JP2001176760A - Dummy wafer and method of heat-treating the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dummy wafer which is mounted on a wafer boat in a semiconductor device manufacturing process and can secure sufficient mechanical strength for the suppression of deformation and a superior breakage resistance. SOLUTION: This dummy wafer has a reinforcing section 14 formed on at least one surface of its main body, having the same shape as that of a semiconductor wafer which is expected to be commercialized. The reinforcing section 14 comprises an annular circumference reinforcing section 18, which reinforces the circumferential section of the body and a radial section 16 which extends radially from the center of the body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a dummy wafer and a heat treatment method, and more particularly, to a dummy wafer mounted on a wafer boat in a semiconductor device manufacturing process, and a heat treatment method using the dummy wafer.

[0002]

2. Description of the Related Art In a manufacturing process of a semiconductor device, various heat treatments such as formation of an oxide film, CVD, and annealing are performed. As a method of such a heat treatment, a method of mounting a plurality of semiconductor wafers on a wafer boat made of quartz or silicon carbide (SiC) and carrying the semiconductor wafer into a diffusion furnace is known.

[0003] In the above-mentioned conventional technique, a plurality of semiconductor wafers are held in a wafer boat in a state of being vertically stacked at predetermined intervals. The semiconductor wafer is carried in that state into a reaction tube or the like and subjected to a heat treatment. At this time, the heat treatment conditions near the upper end and the lower end of the wafer boat are likely to be different from the heat treatment conditions near the center. For this reason, it is not always easy to perform heat treatment on the semiconductor wafer held near the upper or lower end of the wafer boat and the semiconductor wafer held near the center of the wafer boat.

As one of the methods for solving such a problem, a method is known in which a dummy wafer not intended for commercialization is mounted near the upper end and the lower end of a wafer boat. According to the method using a dummy wafer, it is possible to substantially uniformly perform heat treatment on all semiconductor wafers mounted on a wafer boat for the purpose of commercialization. Therefore, according to such a method, the yield related to the heat treatment can be increased.

Since the dummy wafer does not need to be made of a silicon wafer, it may be manufactured from a material other than a silicon wafer, for example, quartz, from an economic viewpoint.
In addition, conventionally, a dummy wafer has the same diameter as those semiconductor wafers because it is necessary to occupy space in a wafer boat as well as a semiconductor wafer intended for commercialization.
And it was formed so as to have the same thickness.

In recent years, the diameter of semiconductor wafers has been increased with the progress of semiconductor manufacturing technology, and semiconductor wafers having a diameter of 300 mm have been put into practical use. Semiconductor wafers having a diameter of 400 mm have also been studied. When the diameter of the dummy wafer is increased in this way, even if a material that is relatively resistant to heat is used, its mechanical strength relatively decreases,
There is a problem that the dummy wafer is deformed by its own weight during the heat treatment.

As a method of solving the above-mentioned problem, for example, it is conceivable to provide a dummy wafer with reinforcement for preventing deformation due to its own weight. As a structure for preventing deformation due to its own weight, for example, as shown in FIG. 12, it is conceivable to provide a reinforcing portion 2 which extends radially from the center of the dummy wafer 1 toward the peripheral edge thereof.

In the structural example shown in FIG. 12, three reinforcing portions 2 are provided at 120-degree intervals on the assumption that the wafer boat supports wafers at three wafer supporting portions. In addition, a notch 4 is provided at an end of the reinforcing portion 2 for engaging with the wafer supporting portion. When the dummy wafer 1 shown in FIG. 12 is mounted on a wafer boat such that the reinforcing portion 2 is supported by the wafer support portion, the weight of the dummy wafer 1 can be supported by the reinforcing portion 2. Therefore, FIG.
Is suitable for preventing deformation of the large-diameter dummy wafer.

[0009]

However, the dummy wafer may be pinched by tweezers or replaced in a groove of a predetermined storage cassette when the dummy wafer is replaced. In such a work, an impact is likely to be applied to a portion other than the reinforcing portion 2, that is, a portion having a small thickness. For this reason,
In the structure shown in FIG. 12, there is a problem that a portion other than the reinforcing portion 2 is easily damaged.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and a first object of the present invention is to provide a dummy wafer having mechanical strength sufficient to suppress deformation and excellent breakage resistance. And It is a second object of the present invention to provide a heat treatment method using the above-mentioned dummy wafer.

