JPH0715887B2 - Metalorganic vapor phase growth equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] An adsorption chamber heated to a low temperature is provided in the middle of a source gas introduction pipe into a reaction chamber so as to adsorb and remove a part of released hydrocarbons. . Then, the metal growth film is highly purified.

[Field of Industrial Application] The present invention relates to improvement of a metal organic chemical vapor deposition apparatus (MOCVD apparatus).

Conventionally, in a method of manufacturing a semiconductor device such as an IC, a vapor phase growth method of growing a semiconductor film, other metal film, and an insulating film on a semiconductor substrate has been widely used, which is one of the basic techniques of semiconductor manufacturing. ing.

Such vapor phase epitaxy methods are roughly classified into a chemical vapor phase epitaxy (CVD) method and a physical vapor deposition (PVD) method.
A recently developed method is MOCVD (Metal Organic Chemical Vapor Deposition).
There is a source gas (raw material gas) of organometallic gas
As a result, it is thermally decomposed to grow a film.

However, this MOCVD method must be carefully considered so that the impurities contained in the source gas are not mixed into the growth film.

[Prior Art] Now, the MOCVD method can grow at low temperature under normal pressure or reduced pressure, and has good coverage (step cover rage) like other CVD methods. For example, an aluminum film can be deposited with good coverage. Can be made. Conventionally, aluminum films have been used as electrode wiring for ICs, but the CVD method is not used as the deposition method because a suitable source gas has not been developed, and PVD methods such as sputtering and vapor deposition are used exclusively. Therefore, there is a drawback that the covering property is poor.

This is because organic aluminum such as trimethylaluminum (TMAL; Al (CH) ₃ ), triethylaluminum (TEAL; Al (CH) ₃ ) and triisobutylaluminum (TIBAL; Al (CH) ₃ ) has been developed, and MOCVD method has been developed. This has made it possible to deposit, thus improving the covering property, and contributing to the high reliability and high quality of ICs.

Further, the MOCVD method is a method that is easily noticed in the field when it is applied to an epitaxial growth method to easily obtain a heterojunction of a compound semiconductor crystal layer when a compound semiconductor device such as GaAs is manufactured.

A conventional schematic cross-sectional view of a MOCVD apparatus grown by such a MOCVD method is shown in FIG. 2, in which 1 is a source container, 11 is a hydrogen gas inlet, 12 is a source gas inlet pipe, 2 is a reaction chamber (chamber), 20 is a wafer, 21 is a susceptor that rotates by mounting a wafer, 22 is a high frequency heating coil, 23 is an exhaust port, and the reaction chamber and the introduction tube are all made of transparent quartz material. is there.

For example, when an aluminum film is grown using such a MOCVD device, a solution of triisobutylaluminum (TIBAL) is put in the source container 1, hydrogen gas is fed into the source container 1 and bubbled, and the hydrogen gas is used as a carrier gas. TIBAL
Gas is introduced into the reaction chamber 2 through the introduction pipe 12
Send to 20 sides. At that time, the heating temperature of the wafer is 250 ° C.
Heat to a degree. Then, a thermally decomposed aluminum film grows on the wafer surface.

Although FIG. 2 exemplifies a vertical reaction chamber, a horizontal reaction chamber is also used.

[Problems to be Solved by the Invention] In the growth method using the MOCVD apparatus as described above, the PVD method is used because the bonding gas of hydrocarbon and metal is thermally decomposed to grow a film. Compared with, there is a drawback that hydrocarbons are easily mixed in the coating. Of the hydrocarbons, hydrogen becomes gaseous and diffuses, so there is no concern, but contamination (contamination) that carbon is mixed in the coating film occurs.

When such a carbon is contained in the growth film, it adversely affects the high-purity IC substrate and deteriorates its quality and reliability.

The present invention proposes a MOCVD device having a structure that reduces the incorporation of carbon into such a grown film.

