the tip slightly springs out from the upper surface of the holder 22. If the wafer 1 is placed on the holder 22, the lower surface of the wafer 1 and the plate spring 23 come into contact with each other. If the plate spring 23 is made to have a dimension to sufficiently perform deformation by weight of the wafer 1, distortion amount due to the deformation can be detected by a distortion gauge 24. Thus, presence or absence of the wafer 1 on a wafer carrier mechanism can be confirmed and also a prescribed location of the wafer can be confirmed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer mechanism for transferring a wafer, and more particularly to the measurement of the presence or absence of a wafer being transferred and the position of a predetermined position of the wafer on a transfer holder.

[0002]

2. Description of the Related Art A semiconductor device represented by a DRAM is manufactured by a plurality of processes such as CVD and etching. In these semiconductor manufacturing processes, a wafer is processed in a reaction chamber in a vacuum environment. When performing this process, a wafer transfer mechanism for transferring a wafer from the atmosphere into a vacuum reaction chamber is required. In recent semiconductor manufacturing apparatuses, single-wafer apparatuses have been increasing. In these apparatuses, wafers are put into a reaction chamber one by one each time the processing is performed, and are unloaded when the processing is completed.

FIG. 5 shows a transfer mechanism for transferring a wafer. The wafer 1 is placed on the holder 2, and a transfer mechanism for transferring the wafer includes arms 3 and 4. The arm 4 is rotatable around a central axis 6 of the vacuum flange 5, and the arm 3 is rotatable around a central axis 7 at the other end of the arm 4. Further, the holder 2 has a structure capable of rotating about a rotation shaft 8 on the arm 3. By driving the rotation shaft 6 from outside the vacuum, rotation around the central axis 6 of the wafer and linear movement in the radial direction are performed. A motor 9 for rotating and driving the arm 4 is attached to the vacuum flange 5.

FIG. 6 shows a method of transferring a wafer 1 in a multi-chamber apparatus, showing a state where a wafer is transferred from a chamber 10 to a chamber 11. The transfer is performed by the following operation.

(1) The rotation of the transport mechanism 12 causes the holder 2
Is directed to the chamber 10 (FIG. 6A).

(2) The holder 2 is put into the chamber 10 by the linear movement of the transport mechanism indicated by the arrow 13 (FIG. 6B).

(3) The wafer 1 is transferred from the table of the chamber 10 onto the holder 2. (4) The holder 2 on which the wafer 1 is placed is taken out of the chamber 10 by the rectilinear movement of the transfer mechanism 12 retreating with the arrow 14 (FIG. 6C).

(5) The holder 2 on which the wafer 1 is mounted is rotated by the rotation of the transfer mechanism 12 to the left as indicated by the arrow 15 in FIG.
(FIG. 6D).

(6) The holder 2 on which the wafer 1 is mounted is moved in the chamber 11 by the linear
(FIG. 6 (e)).

(7) The wafer 1 on the holder 2 is transferred onto a table in the chamber 11. (8) The holder 12 is taken out of the chamber 11 by the rectilinear movement of the transport mechanism 12 in the direction of the arrow 17 (FIG. 6F).

By repeating this series of operations,
The wafer can be transferred from any chamber attached to the periphery of the transfer chamber to the chamber.

In this wafer transfer mechanism, confirmation of the mounting state of the wafer is an important requirement. These semiconductor manufacturing apparatuses operate unattended, and it is necessary to check the presence or absence of a wafer on a transfer mechanism and correctly mount the wafer on a sample table in a reaction chamber. Therefore, a wafer monitor as shown in FIG. 7 is attached to the conventional transfer mechanism. Light-emitting source 19 with wafer 1 on wafer holder 2 mounted above and below it
And the light received by the light receiver 20, the light 2
If the wafer 1 is blocked by the wafer 1, the light 21 does not reach the light receiver 20, and it is confirmed that the wafer exists on the holder 2. Japanese Patent Application Laid-Open No. 62-21649 discloses a structure in which this mechanism is mounted on a wafer holder of a wafer vertical mechanism, instead of a wafer transfer system, to detect a wafer.

[0013]

However, the mechanism for confirming the presence or absence of a wafer with an optical sensor that blocks light is a large structure that matches the shape of the optical sensor. Further, the environment in which this transport mechanism is used is vacuum. An optical sensor emits a large amount of gas in a vacuum due to its complicated shape. For this reason, the vacuum exhaust system of the transfer chamber in which the transfer mechanism is housed must increase its exhaust capacity, exhaust gas released from the optical sensor, and lower the ultimate pressure to a predetermined value. In order to provide a large-capacity evacuation capacity to the vacuum evacuation system, a pump having a large evacuation capacity was required, and the evacuation system was expensive.

When a wafer is placed on a sample table in a reaction chamber, it must be positioned at a predetermined position with an accuracy of about ± 1 mm. For this purpose, it is necessary to confirm the position of the wafer to determine whether or not the wafer is at a predetermined position on the holder of the transfer system that carries the wafer.

It is an object of the present invention to provide a small detector capable of confirming the presence or absence of a wafer and further confirming the position of the wafer by focusing on this problem.

[0016]

According to the present invention, in order to solve the above-mentioned problems, the weight of a wafer mounted on a holder is detected, and its presence and position are determined. The weight is detected by detecting the amount of distortion with a strain gauge attached to a leaf spring disposed on the holder. Also, by attaching a strain gauge directly to the holder, the weight of the wafer placed on the holder is detected. Furthermore, the position of the wafer is detected by attaching a plurality of leaf springs.

