JPH09283455A - Vertical wafer boat - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to support a wafer with its load being nearly evenly dispersed to three points by forming a plurality of supporting sections in main supporters for supporting the wafer by three points and making the thickness of each of the supporting section nearly the same as that of the wafer to be supported. SOLUTION: A wafer boat 1 is constituted of three main supporters 2, an upper supporter 3, and a lower supporter 4. These three main supporters 2 and the upper supporter 3 and the lower supporter 4 are so formed as to be assembled and disassembled by specified stoppers at an upper and a lower end of each of the main supporters 2. In the three main supporters 2, projecting supporting sections 2a are formed at a plurality of levels. The supporting sections 2a of the three main supporters 2 are so formed as to be at the same levels. The projecting directions of the supporting sections 2a are all inwards. The thickness of each supporting section 2a is made nearly the same as that of a mounted wafer 'a' or the thickness of the wafer 'a' ±10% or about. Therefore, the wafer 'a' can be supported with its load being dispersed evenly to the three main supporters.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical wafer boat for mounting a large number of semiconductor wafers for heat treatment at high temperature.

[0002]

2. Description of the Related Art A wafer boat of this type includes a so-called horizontal type in which a plurality of wafers are arranged substantially vertically and arranged side by side to support an outer peripheral edge, and a plurality of wafers are arranged side by side in a vertical direction to surround each wafer. There are two types of so-called vertical type that support the vicinity at a plurality of locations. By the way, in consideration of the merits of downsizing of a heat treatment furnace and ease of transportation, and in recent years, a wafer boat is shifting from a horizontal type to a vertical type along with the increase in diameter of the wafer.

As the vertical wafer boat, there are a type in which the upper portion is supported and suspended, and a type in which the lower portion is supported and raised. As an upright type supporting the lower portion, for example, a configuration disclosed in Japanese Patent Application Laid-Open No. Hei 4-6826 is known as a conventional example. Also in this known vertical wafer boat, the vicinity of the outer periphery of the wafer is supported at four points.

[0004]

This type of vertical wafer board has a structure in which the vicinity of the outer periphery of the wafer is supported at a plurality of points, and therefore, when heat treatment is performed at a high temperature of around 1200 ° C., as shown in FIG. Then, in the wafer a, strain b is applied from the supported portion toward the inside of the wafer.
Occurs. This distortion cannot be visually recognized but can be confirmed by an X-ray photograph.

The phenomenon in which this distortion occurs is called a slip. This slip has a wafer diameter of 8 inches and 12
It tends to increase and increase as the diameter increases to inches. When the slip is large and large, it causes inconveniences such as deterioration of the quality of the wafer, deterioration of the quality of semiconductors such as IC and LSI, and decrease of the yield of semiconductor manufacturing.

Therefore, in the vertical wafer boat,
There is a problem to be solved in eliminating slip.

Therefore, as a result of various studies by the present inventors,
In a vertical wafer boat, the weight of the loaded wafer is not evenly distributed on the support part of the boat, and the vertical wafer boat with a plurality of (for example, 125) wafers is ramped down to about 750 ° C. And then ramped up to about 1150 ° C. over a period of about 60 to 80 minutes. At that time, the temperature rise rate of the wafer and the temperature rise rate of the wafer boat, especially the support portion We have found that slippage occurs due to the difference.

[0008]

As a concrete means for solving the above-mentioned problems of the prior art, the present invention provides a support main body for supporting at least a wafer, and an upper support and a lower support for supporting the support main body vertically. And a plurality of support portions for supporting the wafer at three points are formed on the support body, and the support portions are formed to have substantially the same thickness as the thickness of the wafer. It is provided.

The thickness of the support portion is formed within a range of ± 10% with respect to the thickness of the wafer. The three points of support are such that when the wafer is supported, the center of gravity of the wafer is the center of the wafer. The center angle of the supporting portions at the two points on the carry-in / out side is approximately 140 °, and the central angle between the supporting portions at the two points and the other supporting portions is approximately 110 °, respectively The surface roughness to be applied is Rmax 5 μm or less and Ra 0.5 μm or less, and the support member is
It is formed of either silicon or silicon carbide, and at least the supporting body, the upper supporting body and the lower supporting body are detachable and assembled.

In the vertical wafer boat according to the present invention, by supporting the wafer at three points, the weight of the wafer can be evenly distributed among the three supporting points, and the thickness of the supporting section is substantially the same. By making the thickness the same as, the temperature rise rate due to heat conduction is made the same, so that the occurrence of slip can be eliminated.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in more detail with reference to the embodiments shown in the drawings. FIG. 1 shows a vertical wafer boat 1 of the present invention, which is shown in a partially disassembled state. The wafer boat 1 has three support bodies 2 and an upper support body 3 for supporting a wafer. It is composed of a lower support 4. The support body 2 has a substantially columnar shape, and the upper and lower supports 3 and 4 have a substantially plate shape.