[Means for Solving Problems] The purpose thereof is to provide an adsorption chamber containing an adsorbent in the middle of an introduction pipe for introducing a source gas into a reaction chamber,
A MOCV configured to heat the adsorption chamber to a temperature lower than the temperature at which the source gas decomposes in a gas phase so that a part of hydrocarbons released from the source gas is adsorbed by the adsorbent.
Achieved by the D device.

[Operation] That is, in the MOCVD apparatus according to the present invention, the adsorption chamber heated to a low temperature is arranged in the middle of the source gas introduction pipe,
Part of the liberated hydrocarbon is adsorbed by an adsorbent to remove it. Then, the amount of carbon mixed in the metal growth film can be reduced accordingly.

[Examples] Hereinafter, examples will be described in detail with reference to the drawings.

FIG. 1 is a schematic cross-sectional view of a MOCVD apparatus according to the present invention. 3 is an adsorption chamber made of a transparent quartz tube, 31 is a hydrocarbon adsorbent made of alumina (Al ₂ O ₃ ) powder, and 32 is an adsorbent. Such an adsorption chamber 3 is provided in the middle of the source gas introduction pipe 12 with a heater. The other members are the second
The same members as those in the figure are denoted by the same symbols.

In such a MOCVD apparatus, the heating temperature of the reaction chamber 2 is set to T ₁ , the heating temperature of the adsorption chamber chamber 3 is set to T ₂ , and T ₁
> When T _2, the suction chamber 3 of the heating temperature T _2, occurs a decomposition reaction of the MR → MR ₁ + R _2, the reaction of the next heating temperature T ₂ chambers 2
Then, the decomposition reaction of MR ₁ → M + R ₃ occurs. Here, M is a metal and R is all a hydrocarbon, and the metal M is not lost by this reaction to form a growth film. However, before the amount of hydrocarbon R ₂ enters the reaction chamber 2, The adsorbent 31 adsorbs and removes the adsorbent 31, and thus the carbon content in the metal film is reduced in the decomposition reaction in the reaction chamber 2.

Explaining the example of the aluminum film, the heating temperature (T ₂ ) of the adsorption chamber 3 is set to 150 ° C., the heating temperature (T ₁ ) of the reaction chamber 2 is set to 250 ° C., and hydrogen gas is used as a carrier gas. Isobutyl aluminum (TIBAL) is flowed into the reaction chamber 2 through the adsorption chamber 3. Then, in the adsorption chamber 3, Decomposition reaction occurs, and in the reaction chamber 2, Decomposition reaction occurs. Therefore, the hydrocarbon of (CH ₃ ) ₂ C = CH ₂ is removed before entering the reaction chamber 2, and the amount of carbon contained in the hydrocarbon is reduced.

Although the above description has been given with reference to the example of the aluminum film, it goes without saying that the apparatus according to the present invention is also effective for growing a compound semiconductor film using triethylgallium or the like as a source gas.

[Effects of the Invention] As is clear from the above description, the MOCVD according to the present invention
The device reduces carbon contamination in the grown film,
Has the advantage of high quality and high reliability.

[Brief description of drawings]

FIG. 1 is a sectional view of a MOCVD apparatus according to the present invention, and FIG. 2 is a sectional view of a conventional MOCVD apparatus. In the figure, 1 is a source container, 11 is a hydrogen gas inlet, 12 is a source gas introduction pipe, 2 is a reaction chamber, 20 is a wafer, 21 is a susceptor, 22 is a high frequency heating coil, 23 is an exhaust port, 3 is an adsorption chamber. , 31 is alumina (adsorbent), and 32 is a heater.

Claims (1)

[Claims] 1. An adsorption chamber containing an adsorbent is provided in the middle of an introduction pipe through which a source gas flows into a reaction chamber,
An organometallic structure characterized in that the adsorption chamber chamber is heated to a temperature lower than a temperature at which the source gas is decomposed in a gas phase so that a part of hydrocarbons released from the source gas is adsorbed by the adsorbent. Vapor growth equipment.