[0011]

According to a first aspect of the present invention, there is provided a dummy wafer mounted on a wafer boat used in a semiconductor wafer heat treatment apparatus together with a semiconductor wafer. A main body having the same shape as the wafer, and a reinforcing portion formed on at least one surface of the main body, wherein the reinforcing portion includes an annular circumferential reinforcing portion for reinforcing a circumferential portion of the main body. Features.

According to a second aspect of the present invention, in the dummy wafer according to the first aspect, the reinforcing portion is made of the same material as the main body, and is integrally formed with the main body. .

According to a third aspect of the present invention, there is provided the dummy wafer according to any one of the first and second aspects, wherein the circumferential reinforcing portion is provided with a plurality of cut portions at regular intervals. The thickness of the dummy wafer at the portion where the cut portion is provided is the same as the thickness of the main body.

According to a fourth aspect of the present invention, there is provided the dummy wafer according to any one of the first to third aspects, wherein the reinforcing portion extends radially from the central portion of the main body at equal angles. It is characterized in that it includes a radiating section.

According to a fifth aspect of the present invention, there is provided the dummy wafer according to any one of the first to third aspects, wherein the reinforcing portion is provided so as to be concentric with the circumferential reinforcing portion. It is characterized by including at least one annular reinforcement.

According to a sixth aspect of the present invention, in the dummy wafer according to any one of the first to third aspects, the reinforcing portion includes a central reinforcing portion for reinforcing a central portion of the main body. Features.

According to a seventh aspect of the present invention, there is provided a dummy wafer mounted together with a semiconductor wafer on a wafer boat used in a semiconductor wafer heat treatment apparatus, the main body having the same shape as the semiconductor wafer, and at least one of the main body. And a reinforcing portion formed on the surface of the main body, wherein the reinforcing portion partially overlaps a circumferential portion of the main body, and includes an arc-shaped outer peripheral wall that is recessed from the circumferential side of the main body to the center side. It is characterized by.

[0018] In order to achieve the second object, the present invention is directed to claim 8.
The described invention is a method for heat-treating a semiconductor wafer using a dummy wafer, comprising the steps of: mounting a dummy wafer together with a semiconductor wafer on a wafer boat used in a semiconductor wafer heat treatment apparatus; and Loading the semiconductor wafer into the reaction furnace; and heating the semiconductor wafer in the reaction furnace, wherein the dummy wafer is the dummy wafer according to any one of claims 1 to 7. .

[0019]

Embodiments of the present invention will be described below with reference to the drawings. Elements common to the drawings are denoted by the same reference numerals, and redundant description will be omitted.

Embodiment 1 FIG. 1A is a plan view of a dummy wafer 10 according to the first embodiment of the present invention.
(B) shows the AA 'sectional view. The dummy wafer 10 of the present embodiment is manufactured from a material such as quartz, for example, and has a diameter of 300 mm. Dummy wafer 10
Is provided with a thin plate portion 12 having the same thickness as a 300 mm silicon wafer usually has, and a reinforcing portion 14 provided on one surface of the thin plate portion 12. The reinforcing section 14 includes a radiating section 16 extending radially from the center of the dummy wafer 10 and a circumferential reinforcing section 18 for reinforcing the circumferential section of the dummy wafer 10.

FIG. 2 is a perspective view of a wafer boat 20 for holding the dummy wafer 10. The wafer boat 20 is made of quartz or SiC, and has a supporting column 22 and a supporting portion 24 for supporting a plurality of semiconductor wafers. The dummy boat 10 is mounted on the wafer boat 20 along with a plurality of semiconductor wafers 26 for commercialization. A predetermined number of dummy wafers 10 are mounted on the upper and lower portions of the wafer boat 20 so as to sandwich the semiconductor wafer 26 from above and below.

The semiconductor wafer 26 is loaded into a reaction furnace (not shown) while being mounted on the wafer boat 20. When the wafer boat 20 is carried into the reactor,
Its upper end enters the reactor prior to its center.
Further, the lower end of the wafer boat 20 enters the reaction furnace with a delay from the center. Due to such a difference in the approach time, a difference occurs in the heat treatment conditions between the vicinity of the upper end or lower end of the wafer boat 20 and the vicinity of the center thereof.

