JPH05343324A - Chemical vapor phase epitaxy and apparatus therefor - Google Patents

Abstract

PURPOSE:To prevent the generation of particles, particularly even if water is contained in the specific reaction gas out of reaction gases, in a chemical vapor-phase epitaxy for introducing reaction gases into a reaction tube from a plurality of gas introduction tubes and for depositing, on a substrate, a product by the chemical reaction between reaction gases in the reaction tube. CONSTITUTION:In a chemical vapor-phase epitaxy for introducing reaction gases into a reaction tube 22 containing a substrate 11 from a plurality of gas introduction tubes 24, 25, while the time is staggered, and for depositing, on a substrate 11, a product generated by the chemical reaction between reaction gases in the reaction tube 22; an inert gas 12 has been introduced into the gas introduction tube 25 other than the gas introduction tube 24 for first introducing a reaction gas (NH3) 14 into the reaction tube 22 before another reaction gas (SiHCL3) 15 is introduced into the reaction tube 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention introduces a reaction gas from a plurality of gas introduction pipes into a reaction pipe containing a substrate at a different timing, and generates the reaction gas by a chemical reaction between the reaction gases. The present invention relates to a chemical vapor deposition method for depositing a substance on a substrate, and more particularly to a chemical vapor deposition method that does not generate particles even if a specific reaction gas in a reaction gas contains water.

[0002]

2. Description of the Related Art Next, silicon oxide is formed on the surface of a semiconductor wafer by a chemical reaction of a reaction gas such as a metal halide compound.
A conventional chemical vapor deposition method for forming a (SiO ₂ ) film or a silicon nitride (Si ₃ N ₄ ) film will be described with reference to FIG.

FIG. 2 is an explanatory view of a conventional chemical vapor deposition method. FIG. 2 (a) is a schematic side sectional view of a chemical vapor deposition apparatus,
FIG. 6B is a diagram showing a reaction gas introduction sequence.
A conventional chemical vapor deposition method will be described on the assumption that a silicon nitride film is formed on a semiconductor wafer by the conventional chemical vapor deposition apparatus shown in FIG.

First, as shown in FIG. 1A, a plurality of semiconductor wafers 11 each having a silicon nitride film formed (deposited) on its surface are formed.
A reaction tube 22 with a boat 21
Then, the gas in the reaction tube 22 is exhausted (the inside of the reaction tube 22 is evacuated) via the exhaust tube 22a by an exhaust device (not shown).

Next, the heating furnace body 23 surrounding the reaction tube 22 coaxially is heated to heat the semiconductor wafer 11 housed in the reaction tube 22 together with the boat 21. Then, the temperature of the semiconductor wafer 11 is a predetermined temperature, for example, 80
When the temperature reaches 0 degrees C, the first on-off valve 24a is operated to introduce the NH ₃ (ammonia) gas 14 from the first gas introduction pipe 24 into the reaction pipe 22, and the second on-off valve 25a is operated. Second
From the gas introduction pipe 25 of the metal halogen compound, for example, SiHC
Introduce L ₃ gas 15.

NH thus introduced into the reaction tube 22
_{The 3} gas 14 and the SiHCL ₃ gas 15 chemically react with each other to form a silicon nitride film (not shown) formed by depositing a silicon nitride film, which is a product thereof, on the semiconductor wafer 11.

After that, the heating of the heating furnace body 23 is stopped to lower the temperature in the reaction tube 22, and then the semiconductor wafer 11 is taken out from the reaction tube 22 together with the boat 21 to complete a series of operations. ..

[0008]

By the way, NH ₃ gas 14
And SiHCL ₃ gas 15 are usually staggered in the reaction tube.
It has been introduced within 22. For example, if the introduction start time of the NH ₃ gas 14 into the reaction tube 22 is T _O (see G _{1 in} FIG. 2 (b)),
The introduction start time of the SiHCL ₃ gas 15 into the reaction tube 22 is T ₀ + ΔT
(See G _{2 in} FIG. 2 (b)), that is, SiHCL ₃ gas 15 is N
It is introduced into the reaction tube 22 with a delay of ΔT time (for example, about 1 minute) from the H ₃ gas 14.

1 (b) and 2 (b), the solid line portion shows that the gas is being introduced into the reaction tube 22, and the dotted line portion shows that the gas introduction into the reaction tube 22 is stopped. It has been shown).

For this reason, before the start of introduction of the SiHCL ₃ gas 15, the pipe line of the pipe end portion 25 'of the second gas introduction pipe 25, that is, the second pipe
The pipe end 25 'between the open / close valve 25a and the open end 25b.
NH ₃ gas 14 will enter.

Therefore, by operating the second on-off valve 25a,
Immediately after starting the introduction of the SiHCL ₃ gas 15 into the reaction tube 22 from the second gas introduction pipe 25, the pipe end portion 2 of the second gas introduction pipe 25 is
Moisture (not shown), which is present in the NH ₃ gas 14 invading the 5'pipe, though present in a very small amount, chemically reacts with the SiHCL ₃ gas 15 to cause particles such as silicon oxide (not shown). No.) and NH ₄ CL particles (not shown) are generated.

The particles are continuously carried by the SiHCL ₃ gas 15 continuously introduced into the reaction tube 22 and adhered to the semiconductor wafer 11 or mixed with the silicon nitride film formed on the semiconductor wafer 11. However, the quality will be deteriorated.

The present invention has been made in order to solve such a problem, and an object thereof is to provide a chemical vapor deposition method in which a reaction product does not occur at a high pressure place in a reaction tube. It is in.

[0014]

As shown in FIG. 1, the above-mentioned object is to introduce reaction gas into a reaction tube containing a substrate from a plurality of gas introduction tubes at different timings, and In the chemical vapor deposition method of depositing the product generated by the chemical reaction between the reaction gases on the substrate, the reaction gas 22 is first introduced into the reaction tube 22 before the reaction gas 15 is introduced into the tube. This is achieved by the chemical vapor deposition method characterized in that the inert gas 12 is introduced into the conduits of the gas introduction pipe 25 excluding the gas introduction pipe 24 for introducing.

[0015]

In the chemical vapor deposition method of the present invention, the substrate 11
And a reaction tube that is heated to a high temperature together with this substrate 11.
The gas introduction pipe 25 does not react the reaction gas 15 into the gas introduction pipe 25 except for the gas introduction pipe 24 that first ejects the reaction gas 14 into the inside 22.
The inert gas 12 is introduced until it jets out into the inside 22.

Therefore, although the gas 12 exists in the gas introduction pipe 25, the reaction gas 14 ejected from the gas introduction pipe 24 into the reaction pipe 22 does not exist. Therefore, even if water is present in the reaction gas 14 ejected from the gas introduction pipe 24 into the reaction pipe 22, the reaction gas 14 does not mix with the reaction gas 15 in the gas introduction pipe 25. Therefore, particles that use the moisture and the reaction gas 15 as the source gas are not generated.

Further, in the reaction tube 22, the reaction gas 14 and the reaction gas
No particles are generated by the product of the gas phase reaction by 15.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A chemical vapor deposition method and apparatus according to an embodiment of the present invention will be described below with reference to FIG. FIG. 1 is an explanatory view of a chemical vapor deposition method and an apparatus therefor according to one embodiment of the present invention. FIG. 1 (a) is a schematic side sectional view of a main part of the chemical vapor deposition apparatus, and FIG. ) Is a diagram showing a reaction gas introduction sequence.

In the present specification, the same parts, the same materials and the like are designated by the same reference numerals throughout the drawings. Also for the chemical vapor deposition method of one embodiment of the present invention, similar to the description of the conventional chemical vapor deposition method, the same figure (a)
It is assumed that silicon nitride is deposited on the semiconductor wafer 11 using the chemical vapor deposition apparatus shown in FIG.

Also in the chemical vapor deposition method of one embodiment of the present invention, a semiconductor wafer having silicon nitride deposited on the surface thereof
A boat 21 in which 11 is set in a vertical slice is housed in a reaction tube 22 made of, for example, transparent quartz and heated to about 600 ° C., and then the air in the reaction tube 22 is exhausted (not shown). Exhaust) via the exhaust pipe 22a (reaction tube
Then, the heating furnace body 23 is heated to a growth temperature, for example, 800 ° C., and the reaction tube 22 and the semiconductor wafer 11 housed in the reaction tube 22 together with the boat 21 are heated to a predetermined temperature. For example, the temperature is heated to 800 ° C., but the steps up to here are the same as those in the conventional chemical vapor deposition method described with reference to FIG.

Thereafter, the first opening / closing valve 24a is operated to make the first opening / closing valve 24a.
From the gas inlet pipe 24 of the reaction gas, for example NH₃React gas 14
Introduced into pipe 22 (G in Fig. 2 (b))₁At the same time
Operate the second on-off valve 32a to operate the second inert gas inlet pipe 32
The second opening / closing valve 25a and the opening end 25 of the second gas introduction pipe 25.
In the conduit at pipe end 25 'between b and b, an inert gas,
For example, introduce nitrogen gas 12 (G in the figure (b))₃See this tube
NH in conduit at end 25 ' ₃Prevent gas 14 from entering
It

Next, NH ₃ gas is fed from the first gas introducing pipe 24.
After ΔT, for example, 1 minute, from the start of introduction of 14 into the reaction tube 22, the second on-off valve 25a is operated to introduce the reaction gas 15, for example SiHCL ₃ gas, from the second gas introduction tube 25 into the reaction tube 22. Starting the introduction of 15 (see G _{2 in} Figure (b)),
Operate the on-off valve 32a of the second gas introduction pipe 32
Stop the introduction of nitrogen gas 12 to 25 '(G _{3 in the} same figure (b))
See).

As shown in FIG. 2B, NH ₃ gas 14 and Si to the reaction tube 22 in the chemical vapor deposition method of one embodiment of the present invention are shown.
The introduction sequence of the HCL ₃ gas 15 is the NH ₃ gas 14 and the Si into the reaction tube 22 in the conventional chemical vapor deposition method shown in FIG. 2 (b).
Since the introduction sequence of the HCL ₃ gas 15 is exactly the same, as described above, the NH ₃ gas 14 and SiHC introduced into the reaction tube 22 are introduced.
The L ₃ gas 15 chemically reacts, and a silicon nitride film (not shown) formed by depositing a silicon nitride film, which is a product thereof, on the semiconductor wafer 11 is formed.

However, in the chemical vapor deposition method of one embodiment of the present invention, the tube end portion 2 of the second gas introduction tube 25 is used.
For SiHCl ₃ gas 15 is prevented from mixes with NH ₃ gas 14 in conduit 5 ', NH ₃ even if moisture in the gas 14 is present, the raw material gas and the moisture and SiHCl ₃ gas 15 No silicon oxide-based particles are generated.

Moreover, since no gas phase reaction product with NH ₄ CL is generated, no particles are generated. Therefore, the particles do not adhere to the semiconductor wafer 11 in the reaction tube 22, and the particles do not mix into the silicon nitride film.

Next, the chemical vapor deposition apparatus according to the second embodiment of the present invention shown in FIG. 1 corresponds to the conventional chemical vapor deposition apparatus of FIG. 2, that is, an exhaust apparatus (not shown). A reaction tube 22 provided with an exhaust pipe 22a to be connected to accommodate the semiconductor wafer 11 accommodated in the boat 21 from the open end, a heating furnace body 23 arranged around the reaction tube 22, and a reaction tube 22 Gas 1
Gas introduction pipes 24,25 for introducing 4,15 and semiconductor wafer 1
The inert gas introduction pipes 31 and 32 are newly added to the conventional chemical vapor deposition apparatus which is configured to include the table 20 for mounting and closing the boat 21 for accommodating 1 and closing and opening the open end of the reaction pipe 22. In addition, the opening and closing valves 31a and 32a are opened and closed so that the inert gas can be freely introduced into and blocked from the gas introduction pipes 24 and 25.

Therefore, if the chemical vapor deposition apparatus of one embodiment according to claim 2 of the present invention is adopted, the chemical vapor deposition method of one embodiment according to claim 1 of the present invention is as described above. It is easy to implement.

Naturally, the gas which the inert gas introducing pipes 31, 32 can introduce into the conduits of the gas introducing pipes 24, 25 is not limited to the inert gas. Further, it goes without saying that the chemical vapor deposition method of the present invention is also effective when three or more kinds of reaction gases are used.

[0029]

As described above, the present invention makes it possible to provide a chemical vapor deposition method that does not generate particles and an apparatus therefor (commonly known as a CVD apparatus).

Therefore, the film such as the silicon nitride film formed on the semiconductor wafer by the chemical vapor deposition method of the present invention has a high quality, and the manufacturing yield of the semiconductor device is improved, and the reliability thereof is improved. Become.

[Brief description of drawings]

FIG. 1 is an explanatory view of a chemical vapor deposition method and apparatus therefor according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a conventional chemical vapor deposition method.

[Explanation of symbols]

11 is a semiconductor wafer (substrate), 12 is nitrogen gas (inert gas), 14 is NH ₃ gas (reactive gas), 15 is SiHC
L ₃ gas (reaction gas), 20 is a table, 21 is a boat,
22 is a reaction tube, 22a is an exhaust pipe, 23 is a heating furnace body, 24
Is a first gas introduction pipe, 24a is a first on-off valve, and 25 is
A second gas introduction pipe, 25a is a second on-off valve, 25b is an open end of the second gas introduction pipe, 31 and 32 are active gas introduction pipes,
Reference numerals 31a and 32a denote open / close valves, respectively.

Front page continued (72) Inventor Kenji Itasaka 5950 Soeda, Iriki-cho, