JP3157738B2 - Wafer transfer device and transfer method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a wafer transfer apparatus and method for transferring a wafer between a vertical furnace and a carrier when performing a heat treatment or a chemical vapor deposition of the wafer.

[0002]

2. Description of the Related Art Generally, in a vertical furnace for heat treatment of a semiconductor wafer, the wafer is transferred to a boat made of high-purity quartz or silicon carbide in order to prevent heat resistance and contamination during the heat treatment. Set in a furnace and process. In addition, because the processing time is long, to process multiple wafers simultaneously,
The boat has a plurality of wafer holding plates arranged at equal pitches in the vertical direction. The wafer holding plates are formed in a ring shape or a disk shape in order to improve in-plane uniformity of the wafer.

A conventional vertical furnace wafer transfer apparatus using such a boat is provided with a wafer storage container called a plastic carrier used for transferring wafers between processes.
A wafer is directly transferred to a wafer holding plate of a boat by a transfer fork mounted on a transfer robot capable of up, down, front and back, and turning operations.

An example of the wafer transfer operation of the conventional apparatus corresponding to the boat shape will be described with reference to the perspective views of FIGS. 13, 14 and 15. FIG. 13 shows a ringboad with claws having three to four claws 16 on a ring-shaped wafer holding plate 1a.
14 is shown. The claw 16 is provided for inserting the transfer fork 3 which can be turned up and down, back and forth, and under the wafer 2 so as to be able to carry the wafer. It is set on the nail 16 with a minute gap. As a transfer device using the ring boat 14 with a claw, there is, for example, JP-A-3-263317.

FIG. 14 shows a ring boat 15 with a notch ring having a notch ring-shaped wafer holding plate 1b in which a notch 17 is provided in a part of the ring. The notch 17 of this ring is also used for the transfer
The wafer 3 is provided below the wafer 2 so that it can be transported by being inserted under the wafer 2. There is no need to separate the wafer 2 from the ring surface as in the case of the ring boat 14 with claws, and the wafer 3 is set on the ring upper surface as it is. Is done. The notched ring-shaped wafer holding plate 1b is described in, for example, Japanese Patent Application Laid-Open No. 7-7877.
It is shown in FIG.

FIG. 15 shows a ring boat 6 having a continuous ring-shaped wafer holding plate 1c without a notch. In the case of this boat, the transfer fork 3 is
Since it is impossible to insert the wafer 2 directly under the ring, a fork 4 having a mechanism 18 for lifting the wafer 2 from below the ring is provided separately from the fork 3 for transfer. In this way, the wafer 2 is transferred from the upper surface of the ring to the height where the transfer fork 3 can be inserted, and is transferred to the transfer fork 3. 2 is set on the ring upper surface. As a transfer apparatus using the ring boat 6, there is, for example, Japanese Patent Application Laid-Open No. Hei 5-13547.

[0007]

The first problem is that FIG.
The conventional transfer apparatus for handling a ring boat shown in FIG. 3 and FIG. 14 cannot completely satisfy the original effect of the wafer heat treatment in which the wafers 1a and 1b are formed in a ring shape to improve the in-plane uniformity. . Particularly, in the case of a large-diameter wafer, a crystal slip phenomenon occurs during the heat treatment. The reason for this is that a singular point such as a nail or a notch that makes the contact with the wafer non-uniform is formed, so that the distribution of temperature and stress in the wafer surface becomes uneven.

A second problem is that the conventional transfer apparatus for handling a ring boat shown in FIG. 15 does not have the above-described problems but has a complicated mechanism of the transfer apparatus. The reason for this is that the fork 4 for lifting having a mechanism for lifting the wafer is required separately from the fork 3 for transfer.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a wafer transfer apparatus and a transfer method which employ a ring boat having no singular point so that the in-plane uniformity of the wafer can be improved and at the same time simplify the mechanism. To provide.

[0010]

A wafer transfer device and a transfer method according to the present invention have a ring boat and a carrier to which a wafer holding plate is detachable, and transfer a wafer to a wafer holding plate. Is performed not by using a boat but by providing a preset section including a fixed block and a fixed pin having no operation mechanism. Further, the wafer holding plate of the ring boat adopts a continuous ring shape without a notch or a hollow disk shape having only through holes for fixing pins of the preset portion.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings. Referring to FIG. 1, in a preferred embodiment of the present invention, first, a preset section 8 comprising a fixed block 9 and a plurality of fixed pins 10 is moved to a transfer form of a transfer robot 5 capable of moving up and down, back and forth, and turning. It is arranged within the operation range of the step 3. The fixing block 9 and the fixing pin 10 of the preset section 8 are desirably made of ceramics such as high-purity quartz, silicon carbide, silicon nitride, alumina, zirconia, etc., which have heat resistance and little metal contamination. Further, the upper surface of the fixing block 9 has a strength capable of withstanding the weight of the wafer holding plate 1, the tip surface of the fixing pin 10 has a minimum contact area capable of withstanding the weight of the wafer 2, and the tips of the pins are aligned horizontally.

The ring boat 6 is composed of a column 7 which is integrally supported vertically and a plurality of wafer holding plates 1 which can be separated from the column 7 individually. The column 7 has a groove or a projection so that the wafer holding plate 1 can be arranged and detached at equal intervals. The wafer holding plate 1 is formed in a ring shape, and has an outer shape larger than that of the wafer 2 up to a distance at which a singular point due to contact with the column 7 does not affect the uneven distribution of temperature and stress in the wafer surface. Also, the inner diameter is desirably the largest at a level at which in-plane uniformity is obtained in a process in which the entire peripheral shape of the wafer 2 is mounted and processed.

The transfer fork 3 is mounted on a transfer robot 5 which can be moved up and down, back and forth and pivotally, and is connected to a plastic carrier 11 used as a wafer storage container during the transfer between processes and the preset section 8. The transfer and transfer of the wafer 2 performed between the wafer holder 2 and the transfer and transfer of the wafer holding plate 1 between the preset unit 8 and the column 7 of the ring boat 6 are executed. This transfer fork 3 is also preferably made of ceramics such as high-purity quartz, silicon carbide, silicon nitride, alumina or zirconia which has heat resistance and little metal contamination.

The shape of the transfer fork 3 is such that it can be inserted into the gap between the wafer 2 on the fixing pins 10 and the upper surface of the wafer holding plate 1 on the fixing block 9 in the preset section 8, Since it is necessary to be able to insert the wafer holding plate 1 on which the wafer 2 is placed into the gap between the wafer holding plates 1 arranged at equal intervals on the support 7 of the Further, it is desirable to have concave steps or projections having different contact portions for placing the wafer 2 or the wafer holding plate 1 on this thin plate.

Further, the plane shape can take an arbitrary shape as long as it does not interfere with the fixing block 9 and the fixing pin 10 when it is inserted into the preset portion 8, but in the sense that the strength is permitted in order to reduce the accumulation of dust falling. It is desirable to reduce the area.

Next, the operation of the embodiment of the present invention will be described in detail with reference to FIGS. First, carrier 11
The loading operation for transferring the wafer 2 to the ring boat 6 will be described.

The transfer fork 3 moves forward on the ring boat 6 in a state where the wafer holding plate 1 is assembled, and is inserted into a gap below the wafer holding plate 1 to be transferred. Next, after the target wafer holding plate 1 is lifted by a lifting operation, the wafer holding plate 1 is conveyed to the preset section 8 by retreating and turning. In the preset section 8, the wafer holding plate 1 is slowly moved down and placed on the fixed block 9. At this time, the fixing pins 10 project from the upper surface of the wafer holding plate 1.

The transfer fork 3 retreats from the preset section 8, and then turns in the direction of the carrier 11 in which the wafer 2 is stored to pick up the wafer 2 to be transferred. The operation of the transfer fork 3 at this time is the same as the operation performed to take the target wafer holding plate 1 on the ring boat 6.

The transfer fork 3 on which the wafer 2 is mounted is transported onto the wafer holding plate 1 set in the preset section 8 and slowly descends onto the fixing pins 10 protruding from the upper surface thereof. After placing the wafer 2, the wafer holding plate 1
After retreating to a position where the wafer does not hit, it is lowered on the spot, and then inserted forward under the wafer holding plate 1. Here, when the transfer fork 3 is lifted to lift the wafer holding plate 1, the wafer 2 on the fixing pins 10 is scooped up on the wafer holding plate 1 and transferred onto the wafer holding plate 1.

Transfer fork 3 on which wafer holding plate 1 is mounted
Then, the wafer holding plate 1 on which the wafer 2 is placed is set at the position of the wafer holding plate 1 previously taken out by moving toward the support 7 of the ring boat 6 by turning and moving forward. At this time, the operation of the transfer fork 3 is to lower after the forward insertion, and to place the wafer holding plate 1 on the groove or projection provided on the support 7 of the ring boat 6. Thereafter, the transfer fork 3 retreats toward the next target wafer holding plate 1.

Next, an unloading operation for returning the heat-treated wafer 2 from the ring boat 6 to the carrier 11
Will be described. The operation of transferring the wafer holding plate 1 on which the wafer 2 is mounted from the ring boat 6 to the preset unit 8 by the transfer fork 3 is the same as the operation at the time of loading described above.

When the wafer holding plate 1 on which the wafer 2 is mounted is lowered on the fixed block 9 of the preset section 8, the fixing pins 10 protrude to the upper surface of the wafer holding plate 1 as described above, and lift the mounted wafer 2. . The transfer fork 3 rises after retreating from below the wafer holding plate 1 and is inserted forward into a gap between the wafer holding plate 1 and the wafer 2 lifted by the fixing pins 10. Thereafter, the wafer 2 on the fixing pin 10 is placed on the transfer fork 3 by ascending, and retreats and turns toward the carrier 11.

The operation of storing the wafer 2 in the carrier 11 is the same as the operation of setting the wafer holding plate 1 on the ring boat 6. Although the wafer holding plate 1 remains in the preset section 8, the operation of returning the wafer holding plate 1 to the ring boat 6 is the same as the operation at the time of loading. However, if the next processing step is continuous, the wafer 2 is transported from the carrier 11 at the time of loading to the preset section 8 and the wafer 2 is placed on the wafer holding plate 1 and placed on the ring boat 6. This is a loading operation for setting.

[0024]

Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 3 is a sectional view of the preset unit 8 used in the embodiment of the present invention. FIG. 4 shows the preset section 8
FIG. 5 is a cross-sectional view when the wafer holding plate 1 separated from the ring boat 6 is set, and FIG. 5 is a cross-sectional view when the wafer 2 is further set on the preset unit 8.

First, referring to FIG. 3, the preset section 8 according to the embodiment of the present invention includes one fixing block 9 and four fixing pins 10. The fixing block 9 is made of high-purity alumina and the fixing pin 10 is made of high-purity quartz, and the top surfaces of the respective tips are on the same horizontal plane. The horizontal plane connecting the upper surfaces of the four fixing pins 10 protrudes 10 to 15 mm above the upper surface of the fixing block 9.

A groove 19 into which the transfer fork 3 can be inserted is formed in the fixed block 9, and an arc-shaped recess 20 for mounting the wafer holding plate 1 on the upper surface of the fixed block 9 across the groove 19. The fixing pin 10 is set up inside the concave portion 20 and inside the inner diameter of the wafer holding plate 1.

Referring to FIG. 4, the wafer holding plate 1 is carried and set by the transfer fork 3 in FIG. The wafer holding plate 1 is made of high-purity quartz and has a ring shape with a thickness of 1 to 3 mm. Therefore, even in this state, the upper surfaces of the four fixing pins 10 are 7-14 times higher than the upper surface of the wafer holding plate 1.
mm above. Referring to FIG. 5, the wafer 2 is further conveyed and set on the fixing pins 10 of the preset section 8 by the transfer fork 3 in FIG. At this time, the gap between the wafer 2 and the upper surface of the wafer holding plate 1 is 7 to 14 mm, which is the amount of protrusion described above.

FIG. 6 is a sectional view in which the preset section 8 is constituted by only one fixed block 9.

FIG. 7 is a cross-sectional view of the transfer fork 3 of the embodiment of the present invention in FIG. 1, showing a state where the wafer holding plate 1 is mounted by imaginary lines. FIG. 8 similarly shows the state where the wafer 2 is mounted by imaginary lines.