[0017]

FIG. 1 shows the shape of a holder of a wafer transfer mechanism according to the present invention. Wafer 1 is holder 22
This shows the situation before being mounted on top. A leaf spring 23 is attached to the holder 22. A strain gauge 24 is attached to the leaf spring 23, and the tip of the leaf spring slightly protrudes from the upper surface of the holder 23.

When the wafer 1 is placed on the holder 22, the lower surface of the wafer 1 comes into contact with the leaf spring 23. At this time, if the size of the leaf spring 23 is set to be sufficiently deformed by the weight of the wafer 1, the amount can be detected by the strain gauge 24 by the deformation. The shape of the leaf spring deformed by the wafer may be, for example, a length of 10 mm, a thickness of 0.1 mm, and a width of 4 mm in order to obtain a leaf spring having a deformation of 1 mm under a load of 10 g. Since the weight of the 8-inch wafer is 200 g, the structure can be sufficiently measured. By employing this structure, the presence or absence of a wafer on the holder can be confirmed.

FIG. 2 shows another embodiment. The situation before the wafer 1 is mounted on the holder 25 is shown. Holder 2
5 has a strain gauge 24 attached to the root thereof, and has a structure in which the presence or absence of the wafer 1 can be detected by the amount of deformation of the holder 25. At this time, strain gauge 24
Is located near the rotation center 26 of the holder 25 which is highly sensitive to the mounting of the wafer. Holder 25
Has a structure that is rotatably coupled to the arm 27 at the rotation center 26.

FIG. 3 shows another embodiment. The state before the wafer 1 is mounted on the holder 28 is shown. Holder 2
In FIG. 8, a leaf spring 29 and a strain gauge 30 attached thereto are arranged at three places. When the wafer 1 is placed on the center position of the holder 28 which is a predetermined position, the wafer 1 hits each leaf spring 29, but when the wafer 1 is biased and placed on the holder 28, one of the leaf springs 29 Alternatively, the wafer 1 does not contact the two leaf springs 29.

This situation will be described with reference to FIG. FIG.
(A) shows a state where the wafer is correctly placed at the center of the holder 28. The wafer 1 is placed equally on the three leaf springs 29. FIG. 4B shows a state where the wafer is not placed at a predetermined position. That is, the wafer is in contact with two of the three leaf springs 29. For this reason, the strain gauge 30 of the leaf spring 29 that does not contact the wafer 1
No signal is output, indicating that the wafer 1 is not at a predetermined position. If this happens, stop the device immediately,
The position of the wafer 1 can be corrected to a correct position.

[0022]

According to the present invention, the presence / absence of a wafer on the wafer transfer mechanism can be confirmed and the wafer at a predetermined position can be confirmed. This can prevent the wafer from being damaged by the transfer.

[Brief description of the drawings]

FIG. 1 is a perspective view of a wafer holding unit according to an embodiment of the present invention.

FIG. 2 is a perspective view of a wafer holding unit showing one embodiment of the present invention.

FIG. 3 is a perspective view of a wafer holding unit showing one embodiment of the present invention.

FIG. 4 is a plan view of a wafer holding unit showing an operation of one embodiment of the present invention.

FIG. 5 is a perspective view showing a wafer transfer mechanism.

FIG. 6 is a plan view showing the operation of the wafer transfer mechanism.

FIG. 7 is a perspective view showing the structure of a conventional wafer holding unit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Wafer, 2 ... Holder, 3 ... Arm, 4 ... Arm, 5 ... Vacuum flange, 6 ... Rotation center, 7 ... Rotation center, 8 ... Rotation center, 9 ... Motor, 10 ... Chamber, 11 ... Chamber, 1
2 ... transport mechanism, 13 ... arrow, 14 ... arrow, 15 ... arrow,
16 arrow, 17 arrow, 18 transfer chamber, 19 light emitter, 20 light receiver, 21 light, 22 holder, 23 leaf spring, 24 strain gauge, 25 holder, 26 rotation center, 27 ... arm, 28 ... holder, 29 ... leaf spring, 30 ...
Strain gauge.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasuhide Matsumura 1-280 Higashi-Koigakubo, Kokubunji-shi, Tokyo Inside the Central Research Laboratory of Hitachi, Ltd. Central Research Laboratory (72) Inventor Masakazu Sugaya 1-280 Higashi Koigakubo, Kokubunji-shi, Tokyo Inside Central Research Laboratory, Hitachi, Ltd.

Claims (6)

[Claims] 1. A transfer mechanism for mounting and transferring a wafer, wherein the presence or absence of the wafer is confirmed by detecting the weight of the wafer on the transfer mechanism. 2. The wafer transfer mechanism according to claim 1, wherein the confirmation of the wafer is performed by detecting a deformation of a leaf spring attached to a holder for mounting the wafer. 3. The wafer transfer mechanism according to claim 2, wherein the deformation of the leaf spring is detected by a strain gauge attached to the leaf spring. 4. A wafer transfer mechanism for mounting and transferring a wafer, wherein the presence or absence of the wafer is checked using a strain gauge attached to a wafer holder on which the wafer is mounted. 5. A transfer mechanism for mounting and transferring a wafer, wherein a wafer weight detection mechanism is attached to a plurality of positions of a holder for mounting the wafer. 6. A leaf spring according to claim 5, wherein said leaf spring is used as a wafer weight detecting mechanism, and said leaf spring is deformed.
Wherein the weight detection mechanism is attached at three locations.