The semiconductor wafer 26 is mounted in a region where the heat treatment conditions are substantially uniform among all regions of the wafer boat 20. On the other hand, the dummy wafer 10 is mounted in an area (area near the upper end or near the lower end) where the heat treatment condition is different from that area (area near the center). By mounting the semiconductor wafer 26 and the dummy wafer 10 on the wafer boat 20 in this manner, the wafer boat 20
A uniform heat treatment can be applied to all the semiconductor wafers 26 mounted on the semiconductor device, and a high yield can be obtained.

The dummy wafer 10 includes a wafer boat 20
When mounted on a device, a stress due to its own weight acts. In the present embodiment, such a stress can be carried by the reinforcing portion 14. Therefore, according to the dummy wafer 10 of this embodiment, mechanical strength sufficient to sufficiently suppress deformation due to its own weight can be ensured regardless of the diameter of the semiconductor wafer 26 being increased.

In the present embodiment, the reinforcing portion 14 of the dummy wafer 10 has a circumferential reinforcing portion 1 surrounding the outer periphery thereof.
8 is provided. The outer peripheral portion of the dummy wafer 10 is a portion that is easily affected by an impact during a replacement operation or a cleaning operation. The circumferential reinforcing portion 18 can effectively protect the dummy wafer 10 from damage when such an impact is applied.
Therefore, according to the dummy wafer 10 of the present embodiment, excellent breakage resistance can be realized.

Embodiment 2 FIG. FIG. 3 shows a plan view of a dummy wafer 30 according to the second embodiment of the present invention. The dummy wafer 30 according to the present embodiment has the same structure as the dummy wafer 10 according to the first embodiment, except that the circumferential reinforcing portion 18 includes three cut portions 32. The notch 32 is formed so as to correspond to the support 24 of the wafer boat 20.
It is provided at equal intervals every °.

FIG. 4 shows a state where the dummy wafer 30 is held by the wafer boat 20. As shown in FIG. 4, the dummy wafer 30 is formed such that the cut portion 32 is on the lower side.
In addition, the cut portion 32 is stored in the wafer boat 20 so as to engage with the support portion 24. The thickness of the cut portion 32 is the normal thickness of the dummy wafer 12, that is, the thin plate portion 12.
Is the same as Therefore, according to the dummy wafer 30 of the present embodiment, the distance between the dummy wafer 30 and another wafer can be made equal to the distance between the semiconductor wafers 26.

Embodiment 3 FIG. 5A is a plan view of a dummy wafer 40 according to the third embodiment of the present invention.
(B) shows the AA 'sectional view. The dummy wafer 40 according to the present embodiment has the same structure as the dummy wafer 10 according to the first embodiment, except that the dummy wafer 40 includes a circumferential reinforcing portion 42 instead of the reinforcing portion 14 illustrated in FIG. Circumferential reinforcement 42
Is configured to reinforce the circumferential portion of the dummy wafer 40 in the same manner as the circumferential reinforcing portion 18 in FIG.

When the temperature of the heat treatment is 1100 ° C. or less, a radial reinforcing portion (corresponding to the radiating portion 16 in FIG. 1)
Without providing the peripheral reinforcement portion 42, the dummy wafer 40 can be provided with sufficient strength to prevent deformation due to its own weight. Further, according to the provision of the circumferential reinforcing portion 42, it is possible to ensure the same damage resistance as in the first embodiment. Further, since there is no need to provide a radial reinforcing portion, the dummy wafer 40 of the present embodiment can be more easily produced than the dummy wafer 10 of the first embodiment. Therefore, according to the structure of the present embodiment, 1
It can be used without deformation up to 100 ° C, shows excellent breakage resistance during replacement work and cleaning work, and
The dummy wafer 40 excellent in productivity can be realized.

