TW201700767A - Thermo-resistant substrate and method for manufacturing same Part or the entire surface of the substrate is covered with thermal decomposed boron nitride film - Google Patents

Abstract

The present invention is to provide a thermo-resistant substrate having a structure which is coated with a highly anti-corrosive and thermally decomposable boron nitride film. The thermo-resistant substrate of the present invention has a structure in which the entire or part of the substrate surface is covered with the thermal decomposable boron nitride film, and the thermo- resistant substrate is characterized in that: the aforementioned thermally decomposable boron nitride film comprises more than 0.001 atom% and less than 3 atom% of oxygen. The aforementioned oxygen-containing thermally decomposable boron nitride film may be produced by a chemical vapor deposition method using a gas containing nitrogen atoms and a gas containing borosn atom supplemented with a gas containing oxygen atoms.

Description

Heat resistant substrate and method of manufacturing same

The present invention relates to a heat resistant substrate, and more particularly to a heat resistant substrate having a structure coated with a thermally decomposed boron nitride film.

Thermal decomposition of boron nitride (hereinafter sometimes referred to as "PBN" (Pycolytic Boron Nitride) is produced by, for example, chemical vapor deposition (CVD) method, and is high in insulation and high in heat resistance. Sexual, flexible material. Regarding the production of PBN by a thermal CVD method, a method is known in which a gas containing a B (boron) atom is reacted with a gas containing an N (nitrogen) atom at a high temperature of 1800 to 2000 ° C, and is deposited in a Heating on the object. As the gas to be used, for example, boron trichloride and ammonia are used. Since a high temperature of 1800 ° C or higher is required, a graphite-based jig and a heat insulating material having high heat resistance are generally used as the furnace material of the CVD furnace. PBN is widely used as a catalyst for semiconductor semiconductor lifting, a metal evaporation for molecular beam epitaxy, a ruthenium oxide synthesis ruthenium, and a metal organic chemical vapor deposition (Metal Organic Chemical Vapor) because of its excellent properties such as high heat resistance and strength. Deposition, MOCVD) A fixture such as a fixture. In recent years, corrosive gases such as H ₂ and NH ₃ have been used in MOCVD apparatuses, but PBN has high resistance to such gases, which is also characteristic of PBN.

When a PBN material of this nature is coated on a heat-resistant substrate, the substrate can be used at a high temperature even in a corrosive environment such as H ₂ or NH ₃ . It can be used, for example, for fixtures and heaters.

In the MOCVD apparatus, a heater including a metal wire including tungsten or tantalum, or a heater obtained by coating PBN on carbon, or a heating capable of heating to a temperature of about 1300 to 1500 ° C is used. Device. A heater made of tungsten or tantalum has high resistance to H ₂ and NH ₃ , but has a problem that the metal oxide is evaporated as an impurity or the temperature distribution of the object to be heated is poor. On the other hand, a heater in which carbon is coated with PBN does not evaporate impurities and has a good temperature distribution. However, if it is used for a long time for NH ₃ , local corrosion occurs. If such localized corrosion continues to develop, there is a problem that pores appear in the PBN coating layer, and internal carbon is consumed by H ₂ and NH ₃ .

Although the cause of local corrosion is not known, it is generally considered that corrosion may be caused by a trace amount of moisture (H ₂ O) contained in NH ₃ or a trace amount of moisture attached to the apparatus.

Patent Document 1 describes that the PBN coating layer which is vapor-deposited is annealed at a temperature of 1750 to 2000 ° C to impart water resistance and does not cause deterioration of PBN coating properties. influences. Although it is described that the annealed sample is not resistant to water of 95 to 100 ° C, no detailed information is attached thereto, and no mention is made regarding the resistance to water vapor and NH ₃ in high temperature.

Further, in Patent Document 2, it is described that the high-density PBN of 2.19 to 2.2 g/cm ³ is coated on the graphite body to lower the reactivity with molten aluminum, but the water resistance and NH ₃ resistance at high temperatures are high. , did not make any statement. Further, the reaction temperature is set to 1950 to 2000 ° C to produce a high-density PBN, but it is also necessary to consider the influence of the consumption of the graphite-based furnace material used in the reactor under such conditions, maintenance, and the like.

