JPH1167668A - Epitaxial wafer manufacturing method and apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epitaxial wafer manufacturing method and apparatus which markedly reduces heavy metal contamination generated within a reaction furnace during the periodical maintenance and check process and is free from the effects of heavy metal contamination, even in the epitaxial growth process. SOLUTION: A purge gas injection apparatus for introducing the purge gas into the inside of a reaction furnace is provided. The purge gas injection apparatus is communicated with an interval 43 and interval. 23 via injection pipes 11, 12. At the internal circumference surface of a base plate 3, the purge gas introducing grooves 32, 34 are formed. A communicating hole 41 for communication between the internal side and interval 43 is formed to an upper liner 4. During epitaxial growth, hydrogen gas is caused to flow into the intervals 43, 23, and during the work, nitrogen gas is caused to flow into the intervals 43, 23 as a purge gas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for manufacturing an epitaxial wafer for manufacturing an epitaxial wafer, wherein a susceptor is housed in a reactor,
The present invention relates to a method of manufacturing a single-wafer type epitaxial wafer on which a semiconductor wafer is mounted and epitaxial growth is performed, and an apparatus for manufacturing the same.

[0002]

2. Description of the Related Art When an epitaxial wafer is manufactured by an epitaxial wafer manufacturing apparatus, a single-wafer manufacturing apparatus is most widely used because of its high accuracy and ease of automation. In this single-wafer-type manufacturing apparatus, a source gas such as SiHCl ₃ or HCl is introduced into a heated wafer placed in a reaction furnace for performing an epitaxial growth process and placed on a susceptor and heated. Is grown epitaxially.

[0003] The inner peripheral wall of this reactor is formed of a nonmetal such as quartz or fine ceramic for the purpose of preventing metal contamination, and the outer peripheral wall is formed of metal. Therefore, as shown in FIG. 8, for example, the configuration of this reactor is a base plate 3 forming an outer peripheral wall, and a lower liner 5 and an upper part which are arranged on the inner peripheral side of the base plate 3 and laminated to form an inner peripheral wall. Liner 6, upper dome 71 and lower dome 72 for sealing the top and bottom of the inner peripheral wall
A susceptor 8 for mounting a semiconductor wafer (not shown) is housed therein. The upper dome 7
The first dome 72 and the lower dome 72 are fixed by the clamp ring 30, respectively.

When the lower liner 5 is viewed from above the line EE in FIG. 8, a plan view shown in FIG. 9 is obtained. That is, the lower liner 5 and the base plate 3 are both formed in a substantially donut shape, and as shown in FIG. 10 which is an enlarged view of a main part in FIG. 8, the outer peripheral surface 51 of the lower liner 5 and the outer peripheral surface 61 of the upper liner 6 It is in contact with the inner peripheral surface 31 of the base plate 3 almost entirely.

[0005]

However, these Si
The source gas such as HCl ₃ or HCl can flow into the contact portion 35 between the base plate 3 and the upper and lower liners 5 and 6, and is a metal portion because it has severe corrosiveness in the presence of moisture. If moisture exists in the contact portion 35 between the base plate and the quartz liner, heavy metal contamination occurs in this portion. That is, when the inside of the reactor is exposed to outside air before the reactor is newly used or during periodic maintenance, the source gas reacts with the base plate in the presence of moisture contained in the air to cause heavy metal contamination. Results. These heavy metal contaminations will evaporate slowly or will enter the reactor as dust and contaminate the wafer.

[0006] The production of high quality epitaxial wafers requires that the level of heavy metal contamination be reduced, and that the level of heavy metal contamination must be reduced by at least 70% after new use or regular maintenance.
Purification of the inside of the reaction furnace is performed by performing dummy runs of at least 100 wafers, preferably at least 100 wafers. For example, as shown in FIG. 5, the Fe concentration is reduced to 10 ¹² atoms / cc or less.

