JP2000034184A - Part for oxidation treatment oven for soi substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a part that resists peeling off the SiO2 film that is formed on the thermal oxidation treatment and can prolong the acid cleaning cycle by providing the substrate of which at least periphery is composed of a dense SiC and a porous peeling-resistant layer made of silicon nitride that is formed on the surface of the substrate. SOLUTION: This part comprises (1) at least a substrate, preferably made of the bulk SiC formed by CVD technique, a sintered SiC having the SiC layer formed by the CVD technique, graphite on which a SiC film is formed by the CVD technique, or a SiC formed by oxidizing the Si impregnates into the base material where at least the peripheral part is formed with a dense SiC, and (B) a porous, peeling resistant layer 2, preferably having an open pore porosity of 5-30 vol.% and/or a layer thickness of 10-50 μm. Since the SiO2 film is deeply formed from the layer via the holes 2a to the inner depth to manifest the anchoring effect and is firmly fixed to the peeling-resistant layer 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a component for an SOI substrate thermal oxidation furnace for producing a substrate having an SOI structure by thermally oxidizing a Si wafer at a high temperature.

[0002]

2. Description of the Related Art In recent years, LSIs (large scale i
With the demand for higher integration, higher speed, and lower power consumption of SOI (Silicon on insulatin), the transistors constituting the LSI can be completely insulated and separated.
g) Structured substrates are attracting attention. In particular, SIMOX (se
A paration by implanted oxygen (substrate) substrate has attracted attention as a leading substrate among various SOI structures in that a thin Si layer and a buried SiO ₂ film having a uniform thickness can be obtained with high quality.

[0003] The above SIMOX substrate is formed by implanting oxygen ions into the inside of a Si wafer and then performing a high-temperature annealing treatment and a thermal oxidation treatment at a high temperature of 1300 ° C or more in a SOI substrate thermal oxidation furnace to form a SiO ₂ film. It is manufactured by. Therefore, quartz that softens at 1200 ° C. or more has a significantly reduced mechanical strength during thermal oxidation treatment.
iC or sintered SiC on which SiC is formed by a CVD method is used as a material of a structural member of a SIMOX substrate thermal oxidation treatment furnace.

[0004]

However, in the above-described conventional configuration, SiC is oxidized during the thermal oxidation treatment, and the SiC is oxidized.
Since SiO ₂ having different physical properties such as the coefficient of thermal expansion is deposited on the surface of the structural member, the thermal oxidation treatment is repeated.
As the film formation of iO ₂ progresses, the SiO ₂ film tends to peel off. When the SiO ₂ film is peeled, the peeled film pieces float in the furnace as particles and lower the cleanliness. Therefore, conventionally, the structural member of the SIMOX substrate thermal oxidation processing furnace is frequently subjected to acid cleaning. For example, measures such as removal of the SiO ₂ film are taken.

[0005] Recently, SC has been added to the surface of SiC.
By forming the i ₃ N ₄ film, S
A method of making it difficult to form an iO ₂ film has also been considered. However, even when the formation of the SiO ₂ film is difficult, even if the SiO ₂ film is formed even slightly, the film fragments easily peel off and float as particles in the furnace. As in the case (1), it is necessary to take measures to frequently remove the SiO ₂ film by acid cleaning or the like.

Accordingly, the present invention provides a method of forming an SI that is difficult to peel off the SiO ₂ film so that the period of acid cleaning can be lengthened.
An object of the present invention is to provide a component for an SOI substrate thermal oxidation processing furnace represented by a MOX substrate thermal oxidation processing furnace.

[0007]

Means for Solving the Problems In order to solve the above problems, a component for an SOI substrate thermal oxidation treatment furnace according to the present invention comprises: a base having at least an outer peripheral portion formed of dense silicon carbide; A porous separation preventing layer formed on the surface and made of silicon nitride.

According to the above configuration, as shown in FIG.
The constituent member 3 of the SOI substrate thermal oxidation processing furnace has many holes 2
The structure is such that the silicon nitride separation preventing layer 2 having a is formed on the surface of the base material 1. Therefore, the SOOX of a SIMOX substrate or the like
When the component 3 is present in an oxygen (O ₂ ) atmosphere at a temperature of 1300 ° C. or more during the thermal oxidation treatment of the I-substrate, the peeling prevention layer 2 of the component 3 that comes into contact with oxygen is oxidized and exposed to the outside. The SiO ₂ film 4 is formed on the entire surface of the separation preventing layer 2 including the hole 2a.

At this time, since the physical properties such as the coefficient of thermal expansion are different between SiO ₂ and silicon nitride, for example, as shown in FIG.
When O ₂ film 4 is formed, but will be SiO ₂ film piece is easily peeled off, in the present invention, as shown in FIG. 1, SiO ₂ film 4 a hole from the surface of the peeling prevention layer 2 An anchor effect acts between the SiO ₂ film 4 and the separation preventing layer 2 because it is formed deep inside through the portion 2a. As a result, the SiO ₂ film 4 is in a state of being firmly bonded to the separation preventing layer 2, so that even when the formation of the SiO ₂ film 4 proceeds to a considerable extent, the film pieces are separated and become particles in the furnace. Does not float, and as a result, the period of the acid cleaning of the SiO ₂ film 4 can be lengthened.

The base material is impregnated with bulk SiC formed by the CVD method, sintered SiC formed by the SiC film by the CVD method, graphite formed by the SiC film by the CVD method, and Si. Reaction SiC can be used. In addition, SiC can be mentioned as silicon carbide applicable to the base material. On the other hand, examples of silicon nitride applicable to the peeling prevention layer include Si ₃ N ₄ , Si ₂ N ₃ , and SiN.

The peel prevention layer has an open porosity of 5 to 30.
It is desirable that it be 10% by volume, preferably 10 to 20% by volume. The reason is that if the open porosity is less than 5% by volume,
When the anti-peeling layer is oxidized to form a SiO ₂ film, the formation of SiO ₂ around the hole is small, and the above-described anchor effect becomes insufficient, and the SiO ₂ film is sufficiently prevented from peeling. Because they can no longer do it. On the other hand, when the open porosity is 30% by volume or more, it is difficult to form the peeling prevention layer. The reason why the range of the open porosity of 10 to 20% by volume is particularly preferable is that if the range is within this range, the SiO ₂ film can be sufficiently prevented from peeling and the peel preventing layer can be easily formed. Because it can be.

Further, the peel prevention layer has a thickness of 10 to 50.
μm, preferably 20 to 40 μm. This is because if the thickness is less than 10 [mu] m, since the peeling preventing layer when the SiO ₂ film is formed by oxidation, the SiO ₂ film is not formed until deep inside through the hole, the above-mentioned This is because the anchoring effect becomes insufficient and the separation of the SiO ₂ film cannot be sufficiently prevented. On the other hand, if the layer thickness is 50 μm or more, it is not possible to obtain the effect of preventing peeling that is commensurate with an increase in the manufacturing cost of film formation. The reason why the range of the open porosity of 20 to 40 μm is particularly preferable is that if the range is within this range, the separation of the SiO ₂ film can be sufficiently prevented, and the separation preventing layer can be formed easily and at low cost. Because you can.

The peeling prevention layer is formed by coating a substrate with Si by a CVD method, heating the substrate in a nitrogen (N ₂ ) atmosphere, and converting the Si coating layer into Si ₃ N _4. Can be. This is because when the Si coating layer is converted to Si ₃ N ₄ while being heated to a high temperature, a part of the Si in the coating layer evaporates or the generated Si ₃ N ₄ is decomposed, so that it is formed there. It is considered that the voids left as holes having a predetermined aperture ratio.

As shown in FIG. 3, a SOI substrate thermal oxidation furnace using the above SOI substrate thermal oxidation furnace parts has a susceptor 12 on which a Si wafer 11 is mounted and a plurality of susceptors 12 which are detachable. Boat 13 to support
And a tube 14 for accommodating the susceptor 12 and the boat 13 as constituent members, and these constituent members are parts for a SOI substrate thermal oxidation treatment furnace. According to this configuration, when a thermal oxidation process is performed on the Si wafer 11 at 1300 ° C. or higher, the susceptor 12, the boat 13, and the tube 14 are oxidized, so that a SiO ₂ film is formed on the surface of these components. However, since the surface of the constituent member is formed of a porous silicon nitride peeling prevention layer, the SiO ₂ film is not easily peeled. As a result, the generation of particles due to the separation of the SiO ₂ film is sufficiently prevented.
The thermal oxidation treatment of the i-wafer 11 can be performed with high quality, and the cycle of acid cleaning of the constituent members can be lengthened.

[0015]

EXAMPLES The present invention will be described more specifically with reference to the following examples, but the embodiments of the present invention are not limited to the following examples.

Example 1 First, a bulk SiC formed by a CVD method was processed into a susceptor shape, and then the surface of the bulk SiC was coated with carbon.
Si was coated by VD method. Thereafter, by heating in a nitrogen (N ₂ ) atmosphere to convert the Si coating layer to Si ₃ N ₄ , a susceptor having a porous anti-peeling layer made of Si ₃ N _{4 on the} surface was produced. . Next, the open porosity of the peel prevention layer in the manufactured susceptor was measured by mercury porosimetry. The thickness of the anti-peeling layer was measured with a microscope. As a result, the open porosity was 5% by volume and the layer thickness was 30 μm. Further, the susceptor was placed in an oxygen atmosphere at 1390 ° C. (O ₂ : 60% by volume,
Ar: 40% by volume), and by observing the surface of the susceptor every hour, the time until the SiO ₂ film formed by the oxidation of Si ₃ N ₄ was peeled was measured. It was time.