The transfer fork 3 is made of high-purity quartz or alumina and is a flat plate having a thickness of 3 to 5 mm.
However, an arc-shaped step having a depth of 0.3 to 0.5 mm is provided on the upper surface, and a contact portion on which the wafer 2 and the wafer holding plate 1 are placed is separated. Further, as described in the embodiment of the invention, the transfer fork 3 is mounted on the transfer robot 5 which can be moved up and down, back and forth, and pivotally, and is made of plastic which is a wafer container used for transfer between processes. Reciprocating operation for carrying and transferring the wafer 2 between the carrier 11 and the preset unit 8 and carrying and transferring the wafer holding plate 1 between the preset unit 8 and the support 7 of the ring boat 6 are possible. And

FIG. 9 is a sectional view showing a state in which the wafer holding plate 1 is set on the column 7 of the ring boat 6 according to the embodiment of the present invention in FIG. The part shown by the imaginary line shows a state in which the wafer holding plate 1 has been separated from the column 7. Grooves for positioning and supporting the wafer holding plate 1 are provided at equal pitches in the column 7 of the ring boat 6.

FIG. 10 is a cross-sectional view of the ring boat 6 taken along the line AA in FIG. Ringbo
The wafer 6 is made of high-purity quartz as well as the wafer holding plate 1 including the support 7. The pitch of the grooves provided in the column 7 of the ring boat 6 varies depending on the process to be processed, but is usually 10-1.
When the wafer holding plates 1 are set, the gap between the respective wafer holding plates 1 is 7 to 14 mm.

Next, the operation of the embodiment of the present invention will be described. The operation is basically the same as that of the embodiment of the invention described with reference to FIG. 2, and here, the wafer 2 in the preset unit 8 is described with reference to FIGS.
The state after the transfer operation between the wafer and the wafer holding plate 1 will be described.

First, the state after the loading operation for transferring the wafer 2 to the wafer holding plate 1 will be described. The wafer holding plate 1 separated and conveyed from the ring boat 6 by the transfer fork 3 is placed on the fixed block 9 of the preset section as shown in FIG. Thereafter, the wafer 2 is transferred from the carrier 11 by the transfer fork 3 and is placed on the fixing pins 10 of the preset section as shown in FIG. In this state,
Next, when the wafer holding plate 1 is lifted by the transfer fork 3, the wafer 2 is mounted as it is on the lifted wafer holding plate 1 and is conveyed to the ring boat 6.

Next, an unloading operation for taking out the wafer 2 from the wafer holding plate 1 on which the wafer 2 is placed will be described. The wafer holding plate 1 on which the wafers 2 are separated and conveyed from the ring boat 6 by the transfer forks 3 and on which the wafers 2 are placed is placed on the fixed block 9 of the preset portion as shown in FIG. Is pushed up by the fixing pins 10 and is separated from the wafer holding plate 1. Thereafter, the transfer fork 3 is inserted into this gap, and only the wafer 2 is transferred to the carrier 11.

Next, another embodiment of the present invention will be described with reference to the drawings. FIG. 11 is a configuration perspective view of a two-stage preset unit 12 according to another embodiment of the present invention. FIG. 12 is a configuration perspective view of a two-stage transfer fork corresponding to the two-stage preset unit 12 shown in FIG. According to this configuration, the preset section and the transfer fork are formed in two stages, and the two-stage transfer fork 13 simultaneously holds two wafers or wafers in a manner similar to the above-described series of operations. Transfer of boards becomes possible.

[0037]

According to the wafer transfer apparatus and the transfer method of the present invention, since the ring-shaped wafer holding plate without claws or notches is used, contact with the wafer holding plate on the wafer surface does not occur. A singular point that becomes uniform does not occur. As a result, unevenness in the distribution of temperature and stress in the wafer surface does not occur, and the uniformity in the surface is improved. Can be dispersed, and the crystal slip phenomenon can be prevented.

Further, in the conventional wafer transfer apparatus for handling a ring boat as shown in FIG. 15, a push-up fork having a mechanism for pushing up a wafer is required separately from the transfer fork. According to the present invention, it is possible to cope with this simply by providing a simple fixed block having no operation mechanism and a preset portion including a fixed pin, so that the mechanism of the transfer device is simplified.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a sectional view showing the operation of the embodiment of the present invention.

FIG. 3 is a sectional view of a preset unit used in the embodiment of the present invention.

FIG. 4 is a cross-sectional view when a wafer holding plate is set in a preset unit in FIG. 3;

FIG. 5 is a cross-sectional view when a wafer is set in a preset unit of FIG. 4;

FIG. 6 is a sectional view of a preset unit used in another embodiment of the present invention.

