JP5553066B2 - Epitaxial wafer manufacturing method - Google Patents

Description

  The present invention relates to a method for manufacturing an epitaxial wafer using a vapor phase growth apparatus.

In the production of a silicon epitaxial wafer by a general vapor phase growth, Si is epitaxially grown using a gas such as SiCl ₄ , SiHCl ₃ , SiH ₂ Cl ₂ , or SiH ₄ which is H ₂ and Si source gas.

  The epitaxial growth reaction is often performed at a relatively high temperature of 900 ° C. to 1200 ° C. by lamp heating or the like. Many epitaxial growth apparatuses are of the cold wall type, and the process is performed while cooling the chamber structural members such as quartz and SUS (stainless steel) by water cooling or air cooling.

  The epitaxial growth reaction of Si occurs on the wafer, but at the same time, the reaction also occurs on the chamber structure member, and polysilicon or polychlorinated silane is deposited as a byproduct. A large amount of polysilicon is deposited mainly on the susceptor that supports the wafer and on the gas flow path around the susceptor. Some of them also deposit on the inner wall of the chamber, and this is generally called a wall deposit. Polysilicon and wall deposits need to be removed periodically, and removal by vapor phase etching with HCl is used.

  Such a gas phase etching reaction with HCl is preferably performed at a high temperature in order to increase the reaction efficiency.

  In a cold wall reactor, the temperature of the susceptor easily rises, but it takes time to raise the temperature of the inner wall of the chamber. In some cases, the temperature of the inner wall of the chamber cannot be sufficiently raised. That is, since the temperature of the susceptor can be easily raised to 1100 ° C. or higher where the etching reaction can be efficiently advanced, the etching reaction can be rapidly advanced at the susceptor portion. However, the temperature of the inner wall of the chamber has a structure that cannot raise the temperature as compared with the susceptor, and it takes time to raise the temperature.

  In general, the amount of wall deposit attached to the inner wall is slightly smaller than the deposit on the susceptor, but the etching rate is very slow because the temperature during HCl etching is lower than 700 ° C. compared to the susceptor portion. For this reason, the removal of the wall deposit may be the rate-limiting factor for the HCl etching process.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an epitaxial wafer manufacturing method capable of shortening the temperature raising time and the etching time before cleaning.

The present invention has been made to solve the above-described problem, and uses a cold wall type vapor phase growth apparatus that includes a susceptor for placing a wafer in a chamber and cleans the inside of the chamber by vapor phase etching. An epitaxial wafer manufacturing method comprising:
When the temperature rises before cleaning, the susceptor is brought closer to the inner wall of the chamber, the temperature of the inner wall of the chamber is raised, the susceptor is returned to the original position, and then the chamber and the susceptor are etched by vapor phase etching. Clean and
An epitaxial wafer manufacturing method is provided, wherein an epitaxial wafer is manufactured by vapor-phase growth of an epitaxial layer on a main surface of a wafer placed on the susceptor in the cleaned chamber.

  In this way, if the temperature of the inner wall of the chamber is increased by bringing a susceptor that is easy to heat up, the temperature rise time and the etching time before cleaning can be shortened.

  Further, it is preferable to heat the susceptor to 1100 ° C. or higher when the temperature is raised before the cleaning, and it is preferable to bring the susceptor closer to the chamber inner wall and raise the temperature of the chamber inner wall to 580 ° C. or higher.

  Thereby, the temperature rising time and the etching time before cleaning can be further shortened.

  Further, it is preferable to clean the susceptor and the chamber by vapor phase etching by flowing HCl gas into the chamber during the cleaning.

  Thereby, polysilicon and polychlorinated silane can be easily removed from the susceptor and the chamber.

  As described above, according to the epitaxial wafer manufacturing method of the present invention, the temperature raising time and the etching time before cleaning can be shortened. In particular, polysilicon and polychlorinated silane can be efficiently removed from the susceptor and chamber.

It is sectional drawing which shows an example of the single wafer type vapor phase growth apparatus used by this invention. It is a figure which shows the temperature increase rate of the chamber inner wall of an Example and a comparative example.

  Hereinafter, the present invention will be described in detail, but the present invention is not limited thereto. As described above, there has been a demand for a method of manufacturing an epitaxial wafer that can shorten the temperature raising time and the etching time before cleaning.

  As a result of intensive studies on the above problems, the present inventors can shorten the heating time and the etching time before cleaning by bringing the heated susceptor closer to the inner wall of the chamber and increasing the temperature of the inner wall of the chamber. And the present invention was completed. Hereinafter, the present invention will be described in more detail.

