JP2003100648A - Heat treatment jig of semiconductor wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat treatment jig of semiconductor wafer in which slip of a semiconductor wafer can be suppressed during heat treatment and occurrence of partial haze is suppressed while preventing the appearance from deteriorating. SOLUTION: The heat treatment jig of semiconductor wafer comprises a base body for supporting a semiconductor wafer on the upper surface thereof, at least three holes 1a penetrating the base body 1, and a cover body 2 being fitted to the hole 1a. Since a cover body being fitted to the hole of the basic body is provided, the semiconductor wafer can be supported even at the part of the hole by means of the cover body and thereby the lower surface of the semiconductor wafer can be supported entirely by the entire surface of the basic body. As a result, slip of the semiconductor wafer can be suppressed and generation of haze (uneven reflection of light) can be suppressed while improving the appearance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor wafer (semiconductor manufacturing substrate) heat treatment jig, and more particularly to a semiconductor wafer heat treatment jig capable of suppressing the occurrence of slips by supporting the entire surface of the semiconductor wafer. Regarding jigs.

[0002]

2. Description of the Related Art A semiconductor device manufacturing process includes many heat treatment processes such as oxidation, diffusion, and film formation, and a semiconductor wafer is subjected to various heat treatments. In these heat treatment steps, a plurality of semiconductor wafers are placed on a vertical wafer boat, and the vertical wafer boat is housed in a vertical heat treatment furnace to heat the semiconductor wafers for heat treatment.

This vertical wafer boat has a structure in which a plurality of rod-shaped support members having a large number of slits for mounting semiconductor wafers are erected parallel to the vertical direction, and the slits of the support members are provided. Supports several points on the outer periphery of the semiconductor wafer. The vertical wafer boat supporting the semiconductor wafer is
It is housed in a vertical heat treatment furnace and subjected to a predetermined heat treatment.

As described above, during the heat treatment, since the semiconductor wafer is supported by the slits of the supporting member at several points on the outer peripheral portion thereof, stress due to its own weight is applied from the supporting portion (contact point between the semiconductor wafer and the supporting member). In addition, the semiconductor wafer is subjected to thermal stress due to the temperature difference in the plane of the semiconductor wafer during the heat treatment. Then, when these stresses are superposed and the superposed stress exceeds the shear yield stress value of the silicon crystal of the semiconductor wafer, slip occurs in the semiconductor wafer, which causes deterioration of the quality of the semiconductor wafer.

Further, in recent years, as semiconductor devices have become highly integrated, the diameter of semiconductor wafers has been increasing in order to increase the device yield per semiconductor wafer. The stress received from the supporting portion increases, slipping easily occurs, which is a serious problem.

By the way, as a method for solving the above-mentioned problem, it is conceivable to increase the number of supporting portions for supporting the semiconductor wafer and to support them by a large number of supporting portions. That is, as the semiconductor wafer is supported by a larger number of points, the load at the supporting portion (the contact point between the semiconductor wafer and the supporting member) is dispersed, the stress received from one supporting portion is reduced, and the occurrence of slip can be suppressed. is there. However, in order to support with a large number of supporting portions, it is necessary to process each slit (groove) with high accuracy, which causes a new problem that the processing cost increases. On the other hand, if the processing accuracy is low, even if an attempt is made to support the semiconductor wafer by a large number of supporting portions, the semiconductor wafer is substantially supported at three or four points. As a result, the stress received from one support part cannot be reduced, and it is difficult to suppress the occurrence of slip.

As a method for solving the above-mentioned problems, a method has been proposed in which the supporting portion for supporting the semiconductor wafer is a flat plate-like supporting plate, and the entire lower surface of the semiconductor wafer is supported by the entire supporting plate (special feature). Kaihei 10-24206
7). Specifically, the support plate is formed with an insertion hole for vertically inserting a support pin that supports the lower surface of the semiconductor wafer and moves up and down, and the outer edge portion is welded to a column of a vertical wafer boat. It is fixed by. Then, the semiconductor wafer is transferred onto the support plate by the first substrate support arm of the substrate transfer mechanism, while the second substrate support plate arm is lifted from below the support plate to place the support pin in the insertion hole. After inserting, the tip portion is projected from the upper surface of the support plate, and the semiconductor wafer is mounted on the projected support pins. The first
The substrate supporting arm is detached from the supporting plate, and then the second substrate supporting plate arm is lowered to mount the semiconductor wafer on the supporting plate.

According to this method, since the entire lower surface of the semiconductor wafer is supported by the entire surface of the supporting plate, the stress received from the supporting portion (supporting surface) can be reduced and the occurrence of slip can be suppressed. Further, since the supporting portion is the upper surface of the flat plate-like supporting plate, there is an advantage that it can be relatively easily processed with high precision and can be manufactured at low cost.

[0009]

By the way, as described above, the support plate for supporting the semiconductor wafer is provided with the insertion hole into which the support pin is inserted when the semiconductor wafer is placed or taken out. Therefore, there is a technical problem that haze (unevenness of light reflection) occurs in such a portion, resulting in poor appearance. Further, there is a technical problem that the semiconductor wafer is not supported in such a portion and slip is likely to occur.

The present invention has been made in view of the above-mentioned problems of the prior art, and it is possible to suppress the slip of the semiconductor wafer during the heat treatment, suppress the occurrence of partial haze, and prevent the appearance defect. An object is to provide a jig for heat treatment of a semiconductor wafer.

[0011]

A jig for heat treatment of a semiconductor wafer according to the present invention, which has been made to achieve the above object, is a jig for heat treatment of a semiconductor wafer used in heat treatment of a semiconductor wafer. It is characterized in that it is provided with a base body for supporting the semiconductor wafer on the upper surface, at least three holes penetrating the base body, and a lid body fitted in the holes.

As described above, since the lid that fits into the hole of the base body is provided, the semiconductor wafer can be supported by the lid also in the hole, and the entire lower surface of the semiconductor wafer is supported by the entire base body. be able to. As a result, the occurrence of slip of the semiconductor wafer can be suppressed. Further, since the lid that fits into the hole of the base body is provided, it is possible to suppress the occurrence of haze (unevenness in light reflection) and improve the appearance.

Here, the base body is made of a thin plate, the hole penetrates along the axis of the base body in the upper and lower directions of the base body, and the lid body fitted into the hole is a lid body. It is desirable that it is formed so as to be detached from the base body by the pushing force from the lower surface of.

As described above, since the lid body fitted into the hole is formed so as to be detached from the base body by the pushing force from the lower surface of the lid body, the semiconductor wafer is supported by the base body. In this case, the lid does not drop out from the hole of the base body. On the other hand, as described in the related art, when the support pin is inserted from the lower surface of the base body into the hole, the lid is separated from the upper surface of the base body by the support pin and is pushed up together with the semiconductor wafer above the base body. Therefore, the attachment / detachment operation of the lid body depends on the operation of the support pin, so that the operation of the support pin is not hindered.

Further, it is preferable that the material of the base body and the lid is any one of silicon single crystal, silicon polycrystal, polycrystalline silicon sintered body, quartz glass, silicon nitride, and silicon nitride coated carbon material. Particularly, it is desirable that the base body and the lid are made of the same material. When it is made of such a material, proper heat treatment can be performed without contaminating the semiconductor wafer.

Further, the base body has a diameter of 300 mm,
It has a thickness of 0.8 to 1.2 mm, and the upper surface of the base body is formed into a concave curved surface as a support surface for supporting the wafer, and the center of the concave curved surface is 0.1 to 0.
It is desirable to be formed 2 mm lower. In this way, the center of the concave curved surface is more than the outer edge of the upper surface of the base body.
Since it is formed to be 0.1 to 0.2 mm lower, the semiconductor wafer can be bent by its own weight during heat treatment, and the entire surface of the semiconductor wafer can be evenly supported.

Further, it is preferable that the semiconductor wafer is supported on the upper surface of the base body, and the base body supporting the semiconductor wafer is mounted on a supporting portion of a vertical wafer boat.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a jig for heat treatment of a semiconductor wafer according to the present invention will be described with reference to FIGS. As shown in FIG. 1, this semiconductor wafer heat treatment jig A includes a base body 1 for supporting the semiconductor wafer W on the upper surface, three holes 1a penetrating in the upper and lower directions of the base body 1, and It has a lid 2 that fits into the hole 1a.

As shown in FIG. 4, the hole 1a penetrates the base body 1 along the vertical axis of the base body 1, and the lid body 2 fitted into the hole 1a is a lid body 2. It is formed so as to be detached from the base body 1 by the pushing force from the lower surface of the.

That is, the hole 1a penetrates the base body 1 along the axis of the base body 1, and the inner surface thereof is formed into a conical shape which gradually expands from the lower surface to the upper surface of the base body 1. Has been done. On the other hand, the outer shape of the lid body 2 is formed in a conical shape which gradually expands from the lower portion of the lid body 1 to the upper portion thereof, and is formed so as to fit with the hole 1a. Therefore, the lid 2 fitted in the hole 1a
Is removed from the base body 1 by the push-up force from the lower surface of the cover body 2, and the removed lid body 2 is opened from the top surface of the base body 1 into the holes 1
It can be inserted into a and fitted.

A support pin 4a is provided on the lower surface of the lid 2.
Is formed so that the lid 2 is pushed up by the support pin 4a. The support pin 4a will be described later.

The base body 1 has a diameter of 300 m.
m, the thickness is 0.8 to 1.2 mm, and the upper surface of the base body 1 is formed into a concave curved surface as a support surface for supporting the semiconductor wafer W, and the center of the concave curved surface is the outer edge portion of the upper surface of the base body 1. It is formed lower by 0.1 to 0.2 mm.

The thickness of the base body 1 is set to 0.8 mm or more in order to prevent the base body 1 from bending when it is supported by the slit of the vertical wafer boat.
This is because the bending of the base body 1 causes irregularities in the base body 1 and stress concentration on the semiconductor wafer W. On the other hand, when the thickness of the base body 1 is 1.2 mm or more, the heat capacity of the base body 1 is large, so that heat distribution occurs in the surface of the semiconductor wafer when the furnace is put into the heat treatment furnace, and thermal stress increases. .

The upper surface of the base body 1 is the semiconductor wafer W.
Is formed into a concave curved surface as a supporting surface for supporting the surface of the base body 1, and the center of the concave curved surface is 0.1 to 0.
It is formed 2 mm lower. Thus, the center of the concave curved surface is 0.1 to 0.2 m from the outer edge of the upper surface of the base body 1.
By making the height lower by m, it is possible to avoid local stress concentration on the semiconductor wafer and uniformly support the entire surface of the semiconductor wafer.

It should be noted that slippage may occur if there is a convex portion on the surface of the concave curved surface of the base body, so it is desirable that the irregularities on the surface of the concave curved surface be within 0.1 mm.

The material of the base body 1 is a high-purity silicon single crystal, silicon polycrystal, polycrystalline silicon sintered body,
Quartz glass, silicon nitride, or a graphite material coated with silicon nitride may be used, but silicon of the same quality as that of the semiconductor wafer is more preferable. The silicon sintered body is obtained by pulverizing, molding and sintering granular polysilicon, has high strength and high purity, and has a gettering ability for metal impurities.

The lid 2 is made of the same material as the base body 1, and when combined with the hole 1a of the base body 1, the upper surface of the lid 2 is located on the same plane as the surface of the base body 1. Is desirable. However, as shown in FIG. 5, the upper surface of the lid body 2 is lower than the surface of the base body 1 within a height of 0.1 mm (0
If <S <0.1 mm), it can be used without any problem. When the lid body 2 is projected beyond the surface of the base body 1, stress may be locally concentrated on the semiconductor wafer W and slip may occur. Further, if the upper surface of the lid body 2 is lower than the surface of the base body 1 by 0.1 mm or more, heat unevenness may occur in the semiconductor wafer W and the quality may deteriorate. Therefore, the upper surface of the lid body 2 is lower than the surface of the base body 1 within 0.1 mm (0 <S <0.1 m
m) is desirable.

In order to prevent the lid body 2 from adhering to the semiconductor wafer W when the semiconductor wafer W is detached from the base body 1, the surface of the lid body 2 in contact with the semiconductor wafer W has a surface roughness of 0.2 μm. More preferably, it is 0.4 μm.

Next, a method of using the semiconductor wafer heat treatment jig A will be described. As shown in FIG. 1, this semiconductor wafer heat treatment jig A superposes the semiconductor wafers W outside the vertical wafer boat 3, and the superposed semiconductor wafer heat treatment jigs A are supported by the vertical wafer boat 3. Three
It is placed on the support portion 3b formed on a. After that, the vertical wafer boat 3 containing the semiconductor wafers is transported to a heat treatment furnace and subjected to a predetermined heat treatment.

Next, the superposition of the semiconductor wafer and the semiconductor wafer heat treatment jig and the taking out of the semiconductor wafer from the semiconductor wafer heat treatment jig will be described in detail. The semiconductor wafer heat treatment jig A was attached to the vertical wafer boat 3
Since the process after mounting on the supporting portion 3b formed on the support column 3a is the same as the conventional case, the description thereof will be omitted.

When the semiconductor wafer W and the semiconductor wafer heat treatment jig A are superposed on each other by using an automatic transfer device (not shown), the support pins 4a corresponding to the holes 1a of the base body 1 as shown in FIG. It is performed on the stage 4 provided with. Note that FIG.
As shown in FIG. 3, three support pins 4a are formed at positions corresponding to the holes 1a of the base body 4, and the support pins 4a are formed in a conical shape.

Next, the superposition of the semiconductor wafer and the semiconductor wafer heat treatment jig A will be described with reference to FIG.
As shown in (b), first, the substrate main body 1 is taken out from the cartridge in which the substrate main body 1 is stored by the transfer fork of the automatic transfer device, and placed on the stage 4. When the base body 1 is placed on the stage 4, the support pins 4a are inserted through the holes 1a of the base body 1 and the lid body 2 fitted in the holes 1a is inserted.
Is pushed up from the lower surface of the base body 1. Then, the lid 2 is removed from the base body 1 and placed on the support pins 4a. Since the lower surface of the lid body 2 is provided with the hole 2a into which the support pin 4a is inserted, the lid body 2 is formed by the base body 1
The lid 2 does not fall off from the support pin 4 even when it is removed from the support pin 4a and placed on the support pin 4a.

After that, as shown in FIG. 3C, the semiconductor wafer W is taken out by a transfer fork, placed on the lid body 2 placed on the support pins 4a, and then shown in FIG. When the transfer fork is inserted into the gap B shown and the base body 1 and the semiconductor wafer W are lifted, the base bodies 1 are in an overlapped state (FIG. 3 (d)). The lid body 2 is housed inside the hole 1a again with the lifting operation of the transfer fork. Then, the semiconductor wafer W and the base body 1 are maintained in an overlapping state and loaded on the vertical wafer boat.

On the other hand, when the semiconductor wafer W is detached from the base body 1, the operation is the reverse of the operation described above. That is,
When the semiconductor wafer W and the base body 1 that are overlapped with each other are placed on the stage 4, the lid body 2 is removed from the base body 1 and is positioned on the support pins 4a (FIG. 3C). After that, a transfer fork is inserted into the gap C, and the semiconductor wafer W is lifted and conveyed (FIG. 3B). After that, a transfer fork is inserted into the gap B, and the base body 1 is lifted and conveyed. When the base body 1 is lifted, the lid body 2 is housed inside the hole 1a again.

[0035]

EXAMPLES Examples of the present invention will be shown, but the present invention is not limited thereto. (Example) A jig for heat treatment of a semiconductor wafer (base body) corresponding to a heat treatment of 300 mm diameter silicon wafer was manufactured. The base body 1 is made of single crystal silicon and has a diameter of 300 mm and a thickness of 1.0 mm. Further, the base body 1 was provided with three holes 1a of about 10 mm in diameter for overlapping. The hole 1a has a tapered shape, and the lid 2 for closing the hole 1a is made of single crystal silicon in the same shape as the hole 1a.

The upper surface of the base body 1 is formed into a concave curved surface, and the center of the concave curved surface is closer to the outer edge of the upper surface of the base body 1.
It was formed to be 0.2 mm lower. In addition, the unevenness of the surface of the concave curved surface was set within 0.1 mm. Therefore, with respect to the upper surface of the lid body 2, from the surface of the base body 1,
The height was set within 0.1 mm (0 <S <0.1 mm).

The surface roughness of the lid 2 in contact with the wafer W is
0.2 μm, and the surface roughness of the upper surface of the base body 1 was set to 0.
It was set to 4 μm.

FIG. 1 shows the base body 1 thus constructed and the vertical wafer boat 3 on which the base body 1 is mounted. Further, the vertical wafer boat 3 is made of polycrystal silicon and is of a three-point support type, and a support portion 3b is provided on the column 3a so that the base body 1 can be mounted.

Then, using the base body 1 and the vertical wafer boat 3, the occurrence of slip due to heat treatment of a silicon wafer having a diameter of 300 mm was evaluated. The heat treatment is carried out at 700 ° C. in a furnace and the temperature is raised to 1200 ° C.
It was kept at 0 ° C for 2 hours, then cooled to 700 ° C, and taken out of the furnace.

Argon gas was used as the atmosphere in the furnace, 10 silicon wafers (Sample Nos. 1 to 10) were loaded in a vertical wafer boat, and 5 dummy wafers were loaded above and below this wafer. The wafer oxygen concentration is 1.25 to 1.
30 × 10 ¹⁸ atoms / cm ³ (old ASTM)
Is. The susceptibility to slipping varies depending on the wafer oxygen concentration, and the lower the enzyme concentration, the more likely slipping occurs. Enzyme concentration 1.30 × 10 ¹⁸ atoms / c
If it is less than m ³ , the condition is such that slipping is likely to occur.

The evaluation of the slip generated on the wafer was performed by X-ray topography observation. The X-ray used was MoKα1, accelerating voltage 60 kV, current 300 mA, and the diffraction surface was (22
0). The average length of the slips generated on the wafer was defined as the slip length. 10 wafers (Sample No. 1 to 1)
The results of slip evaluation of 0) are shown in Table 1. Observation of the back surface of the wafer revealed that no cloud was present on any of the wafers.

(Comparative Example) In order to compare with the example of the present invention, heat treatment was performed under the same conditions as those of the example, except that the base body was not provided with a lid (comparative example 1). After observing the back surface of the wafer after the heat treatment,
In each of the wafers, clouding was confirmed at a position corresponding to the hole in the base body.

Further, when the vertical wafer boat supporting four points directly supports the semiconductor wafer without using the base body (Comparative Example 2), the heat treatment was performed under the same conditions as in the Examples. In addition, slip evaluation was performed in the same manner as in the example, and the results are shown in Table 1.

Further, in the case of using a base body having no concave curved surface as a reference example, slip evaluation was performed in the same manner as in the example. The results are shown in Table 1.

[0045]

[Table 1]

From the results shown in Table 1, when the jig for heat treating a semiconductor wafer according to the present invention was used, the occurrence of slip was suppressed and a great improvement was observed.

In the above embodiment, the case where the number of holes formed in the main body of the base body is three has been described, but the present invention is not limited to this, and the holes can be formed in correspondence with the number of support pins. It may be three or more. Further, in the above-described embodiment, the case of being used for the vertical wafer boat has been described, but it is naturally applicable to a semiconductor wafer heat treatment jig such as a so-called susceptor.

[0048]

As is apparent from the above description, according to the present invention, it is possible to prevent the semiconductor wafer from slipping during the heat treatment, suppress the occurrence of partial haze, and prevent the appearance defect from occurring. A jig for use can be obtained.

[Brief description of drawings]

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

FIG. 2 is a stage for stacking a semiconductor wafer and a semiconductor wafer heat treatment jig,
Is a plan view and (b) is a side view.

FIG. 3 is a side view showing a step of stacking a semiconductor wafer and a semiconductor wafer heat treatment jig.

FIG. 4 is a schematic side view showing attachment / detachment of a lid of a base body.

FIG. 5 is a side cross-sectional view showing the relationship between the surface of the base body and the surface of the lid body.

[Explanation of symbols]

1 Base body 1a hole 2 lid 2a hole 3 Vertical wafer boat 3a prop 3b support 4 stages 4a Support pin A Semiconductor wafer heat treatment jig B gap C gap S height difference

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Mikiro Shimizu             Niigata Prefecture Kitabamura-gun Seiro-cho Higashiko 6-86-5             Niigata Toshiba Ceramics Co., Ltd. F-term (reference) 5F031 CA02 FA01 FA07 GA02 HA01                       HA05 HA07 HA33 HA61 MA30                       PA11 PA14 PA18                 5F045 DP19 EM09

Claims (5)

[Claims] 1. A jig for heat treatment of a semiconductor wafer, which is used during heat treatment of a semiconductor wafer, comprising a base body for supporting the semiconductor wafer on an upper surface thereof.
A jig for heat treating a semiconductor wafer, comprising at least three holes penetrating the base body, and a lid body fitted into the holes. 2. The base body is made of a thin plate, the hole penetrates along the axis of the base body in the directions of the upper and lower surfaces of the base body, and the lid body fitted into the hole is a lid body. The jig for heat treating a semiconductor wafer according to claim 1, wherein the jig for heat treatment of the semiconductor wafer is formed so as to be detached from the main body of the base body by the pushing force from the lower surface. 3. The material of the base body and the lid body is any one of silicon single crystal, silicon polycrystal, polycrystalline silicon sintered body, quartz glass, silicon nitride, and silicon nitride-coated carbon material. The semiconductor wafer heat treatment jig according to claim 1 or 2. 4. The base body has a diameter of 300 mm and a thickness of 0.8 to 1.2 mm, and an upper surface of the base body is formed into a concave curved surface as a support surface for supporting a wafer, and the center of the concave curved surface is the base body. From the outer edge of the upper surface, 0.1
The jig for heat treatment of a semiconductor wafer according to any one of claims 1 to 3, wherein the jig is formed to be lower by 0.2 mm. 5. The substrate body supporting the semiconductor wafer on the upper surface of the substrate body, and the substrate body supporting the semiconductor wafer,
The semiconductor wafer heat treatment jig according to any one of claims 1 to 4, wherein the jig is mounted on a supporting portion of a vertical wafer boat.