FIG. 7 is a sectional view in which a wafer holding plate is mounted on a transfer fork used in an embodiment of the present invention.

FIG. 8 is a cross-sectional view in which a wafer is mounted on a transfer fork used in an embodiment of the present invention.

FIG. 9 is a sectional view in which a wafer holding plate is set on a ring boat used in the embodiment of the present invention.

FIG. 10 is a view taken in the direction of arrows AA in FIG. 9;

FIG. 11 is a perspective view of a two-stage preset unit used in another embodiment of the present invention.

FIG. 12 is a perspective view of a two-stage transfer fork used in another embodiment of the present invention.

FIG. 13 is a perspective view showing a conventional wafer transfer method using a claw ring boat.

FIG. 14 is a perspective view showing a conventional wafer transfer method using a notch ring ring boat.

FIG. 15 is a perspective view showing a conventional wafer transfer method using a ring boat of a continuous ring.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wafer holding plate 1a Ring-shaped wafer holding plate with a claw 1b Notched ring-shaped wafer holding plate 1c Ring-shaped wafer holding plate 2 Wafer 3 Transfer fork 4 Push-up fork 5 Transfer robot 6 Ring boat 7 Support 8 Preset portion 9 Fixed block 10 Fixing pin 11 Carrier 12 Two-stage preset portion 13 Two-stage transfer fork 14 Ring boat with claw 15 Ring boat with notch 16 Claw 17 Notch 18 Push-up mechanism 19 Groove 20 Arc-shaped recess

Claims (9)

(57) [Claims] 1. A carrier for accommodating wafers at equal horizontal intervals, a ring boat for accommodating wafers at equal horizontal intervals and taking in and out of a vertical furnace, and upper and lower carriers for transferring wafers between the carrier and the ring boat. A wafer transfer device having a transfer fork capable of rotating back and forth, a preset portion for transferring a wafer at an intermediate position between the carrier and the ring boat , and the ring boat includes a wafer. Put on detachable
A wafer holding plate having a ring shape, wherein the wafer is transferred to the wafer holding plate in the preset section;
A wafer transfer device configured to be mounted . Wherein said ring boat has a plurality of supports, the wafer holding plate wafer transfer according to claim 1, wherein is supported horizontally at equal intervals removably in the grooves or projections provided on said post Loading device. 3. The preset section comprises a fixed block and a fixed pin, a groove on which the transfer fork can be inserted is provided on the upper surface of the fixed block, and the wafer holding plate is mounted on the upper surface of the fixed block across the groove. 2. The wafer transfer device according to claim 1, wherein an arc-shaped concave portion for mounting is provided, and the fixing pin is erected in the concave portion and inside the inner diameter of the wafer holding plate with the groove interposed therebetween. 4. The wafer transfer device according to claim 3, wherein a height of the fixing pin is larger than a thickness of the transfer fork. 5. The wafer transfer apparatus according to claim 1, wherein the preset section has a fixed block and a fixed pin integrally formed. 6. The wafer transfer apparatus according to claim 1, wherein the preset unit includes a plurality of fixed blocks each having a fixed pin. 7. The transfer fork includes a first arc-shaped concave portion on which the wafer holding plate is mounted, and a second arc-shaped concave portion formed inside the concave portion and concentric with the concave portion, for mounting a wafer.
2. The wafer transfer device according to claim 1, further comprising: an arc-shaped concave portion. 8. A step of transferring a wafer holding plate from the ring boat onto a fixed block of the preset unit; a step of transferring a wafer from the carrier onto a fixed pin of the preset unit; A step of inserting the wafer transfer fork into the groove and lifting the wafer holding plate, and a step of further raising the wafer holding plate and transferring the wafer on the fixing pin to the wafer holding plate as it is,
Transporting and holding the wafer holding plate on which the wafer is mounted from the preset section to the ring boat. 9. A step of transferring a wafer holding plate on which a wafer is placed from the ring boat after the heat treatment to the preset section, and lowering the wafer holding plate on a fixed block in the preset section, A step of placing the wafer on the fixed block and placing the wafer on the fixed pin, inserting a wafer mounting fork between the fixed pins, raising the wafer as it is, placing the wafer on the wafer mounting fork, and placing the wafer on the carrier. A wafer transfer method, wherein the wafer is transferred and stored.