JPH0666375B2 - Wafer transfer method - Google Patents

Description

The present invention relates to a wafer transfer method, and more particularly to a wafer transfer method suitable for clean transfer of wafers.

[Conventional technology]

The conventional transfer method is described in, for example, Electronic Materials, March 1985.
Mon, as described in FIG. 4 of the "Reactive Ion Etcher" discussed on pages 64 to 69, the wafer is unloaded from the cassette by an arm, Some things have been taken care that particle generation does not occur.

[Problems to be solved by the invention]

The above-mentioned prior art does not consider the positioning of the wafer on the arm when mounting the wafer on the arm from within the cassette, and therefore it is necessary to accurately determine the position of the wafer within the cassette in advance. is there. Therefore,
If the orientation flats (hereinafter referred to as "orifla") of the wafers stored in the cassette are in different directions, the wafer storage position in the cassette is shifted,
Since the wafer ends are not aligned, in such a device, the orientation flats are normally aligned in the cassette to align the wafer storage positions. In this work, since the wafer is rotated in a state where the wafer is stored in the cassette, particles are generated by the rubbing with the wafer storage groove portion and attached to the wafer, or particles generated on the roller for rotating the wafer are attached, There is a problem that this further adheres to the wafer and deteriorates the yield of the wafer.

An object of the present invention is to perform positioning without fail by aligning the orientation flat and simply while the wafer is being placed on the arm, so that each wafer can be reliably positioned and the generation of particles can be suppressed. ,
It is an object of the present invention to provide a wafer transfer method capable of highly reliable and clean transfer.

[Means for solving problems]

In the wafer transfer method for receiving a wafer from a cassette, mounting the wafer on an arm, and transferring the wafer, the arc width along the circumferential side surface of the wafer is at least wider than the width of the orientation flat. The arc-shaped wafer contact part
The arm provided at the end of the wafer mounting surface on the base side of the arm is inserted into the wafer lower surface position in the cassette, and the arm is provided at the wafer lower surface position in the cassette. Wafers in a cassette to be placed on the arm are pressed against the wafer contact portion from the tip side of the arm by pushing the rollers out by the wafer pushing-out means having two or more rollers arranged at predetermined intervals on the opposite side. , The wafer is positioned on the arm regardless of the position of the orientation flat of the wafer by using the mutual centering action of the wafer contact portion and the roller generated by the pressing, and the wafer is placed on the arm and the wafer is moved by the arm. Is achieved by transporting

[Action]

The abutting part of the arm is shaped like an arc along the circumference of the wafer, the roller is placed on the opposite side of the abutting part, and moreover, one end of the orientation flat is aligned with at least the arc end on both sides from the center line of the arc. Is arranged so that the roller and the wafer are in contact with each other at a position wider than the shortest distance between the other end of the orientation flat and the center line of the arc when the wafer is brought into contact with the wafer, and the arm is inserted into the wafer lower surface position in the cassette, The wafer is pushed out by the pushing out of the roller by the wafer pushing means, and the wafer is pressed against the abutting portion of the arm, so that no matter where the orientation flat position is, the mutual centering action of the roller and the abutting portion causes the wafer to move to a predetermined position. Since the wafers are positioned on the wafer and then transferred on the wafer, the wafers are surely positioned on the arm one by one, and the wafer is scraped in the cassette. Pressed the less particle generation, high perform clean conveyed reliability.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows the overall structure of the wafer transfer apparatus. In this case, the case where the wafer is transferred from the cassette in which the wafer is stored will be described. The cassette mounting table 6 includes a housing 17
It is attached to the upper part of a shaft 18 which is guided and supported in the axial direction so as to be movable in the axial direction by a bearing 16 provided therein, and the cassette 1 containing the wafer 2 is mounted on the upper surface.

A female screw portion is provided below the shaft 18, and a screw shaft 7 driven by a motor 15 via a belt 9 and pulleys 8 and 14 is engaged therewith. The pulley 8 is attached to the lower part of the screw shaft.