[Advanced technical literature] (Patent Literature)

Patent Document 1: Japanese Patent No. 2729289

Patent Document 2: Japanese Patent No. 3415626

The present invention has been made in view of the above problems, and an object thereof is to provide a heat-resistant substrate which can be used for a semiconductor, an LED, a solar cell manufacturing apparatus, and the like, and has a structure of a thermally decomposable boron nitride film having high corrosion resistance. Wrapped.

In order to solve the above problems, the present invention provides a heat-resistant substrate having a structure in which a part or the entire surface of a substrate is coated with a thermally decomposed boron nitride (PBN) film, which is characterized by: the aforementioned thermally decomposed boron nitride The film contains 0.001 atom% or more and 3 atom% or less of oxygen (O).

By containing 0.001 atom% or more and 3 atom% or less of oxygen in the PBN film, the density of the thermally decomposed boron nitride film can be increased, the thermal decomposition boron nitride film can be made dense, and the occurrence of moisture and NH ₃ can be suppressed. reaction.

In this case, the density of the thermally decomposed boron nitride film can be 2.00 g/cm ³ or more and 2.20 g/cm ³ or less.

Further, the substrate may include any one of graphite, a carbon/carbon composite material, thermally decomposed graphite, tantalum carbide, tungsten, and rhodium.

When these heat-resistant substrates are used as, for example, a heater of an MOCVD apparatus, local corrosion does not occur even when used for a long period of time in a corrosive environment.

Moreover, the present invention provides a method for producing a heat-resistant substrate, which is a method for producing a heat-resistant substrate, which utilizes a raw material gas and coats a thermally decomposed boron nitride film on a substrate by a chemical vapor deposition (CVD) method. A heat-resistant substrate comprising a gas containing a nitrogen atom and a gas containing a boron atom, the method for producing the heat-resistant substrate characterized by mixing a gas containing an oxygen atom into the raw material gas, The thermal decomposition boron nitride film contains 0.001 atom% or more and 3 atom% or less of oxygen.

As described above, by supplying the gas containing the oxygen atom (O), the PBN film can be made denser without increasing the reaction temperature.

According to the present invention, there can be provided a heat-resistant substrate which is structured to be coated with a thermally decomposable boron nitride film having high corrosion resistance. The heat-resistant substrate can be used in semiconductors, LEDs, solar cell manufacturing apparatuses, and the like, and local corrosion does not occur even when used for a long period of time in a corrosive environment. Moreover, the production method of the present invention can also be suppressed due to a high reaction temperature. The consumption of the furnace material, so the number of maintenance of the reactor is reduced, and the productivity can be improved.

01‧‧‧Heat resistant substrate

02, 9‧‧‧Substrate

03‧‧‧ Thermal decomposition of boron nitride film

1‧‧‧External management

2‧‧‧中管

3‧‧‧Inside

4‧‧‧Supply tube

5‧‧‧Cylinder

6‧‧‧heater

7‧‧‧Standard

8‧‧‧Rotating mechanism

10‧‧‧Support fixture

11‧‧‧PBN film

Fig. 1 is an explanatory view showing an example of a heat resistant base material of the present invention.

Fig. 2 is a schematic cross-sectional view of a reaction furnace and a supply pipe which can be used in the present invention.

Fig. 3 is an explanatory view showing a coating method of thermally decomposed boron nitride in the examples.

Fig. 4 is a graph showing the relationship between the oxygen concentration and the oxygen supply amount in the PBN film on the surface of the graphite substrate in the examples.

Fig. 5 is a graph showing the relationship between the density of the PBN film on the surface of the graphite substrate and the amount of supplied oxygen in the examples.

Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to the following description.