  In the epitaxial wafer manufacturing method of the present invention, a cold wall type vapor phase growth apparatus that includes a susceptor for placing the wafer W in a chamber and cleans the inside of the chamber by vapor phase etching is used. FIG. 1 shows an example of a single wafer type vapor phase growth apparatus that can be used in the method for producing an epitaxial wafer of the present invention. As shown in FIG. 1, a cold wall type vapor phase growth apparatus 20 includes a susceptor 2 on which a wafer W is placed in a chamber 1.

  Further, the vapor phase growth apparatus 20 sandwiches the SUS chamber base 3 from above and below, covers the quartz base 4 and 4 ′ forming the chamber 1, and the SUS chamber base provided inside the chamber 1. And a susceptor 2 for supporting the opaque quartz members 5 and 5 'and the wafer W on the upper surface.

  The susceptor 2 is connected to a rotating mechanism 6 and is rotating during vapor phase growth. SUS is used inside the rotation mechanism 6, and a gas introduction pipe 7 for purging the inside of the rotation mechanism 6 is provided. Further, the susceptor 2 is supported by the support structure 10 so as to move up and down, approach the inner wall (the upper transparent quartz member 4) of the chamber 1, and return to the original position.

In the chamber 1, a vapor phase growth gas containing a source gas (for example, SiCl ₄ , SiHCl ₃ , SiH ₂ Cl ₂ , SiH ₄ , and a dopant gas) and a carrier gas (for example, hydrogen) in the chamber 1 is supplied to the susceptor 2. There is provided a gas phase growth gas introduction pipe 8 which is introduced into the upper region and supplied onto the main surface of the wafer W on the susceptor. Further, the chamber 1 is provided with a gas discharge pipe 9 on the side opposite to the side where the vapor phase growth gas introduction pipe 8 is provided.

  As a vapor phase growth apparatus that can be used in the method of manufacturing an epitaxial wafer of the present invention, a batch type gas deposition apparatus can be used as long as the susceptor approaches the inner wall of the chamber and returns to the original position as described above. A phase growth apparatus may be used.

  In the present invention, when raising the temperature before cleaning, the susceptor 2 is brought closer to the inner wall of the chamber 1 and the temperature of the inner wall of the chamber 1 is raised, and then the susceptor 2 is returned to its original position. Thereby, the susceptor 2 that easily raises the temperature helps to raise the temperature of the inner wall of the chamber 1 (the inner wall of the upper transparent quartz member 4 on the susceptor 2 side), and the temperature raising time before cleaning can be shortened. Further, this sufficiently raises the temperature of the inner wall of the chamber 1 and promotes the removal of the wall deposit attached thereto, thereby shortening the etching time.

  Here, bringing the susceptor 2 close to the inner wall of the chamber 1 usually means bringing the susceptor 2 at the position during vapor phase growth closer to the inner wall side of the chamber 1 than the position by the support structure 10 or the like. Returning the susceptor 2 to the original position means returning the approached susceptor 2 to the position at the time of vapor phase growth.

  The heating of the chamber 1 and the susceptor 2 can be performed with a known heating device (not shown). For example, as a heating device for the chamber 1 and the susceptor 2, a so-called lamp heating method is exemplified.

  At this time, it is preferable to heat the susceptor 2 to 1100 ° C. or higher, and to bring the susceptor 2 closer to the inner wall of the chamber 1 and to increase the temperature of the inner wall of the chamber 1 to 580 ° C. or higher. Thereby, the temperature rising time and the etching time before cleaning can be further shortened.

  Thereafter, at the time of cleaning, the chamber 1 and the susceptor 2 are cleaned by vapor phase etching. At this time, the gas flow path and the like around the susceptor that are at a high temperature can be simultaneously cleaned. At the time of this cleaning, it is preferable to flow HCl gas into the chamber 1 to clean the susceptor 2 and the chamber 1 by vapor phase etching. Thus, an epitaxial wafer manufacturing method can be obtained in which polysilicon and polychlorinated silane can be more easily removed from the susceptor 1, the gas flow path around the susceptor 1, the chamber 2, and the like. Note that the chamber 1 can be heated to 1100 to 1200 ° C. during cleaning.

  In the present invention, an epitaxial wafer is produced by vapor-phase growth of an epitaxial layer on the main surface of the wafer W in the chamber 1 cleaned as described above. Hereinafter, the vapor phase growth of the present invention will be described in detail by taking the single wafer type vapor phase growth apparatus shown in FIG. 1 as an example, but the vapor phase growth of the present invention is not limited to this. First, the wafer W is put into the chamber 1 adjusted to the charging temperature (for example, 650 ° C.), and is placed on the counterbore on the upper surface of the susceptor 2 so that the main surface thereof faces upward.