The slit plates 10 and 11 are attached to the motor shaft of the motor 15 to which the pulley 14 is attached.
Sensors 12 and 13 are provided at 0 and 11, respectively.

An upper arm of the cassette table 6 is provided with a wafer detection sensor 5 positioned below the lowest wafer 2 in the cassette 1, and an arm which can be inserted and removed between the wafer 2 and the wafer detection sensor 5 by a driving device (not shown). 3 is provided, and the roller 22 is provided on the side opposite to the arm 3 of the wafer 2. In this case, the roller 22 is movably guided to the wafer 2 side by the bearing 21, and the air cylinder 1 is moved through the leaf spring 20.
It is connected to 9. The leaf spring 20 serves to absorb impact and prevent overload. In this case, the air cylinder 19, the leaf spring 20, the bearing 21, and the roller 22 form a wafer pushing means.

As shown in FIG. 2, an arc-shaped contact portion 4 matching the diameter of the wafer 2 is provided on the base side of the arm 3, and the arc-shaped chord width L ₁ is larger than the orientation flat width L of the wafer 2. It's big. Further, in this case, the wafer mounting surface of the arm 3 is provided with three wafer support members 23 made of silicon rubber in order to prevent slippage and reduce the contact area with the wafer.

As shown in FIG. 2, the roller 22 is located on the opposite side of the contact portion 4, and one end of the orientation flat is aligned with at least the arc end portions on both sides of the center line of the arc of the contact portion 4 so that the wafer is placed on the arc portion. When the roller 22 and the wafer 2 are in contact with each other at a distance L ₃ wider than the shortest distance L ₂ between the other end of the orientation flat and the center line of the circular arc when abutting, the distance from the center line to the contact point is L _3. It is arranged. In this case, two rollers 22 are provided.
Resins such as tetrafluoroethylene resin, polyacetal resin, and polyimide resin are desirable from the viewpoint of preventing the generation of particles.

The operation of the apparatus configured as above will be described. In FIG. 1, the motor 15 is rotated by a control device (not shown) to rotate the screw shaft 7 to move the shaft 18 downward, and the cassette 1 on the cassette mounting table 6 is lowered.
The wafer 2 stored in the lowest position in the cassette 1 approaches the wafer detection sensor 5.

When the wafer 2 descends to a predetermined position, that is, a position where the arm 3 can be inserted, the wafer detection sensor 5 detects this and sends a signal to the control device to stop the motor 15.

At this position, the arm 3 is inserted into the cassette 1 by the control device and positioned below the wafer 2. The relationship between the wafer 2 and the arm 3 at this time is shown in FIG. As shown in FIG. 3, the cassette 1 is stopped so as to have a gap δ between the lowermost wafer 2a and the wafer support member 23 of the arm 3, and the arm 3 is inserted with a gap δ. At this time, even if the wafer 2a is displaced and sticks out of the cassette 1, the wafer 2a is pushed into the cassette 1 by inserting the arm 3 into the cassette 1. Further, when the arm 3 is inserted, the wafer 2a and the upper wafer 2b are placed and housed in the groove portion in the cassette 1 with the pitch P.

In this state, as shown in FIGS. 1 and 4, the roller 22 moves to the arm 3 side via the leaf spring 20 by the contraction operation of the air cylinder 19 controlled by the controller in this case, and 2a is pushed out to the base side of the arm 3. As a result, the wafer 2 a hits the contact portion 4 of the arm 3 and is positioned with respect to the arm 3. At this time,
The wafer 2a is supported by the groove in the cassette 1 and moves.