The present inventors conducted intensive studies on improving the corrosion resistance of the PBN film, and as a result, the following problems were considered: the trace amount of moisture contained in the NH ₃ and the moisture adhering to the furnace reacted with PBN at a high temperature to form boron oxide (hereinafter referred to as B ₂ O ₃ ), and it evaporates at a high temperature, and therefore, pores may occur on the PBN film. In the period in which the experiment was repeated to suppress the formation of the B ₂ O ₃ , if a small amount of oxygen was contained in the PBN film, the density of the PBN film was increased, and the generation of voids was suppressed, and the present invention was completed.

Hereinafter, description will be made with reference to the drawings.

An example of the heat resistant base material of the present invention is shown in Fig. 1. In the heat-resistant substrate 01, part or the entire surface of the substrate 02 is covered with a thermally decomposable boron nitride film 03, and the thermally decomposed boron nitride film 03 contains 0.001 atom% or more and 3 atom% or less of oxygen. In the example shown in Fig. 1, although the entire substrate 02 is coated, the coating range is not particularly limited. In the present invention, the term "heat-resistant substrate" means the entire structure 01 in which the substrate 02 and the thermally decomposed boron nitride film 03 are combined unless otherwise specified.

In the heat-resistant substrate of the present invention, the thermally decomposed boron nitride film 03 on the surface of the substrate 02 contains 0.001 atom% or more and 3 atom% or less of O (oxygen). As described above, the density of the thermally decomposed boron nitride film can be set to 2.01 g/cm ³ or more and 2.20 g/cm ³ or less, and it is considered that the reaction between PBN and water can be suppressed. Further, it is considered that by dissolving O (oxygen) in a hexagonal layer or substituting to a N (nitrogen) position, reactivity with water can be reduced, and generation of pores can be suppressed. When the oxygen atom is less than 0.001 atom%, the PBN density hardly increases. Further, if it is intended to contain more than 3 atom% of oxygen atoms, the amount of oxygen supplied increases, so that the consumption of the graphite-based furnace material is intensified. Further, if the amount of oxygen added is increased, the formation of B ₂ O ₃ in the PBN film may cause a problem of the PBN film or a decrease in the PBN yield, which is not preferable. More preferably, the oxygen content is set to 0.015 atom% or more, or the density is set to 2.05 g/cm ³ or more.

The coated substrate 02 may comprise, for example, any of graphite, carbon/carbon composite (carbon/carbon composite), thermally decomposed graphite, tantalum carbide, tungsten, and tantalum. They can also be used in their composite materials. Such a substrate has high heat resistance and is suitable for use in semiconductors, LEDs, and solar cell manufacturing apparatuses. Of course, it is not limited to these materials, and can be appropriately determined.

The thermal decomposition boron nitride film 03 containing oxygen can be produced by a CVD method as described above. Specifically, it can be produced by adding a gas containing an N (nitrogen) atom such as ammonia, a gas containing a B (boron) atom such as boron trichloride, and a gas containing an O (oxygen) atom by performing CVD. The gas containing an O (oxygen) atom is not particularly limited, and a conventional gas having an O atom in the molecule can be used. It is preferred to use at least one gas selected from the group consisting of O ₂ , O ₃ , H ₂ O, NOx, and COx. These gases are inexpensive and stable.

When O ₂ gas (oxygen) is supplied as a gas containing an oxygen atom, it is preferable to use, for example, a molar ratio (O/B ratio) of a supply amount of oxygen and boron to a gas containing a B (boron) atom. The supply is performed in a range of 4 × 10 ^-5 to 1.8 × 10 ^-1 so that the thermally decomposed boron nitride film contains 0.001 atom% or more and 3 atom% or less of oxygen. When a gas other than the O ₂ gas, for example, O ₃ , H ₂ O, NOx, COx, or a mixed gas thereof, is supplied, it is preferable to supply the gas in such a manner that the O/B ratio is in the same range. Although depending on the reactor to be used, if the O/B ratio is less than the above range, it may be difficult to contain sufficient oxygen in the thermally decomposed boron nitride film. If it is more than this range, the amount of oxygen supplied may increase, and the graphite member used for the high-temperature reaction furnace may be excessively consumed, which is not preferable. A more preferable O/B ratio is in the range of 4 × 10 ^-4 to 1.6 × 10 ^-1 .

