JP2023096893A - Tray for insulating film forming apparatus, insulating film forming apparatus, and method for forming insulating film - Google Patents

Abstract

To provide a tray for an insulating film forming apparatus that makes it possible to form an insulating film only on the backside of a wafer without forming an insulating film on the wafer periphery.SOLUTION: A tray 1 for an insulating film forming apparatus has a tray body 11 on which semiconductor wafers are placed, and the tray body 11 has a cylindrical opening 11c penetrating from the top 11a to the bottom 11b of the tray body 11 and an annular support 11d located at the periphery of the opening 11c, which supports the outer periphery of the semiconductor wafer.SELECTED DRAWING: Figure 1

Description

The present invention relates to a tray for insulating film forming apparatus, an insulating film forming apparatus, and an insulating film forming method.

In recent years, in various semiconductor devices such as MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), DRAM (Dynamic Random Access Memory), power transistor and back-illuminated solid-state imaging device, silicon wafers such as silicon wafers is generally used as a substrate.

For example, an epitaxial silicon wafer is produced by placing the silicon wafer in a single-wafer epitaxial growth furnace, supplying a source gas such as dichlorosilane gas or trichlorosilane gas into the epitaxial growth furnace together with a carrier gas such as hydrogen gas, and growing the silicon wafer on the silicon wafer. It can be obtained by growing a silicon epitaxial layer.

By the way, in the case of forming an epitaxial layer with high resistivity on the front surface of a semiconductor wafer with low resistivity, dopant in the semiconductor wafer jumps out from the back surface of the semiconductor wafer into the gas phase and is incorporated into the epitaxial layer. So-called auto-doping is likely to occur. Therefore, prior to the growth of the epitaxial layer, an insulating film such as an oxide film is formed on the back surface of the semiconductor wafer as a protective film that suppresses autodoping (see, for example, Patent Document 1).

The insulating film can be formed by, for example, a chemical vapor deposition (CVD) method. For example, in the normal pressure CVD method in which CVD is performed at normal pressure, after placing a semiconductor wafer on a tray with the surface (that is, the back surface) on which an insulating film is to be formed facing upward, the semiconductor wafer is heated. The insulating film is formed on the back surface of the semiconductor wafer by supplying the raw material gas for the insulating film onto the semiconductor wafer.

In the above-described conventional method, the raw material gas for the insulating film reaches the outer edge of the front surface of the wafer, so the insulating film is formed not only on the back surface of the semiconductor wafer, but also on the wafer edge (end surface) and the outer edge of the front surface. be. On the other hand, when an epitaxial layer is formed on a semiconductor wafer in which an insulating film is formed on the outer periphery of the wafer from the outer edge of the back surface to the wafer edge and the outer edge of the front surface, cracks occur in the outer periphery of the wafer and the epitaxial layer becomes abnormal. Growth, so-called nodules, may occur. Therefore, when an insulating film is formed on the back surface of the wafer by the conventional method, the insulating film formed on the outer periphery of the wafer is then removed. The insulating film on the outer periphery of the wafer can be wiped off by a wiping method using a nozzle impregnated with a removing liquid such as hydrofluoric acid (HF) liquid.

WO2011/070741

When removing the insulating film on the outer periphery of the wafer by the above-mentioned wiping method, the removal liquid not only permeates the insulating film on the outer periphery of the wafer but also part of the insulating film on the back surface of the wafer, so-called "bleeding" may occur. There is If such bleeding occurs, the semiconductor wafer becomes a defective product and cannot be used as a substrate for an epitaxial wafer. Therefore, it is necessary to form an insulating film again after removing the formed insulating film once, and there is a problem that the productivity is lowered.

In order to prevent the occurrence of bleeding as described above, it is preferable to form an insulating film only on the back surface of the semiconductor wafer without forming the insulating film on the outer periphery of the semiconductor wafer.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide an insulating film forming apparatus capable of forming an insulating film only on the rear surface of a wafer without forming an insulating film on the outer periphery of the wafer. It is to provide a tray.

The present invention for solving the above problems is as follows.
[1] A tray for placing the semiconductor wafer in an insulating film forming apparatus for forming an insulating film on the back surface of a semiconductor wafer,
Equipped with a tray body on which a semiconductor wafer is placed,
The tray body is
a cylindrical opening penetrating from the upper surface to the lower surface of the tray body;
an annular support portion positioned at the periphery of the opening and supporting the outer peripheral portion of the semiconductor wafer;
A tray for an insulating film forming apparatus, comprising:

[2] The opening has a cylindrical first portion arranged on the lower surface side of the tray body and a cylindrical second portion arranged on the upper surface side and accommodating the semiconductor wafer. and the second portion has a central axis that is the same as the central axis of the first portion of the tray body and a diameter that is larger than the diameter of the first portion; The tray for an insulating film forming apparatus according to [1], wherein the peripheral edge of the portion 1 constitutes the support portion.

[3] further comprising an annular member disposed on the support portion of the tray body and having an inner diameter smaller than the diameter of the opening in the lower surface of the tray body;
The tray for an insulating film forming apparatus according to [1] or [2], wherein the supporting portion supports the outer peripheral portion of the semiconductor wafer via the annular member.

[4] An apparatus for forming an insulating film on the back surface of a semiconductor wafer,
The tray according to any one of [1] to [3];
a raw material gas supply unit disposed below the tray for supplying the raw material gas for the insulating film toward the back surface of the semiconductor wafer placed on the tray through the opening of the tray;
a heater disposed above the tray for heating the semiconductor wafer;
An insulating film forming apparatus comprising:

[5] further comprising an inert gas supply unit disposed above the tray and below the heater, and supplying an inert gas toward the front surface of the semiconductor wafer placed on the tray; The insulating film forming apparatus according to [4].

[6] comprising a plurality of trays;
The plurality of trays are continuously transported between the raw material gas supply unit and the inert gas supply unit so that the insulating film can be continuously formed on a plurality of semiconductor wafers. The insulating film forming apparatus according to [4] or [5], wherein

[7] A semiconductor wafer is placed on the tray of the insulating film forming apparatus according to any one of [4] to [6], and then the semiconductor wafer is placed between the source gas supply section and the heater. After the semiconductor wafer is placed between the semiconductor wafers, while the heater is heating the semiconductor wafer to a predetermined temperature, while supplying an inert gas, the raw material gas for the insulating film is supplied from the raw material gas supply unit to the semiconductor wafer. forming an insulating film on the back surface of the insulating film.

[8] After placing a semiconductor wafer on the tray of the insulating film forming apparatus according to [5], and then placing the semiconductor wafer between the source gas supply unit and the inert gas supply unit In a state in which the semiconductor wafer is heated to a predetermined temperature by the heater, the inert gas is supplied from the inert gas supply unit toward the front surface of the semiconductor wafer, and the raw material gas supply unit supplies the The method for forming an insulating film according to [7] above, wherein an insulating film is formed on the back surface of the semiconductor wafer by supplying a raw material gas for the insulating film.

[9] The method for forming an insulating film according to [7] or [8], wherein the semiconductor wafer is a silicon wafer.

[10] The insulating film forming method according to any one of [7] to [9], wherein the insulating film is an oxide film.

According to the present invention, the insulating film can be formed only on the back surface of the semiconductor wafer without forming the insulating film on the outer periphery of the semiconductor wafer.

1A is a top view and FIG. 1B is a cross-sectional view taken along line AA of FIG. FIG. 10 is a view showing another example of a tray for an insulating film forming apparatus according to the present invention, where (a) is a top view and (b) is a cross-sectional view taken along line AA of (a); FIG. 10 is a diagram showing still another example of the tray for the insulating film forming apparatus according to the present invention, (a) being a cross-sectional view, and (b) and (c) showing the relationship between the width of the annular member and the region where the insulating film is not formed. FIG. 4 is a diagram showing; It is a figure which shows a suitable example of the insulating film formation apparatus by this invention. It is a figure which shows the detail of the tray used for the example of an invention. It is a figure which shows the relationship between the position of the wafer radial direction of a silicon wafer, and the thickness of an oxide film.

(Tray for insulating film forming equipment)
Hereinafter, embodiments of the present invention will be described with reference to the drawings. The semiconductor wafer has a front surface, which is a flat surface on which devices are formed, a back surface, which is a flat surface opposite to the front surface, and the front surface and the back surface which are positioned radially outward of the wafer. It has a wafer edge connecting the outer edge of the front surface and the outer edge of the back surface. A tray for an insulating film forming apparatus according to the present invention is a tray on which a semiconductor wafer is placed in an insulating film forming apparatus for forming an insulating film on the back surface of a semiconductor wafer. A tray for an insulating film forming apparatus has a tray body on which a semiconductor wafer is placed. Here, the tray body is characterized by having a cylindrical opening penetrating from the upper surface to the lower surface of the tray body, and an annular supporting portion positioned at the periphery of the opening and supporting the outer peripheral portion of the semiconductor wafer. do.

As described above, in the conventional insulating film forming apparatus, the surface on which the insulating film is to be formed, i.e., the back surface side, is placed on the tray facing upward, and the raw material gas is supplied from above the wafer to insulate the back surface of the wafer. form a film. At that time, an insulating film is formed not only on the back surface of the wafer but also on the edge surface and the front surface of the wafer. The insulating film formed on the outer periphery of the wafer from the outer edge of the back surface to the edge of the wafer and the outer edge of the front surface causes nodules and must be removed.

The inventors of the present invention have diligently studied ways to form an insulating film only on the rear surface of the wafer while suppressing the formation of the insulating film on the outer periphery of the wafer as described above. In the process, focusing on the tray on which the semiconductor wafer is placed, a cylindrical opening is provided through the tray, the semiconductor wafer is placed so as to close this opening, and the outer periphery of the wafer is formed at the peripheral edge of the opening. I decided to support the department. Then, as shown in Examples to be described later, it was found that by using the tray as described above, an insulating film can be formed only on the rear surface of the wafer without forming an insulating film on the outer peripheral portion of the wafer. I completed it. Hereinafter, the tray for insulating film forming apparatus according to the present invention will be described in detail.

FIG. 1 shows an example of a tray for an insulating film forming apparatus according to the present invention, where (a) is a top view and (b) is a sectional view taken along the line AA of (a). The insulating film forming apparatus tray 1 shown in FIG. 1 includes a tray main body 11 that constitutes the base of the tray. Both the upper surface 11a and the lower surface 11b of the tray body 11 are flat. The tray body 11 also has a cylindrical opening 11c penetrating from the upper surface 11a to the lower surface 11b, and a supporting portion 11d located on the periphery of the opening 11c on the upper surface 11a and supporting the semiconductor wafer.

When a semiconductor wafer is placed on the tray 1 having such a structure, the rear surface of the wafer on which the insulating film is formed faces downward, and the peripheral portion of the semiconductor wafer is supported by the supporting portion 11d around the opening 11c. A semiconductor wafer is placed on the As described above, since the upper surface 11a of the tray body 11 is flat, the upper surface of the support portion 11d is also flat. Therefore, the upper surface 11a of the tray body 11 is in surface contact with the peripheral portion of the back surface of the semiconductor wafer.

When the tray 1 on which the semiconductor wafers are placed as described above is viewed from below, the rear surface of the semiconductor wafers is exposed, while the outer peripheral portion of the wafers is masked by the support portion 11d of the tray body 11 . Therefore, when the raw material gas for the insulating film is supplied from below the tray 1, the raw material gas is supplied only to the area of the back surface of the wafer exposed by the opening 11c, and is not supplied to the outer periphery of the wafer. As a result, the insulating film can be formed only on the rear surface of the wafer without forming the insulating film on the outer periphery of the wafer.

The tray body 11 is preferably made of a material that has heat resistance and deformation resistance against the temperature at which the insulating film is formed and that does not contaminate the semiconductor wafer. For example, the tray body 11 can be made of sintered silicon carbide or of sintered silicon carbide coated with a silicon carbide film.

The size of the tray main body 11 can be appropriately set according to the diameter and number of semiconductor wafers to be placed, the material constituting the tray main body 11, and the like.

As described above, the opening 11c defines a region where an insulating film is formed on the rear surface of the wafer when the semiconductor wafer is placed. The diameter of the opening 11c depends on the diameter of the semiconductor wafer to be mounted and the size (width) of the peripheral region where the insulating film is not formed, but is preferably smaller than the diameter of the semiconductor wafer by 2 mm or more and 6 mm or less.

Although only one opening 11c is provided in the tray 1 shown in FIG. It can also be used as an equipment tray.

FIG. 2 shows another example of a tray for an insulating film forming apparatus according to the present invention, where (a) is a top view and (b) is a sectional view taken along the line AA of (a). The tray 2 for an insulating film forming apparatus shown in FIG. 2 includes a tray body 21 constituting a base body of the tray 2 in the same manner as the tray 1 shown in FIG. Flat. The tray body 21 has a cylindrical opening 21c penetrating from the upper surface 21a to the lower surface 21b. The opening 21c has a cylindrical first portion 21d arranged on the side of the lower surface 21b of the tray body 21 and a cylindrical second portion 21e arranged on the side of the upper surface 21a to accommodate the semiconductor wafer. and The second portion 21e is defined by the sidewall S and the bottom portion B, the second portion 21e has the same central axis as the central axis of the first portion 21d and It has a diameter larger than the diameter. At least part of the bottom portion B, which is the peripheral edge of the first portion 21d, constitutes the support portion 21f.

The tray 2 having such a configuration accommodates the semiconductor wafers forming the insulating film in the second portion 21e, so that the semiconductor wafers can be better held, and the semiconductor wafers can be better aligned. can.

The diameter of the second portion 21e of the tray body 21 depends on the diameter of the semiconductor wafer to be accommodated, but is larger than the diameter of the semiconductor wafer, and the difference between the diameter of the second portion 21e and the diameter of the semiconductor wafer is 2 mm or more. It is preferably 6 mm or less. This allows the semiconductor wafer to be better held in better alignment. The depth of the second portion 21e is preferably designed such that the depth of the first portion 21d is 1 mm or more and 2 mm or less. Thereby, the semiconductor wafer can be held better.

Other configurations of the tray 2 may be the same as those of the tray 1 shown in FIG.

When a semiconductor wafer is placed on the tray 2 having such a configuration, the back side of the wafer on which the insulating film is formed is directed downward and accommodated in the second portion 21e. A semiconductor wafer is placed so that the outer periphery of the wafer is supported by 21f. As a result, the upper surface of the support portion 21f of the tray body 21 is in surface contact with the peripheral portion of the back surface of the semiconductor wafer, and the peripheral portion of the wafer is masked by the support portion 21f.

When the raw material gas for the insulating film is supplied from below the tray 2 on which the semiconductor wafer is placed, the raw material gas is supplied only to the area of the back surface of the wafer exposed by the first portion 21d, and is not supplied to the outer periphery of the wafer. . As a result, the insulating film can be formed only on the rear surface of the wafer without forming the insulating film on the outer periphery of the wafer.

FIG. 3 shows still another example of the tray for the insulating film forming apparatus according to the present invention, (a) being a cross-sectional view, (b) and (c) showing the width of the annular member and the area where the insulating film is not formed. is a diagram showing the relationship of The tray 3 shown in FIG. 3 is mounted on the support portion 21f of the tray 2 shown in FIG. An annular member 22 having an inner diameter is arranged. Both the upper surface 22a and the lower surface 22b of the annular member 22 are flat. In the tray 3 shown in FIG. 3, the diameter of the first portion 21d is smaller than the diameter of the semiconductor wafer W, but the inner diameter of the annular member 22 is smaller than the diameter of the semiconductor wafer. If so, the diameter of the first portion 21d may be the same as or larger than the diameter of the semiconductor wafer W.

When a semiconductor wafer is placed on the tray 3 having such a configuration, the semiconductor wafer is placed on the annular member 22 with the back side of the wafer facing downward and housed in the second portion 21e. Then, the upper surface 22a of the annular member 22 comes into surface contact with the peripheral portion of the back surface of the semiconductor wafer.

When the raw material gas for the insulating film is supplied from below the tray 3, since the inner diameter of the annular member 22 is smaller than the diameter of the first portion 21d, the outer peripheral portion of the wafer is masked by the annular member 22. Only the area of the back surface of the wafer exposed by the opening 22c of the annular member 22 is supplied. As a result, the insulating film can be formed only on the rear surface of the wafer without forming the insulating film on the outer periphery of the wafer.

Since the inner diameter of the annular member 22 is smaller than the diameter of the first portion 21d of the tray body 21, by changing the inner diameter of the annular member 22, the size of the region where the insulating film is formed on the back surface of the semiconductor wafer can be easily adjusted. can be changed to Specifically, as shown in FIG. 3B, when the diameter of the opening 22c of the annular member 22 (that is, the inner diameter of the annular member 22) is relatively large, the area where the insulating film is not formed becomes small. . On the other hand, as shown in FIG. 3C, when the diameter of the opening 22c of the annular member 22 (that is, the inner diameter of the annular member 22) is relatively small, the region where the insulating film is not formed becomes large.

The inner diameter of the annular member 22 can be appropriately set according to the region where the insulating film is formed, and is not particularly limited. On the other hand, the outer diameter of the annular member 22 is preferably 2 mm or more smaller than the diameter of the second portion 21e and 1 mm or more larger than the diameter of the first portion 21d.

The annular member 22 is preferably made of a material that has heat resistance and deformation resistance against the temperature at which the insulating film is formed and that does not contaminate the semiconductor wafer. For example, the annular member 22 can be made of sintered silicon carbide or sintered silicon carbide coated with a silicon carbide film.

The tray 3 shown in FIG. 3 is configured as a tray in which the annular member 22 is arranged on the support portion 21d of the tray 2 shown in FIG. It can also be configured as a tray with an annular member 22 disposed thereon. At that time, if the inner diameter of the annular member 22 is smaller than the diameter of the semiconductor wafer W, the diameter of the opening 11c need not be smaller than the diameter of the semiconductor wafer W. It may be configured to be the same as or larger than the diameter.

(insulating film forming device)
An insulating film forming apparatus according to the present invention is an apparatus for forming an insulating film on the back surface of a semiconductor wafer, and includes a tray for the insulating film forming apparatus according to the present invention described above, and a material gas for the insulating film disposed below the tray. A raw material gas supply unit for supplying raw material gas to the back surface of a semiconductor wafer placed on the tray through the opening of the tray, and a heater arranged above the tray for heating the semiconductor wafer. do.

FIG. 4 shows a preferred example of an insulating film forming apparatus according to the present invention. The insulating film forming apparatus 100 shown in FIG.

The tray 2 is the tray 2 according to the present invention shown in FIG. 2, and the details thereof have already been explained, and therefore are omitted. A transport roller 2a is provided below the tray 2 so that the tray 2 can be transported.

The raw material gas supply unit 4 is arranged below the tray 2 and supplies the raw material gas for the insulating film to the rear surface of the semiconductor wafer W placed on the tray 2 through the opening 21c (first portion 21d) of the tray 2. supply towards In the example shown in FIG. 4, silane (SiH ₄ ) and oxygen gas (O ₂ ), which are source gases for forming a silicon oxide film, are supplied. It can also be configured to supply other raw material gases so as to form a film.

Further, as shown in FIG. 4, the raw material gas supply unit 4 supplies an inert gas such as nitrogen or a rare gas so as to surround the raw material gas in order to reduce the contamination of the raw material gas with impurities. It is preferable to configure

The heater 6 is arranged above the tray 2 and heats the semiconductor wafer W to a temperature at which the raw material gas supplied to the back surface of the semiconductor wafer W is decomposed and an insulating film is formed on the back surface of the semiconductor wafer W.

Also, as shown in FIG. 4, an inert gas is placed above the tray 2 and below the heater 6 to supply the inert gas toward the front surface of the semiconductor wafer W placed on the tray 2. Preferably, a feeder 5 is provided. As a result, even when the semiconductor wafer W is pressed downward when the insulating film is formed and the raw material gas is supplied to the rear surface of the semiconductor wafer W by the raw material gas supply unit 4, the semiconductor wafer W is prevented from floating. be able to.

Here, the operation of the insulating film forming apparatus 100 will be described. First, on the tray 2, the semiconductor wafer W is placed in the second portion 21e with the back surface side on which the insulating film is formed facing downward, and the first portion 21d is closed and the peripheral edge of the first portion 21d is covered. The support portion 21f is placed so as to support the peripheral portion of the semiconductor wafer.

Next, the tray 2 is arranged above the source gas supply section 4 and below the inert gas supply section 5 . Subsequently, after the semiconductor wafer W is heated to a predetermined temperature by the heater 6 , the raw material gas for the insulating film is supplied from the raw material gas supply unit 5 while supplying the inert gas from the inert gas supply unit 5 to the opening of the tray 2 . It is supplied toward the back surface of the semiconductor wafer W via the portion 21c (first portion 21d). Thus, the insulating film can be formed on the back surface of the semiconductor wafer W without forming the insulating film on the outer peripheral portion of the semiconductor wafer W. FIG.

In addition, it is preferable that the insulating film forming apparatus 100 includes a plurality of trays 2 and is configured to continuously transport the plurality of trays 2 between the source gas supply unit 4 and the inert gas supply unit 5 . . Thereby, the insulating film can be formed on a plurality of semiconductor wafers W continuously.

(Insulating film forming method)
In the method for forming an insulating film according to the present invention, a semiconductor wafer is placed on the tray for the insulating film forming apparatus according to the present invention, then the semiconductor wafer is placed between the source gas supply unit and the heater, and then the semiconductor is heated by the heater. The insulating film is formed on the back surface of the semiconductor wafer by supplying the raw material gas for the insulating film from the raw material gas supply unit while the wafer is heated to a predetermined temperature.

An example of the method for forming an insulating film according to the present invention will be described below using the preferred insulating film forming apparatus 100 according to the present invention shown in FIG. 4 as an example. First, on the tray 2, the semiconductor wafer W is placed in the second portion 21e with the back surface side on which the insulating film is formed facing downward, and the first portion 21d is closed and the peripheral edge of the first portion 21d is covered. The support portion 21f is placed so as to support the peripheral portion of the semiconductor wafer.

The semiconductor wafer W is not particularly limited, and may be a silicon wafer, a germanium wafer, a silicon carbide wafer, a gallium arsenide wafer, or the like. In particular, as the semiconductor wafer W, a silicon wafer can be suitably used.

Also, the insulating film is not particularly limited, but may be an oxide film, a nitride film, or the like. For example, in the case of an epitaxial silicon wafer in which a silicon epitaxial layer is formed on a silicon wafer, the oxide film can be a silicon oxide film or a silicon nitride film.

Next, the tray 1 is arranged above the source gas supply section 4 and below the inert gas supply section 5 .

Subsequently, after the semiconductor wafer W is heated to a predetermined temperature by the heater 6 , the raw material gas for the insulating film is supplied from the raw material gas supply unit 4 while supplying the inert gas from the inert gas supply unit 5 to the tray 2 . is supplied toward the back surface of the semiconductor wafer W through the opening 21c (first portion 21d). The temperature of the semiconductor wafer during the formation of the insulating film depends on the type of insulating film to be formed. is preferred.

As the raw material gas supplied from the raw material gas supply unit 4, an appropriate gas can be used according to the raw material of the insulating film. For example, when the insulating film is a silicon oxide film, SiH ₄ gas and O ₂ gas can be used as source gases. Also, when the insulating film is a silicon nitride film, SiH ₄ gas and N ₂ gas or ammonia (NH ₃ ) gas can be used.

As the inert gas supplied from the inert gas supply unit 5, N ₂ gas, rare gas, or the like can be used.

Thus, the insulating film can be formed on the back surface of the semiconductor wafer W without forming the insulating film on the outer peripheral portion of the semiconductor wafer W. FIG.

Examples of the present invention will be described below, but the present invention is not limited to these examples.

(Invention example)
A silicon oxide film was formed only on the back surface of the silicon wafer using the insulating film forming apparatus 100 shown in FIG. 4 having the tray 2 shown in FIG. Details of the dimensions of the tray 2 are shown in FIGS. 5(a) and (b).

Specifically, first, a silicon wafer having a diameter of 200 mm is prepared and accommodated in the second portion 21e with the back surface side on which an insulating film is formed facing downward to close the first portion 21d. The peripheral portion of the silicon wafer was placed so as to be supported by the supporting portion 21f on the peripheral edge of 21d.

Next, the tray 2 was placed above the source gas supply section 4 and below the inert gas supply section 5 of the insulating film forming apparatus 100 .

Subsequently, the silicon wafer was heated to 450° C. by the heater 6 and held, and SiH ₄ gas and O ₂ gas were supplied from the source gas supply unit 4 while N ₂ gas was supplied from the inert gas supply unit 5. . In this way, a silicon oxide film was formed only in a region with a diameter of 196 mm from the center on the back surface of the silicon wafer.

(conventional example)
As in Invention Example 1, a silicon oxide film was formed on the back surface of the silicon wafer. However, the formation of the silicon oxide film was performed using the apparatus described in Patent Document 1, and as a result, the silicon oxide film was formed on the rear surface and the peripheral portion of the silicon wafer.

