JPH1036191A - Silicon film formation method using vapor phase growth apparatus - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To reduce the frequency of cleaning in a reaction chamber and improve the operation rate of an apparatus. In a method for forming a silicon film using a vapor phase growth apparatus, a silicon film is formed on a substrate mounted on a susceptor, and the temperature at which the silicon film is formed is set to 9 degrees.
The temperature is set to 50 ° C. or higher, and the flow rate ratio of the carrier gas and the silicon source gas used for film formation is set to carrier gas: silicon source gas = 1: 0.0011 to 0.0020, and the accumulation of the silicon film formed on the substrate is performed. The film thickness is 100 μm or more
Every 200 μm, the silicon laminated on the susceptor is etched, and the surface of the susceptor 5 is coated with silicon.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicon film forming method using a vapor phase growth apparatus.

[0002]

2. Description of the Related Art Conventionally, as a silicon vapor phase growth apparatus used for epitaxially growing silicon on a substrate, for example, there is an apparatus whose schematic cross section is shown in FIG. This will be described.

In this apparatus, an inner bell jar 8 made of quartz is provided on a base 1 to constitute a reaction chamber 20. An outer bell jar 9 is provided on the outer periphery of the inner bell jar 8.

[0004] On the other hand, a susceptor support 6 is provided on the base 1, and the susceptor support 6 is rotatable in the plane thereof.
The susceptor 5 is supported. At the bottom of the susceptor 5,
For example, a high-frequency heating coil 2 is provided so that the susceptor 5 can be heated and maintained at a predetermined temperature.

A substrate 30 on which a silicon film is to be formed is placed on the susceptor 5. A quartz gas nozzle 11 for supplying a raw material gas or the like is provided at the center of the reaction chamber 20 so as to pass through the center of the susceptor 5.
The gas nozzle 11 is provided with a plurality of gas ejection ports 11h. The height of the gas nozzle 11 can be adjusted by a vertical adjustment mechanism (not shown), and the gas flow rate can be adjusted. It has been made like that.

In order to form an epitaxial film on the surface of the substrate 30 using the above-described silicon vapor phase growth apparatus, first, N ₂ gas is injected into the reaction chamber 20 from the gas injection port 11 h by the gas nozzle 11. At the same time, the gas is exhausted from the exhaust port 7 and the inside of the reaction chamber 20 is replaced with N ₂ gas.
From 1 h, H ₂ gas is ejected into the reaction chamber 20 to replace the atmosphere in the reaction chamber 20 with H ₂ gas.

Next, the substrate 30 is heated to 1050 ° C. to 1100 ° C. by the coil 2 in an H ₂ gas atmosphere,
The 0 native oxide film is removed. Subsequently, the substrate 30 is placed at 950
° C. and cooled to ～1030 ° C., the silicon source gas _{(Si n H 2n + 2 (} n ≧ 1)) and H ₂ gas as a carrier gas, for example, supplying the silicon source gas and PH ₃ or the like doping material gas such as SiH ₄ I do. In this case, the flow ratio between the carrier gas and the silicon source gas is set to about 1: 0.0024: carrier gas: silicon source gas. In this way, in the reaction chamber 20, an epitaxial silicon film is grown and formed on the surface of the substrate 30.

[0008]

However, when the above-described epitaxial growth of silicon on the substrate 30 is performed, not only the surface of the susceptor 5 holding the substrate 30 but also the reaction chamber of the inner bell jar 8 is formed not only on the substrate 30. A silicon film is formed on the wall, the ceiling of the reaction chamber 20, and the gas nozzle 11.

The silicon film formed on the portion other than the surface of the substrate 30, for example, the silicon film formed on the inner wall of the reaction chamber of the inner bell jar 8, has a temperature of 100 ° C. to 500 ° C. Since the surface of the silicon film is lower than that of the surface 30, the denseness of the silicon film is poor and the adhesive strength is weak. Therefore, when epitaxial growth is performed continuously without removing these silicon films, these silicon films are peeled off and adhere to the surface of the substrate 30, causing crystal defects of the epitaxial film on the surface of the substrate 30, or protrusions. Or to generate.

Therefore, it is necessary to perform wet cleaning of the inner bell jar 8 with sulfuric acid or the like, that is, cleaning of the reaction chamber, at the same time as cleaning of the susceptor 5 for every fixed number of batches. It has been determined that this cleaning in the reaction chamber is necessary when 35 or more dust particles are visually present on the silicon film on the 5-inch substrate 30. For example, when the flow rate ratio between the carrier gas and the silicon source gas is set to about 1: 0.0024 of carrier gas: silicon source gas, it is known that the process needs to be performed for each cumulative film thickness of about 60 μm. However, if these operations are performed, it takes a very long time before the vapor phase growth apparatus can perform the epitaxial growth again, and the production efficiency is reduced.