In the present invention, since the gas containing an oxygen atom can be supplied in advance by mixing with a gas containing a nitrogen atom or a gas containing a boron atom, a mixed gas having a fixed composition ratio can be supplied. When the mixed gas is supplied, for example, a gas containing a boron atom or a gas containing a nitrogen atom can be separated and supplied by using a double or triple feed pipe 4 as shown in Fig. 2, and a gas containing an oxygen atom can be supplied. . When the supply is performed in this manner, it is possible to suppress the reaction of the material gas and block the supply tube in the stage before the supply to the film formation apparatus. Further, the upper side in the right frame of Fig. 2 is a schematic view of a double tube composed of the outer tube 1 and the inner tube 3, and the lower side of the frame is a schematic view of the triple tube having the middle tube 2 on the basis of this. The left side of Fig. 2 is a cross-sectional view of the reactor, and the substrate is placed on the stowage stage 7 including the rotating mechanism 8 in the cylinder 5, heated by the heater 6, and the gas is supplied from the supply pipe 4 to perform CVD. . Further, in addition to the double or triple feed pipe 4, a multiple pipe of a quadruple pipe or a quadruple pipe or more may be used.

[Examples]

Hereinafter, the invention will be more specifically described by way of examples and comparative examples, but the invention is not limited by the description below.

<Example 1>

In Example 1, a heat-resistant substrate was produced by thermal CVD using the reactor shown in Fig. 2 . Using a double tube, ammonia gas _{(NH 3) 18SLM (standard L} / M), boron trichloride gas (BCl ₃₎ 5 SLM, and O ₂ gas 0.1sccm (standard cc / m) is supplied into the reactor, The PBN was covered on the surface of a graphite substrate of 50 mm × 50 mm × 10 mmt so that the thickness of the PBN became 0.3 mm. The furnace temperature at this time was maintained at 1900 ° C and the pressure was 100 Pa. As shown in Fig. 3, the portion of the substrate 9 supported by the support jig 10 at the time of covering is not covered by the PBN film 11, and is an uncovered portion where the graphite is exposed (Fig. 3, b, c), so the support point is changed. , again covering the PBN in the same way (Fig. 3, c, d). The oxygen concentration in the PBN film of the obtained heat-resistant substrate was measured using EDAX Genesis EDS manufactured by AMETEK, Inc., and found to be 0.001 atom%. Further, the density of the PBN film was measured by the Archimedes method and found to be 2.01 g/cm ³ .

Next, the heat-resistant substrate was heated to 1600 ° C in a vacuum and exposed to an ammonia atmosphere of 2000 Pa for 150 hours. After the cooling, the heat-resistant substrate was taken out, and as a result, no pores reaching the substrate were observed on the PBN film.

<Example 2>

In Example 2, a heat-resistant substrate was produced by thermal CVD using the reactor shown in Fig. 2 . Using a double tube, ammonia gas 18SLM, boron trichloride gas 5SLM, and O ₂ gas 1 sccm were supplied to the reaction furnace on a surface of a graphite substrate of 50 mm × 50 mm × 10 mmt so that the thickness of the PBN became 0.3 mm. The way to cover the PBN. The furnace temperature at this time was maintained at 1900 ° C and the pressure was 100 Pa. The support point was changed, and the uncovered portion of the graphite was again covered in the same manner by PBN. The oxygen concentration in the PBN film of the heat-resistant substrate produced in this manner was measured and found to be 0.015 atom%. Further, the density of the PBN film was measured and found to be 2.05 g/cm ³ .

Next, the heat-resistant substrate was heated to 1600 ° C in a vacuum and exposed to an ammonia atmosphere of 2000 Pa for 150 hours. After the cooling, the heat-resistant substrate was taken out, and as a result, no pores reaching the substrate were observed on the PBN film.