However, as described above, in order to reduce the heavy metal contamination to the required standard value, it is necessary to perform at least 70 or more dummy runs, and the semiconductor wafer used for this is discarded, and the dummy run is performed. Cost and time are wasted. Also, in the epitaxial growth after the start mass, 10 ¹¹ decrease in the Fe concentration, as shown in FIG. 6 at
It was about oms / cc, and no further reduction could be expected with the conventional reactor.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has been made to significantly reduce heavy metal contamination occurring in a reactor during periodic maintenance and maintenance, and to prevent epitaxial metal growth from being affected by heavy metal contamination during epitaxial growth. It is an object of the present invention to provide a wafer manufacturing method and a manufacturing apparatus therefor.

[0009]

Therefore, according to the present invention, there is provided a method for producing an epitaxial wafer in which a semiconductor wafer and a source gas are reacted in a reaction furnace to grow epitaxial, while a purge gas is introduced into the reaction furnace. The epitaxial growth is performed.

In a method of manufacturing an epitaxial wafer for growing an epitaxial wafer by reacting a semiconductor wafer with a source gas in the reactor, a base plate for forming an outer wall of the reactor during an operation other than the epitaxial growth such as maintenance and inspection. And a liner forming the inner peripheral wall of the reaction furnace.

Further, a source gas ejection part, a source gas discharge part, a base plate forming an outer peripheral wall, a liner provided on an inner peripheral side of the base plate to form an inner peripheral wall, and upper and lower portions of the inner peripheral wall are respectively formed. In an epitaxial wafer manufacturing apparatus provided with a reaction furnace including a lower dome and an upper dome to be hermetically sealed, a purge gas ejection device communicating between the base plate and the liner is provided.

[0012]

The object of the present invention is to reduce metal contamination generated in a reactor of an epitaxial wafer manufacturing apparatus. As a means for purifying the gas by flowing a gas different from the source gas into the reaction furnace (hereinafter, referred to as "purge"), the coexistence of the three elements of the source gas, the metal portion, and the moisture is minimized. This is to effectively eliminate the resulting small metal contamination sources. In particular, since this metal contamination occurred most on the contact surface between the liner and the base plate forming the outer wall of the reactor by contacting the outer surface of the liner as described above, the purge gas can be uniformly flowed into this portion. The reactor is configured as follows.

The flow of the purge gas is most effective when it is performed both during the epitaxial growth and during other periodic maintenance. During the epitaxial growth, a hydrogen gas that does not affect the growth is flowed. On the other hand, during the process of being exposed to the atmosphere other than that, if hydrogen gas flows out into the room, it may cause a fire or explosion. Therefore, an inert gas such as nitrogen gas or Ar is introduced.

As means for injecting the purge gas, a purge gas ejection device is communicated between the base plate and the liner and communicates therewith, and a purge gas inflow groove is formed between the base plate and the liner along the circumference thereof. Thus, the purge gas from the purge gas ejection device is provided so as to flow smoothly and uniformly between the base plate and the liner.

Further, a communication hole is formed in the liner for communicating the outer peripheral side and the inner peripheral side thereof, and purge gas flowing into the reaction furnace from the inner peripheral side of the communication hole flows along the inner peripheral wall of the liner. Communication holes are formed in various directions. Thus, the purge gas flowing into the reaction furnace flows below the susceptor while generating a vortex, and is provided so as not to affect the inflow of the source gas.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a partially cut-away side view of a reaction furnace of an epitaxial wafer manufacturing apparatus according to the present invention, and FIG. 2 is a plan view of the reaction furnace imagined with an upper dome removed from the line AA in FIG. 1. 3 is a sectional view of a main part of the reactor taken along the line DD in FIG. 2, FIG. 4 is a plan sectional view taken along the line BB in FIG.
FIG. 6 is a plan sectional view taken along line CC of FIG. 1, FIG. 6 is a graph comparing the change in Fe concentration in the dummy run with the conventional technology, and FIG. 7 is a graph comparing the change in Fe concentration in mass production with the conventional technology.

As shown in FIG. 1, the epitaxial wafer manufacturing apparatus according to the present embodiment is a single wafer type manufacturing apparatus, and includes a base plate 3 forming an outer peripheral wall in the same manner as in a conventional reaction furnace.
A lower liner 2 and an upper liner 4 which are arranged and laminated on the inner peripheral side of the base plate 3 to form an inner peripheral wall, and an upper dome 71 which seals up and down the inner peripheral wall.
The susceptor 8 is accommodated therein, and the upper dome 71 and the lower dome 72 are fixed by the clamp ring 30, respectively. The upper and lower liners 2, 4 are made of quartz.

As shown in FIG. 2, the reactor of the present embodiment is provided with a purge gas ejection device 1 into which a purge gas flows, and as shown in FIG. 12 through the upper liner 4
And a gap 23 formed between the lower liner 2 and the base plate 3. Further, on the inner peripheral surface of the base plate 3 are formed purge gas inflow grooves 32 and 34 for making the flow of the purge gas into the gaps 23 and 43 smoother.

As shown in FIG. 4, the gap 43 is formed between the upper liner 4 and the base plate 3, and the purge gas inflow groove 34 is also formed to follow the gap 43. The upper liner 4 has a communication hole 41 for communicating the inside of the upper liner 4 with the gap 43.

As shown in FIG. 5, the gap 23 is formed in a part of an arc between the lower liner 2 and the base plate 3, and the purge gas inflow groove 32 is also formed in an arc following the gap 23. I have.

When epitaxial growth is performed on a semiconductor wafer (not shown), a semiconductor wafer is inserted from the wafer insertion portion 9 and placed on the susceptor 8, and a source gas is supplied from a source gas ejection portion 91. , From the source gas discharge unit 92.

Next, the operation of this embodiment will be described.
In manufacturing an epitaxial wafer using the manufacturing apparatus of the present embodiment, different types of purge gases are introduced and purged during epitaxial growth and other operations such as maintenance and inspection.

First, during maintenance and inspection work, nitrogen gas as a purge gas is caused to flow into both the gap 23 and the gap 43 at a rate of 0.5 l / min. This prevents the outside air from entering the gaps 23 and 43, so that there is no adhesion of water which has conventionally occurred during operations such as maintenance and maintenance, and a reaction when the source gas flows in can be prevented.

Next, during the epitaxial growth, a hydrogen gas which is not corrosive and does not affect the epitaxial growth is introduced as a purge gas. This purge gas flows into both the gap 23 and the gap 43 at a rate of 2.0 l / min. This can prevent the source gas from entering these gaps. As shown in FIG.
Most of the purge gas that has flowed into the gap 43 is discharged into the reactor through the communication hole 41. However, since the communication hole 41 is formed in the tangential direction of the inner peripheral surface of the upper liner 4,
The discharged purge gas forms a vortex and merges with the inflow of the source gas near the semiconductor wafer without affecting the epitaxial growth.

FIG. 6 shows a comparison of the state of heavy metal contamination between the reactor of this embodiment and the reactor of the prior art according to the Fe concentration.
And the result as shown in FIG. 7 was obtained. That is, FIG.
As shown in FIG.
The concentration is about one tenth of the conventional one. Further, the Fe concentration before the start of the dummy run was 10% in the conventional reactor.
This value is substantially the same as the value after the end of the dummy run of 0 sheets. further,
Even in mass production after the dummy run, as shown in FIG. 7, the contamination level can be maintained at about 10 ¹⁰ atoms / cc, which is much lower than the conventional level.

In the above embodiment, the gap 23 is formed by forming a concave portion on the outer periphery of the upper and lower liners 2, 4.
43, the purge gas inflow grooves 32, 34 are formed on the inner peripheral side of the base plate 3. However, the present invention is not limited to this, and a gap and a purge gas inflow groove may be formed between the liner and the base plate. I just need. Further, if the gap between the liner and the base plate is formed so that the purge gas can flow uniformly and smoothly, it is not always necessary to provide the purge gas inflow groove.

Further, in the above embodiment, the hydrogen gas was introduced during the epitaxial growth and the nitrogen gas was introduced as the purge gas during the operation. However, the present invention is not limited to this. For example, an inert gas such as He or Ar may be used. The effect of is obtained.

[0028]

According to the present invention, the configuration is as described above.
It has an excellent effect of significantly reducing heavy metal contamination generated in the reactor due to contact with outside air during regular maintenance and inspection and the like, and is not affected by this heavy metal contamination even during epitaxial growth. Further, even after the start of mass production, there is an excellent effect that the level of heavy metal contamination can be significantly reduced as compared with a conventional reactor, and a higher quality epitaxial wafer can be manufactured.