This state of positioning will be described with reference to FIGS. 6 to 8. 6A to 6C show a process in which the wafer 22 deviated from the center of the arc portion of the arm 3 and accommodated in the cassette is pressed against the contact portion 4 of the arm 3 by the roller 22. . First, as shown in (a), in this case, the roller 22b hits the wafer 2 and pushes it toward the arm 3, and then, as shown in (b), in this case, at one end of the abutting portion, the circumferential side surface of the wafer 2 is attached. By hitting the roller 22b further, the wafer 2 is housed in the contact portion 4 as shown in (c) by rotating clockwise around the contact point between the wafer 2 and the contact portion 4. To be

Note that, for example, when the orientation flat of the wafer 2 hangs on the arc portion of the contact portion 4 as shown in FIG. 7, a clockwise rotation is made around the contact point O between the corner of the orientation flat and the contact portion 4. The moment F _{1 2} and the counterclockwise moment F _{1 1} are applied, and in this case F _{1 1} <F _{1 2} , the wafer 2
Tries to rotate to the right around the contact point O, but in this case, the center of the wafer 2 is on the left side of the line connecting the contact point O and the roller 22a when viewed from the O side (that is, the wafer 2 contacts the contact point O).
When a right rotation about the contact point O is performed, the distance between the contact point O, which is the radius around the contact point O, and the roller 22a gradually increases.
Since it is constrained by a and cannot rotate, the center of the arc of the contact portion 4 and the center of the wafer 2 coincide with each other, so that the wafer 2 can be positioned. In addition, when the orientation flat is located on the opposite side, the positioning can be performed in a similar manner only by reversing the action relationship of the forces.

Further, for example, when the orientation flat of the wafer 2 is inclined to the rollers 22a and 22b as shown in FIG. 8, only the roller 22b acts on the wafer 2 and its force F ₂ is between the wafer 2 and the arc portion. Acts on the contact position, so that even if the point of action deviates from the center of the wafer 2, the force for pressing the wafer 2 against the circular arc portion is strong and the wafer 2 cannot be rotated. The center of the arc of the portion 4 and the center of the wafer 2 can be aligned and positioned.

Next, after the wafer 2a is positioned with respect to the arm 3, as shown in FIG. 5, the roller 22 is returned to the original position and separated from the wafer 2a, and the cassette mounting table 6 is lowered by the movement amount S. As a result, the wafer support member 2 of the arm 3 is
The wafer 2 a is placed on the wafer 3. After that, the arm 3 is moved to carry the wafer 2a out of the cassette 1. The control of the movement amount S for lowering the cassette mounting table 6 is
The rotation of the motor 15 shown in FIG. 1 is detected by the sensors 12 and 13, the detection signal is sent to the control device, and the control device integrates the rotation amount of the motor 15 to convert it into the movement amount of the cassette mounting table 6. This is performed by controlling the motor 15.

The operation described above is repeated to repeat the wafer 2 in the cassette 1.
Are sequentially carried out from the bottom.

As shown in FIG. 5, the height of the contact portion 4 of the arm 3 is such that when the wafer 2a is placed on the arm 3, the upper wafer 2b is displaced and sticks out of the cassette 1. Even if it is present, the gap α ₁ is provided so as not to hit the upper wafer 2b. The height H of the contact portion 4 and the wafers 2a and 2b are set to satisfy the following equation. The fifth
In the figure, 2b shows the upper wafer after the movement, and 2b '
Indicates the upper wafer before transfer. Reference numeral 2a denotes a lower wafer after movement, 2a 'denotes a lower wafer before movement, and 2a "
Indicates the position on the assumption that the lower wafer is not placed on the arm 3 and descends as it is.

P- (α ₀ + α ₁ ) <H <δ (1) where, H: height of the contact portion 4 from the upper surface of the wafer support member 23 P: wafer accommodating groove pitch in the cassette 1 δ: arm Gap between the upper surface of the wafer support member 23 and the lower surface of the wafer 2a when inserting 3 3 α ₀ : Amount of movement of the wafer 2a when placing the wafer 2a on the arm 3 (α ₀ = S−δ) α ₁ : After moving the cassette 1 The minimum gap between the lower surface of the wafer 2b and the upper surface of the contact portion S is the movement amount of the cassette 1 when the wafer 2a is placed on the arm 3.