<Example 3>

In Example 3, a heat-resistant substrate was produced by thermal CVD using the reactor shown in Fig. 2. Using a double tube, ammonia gas 18SLM, boron trichloride gas 5SLM, and O ₂ gas 100sccm were supplied to the reaction furnace on the surface of a 50 mm × 50 mm × 10 mmt graphite substrate so that the thickness of the PBN became 0.3 mm. The way to cover the PBN. The furnace temperature at this time was maintained at 1900 ° C and the pressure was 100 Pa. The support point was changed, and the uncovered portion of the graphite was again covered in the same manner by PBN. The oxygen concentration in the PBN film of the heat-resistant substrate produced in this manner was measured and found to be 0.70 atom%. Further, the density of the PBN film was measured and found to be 2.14 g/cm ³ .

Next, the heat-resistant substrate was heated to 1600 ° C in a vacuum and exposed to an ammonia atmosphere of 2000 Pa for 150 hours. After cooling, the heat-resistant substrate was taken out, and no pores reaching the substrate were found on the PBN film.

<Example 4>

In Example 4, a heat-resistant substrate was produced by thermal CVD using the reactor shown in Fig. 2. Using a double tube, ammonia gas 18SLM, boron trichloride gas 5SLM, and O ₂ gas 400sccm were supplied to the reaction furnace on a surface of a graphite substrate of 50 mm × 50 mm × 10 mmt so that the thickness of the PBN became 0.3 mm. The way to cover the PBN. The furnace temperature at this time was maintained at 1900 ° C and the pressure was 100 Pa. The support point was changed, and the uncovered portion of the graphite was again covered in the same manner by PBN. The oxygen concentration in the PBN film of the heat-resistant substrate produced in this manner was measured and found to be 2.7 atom%. Further, the density of the PBN film was measured and found to be 2.19 g/cm ³ .

Next, the heat-resistant substrate was heated to 1600 ° C in a vacuum and exposed to an ammonia atmosphere of 2000 Pa for 150 hours. After cooling, the heat-resistant substrate was taken out, and no pores reaching the substrate were found on the PBN film.

<Example 5>

In Example 5, a heat-resistant substrate was produced by thermal CVD using the reactor shown in Fig. 2. Using a double tube, ammonia gas 18SLM, boron trichloride gas 5SLM, and O ₂ gas 450sccm were supplied to the reaction furnace on a surface of a graphite substrate of 50 mm × 50 mm × 10 mmt so that the thickness of the PBN became 0.3 mm. The way to cover the PBN. The furnace temperature at this time was maintained at 1900 ° C and the pressure was 100 Pa. The support point was changed, and the uncovered portion of the graphite was again covered in the same manner by PBN. The oxygen concentration in the PBN film of the heat-resistant substrate produced in this manner was measured and found to be 3.0 atom%. Further, the density of the PBN film was measured and found to be 2.19 g/cm ³ .

Next, the heat-resistant substrate was heated to 1600 ° C in a vacuum and exposed to an ammonia atmosphere of 2000 Pa for 150 hours. After cooling, the heat-resistant substrate was taken out, and no pores reaching the substrate were found on the PBN film.

<Comparative Example 1>

In Comparative Example 1, a heat-resistant substrate outside the scope of the present invention was produced by thermal CVD using the reactor shown in Fig. 2 . In the case where O ₂ is not introduced, ammonia gas 18SLM and boron trichloride gas 5SLM are supplied to the reaction furnace by a double tube, and the thickness of the PBN is made on the surface of a graphite substrate of 50 mm × 50 mm × 10 mmt. Become a 0.3mm way to cover the PBN. The furnace temperature at this time was maintained at 1900 ° C and the pressure was 100 Pa. The support point was changed, and the uncovered portion of the graphite was again covered in the same manner by PBN. The oxygen concentration in the PBN film of the heat-resistant substrate produced in this manner was measured and found to be below the detection limit (<0.001 atom%). Further, the density of the PBN film was measured and found to be 1.99 g/cm ³ .

Next, the heat-resistant substrate was heated to 1600 ° C in a vacuum and exposed to an ammonia atmosphere of 2000 Pa for 150 hours. After cooling, the heat-resistant substrate was taken out, and holes reaching the substrate were found on the PBN film.

<Comparative Example 2>

In Comparative Example 2, a heat-resistant substrate outside the scope of the present invention was produced by thermal CVD using the reactor shown in Fig. 2 . Using a double tube, ammonia gas 18SLM, boron trichloride gas 5SLM, and O ₂ gas 600sccm were supplied to the reaction furnace on a surface of a graphite substrate of 50 mm × 50 mm × 10 mmt so that the thickness of the PBN became 0.3 mm. The way to cover the PBN. The furnace temperature at this time was maintained at 1900 ° C and the pressure was 100 Pa. The support point was changed, and the uncovered portion of the graphite was again covered in the same manner by PBN. The oxygen concentration in the PBN film of the heat-resistant substrate produced in this manner was measured and found to be 4.3 atom% outside the range of the present invention. Further, the density of the PBN film was measured and found to be 2.21 g/cm ³ .

However, when it was produced by the method of Comparative Example 2, the oxygen supply amount was large compared with the other methods, and therefore the graphite member used in the reaction furnace was suddenly consumed. With this method, the maintenance frequency is high and the productivity is lowered, which is not preferable.

The results of the above Examples 1 to 5 and Comparative Examples 1 and 2 are summarized in Table 1, as shown below.

Further, the relationship between the oxygen supply amount and the oxygen concentration of the PBN film and the PBN density is shown in Figs. 4 and 5 .

Next, an example in which a substrate other than graphite is used will be described.

<Examples 6 to 10>

In Examples 6 to 10, a heat-resistant substrate was produced by thermal CVD using the reactor shown in Fig. 2. Using a triple tube, ammonia 18 SLM, boron trichloride gas 5SLM, and O ₂ gas 100 sccm are supplied to the reaction furnace, carbon/carbon composite material of 50 mm × 50 mm × 10 mmt, thermally decomposed graphite, tantalum carbide, tungsten, On the surface of each of the substrates, the PBN was covered so that the thickness of the PBN became 0.3 mm. The furnace temperature at this time was maintained at 1900 ° C and the pressure was 100 Pa. The support point was changed, and the uncovered portion of the graphite was again covered in the same manner by PBN. The oxygen concentration in the PBN film of each heat-resistant substrate produced in this manner was measured and found to be 0.65 to 0.71 atom%. Further, the density of the PBN film was measured and found to be 2.12 to 2.15 g/cm ³ .

Further, the resistance test was carried out in the same manner as in Examples 1 to 5. As a result, pores reaching the substrate were not found on the PBN film.

Furthermore, the present invention is not limited to the above embodiment. The above-described embodiment is exemplified, and a technical solution having substantially the same configuration as the technical idea described in the patent application scope of the present invention and exhibiting the same operational effects is included in the technical scope of the present invention.

01‧‧‧Heat resistant substrate

02‧‧‧Substrate

03‧‧‧ Thermal decomposition of boron nitride film

Claims (4)

A heat-resistant substrate having a structure in which a part or the entire surface of the substrate is coated with a thermally decomposed boron nitride film, and the heat-resistant substrate is characterized in that the thermally decomposed boron nitride film contains 0.001 atom% or more and 3 atom% or less. Oxygen. The heat-resistant substrate according to claim 1, wherein the thermal decomposition boron nitride film has a density of 2.00 g/cm ³ or more and 2.20 g/cm ³ or less. The heat resistant substrate according to claim 1 or 2, wherein the substrate is any one of graphite, a carbon/carbon composite material, thermally decomposed graphite, tantalum carbide, tungsten, and rhenium. A method for producing a heat-resistant substrate, which is a method for producing a heat-resistant substrate, which uses a raw material gas and coats a thermally decomposed boron nitride film on a surface of a substrate by a chemical vapor deposition method to produce a heat-resistant substrate. The material gas includes a gas containing a nitrogen atom and a gas containing a boron atom, and the method for producing the heat resistant substrate is characterized in that the thermally decomposed boron nitride film is formed by mixing a gas containing an oxygen atom into the material gas. It contains 0.001 atom% or more and 3 atom% or less of oxygen.