  Here, hydrogen gas is introduced into the chamber 1 through the vapor phase growth gas introduction pipe 8 and the purge gas introduction pipe 7 from the stage before the wafer W is introduced.

  Next, the wafer W on the susceptor 2 is heated to a hydrogen heat treatment temperature (for example, 1050 to 1200 ° C.) by a heating device.

  Next, vapor phase etching for removing the natural oxide film formed on the main surface of the wafer W is performed. Note that this vapor phase etching is performed until immediately before the vapor phase growth which is the next step.

Next, the temperature of the wafer W is lowered to a desired growth temperature (for example, 1050 to 1180 ° C.), and source gases (for example, SiCl ₄ , SiHCl ₃ , and the like) are formed on the main surface of the wafer W via the gas phase growth gas introduction pipe 8. SiH ₂ Cl ₂ , SiH _4, dopant gas, etc.) are vapor-phase-grown on the main surface of the wafer W by supplying a purge gas (for example, hydrogen) approximately horizontally through the purge gas introduction pipe 7. An epitaxial wafer can be manufactured.

  Finally, the epitaxial wafer is taken out, cooled to a temperature (for example, 650 ° C.), and carried out of the chamber 1.

  EXAMPLES Hereinafter, although the Example and comparative example of this invention are given and demonstrated further in detail, this invention is not limited to the following Example.

〔Example〕
A single-phase vapor phase growth apparatus shown in FIG. 1 was prepared. The susceptor was heated from 700 ° C. to 1200 ° C. with a heating device, the heated susceptor was held at 1200 ° C., and the wafer mounting surface was brought close to the chamber inner wall to raise the temperature of the chamber inner wall. FIG. 2 shows the result of measuring the temperature change of the inner wall of the chamber with a pyrometer. The horizontal axis of FIG. 2 shows the elapsed time, where 1 is the time until the inner wall of the chamber of the comparative example described later reaches 580 ° C.

  Thereafter, the susceptor was returned to the original position, and HCl gas was flowed to clean the polysilicon and polychlorinated silane adhering to the chamber and the susceptor by vapor phase etching. In the cleaned chamber, an epitaxial layer was vapor-grown on the main surface of the wafer to produce an epitaxial wafer.

[Comparative example]
A single-phase vapor phase growth apparatus of FIG. 1 was prepared. The temperature in the chamber was raised with a commonly used heater without moving the susceptor. FIG. 2 shows the result of measuring the temperature change of the inner wall of the chamber with a pyrometer.

  Thereafter, the chamber and susceptor were cleaned by vapor phase etching. In the cleaned chamber, an epitaxial layer was vapor-grown on the main surface of the wafer to produce an epitaxial wafer.

  As shown in FIG. 2, the time required for the inner wall of the chamber to reach about 580 ° C. could be shortened. In the example, the time required from cleaning to vapor phase growth was 80% compared to the comparative example.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

DESCRIPTION OF SYMBOLS 1 ... Chamber, 2 ... Susceptor, 3 ... Chamber base, 4, 4 '... Transparent quartz member, 5, 5' ... Opaque quartz member, 6 ... Rotation mechanism, 7 ... Purge gas introduction pipe, 8 ... Gas introduction for vapor phase growth Tube 9 gas discharge tube 10 support structure 20 vapor phase growth apparatus W wafer

Claims (4)

A method of manufacturing an epitaxial wafer using a cold wall type vapor phase growth apparatus comprising a susceptor for placing a wafer in a chamber and cleaning the inside of the chamber by vapor phase etching,
When the temperature rises before cleaning, the susceptor is brought closer to the inner wall of the chamber, the temperature of the inner wall of the chamber is raised, the susceptor is returned to the original position, and then the chamber and the susceptor are etched by vapor phase etching. Clean and
An epitaxial wafer manufacturing method comprising: manufacturing an epitaxial wafer by vapor-phase-growing an epitaxial layer on a main surface of a wafer placed on the susceptor in the cleaned chamber.   The method for producing an epitaxial wafer according to claim 1, wherein the susceptor is heated to 1100 ° C. or higher when the temperature is raised before the cleaning.   3. The method for manufacturing an epitaxial wafer according to claim 1, wherein the temperature of the inner wall of the chamber is raised to 580 ° C. or more by bringing the susceptor closer to the inner wall of the chamber when the temperature is raised before the cleaning. 4. The method of manufacturing an epitaxial wafer according to claim 1, wherein at the time of cleaning, HCl gas is flowed into the chamber to clean the susceptor and the chamber by vapor phase etching. 5.

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