These three support bodies 2 and the upper support 3
The lower support 4 and the lower support 4 are formed at the upper and lower ends of each support body 2 so as to be assembled by a predetermined locking means. This predetermined locking means has substantially the same structure at the upper and lower locking parts, and one of them is shown in FIGS.
This will be described with reference to FIG.

Outward hooks 5 are integrally formed on the upper and lower ends of one of the support bodies 2, and a concave engaged portion 5a is formed inside the position close to the hook 5. The other upper support 3 and the lower support 4 are provided with a locking hole 6 into which the hook 5 is fitted and locked, and a stopper piece 7 rotatably provided. A step portion 6a is formed in the locking hole 6 so that the hook portion 5 is substantially engaged.

A boss portion 7a for allowing rotation is integrally formed on the stopper piece 7, and a rotary engaging portion 7b is formed on an engaged portion 5a formed on the support body 2.
The boss portion 7a is mounted in a shaft hole 8 provided in the upper and lower supports 3 and 4 so as to be rotatable.

By using the locking means having such a structure, first, the lower end portions of the three supporting main bodies 2 are mounted in the corresponding locking holes 6 with respect to the lower support body 4 and are brought into the standing state,
The upper support 3 is placed on the upper end of the support body 2, and the upper ends are mounted in the corresponding locking holes 6, respectively.

In this mounted state, the end portions of the respective support main bodies 2 are slightly moved outwardly so that the hook portion 5 and the step portion 6a are engaged with each other, and in this state, the stopper pieces 7 are provided. When the rotary engagement portion 7b engages with the engaged portion 5a formed on the inner surface of the support body 2 by rotating the support body 2 respectively, the support body 2 does not move inward, and the hook portion 5 The engagement between the step portion 6a and the step portion 6a is maintained in a stable state, and as shown in FIG. 4, the assembly of the vertical wafer boat 1 is completed. When disassembling, the reverse operation to the above may be performed. The stopper piece 7 is provided in a rotatable state, but instead of this, for example, a separate wedge member may be dropped into the locking hole 6.

In order to mount a wafer a on the three support bodies 2, a plurality of stages (for example, 125 stages) of support portions 2a are formed in a protruding manner so as to be aligned at the same level, and each support portion 2a is entirely formed. It projects inward.

The thickness of each supporting portion 2a in this case is substantially the same as the thickness of the wafer a to be placed, as shown in FIG.
Alternatively, the thickness of the wafer a is about ± 10%. This is because the rate of temperature rise of the supporting portion 2a is
This is because it is approximately equal to or infinitely close to.

The surface roughness of the surface of each supporting portion 2a that contacts the wafer a is Rmax of 5 μm or less and Ra.
It is set to 0.5 μm or less. This is to prevent non-uniformity of the weight of the supporting portion 2a due to the roughness of the surface roughness, and to prevent slipping.

The connection between the three support bodies 2 and the upper and lower supports 3, 4 is as described above, but the use of three support bodies 2 means that the wafer a is supported at three points. That is, the weight of the wafer a needs to be evenly distributed in each of the supporting portions 2a.

Therefore, as shown in FIG. 6, it is necessary to mount the three support bodies 2 at a predetermined angular interval. The wafer a is formed with a so-called orientation flat c for aligning the direction, and the orientation is not necessarily limited, but the orientation of the orientation flat c is brought to the front side and the wafer a is loaded into the vertical wafer boat 1. And be delivered.

Considering these points, among the three-point support,
The two support bodies 2 located on the front side are arranged such that the center angle of the center of the center of gravity of the wafer a to be loaded is the angle at which the wafer a can be carried in and out, that is, an angle range of about 140 °. The support body 2 at one point located on the rear surface side with respect to the support body 2 at two sides is set such that the central angle from the support body 2 at the two points is within an angle range of about 110 °. .

By setting the angular range of each point in the three-point support as described above, loading and unloading of the wafer a with respect to the vertical wafer boat 1 can be easily performed, and the load of the wafer a with respect to each supporting point is substantially equal. Will be dispersed in. In particular, since it is a three-point support, even if there is some error (including overall distortion) in the flatness of the wafer a, the deviation of the load on the support portion 2a is greater than that of the four-point support. Hardly occurs.

The above-mentioned constituent members are formed of a material having excellent heat resistance as in the conventional case, but at least the supporting portion 2a on which the wafer a is placed is formed thin by adjusting the temperature rise rate to the wafer a. Therefore, it is preferable to use silicon or silicon carbide. And
The wafer boat according to the present invention is an assembling type and a vertical type, and can be used as a hanging type or a lower supporting type.

Then, the vertical wafer boat 1 of the present invention was actually used to perform heat treatment in the same manner as in the conventional example. That is, after mounting 125 wafers a, 750
The vertical wafer boat 1 was loaded into the heat treatment furnace that was ramped down to about 0 ° C., and then the heat treatment was performed by ramping it up to about 1150 ° C. for about 60 minutes.
As a result, a slight distortion was confirmed in the portion supported by the supporting portion 2a, but the large distortion as seen in the conventional example was not recognized, and the distortion was not substantially associated with the deterioration of the quality of the semiconductor product. there were. Therefore, the slip phenomenon was significantly improved.

[0026]

As described above, the vertical wafer boat according to the present invention includes at least a supporting body for supporting the wafer, an upper supporting body and a lower supporting body for supporting the supporting body vertically. A plurality of supporting portions for supporting the wafer at three points are formed on the supporting body, and since the supporting portions are formed to have substantially the same thickness as the thickness of the wafer, they are mounted by three-point supporting in particular. The load of the wafer can be distributed and supported substantially evenly at three points, and the thickness of the supporting portion is made substantially the same as the thickness of the wafer,
The temperature rises in the same way as with a wafer, and it has an excellent effect that both sides can avoid slip.

Further, the thickness of the supporting portion is formed within a range of ± 10% with respect to the thickness of the wafer, and the three points of supporting are centered on the center of gravity of the wafer when supporting the wafer. As a result, the central angle of the supporting portions at the two points on the loading / unloading side of the wafer is approximately 140 °, and the central angle between the supporting portions at the two points and the other supporting portions are approximately 110 °, respectively. By making the temperature rise rate substantially the same as that of the wafer and setting the angle of the three-point support, the heat treatment can be performed by receiving an even load, so that the slip can be prevented as described above.

[Brief description of drawings]

FIG. 1 is a perspective view showing an exploded part of a vertical wafer boat according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of a main part before locking showing an example of locking means in the embodiment.

FIG. 3 is a schematic sectional view of an essential part after locking showing an example of locking means in the same embodiment.

FIG. 4 is a perspective view showing a part of the same embodiment after completion of assembly, with the part thereof removed.

FIG. 5 is a partially enlarged front view showing a state in which a wafer is mounted on the vertical wafer boat of the embodiment.

FIG. 6 is an explanatory diagram showing a positional relationship of three-point support in the vertical wafer boat of the embodiment.

FIG. 7 is a schematic plan view for explaining the state of a wafer that has been heat-treated by a conventional apparatus.

[Explanation of symbols]

1 ... Vertical wafer boat, 2 ... Support body, 2a
…… Supporting part, 3 …… Upper support, 4 …… Lower support,
5 ... end of support body, 5a ... engaged portion, 6 ...
Locking hole, 6a ... Step, 7 ... Stopper, 7a ...
… Boss part, 7b …… Rotating engagement part, 8 …… Shaft hole, a
…… Wafer, b… Distortion, c… Orifla

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location H01L 21/68 H01L 21/68 N

Claims (6)

[Claims] 1. A support main body that supports at least a wafer, an upper support and a lower support that support the support main up and down, and the support main body has a plurality of support portions that support the wafer at three points. The vertical wafer boat is characterized in that the supporting portion is formed to have substantially the same thickness as the thickness of the wafer. 2. The vertical wafer boat according to claim 1, wherein the thickness of the support portion is within a range of ± 10% with respect to the thickness of the wafer. 3. The supporting of the three points is such that, when the wafer is supported, the center angle of the two supporting portions on the loading / unloading side of the wafer is about 140 ° with the center of gravity of the wafer as the center, and the two points are supported. The vertical wafer boat according to claim 1 or 2, wherein the central angle between the portion and the other supporting portion is approximately 110 °. 4. The vertical wafer board according to claim 1, 2 or 3, wherein surface roughness of a surface of the supporting portion that contacts the wafer is Rmax 5 μm or less and Ra 0.5 μm or less. 5. The vertical wafer boat according to claim 1, 2, 3 or 4, wherein the support member is formed of either silicon or silicon carbide. 6. The vertical wafer boat according to claim 1, wherein at least the supporting main body, the upper supporting body and the lower supporting body are of a removably assembled type.