Example 2 A susceptor was prepared in the same manner as in Example 1, and the open porosity and layer thickness of the peel-prevention layer were measured. The open porosity was 30% by volume and the layer thickness was 30 μm. Then, the susceptor was left in an oxygen atmosphere at 1390 ° C. in the same manner as in Example 1, and the time until the SiO ₂ film was peeled was measured to be 922 hours.

Example 3 A susceptor was prepared in the same manner as in Example 1, and the open porosity and the layer thickness of the anti-peeling layer were measured. The open porosity was 15% by volume and the layer thickness was 10 μm. The susceptor was left in an oxygen atmosphere at 1390 ° C. in the same manner as in Example 1 to measure the time until the SiO ₂ film was peeled off, and it was 872 hours.

Example 4 A susceptor was prepared in the same manner as in Example 1, and the open porosity and the layer thickness of the anti-peeling layer were measured. The open porosity was 15% by volume and the layer thickness was 50 μm. Then, the susceptor was left in an oxygen atmosphere at 1390 ° C. in the same manner as in Example 1 to measure the time until the SiO ₂ film was peeled off, and it was 1050 hours.

Comparative Example 1 Bulk SiC formed by the CVD method was formed in the shape of a susceptor, and the time until the SiO ₂ film was peeled off was left in an oxygen atmosphere at 1390 ° C. in the same manner as in Example 1. It was 290 hours when measured. The open porosity and the thickness of the bulk SiC formed by the CVD method were not measured because the bulk SiC was dense and did not have a separation preventing layer.

Comparative Example 2 Bulk SiC formed by the CVD method was
After being formed into a shape, the surface of this bulk SiC is_Four
And NH_ThreeBy reacting with_ThreeN_FourFrom
Was formed. And the open porosity of this coating layer
When the layer thickness was measured, the open porosity was 0% by volume and
And the layer thickness was 30 μm. After this, this susceptor
As in Example 1, it was left in an oxygen atmosphere at 1390 ° C.
T SiO _TwoThe time required for the film to peel was measured.
It was 325 hours.

Comparative Example 3 A susceptor was prepared in the same manner as in Example 1, and the open porosity and layer thickness of the peel-preventing layer were measured. The open porosity was 3% by volume and the layer thickness was 30 μm. And
The susceptor was left in an oxygen atmosphere at 1390 ° C. in the same manner as in Example 1 to measure the time until the SiO ₂ film was peeled off, and it was 530 hours.

Comparative Example 4 A susceptor was prepared in the same manner as in Example 1, and the open porosity and layer thickness of the anti-peeling layer were measured. The open porosity was 15% by volume and the layer thickness was 8 μm. And
The susceptor was left in an oxygen atmosphere at 1390 ° C. in the same manner as in Example 1 to measure the time until the SiO ₂ film was peeled off, and it was 540 hours.

Table 1 shows the results of the above measurements.

[0025]

[Table 1]

[0026]

As described above, the present invention relates to a base material having at least an outer peripheral portion formed of dense silicon carbide, and a porous separation preventing layer formed of silicon nitride formed on the surface of the base material. In the thermal oxidation treatment,
Even when the formation of the O ₂ film progresses to a considerable extent, the film pieces do not separate and do not float as particles in the furnace,
As a result, it is possible to lengthen the period of the acid cleaning of the SiO ₂ film.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a state in which a SiO ₂ film is formed on a porous separation preventing layer.

FIG. 2 is an explanatory diagram showing a state where a SiO ₂ film is formed on the surface of SiC.

FIG. 3 is a schematic configuration diagram of a SOI substrate thermal oxidation processing furnace.

[Explanation of symbols]

1 substrate 2 peel preventing layer 2a hole 3 component 4 SiO ₂ film 11 Si wafer 12 susceptor 13 Boats 14 tube

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Sadao Nakajima 3-19-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo F-term in Japan Telegraph and Telephone Co., Ltd.

Claims (5)

[Claims] 1. An SOI comprising: a base material having at least an outer peripheral portion formed of dense silicon carbide; and a porous anti-peeling layer formed on a surface of the base material and made of silicon nitride. Parts for substrate thermal oxidation furnace. 2. The base material is formed by bulk SiC formed by CVD, sintered SiC formed by SiC by CVD, graphite formed by SiC by CVD, or a reaction impregnated with Si. 2. The SOI substrate thermal oxidation furnace part according to claim 1, wherein the part is made of SiC. 3. The peel prevention layer has an open porosity of 5 to 30.
The component for a thermal oxidation treatment furnace for an SOI substrate according to claim 1 or 2, wherein the content is% by volume. 4. The peel prevention layer has a thickness of 10 to 50 μm.
4. The SOI substrate thermal oxidation furnace component according to claim 1, wherein m is m. 5. 5. The component for an SOI substrate thermal oxidation processing furnace according to claim 1, wherein the component is a susceptor for mounting a Si wafer in the SOI substrate thermal oxidation processing furnace, and the susceptor is a susceptor. A component for a SOI substrate thermal oxidation treatment furnace, which is a boat to be supported or a tube for accommodating the susceptor and the boat.