[Brief description of the drawings]

FIG. 1 is a partially cut-away side view of a reaction furnace of an epitaxial wafer manufacturing apparatus according to the present invention.

FIG. 2 is a plan view of the reaction furnace imagining a state where an upper dome is removed as viewed from a line AA in FIG. 1;

FIG. 3 is a cross-sectional view of a main part of the reactor taken along line DD in FIG. 2;

FIG. 4 is a plan sectional view taken along line BB of FIG. 1;

FIG. 5 is a plan sectional view taken along line CC of FIG. 1;

FIG. 6 is a graph comparing the change in Fe concentration in a dummy run with that of the related art.

FIG. 7 is a graph comparing the change in Fe concentration during mass production with that of the conventional technique.

FIG. 8 is a partially cut-away side view showing the configuration of a conventional single-wafer epitaxial wafer manufacturing apparatus.

FIG. 9 is a plan view showing the relationship between the base plate and the liner as viewed from the line EE in FIG. 8;

FIG. 10 is an enlarged side sectional view taken along line FF of FIG. 9;

[Explanation of symbols]

 1 Purge Gas Injection Device 11 Injection Pipe 12 Injection Pipe 2 Lower Liner 23 Clearance 3 Base Plate 30 Clamp Ring 32 Inner Surface 32 Purge Gas Inflow Groove 34 ‥‥ Purge gas inflow groove 35 部分 Contact portion 4 ‥‥‥ Upper liner 41 ‥‥ Communication hole 43 ‥‥ Gap 5 ‥‥‥ Lower liner 51 ‥‥ Outer surface 6 ‥‥‥ Upper liner 61 ‥‥ Outer surface 71 ‥‥ Upper dome 72 Lower dome 8 Susceptor 9 Wafer insertion section 91 Source gas ejection section 92 Source gas discharge section

Claims (10)

[Claims] 1. A method of manufacturing an epitaxial wafer in which a semiconductor wafer and a source gas are reacted in a reaction furnace to grow epitaxial, wherein the epitaxial growth is performed while flowing a purge gas into the reaction furnace. Manufacturing method of epitaxial wafer. 2. The epitaxial wafer according to claim 1, wherein the position at which the purge gas flows is between a base plate forming an outer wall of the reactor and a liner forming an inner peripheral wall of the reactor. Production method. 3. A method of manufacturing an epitaxial wafer in which a semiconductor wafer and a source gas are reacted in a reactor to grow epitaxial, wherein a base plate for forming an outer wall of the reactor during an operation other than the epitaxial growth such as maintenance and inspection. And a purge gas flowing between the reactor and a liner forming an inner peripheral wall of the reaction furnace. 4. The method for producing an epitaxial wafer according to claim 1, wherein the purge gas is an inert gas. 5. The method according to claim 1, wherein the purge gas is hydrogen gas. 6. The method according to claim 3, wherein the purge gas is a nitrogen gas. 7. A base plate forming an outer peripheral wall, a source gas ejecting part, a source gas discharging part, a liner provided on an inner peripheral side of the base plate to form an inner peripheral wall,
In an epitaxial wafer manufacturing apparatus provided with a reaction furnace including a lower dome and an upper dome for sealing the upper and lower portions of the inner peripheral wall, a purge gas ejection device communicating between the base plate and the liner is provided. Epitaxial wafer manufacturing equipment. 8. A method for communicating with a purge gas ejection device,
8. A purge gas inflow groove is formed between the base plate and the liner along the circumference thereof.
The epitaxial wafer manufacturing apparatus according to the above. 9. The epitaxial wafer manufacturing apparatus according to claim 7, wherein a communication hole is formed in the liner for communicating between the outer peripheral side and the inner peripheral side. 10. The communication hole is formed such that purge gas flowing into the reaction furnace from the inner peripheral side of the communication hole formed in the liner flows along the inner peripheral wall of the liner. An epitaxial wafer manufacturing apparatus according to claim 9.