Here, the term "cumulative film thickness" means a value obtained by accumulating the film thickness of each film formed by performing a plurality of film formations capable of forming a good quality film.

[0012]

According to the present invention, there is provided a method of forming a silicon film using a vapor phase growth apparatus, wherein the silicon film is formed on a substrate mounted on a susceptor, and the silicon film is formed. The temperature at the time of performing the heat treatment was set to 950 ° C. or higher, and the flow rate ratio between the carrier gas and the silicon source gas used at the time of film formation was determined as follows: carrier gas: silicon source gas = 1: 0.001
1 to 0.0020.

According to the present invention, in a method of forming a silicon film using a vapor phase growth apparatus, the silicon film forming temperature and the flow rate ratio between the carrier gas and the silicon raw material gas used in the film formation are set to predetermined values. The cleaning cycle in the reaction chamber can be extended, the frequency of cleaning can be reduced, and the operation rate of the apparatus can be improved.

[0014]

Embodiments of the present invention will be described below. As the silicon vapor phase growth apparatus, the apparatus described with reference to FIG. 1 can be used. That is, in the vapor phase growth apparatus applied to the method of the present invention, the inner bell jar 8 made of quartz is provided on the base 1 as described with reference to FIG. An outer bell jar 9 is provided on the outer periphery of the inner bell jar 8.

On the other hand, a susceptor support 6 is provided on the base 1, and the susceptor support 6 is rotatable in an in-plane direction.
The susceptor 5 is supported. At the bottom of the susceptor 5,
For example, a high-frequency heating coil 2 is provided so that the susceptor 5 can be heated and maintained at a predetermined temperature.

A substrate 30 on which a silicon film is to be formed is placed on the susceptor 5. A quartz gas nozzle 11 for supplying a raw material gas or the like is provided at the center of the reaction chamber 20 so as to pass through the center of the susceptor 5.
The gas nozzle 11 is provided with a plurality of gas ejection ports 11h. The height of the gas nozzle 11 can be adjusted by a vertical adjustment mechanism (not shown), and the gas flow rate can be adjusted. Has been made.

An epitaxial film is formed on the surface of the substrate 30 by using the above-described silicon vapor deposition apparatus. FIG. 3A shows the programming of the temperature when this silicon film is formed, and FIG. 3B shows the supply time zone of each gas supplied at this time by a solid line. First, the gas nozzle 11
N ₂ gas is ejected from the gas ejection port 11 h into the reaction chamber 20, exhausted from the exhaust port 7, and the inside of the reaction chamber 20 is replaced with N ₂ gas. H _{2 is} introduced into the reaction chamber 20 from the outlet 11h.
A gas is ejected to replace the atmosphere in the reaction chamber 20 with H ₂ gas.

Next, the substrate 30 is heated to 1050 ° C. to 1100 ° C. by the coil 2 in an H ₂ gas atmosphere,
Then, the natural oxide film on 0 is removed. Subsequently, the substrate 30 is moved to 95
0 ℃ ~1030 was cooled to ° C., the H ₂ gas as a carrier gas, the silicon source gas _{(Si n H 2n + 2 (} n ≧ 1)) for example for supplying a doping gas such as SiH ₄ and PH _3. In this case, in particular, in the present invention, the flow ratio of the carrier gas to the silicon source gas is set such that carrier gas: silicon source gas = 1: 0.0011 to 0.00.
20, for example, about 1: 0.0017.

The flow rate ratio between the carrier gas and the silicon source gas is set as follows: carrier gas: silicon source gas = 1: 0.00
When silicon is vapor-phase-grown on the substrate 30 by using the above-described apparatus at a ratio of 11 to 0.0020, for example, about 1: 0.0017, the inner
It was found that the amount of the silicon film (generally a polycrystalline film) deposited on the inner wall of the reaction chamber was small. In the cycle of the cleaning in the reaction chamber, the accumulated film thickness capable of repeatedly forming good quality films was extended to about 120 μm. This is a polycrystalline silicon film formed on a portion other than the surface of the substrate 30,
For example, it is considered that the polycrystalline silicon film formed on the inner wall of the reaction chamber of the inner bell jar 8 has better denseness and is less likely to be peeled as compared with the related art.

As described above, the flow rate ratio between the carrier gas and the silicon source gas is determined by the following equation: carrier gas: silicon source gas =
1: When 0.0011 to 0.0020, it was found that the cycle of the cleaning in the reaction chamber could be extended, but on the other hand, the cycle of the cleaning in the reaction chamber was 120
When the thickness is about μm, a silicon film (polycrystalline silicon) deposited on the susceptor 5 becomes a problem.

That is, conventionally, when the cycle of cleaning in the reaction chamber is about 60 μm in cumulative film thickness, polycrystalline silicon is deposited on the susceptor 5, and when the substrate 30 is set and taken out, the polycrystalline silicon is separated and dust is generated. Since the cleaning in the reaction chamber is performed before the occurrence of the above, the presence of the polycrystalline silicon on the susceptor 5 did not cause much problem. However,
In the case of the method of the present invention, when the cumulative film thickness of the cleaning cycle in the reaction chamber becomes about 120 μm, the cycle of the cleaning in the reaction chamber is extended, so that a problem occurs due to unnecessary silicon deposition on the susceptor 5. In other words, the polycrystalline silicon deposited on the susceptor 5 before the cleaning in the reaction chamber may cause the substrate 30 to rub against the susceptor 5 when the substrate 30 is placed on the susceptor 5, taken out, and replaced. For various reasons, the polycrystalline silicon on the susceptor 5 is peeled off to generate dust,
The dust adheres to the surface of the substrate 30 and causes the quality of the epitaxial film on the substrate 30 to deteriorate.

Therefore, in the present invention, in particular, the substrate 30 is not installed in the silicon vapor growth apparatus shown in FIG. 1 when the cumulative thickness of the epitaxial growth film is about every 100 μm to 200 μm, for example, every 100 μm to 120 μm. In this state, the temperature of the susceptor 5 is set to
At 00 ° C., the polycrystalline silicon deposited on the surface of the susceptor 5 is removed by etching with HCl gas. After the polycrystalline silicon deposited on the surface of the susceptor 5 is removed by etching, silicon coating is performed on the susceptor 5 under the same conditions as when an epitaxial film is grown on the substrate 30.

In this way, the susceptor 5 is etched so that the cumulative thickness of the epitaxially grown film is 100 μm to 200 μm.
μm, for example, every 120 μm, and then
By performing a silicon coating on the susceptor 5,
Even when the cycle of the cleaning in the reaction chamber was extended compared to the conventional case, it was possible to prevent the polycrystalline silicon dust deposited on the susceptor 5 from adhering to the surface of the substrate. In this case, the cleaning cycle in the reaction chamber was extended to a cumulative film thickness of 400 μm or more.

FIG. 2 is a diagram showing the relationship between the flow ratio of the carrier gas and the silicon source gas and the cumulative thickness of silicon up to the cleaning of the reaction chamber. According to FIG. 2, the flow rate ratio between the carrier gas and the silicon source gas during the vapor phase growth of silicon is set as follows: carrier gas: silicon source gas = 1: 0.
Compared to the conventional method (accumulated film thickness = 60 μm), according to the method of the present invention, the accumulated film thickness = 400 μm, so that the cleaning cycle in the reaction chamber could be extended to about 7 times.

As shown in FIG. 2, the flow rate ratio between the carrier gas and the silicon source gas during the vapor phase growth of silicon is determined by the ratio of carrier gas: silicon source gas = 1: 1.
When the content is 0.0020 or less, the accumulated film thickness can be remarkably increased as compared with the related art. However, if the amount of the silicon source gas is too small, the growth rate of the silicon film becomes low, which causes an industrial problem. That is, when the flow ratio of the carrier gas and the silicon source gas is set to carrier gas: silicon source gas = 1: 0.0011, the silicon film forming rate is about 0.15 μm / min, and the carrier gas: silicon source gas = 1 : In the conventional case of 0.0024, it is about 0.30 μm / min, which is about half, and the film formation time is extremely long, and if carrier gas: silicon raw material gas is less than 1: 0.0011, industrial Is not practical. In addition, when the film formation time is long, there is a possibility that characteristics such as film quality of a silicon film to be formed may change.

In the present invention, the flow rate ratio between the carrier gas and the silicon source gas is set to a value lower than that of the conventional silicon source gas, so that the silicon film formation rate is reduced. However, the ratio of the silicon film formation time in one batch for performing silicon epitaxy is as small as about 10%. Therefore, even if the flow rate ratio between the carrier gas and the silicon source gas in the present invention is adjusted and the time required for silicon film formation per batch is extended, the cleaning time of the reaction chamber 20 can be shortened. Considering the balance,
It can be said that there is almost no effect on the productivity of the silicon epitaxial film.

Here, in the method of the present invention, the flow rate ratio between the carrier gas and the silicon source gas is specified in the range of carrier gas: silicon source gas = 1: 0.0011 to 0.0020.

As described above, in the method of forming a silicon film using the vapor phase growth apparatus, the silicon film is formed on the substrate 30 placed on the susceptor 5 and the silicon film is formed. The temperature is set to 950 ° C. or higher, and the flow rate ratio between the carrier gas and the silicon source gas used for film formation is
Carrier gas: silicon source gas = 1: 0.0011-
The silicon layer deposited on the susceptor is etched every time the cumulative thickness of the silicon layer formed on the substrate 30 becomes 100 to 200 μm, and the silicon layer is formed by a silicon coating method. The cleaning cycle in the reaction chamber 20 was able to be greatly extended by performing. Further, by reducing the frequency of cleaning the reaction chamber 20, the operation rate of the apparatus could be improved.

In the above-described embodiment, the silicon source gas (Si _n H _{2n + 2} (n ≧ 1))
Although the case where H ₄ is used has been described, the present invention is not limited to this example, and Si ₂ H ₆ or the like can be used.

Further, the shape of the reaction chamber 20 is not limited to the above-described one, and various shapes can be used as long as it is a hot wall type. Further, the silicon film deposited on the substrate 30 is not limited to a single crystal,
It can also be used when forming a polycrystalline or amorphous silicon semiconductor film.

[0031]

According to the present invention, in a method of forming a silicon film using a vapor phase epitaxy apparatus, a silicon film is formed on a substrate 30 mounted on a susceptor 5 to form a silicon film. In this case, the temperature was set at 950 ° C. or higher, and the flow rate ratio between the carrier gas and the silicon source gas used for the film formation was determined as follows: carrier gas: silicon source gas = 1: 0.001
The silicon deposited on the susceptor is etched every time the cumulative thickness of silicon deposited on the substrate becomes 100 to 200 μm, and the silicon is formed by a method of performing silicon coating. By performing the membrane, the washing cycle in the reaction chamber 20 could be greatly extended.

Further, by reducing the frequency of cleaning the reaction chamber 20, the number of sheets to be processed per cleaning cycle of the reaction chamber can be increased, and the operation rate of the apparatus can be improved.

Further, since the cycle for cleaning the reaction chamber can be extended, the number of times the quartz parts in the reaction chamber 20 are subjected to chemical treatment by cleaning is reduced. For this reason, the so-called "devitrification" of quartz parts changes from transparent to ground glass.
The time until is extended. For this reason, the period during which the quartz parts can be used can be extended, and the cost of the chemicals used for cleaning and the quartz parts can be significantly reduced.

[Brief description of the drawings]

FIG. 1 shows a schematic sectional view of an example of a vapor phase growth apparatus.

FIG. 2 is a diagram showing a relationship between a flow ratio between a carrier gas and a silicon source gas and a cumulative silicon film thickness up to cleaning of a reaction chamber.

FIG. 3A shows temperature programming when a silicon film is formed using a vapor phase growth apparatus in the method of the present invention. B The supply time zone of each gas to be supplied when a silicon film is formed using the vapor phase growth apparatus in the method of the present invention is indicated by a solid line.

[Explanation of symbols]

1 base, 2 coils, 5 susceptor, 6 susceptor support, 7 exhaust port, 8 inner bell jar, 9 outer bell jar, 10 sight glass, 11 gas nozzle, 11h
Gas spout, 20 reaction chambers, 30 substrates

Claims (2)

[Claims] 1. A method for forming a silicon film using a vapor phase epitaxy apparatus, the method comprising: setting a temperature at which a silicon film is formed on a substrate held on a susceptor to 950 ° C. or higher; The flow ratio between the carrier gas and the silicon source gas is defined as follows: carrier gas: silicon source gas = 1:
A silicon film forming method using a vapor phase epitaxy apparatus, characterized in that silicon is formed on the substrate, with 0.0011 to 0.0020. 2. When the cumulative film thickness of silicon formed on the substrate becomes 100 μm to 200 μm, the silicon laminated on the susceptor is etched in a state where the substrate is not placed on the susceptor. The method of claim 1, further comprising performing a silicon coating on the surface of the susceptor.