As described above, according to the present embodiment, the contact portion 4 provided on the arm 3 is
By pressing the wafer 2 with the rollers 22 provided at predetermined intervals, the wafer 2 can be positioned at a predetermined position with respect to the arm 3 every time the wafer 2 is carried out. Since the amount of displacement is small, the generation of particles can be suppressed, and highly reliable and clean unloading can be performed.

Further, since the wafer 2 is pushed out by the roller 22 when the wafer 2 is placed in the groove portion of the cassette 1, the contact between the wafer 2 and the groove portion of the cassette 1 is small and the generation of particles can be reduced.

Further, since the roller 22 is used to push out the wafer 2, the contact between the wafer 2 and the roller 22 becomes a rolling contact, and the generation of particles is extremely reduced.

Further, since the non-slip wafer supporting member 23 is attached to the mounting portion of the wafer 2 of the arm 3, the wafer 2 is not displaced when the positioned wafer 2 is unloaded from the cassette 1.

Further, since the leaf spring 20 is interposed between the roller 22 and the air cylinder 19 that moves the roller 22, the wafer 2
It is possible to prevent the wafer 2 from being damaged without giving a strong impact to the wafer 2. The leaf spring 20 may be replaced with another one as long as it can absorb a shock.

In this embodiment, the cassette 1 is lowered and the wafer 2
However, the wafer 2 may be placed by elevating the arm 3.

In addition, although the case where the wafer is carried out from the cassette has been described in the present embodiment, the method of positioning and carrying the wafer is not limited to this.

〔The invention's effect〕

According to the present invention, it is possible to easily perform positioning while placing the wafer on the arm without performing positioning by aligning the orientation flat, and it is possible to reliably perform the positioning of the individual wafers and to prevent particle Since the occurrence can be suppressed, there is an effect that highly reliable and clean conveyance can be performed.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a wafer transfer apparatus according to an embodiment of the present invention, FIG. 2 is a plan view of FIG. 1 seen from AA, and FIGS. 3 to 5 show a wafer and an arm. And FIG. 6 to FIG. 8 are plan views showing the positioning of the wafer. 1 ... Cassette, 2 ... Wafer, 3 ... Arm, 4 ...
Contact part, 5 ... Wafer detection sensor, 6 ... Cassette mounting table, 19 ... Air cylinder, 22 ... Roller

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Tsunehiko Tsubone 794 Higashi-Toyoi, Kudamatsu City, Yamaguchi Prefecture Stock company Hitachi Kasado Plant (72) Inventor Hironobu Kawahara 502 Kintatemachi, Tsuchiura City, Ibaraki Japan (56) Reference JP-A-50-1639 (JP, A) JP-A-61-273441 (JP, A) JP-A-54-41079 (JP, A) Actual development Sho-59-107140 ( JP, U) Actual development Sho 59-2135 (JP, U)

Claims (1)

[Claims] 1. A wafer transfer method for receiving a wafer from a cassette, mounting the wafer on an arm, and transferring the wafer, wherein a chord width of an arc along a circumferential side surface of the wafer is at least greater than a width of an orientation flat. The widened arcuate wafer contact portion is provided at the end of the wafer mounting surface on the base side of the arm, and the arm provided with the wafer contact portion is inserted into the wafer lower surface position in the cassette. The arm is placed on the arm by pushing the rollers by a wafer pushing means having two or more rollers arranged at a predetermined distance on the opposite side of the wafer contact portion at the wafer lower surface position in the cassette. The wafer in the cassette is pressed against the wafer contacting portion from the tip side of the arm, and the wafer contacting portion and the roller generated by the pressing contact with each other. Aligning the wafer on the arm regardless of the position of the orientation flat of the wafer by using a centering action, placing the wafer on the arm, and transporting the wafer by the arm. Wafer transfer method.