<Evaluation of thickness of oxide film>
The thickness of the formed oxide film was measured for the silicon wafers of the invention example and the conventional example. Specifically, using a film thickness measuring device (Nanospec 8000XSE manufactured by NANOMETRICS), as shown in FIG. The thickness of the oxide film was measured at a position of 99 mm in the radial direction of the wafer. The obtained measurement results are shown in FIG.

As is clear from FIG. 6, in the conventional example, an oxide film having a thickness of about 3500 Å is formed over the entire silicon wafer. On the other hand, in the invention example, the thickness of the oxide film at the position 99 mm from the center is zero, and it can be seen that the oxide film can be formed only on the back surface of the wafer without forming the oxide film on the outer periphery of the wafer. .

INDUSTRIAL APPLICABILITY According to the present invention, the insulating film can be formed only on the rear surface of the wafer without forming the insulating film on the outer periphery of the wafer, which is useful in the semiconductor wafer manufacturing industry.

1, 2, 3 Tray 2a Conveying roller 4 Source gas supply unit 5 Inert gas supply unit 6 Heaters 11, 21 Tray bodies 11a, 21a Upper surfaces 11b, 21b Lower surfaces 11c, 21c Openings 11d, 21f Support 21d First portion 21e second portion 22 annular member 21a upper surface 21b of annular member lower surface 21c of annular member opening B of annular member bottom S side wall W semiconductor wafer

Claims (10)

A tray for mounting the semiconductor wafer in an insulating film forming apparatus for forming an insulating film on the back surface of a semiconductor wafer,
Equipped with a tray body on which a semiconductor wafer is placed,
The tray body is
a cylindrical opening penetrating from the upper surface to the lower surface of the tray body;
an annular support portion positioned at the periphery of the opening and supporting the outer peripheral portion of the semiconductor wafer;
A tray for an insulating film forming apparatus, comprising: The opening has a cylindrical first portion arranged on the lower surface side of the tray body and a cylindrical second portion arranged on the upper surface side and accommodating the semiconductor wafer. , the second portion has a central axis that is the same as the central axis of the first portion of the tray body and has a diameter larger than that of the first portion; 2. The tray for an insulating film forming apparatus according to claim 1, wherein the peripheral edge of the tray constitutes the support portion. further comprising an annular member disposed on the support portion of the tray body and having an inner diameter smaller than the diameter of the opening at the lower surface of the tray body;
3. The tray for an insulating film forming apparatus according to claim 1, wherein said supporting portion supports an outer peripheral portion of said semiconductor wafer via said annular member. An apparatus for forming an insulating film on the back surface of a semiconductor wafer,
A tray according to any one of claims 1 to 3;
a raw material gas supply unit disposed below the tray for supplying the raw material gas for the insulating film toward the back surface of the semiconductor wafer placed on the tray through the opening of the tray;
a heater disposed above the tray for heating the semiconductor wafer;
An insulating film forming apparatus comprising: 5. An inert gas supply unit disposed above said tray and below said heater for supplying an inert gas toward the front surface of said semiconductor wafer placed on said tray. The insulating film forming apparatus according to 1. comprising a plurality of said trays,
The plurality of trays are continuously transported between the raw material gas supply unit and the inert gas supply unit so that the insulating film can be continuously formed on a plurality of semiconductor wafers. 6. The insulating film forming apparatus according to claim 4 or 5, wherein: After placing a semiconductor wafer on the tray of the insulating film forming apparatus according to any one of claims 4 to 6, and then placing the semiconductor wafer between the source gas supply unit and the heater, The insulating film is formed on the back surface of the semiconductor wafer by supplying the raw material gas for the insulating film from the raw material gas supply unit while the semiconductor wafer is heated to a predetermined temperature by the heater. Membrane formation method. A semiconductor wafer is placed on the tray of the insulating film forming apparatus according to claim 5, and after the semiconductor wafer is placed between the source gas supply section and the inert gas supply section, the heater While the semiconductor wafer is heated to a predetermined temperature, the inert gas is supplied from the inert gas supply unit toward the front surface of the semiconductor wafer, and the raw material for the insulating film is supplied from the raw material gas supply unit. 8. The method of forming an insulating film according to claim 7, wherein the insulating film is formed on the back surface of the semiconductor wafer by supplying gas. 9. The method of forming an insulating film according to claim 7, wherein said semiconductor wafer is a silicon wafer. 10. The insulating film forming method according to claim 7, wherein said insulating film is an oxide film.

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