Embodiment 4 FIG. 6 shows a plan view of a dummy wafer 50 according to the fourth embodiment of the present invention. The dummy wafer 50 according to the present embodiment has the same structure as the dummy wafer 40 according to the third embodiment except that three notches 52 are provided in the circumferential reinforcing portion 42. The notches 52 are provided at regular intervals of 120 ° so as to correspond to the supports 24 (see FIG. 4) of the wafer boat 20.

As in the case of the second embodiment, the dummy wafer 50 is formed so that the cut portion 32 is on the lower side, and
The cut portion 32 is housed in the wafer boat 20 so as to engage with the support portion 24 (see FIG. 4). Therefore, according to the dummy wafer 50 of the present embodiment, the space between the dummy wafer 50 and another wafer can be made equal to the space between the semiconductor wafers 26.

Embodiment 5 FIG. FIG. 7A is a plan view of a dummy wafer 60 according to the fifth embodiment of the present invention.
(B) shows the AA 'sectional view. The dummy wafer 60 according to the present embodiment has the same structure as the dummy wafer 10 according to the first embodiment except that the dummy wafer 60 includes a reinforcing portion 62 instead of the reinforcing portion 14 shown in FIG. The reinforcing portion 62 has an annular circumferential reinforcing portion 64 corresponding to the circumferential reinforcing portion 18 in FIG.
And an annular reinforcing portion (hereinafter, referred to as “annular reinforcing portion”) 66 provided inside the circumferential reinforcing portion 64.
The circumferential reinforcing portion 64 and the annular reinforcing portion 66 are provided so as to be concentric with each other.

According to the reinforcing portion 62 used in the present embodiment, a large reinforcing effect can be obtained as compared with the reinforcing portion 14 in the first embodiment. Therefore, according to the structure of the present embodiment, it is possible to obtain more excellent breakage resistance than in the case of the first embodiment. Dummy wafer 6 of the present embodiment
A value of 0 is particularly effective when the replacement or cleaning of the dummy wafer is frequently performed because of having such excellent damage resistance.

Embodiment 6 FIG. FIG. 8 shows a plan view of a dummy wafer 70 according to the sixth embodiment of the present invention. The dummy wafer 70 according to the present embodiment has the same structure as the dummy wafer 60 according to the fifth embodiment except that the circumferential reinforcing portion 64 includes three cut portions 72. The notches 72 are provided at regular intervals of 120 ° so as to correspond to the supports 24 (see FIG. 4) of the wafer boat 20.

As in the case of the second embodiment, the dummy wafer 70 is formed so that the cut portion 72 is on the lower side, and
The notch 72 is housed in the wafer boat 20 so as to engage with the support 24 (see FIG. 4). Therefore, according to the dummy wafer 70 of the present embodiment, the interval between the dummy wafer 70 and another wafer can be made equal to the interval between the semiconductor wafers 26.

By the way, the fifth and sixth embodiments described above.
In the embodiment, only one annular reinforcing portion 64 is provided inside the circumferential reinforcing portion 66. However, the present invention is not limited to this, and two or more annular reinforcing portions may be provided.

Embodiment 7 FIG. 9A is a plan view of a dummy wafer 80 according to the seventh embodiment of the present invention.
(B) shows the AA 'sectional view. The dummy wafer 80 of the present embodiment has the same structure as the dummy wafer 10 of the first embodiment, except that a dummy portion 80 is provided instead of the reinforcing portion 14 shown in FIG. The reinforcing portion 82 has an annular circumferential reinforcing portion 84 corresponding to the circumferential reinforcing portion 18 in FIG.
And a circular center reinforcing portion 86 provided at the center of the dummy wafer 80.

The dummy wafer that is heat-treated together with the semiconductor wafer 26 may be twisted due to thermal deformation. The dummy wafer having such a twist is difficult to restore even after annealing near the softening temperature of quartz.

When a thick portion (center reinforcing portion 86) is provided at the center of the dummy wafer 80 as in the structure of the present embodiment, the dummy wafer 80 can be moved to the center without the above-mentioned twisting. Is thermally deformed so as to depress. The recessed dummy wafer 80 can be used as it is by turning it over and mounting it on the wafer boat 20 thereafter. Further, such a depression is caused by the dummy wafer 8.
By turning over 0 and performing appropriate annealing, it can be easily eliminated. Therefore, according to the dummy wafer 80 of the present embodiment, a sufficiently long usable period can be secured.

Embodiment 8 FIG. FIG. 10 shows a plan view of a dummy wafer 90 according to the eighth embodiment of the present invention. The dummy wafer 90 according to the present embodiment has a notch 92 in the circumferential reinforcement 84.
, Except that it has three locations, and has the same structure as the dummy wafer 80 of the seventh embodiment. The notch 92
Corresponding to the support portions 24 of the wafer boat 20 (see FIG. 4), they are provided at regular intervals of 120 °.

As in the case of the second embodiment, the dummy wafer 90 is formed so that the cut portion 92 is on the lower side, and
The cut portion 92 is stored in the wafer boat 20 so as to engage with the support portion 24 (see FIG. 4). Therefore, according to the dummy wafer 90 of the present embodiment, the distance between the dummy wafer 90 and another wafer can be made equal to the distance between the semiconductor wafers 26.

In the first to eighth embodiments, the reinforcing portion is provided only on one surface of the dummy wafer. However, the present invention is not limited to this, and the reinforcing portion may be provided on both surfaces of the dummy wafer. It may be.

Embodiment 9 FIG. 11 shows a plan view of a dummy wafer 100 according to Embodiment 9 of the present invention. The dummy wafer 100 according to the present embodiment includes the reinforcing portion 1 instead of the reinforcing portion 14.
02, except that it has the same structure as the dummy wafer 10 of the first embodiment. The reinforcing portion 102 in the present embodiment includes a circular inner peripheral wall 104 surrounding the center of the dummy wafer 100 and an arc-shaped outer peripheral wall 106 recessed toward the center of the dummy wafer 100.

The inner peripheral wall 104 of the reinforcing portion 102 can be formed by grinding the vicinity of the center of the dummy wafer 100 into a circular shape. Further, the outer peripheral wall 106 of the reinforcing portion 102 is
It can be formed by grinding the vicinity of the periphery of the dummy wafer 100 into a fan shape. All of these grindings can be easily performed using general processing equipment for rotating the abrasive. Therefore, the dummy wafer 100 of the present embodiment is
Is easier to manufacture than the other dummy wafers described above.

The reinforcing portion 102 of the present embodiment reinforces the circumference of the dummy wafer 100 by about half, and also increases the radial strength of the dummy wafer 100. That is, the reinforcing portion 102 has both the advantages of the radiating portion 16 in the first embodiment and the advantages of the circumferential reinforcing portion 18. Therefore, the dummy wafer 100
Has an excellent effect that damage is less likely to occur in a process such as transportation, deformation is less likely to occur in a process such as heat treatment, and manufacturing is easy.

[0046]

Since the present invention is configured as described above, it has the following effects. Claim 1
According to the described invention, the provision of the circumferential reinforcing portion can enhance the breakage resistance of the dummy wafer. Therefore,
According to the present invention, handling of a dummy wafer is facilitated,
In addition, the usable period can be lengthened.

According to the second aspect of the present invention, since the reinforcing portion is integral with the main body, the dummy wafer can be easily manufactured. Further, according to the present invention, since the amount of thermal deformation of the main body and the reinforcing portion is the same, deformation of the dummy wafer during heating can be prevented.

According to the third aspect of the present invention, the gap between the dummy boat and other wafers is scheduled to be commercialized by engaging the supporting portion of the wafer boat with the notch provided in the reinforcing portion. Can be matched to the distance between the semiconductor wafers.

According to the fourth aspect of the present invention, the stress caused by the weight of the dummy wafer can be applied to the radiating portion of the reinforcing portion. Therefore, according to the present invention, the deformation of the dummy wafer due to its own weight can be effectively prevented.

According to the fifth aspect of the present invention, by providing at least one annular reinforcing portion inside the circumferential reinforcing portion,
The breakage resistance of the dummy wafer can be further improved.

According to the sixth aspect of the invention, the provision of the center reinforcing portion can effectively prevent the dummy wafer from being twisted. Thus, according to the present invention,
The usable period of the dummy wafer can be sufficiently lengthened.

According to the invention described in claim 7, the circumferential portion of the dummy wafer main body can be reinforced by the reinforcing portion, and the radial strength of the dummy wafer main body can be increased. Further, in the present invention, the outer peripheral wall of the reinforcing portion has an arc shape. For this reason, the dummy wafer of the present invention can be easily manufactured using general processing equipment.

According to the eighth aspect of the present invention, a heat treatment can be performed by setting a reinforced dummy wafer together with a semiconductor wafer in a wafer boat. The dummy wafer has sufficient mechanical strength and can suppress deformation due to its own weight during heating, so that stable heat treatment can be performed. Further, since the dummy wafer has excellent breakage resistance, the above heat treatment can be performed economically.

[Brief description of the drawings]

FIG. 1 is a front view and a side view of a dummy wafer according to a first embodiment of the present invention.

FIG. 2 is a perspective view of a wafer boat on which the dummy wafer shown in FIG. 1 is mounted.

FIG. 3 is a front view and a side view of a dummy wafer according to a second embodiment of the present invention.

FIG. 4 is a perspective view of a wafer boat on which the dummy wafer shown in FIG. 3 is mounted.

FIG. 5 is a front view and a side view of a dummy wafer according to a third embodiment of the present invention.

FIG. 6 is a front view of a dummy wafer according to a fourth embodiment of the present invention.

FIG. 7 is a front view and a side view of a dummy wafer according to a fifth embodiment of the present invention.

FIG. 8 is a front view of a dummy wafer according to a sixth embodiment of the present invention.

FIG. 9 is a front view and a side view of a dummy wafer according to a seventh embodiment of the present invention.

FIG. 10 is a front view of a dummy wafer according to an eighth embodiment of the present invention.

FIG. 11 is a front view of a dummy wafer according to a ninth embodiment of the present invention.

FIG. 12 is a front view of a conventional dummy wafer.

[Explanation of symbols]

10; 30; 40; 50; 60; 70; 80; 90 Dummy wafer 14; 62; 82; 102 Reinforcement part 16 Radiant part 18; 42; 64; 84 Circumferential reinforcement part 20 Wafer boat 22 Support pillar 24 Support part 26 Semiconductor Wafer 32; 52; 72; 92 Cut section 66 Annular reinforcing section 86 Center reinforcing section

Claims (8)

[Claims] 1. A dummy wafer mounted together with a semiconductor wafer on a wafer boat used in a semiconductor wafer heat treatment apparatus, the main body having the same shape as the semiconductor wafer, and a reinforcing portion formed on at least one surface of the main body. Wherein the reinforcing portion includes an annular circumferential reinforcing portion for reinforcing a circumferential portion of the main body. 2. The dummy wafer according to claim 1, wherein the reinforcing portion is made of the same material as the main body, and is formed integrally with the main body. 3. A plurality of cut portions are provided at equal intervals in the circumferential reinforcing portion, and a thickness of the dummy wafer in a portion where the cut portions are provided is the same as a thickness of the main body. The dummy wafer according to claim 1, wherein: 4. The dummy wafer according to claim 1, wherein the reinforcing portion includes a radiating portion extending radially from the center of the main body at equal angles. 5. The reinforcing member according to claim 1, wherein the reinforcing portion includes at least one annular reinforcing portion provided concentrically with the circumferential reinforcing portion. Dummy wafer. 6. The apparatus according to claim 1, wherein the reinforcing portion includes a center reinforcing portion for reinforcing a center portion of the main body.
The dummy wafer according to any one of the above items. 7. A dummy wafer mounted together with a semiconductor wafer on a wafer boat used in a semiconductor wafer heat treatment apparatus, the main body having the same shape as the semiconductor wafer, and a reinforcing portion formed on at least one surface of the main body. A dummy wafer, wherein the reinforcing portion partially overlaps a circumferential portion of the main body and includes an arc-shaped outer peripheral wall that is recessed from a circumferential side of the main body to a center side. 8. A method for heat treating a semiconductor wafer using a dummy wafer, comprising: mounting a dummy wafer together with a semiconductor wafer on a wafer boat used in a semiconductor wafer heat treatment apparatus; Loading the semiconductor wafer in the reaction furnace; and heating the semiconductor wafer in the reaction furnace, wherein the dummy wafer is the dummy wafer according to any one of claims 1 to 7. Heat treatment method.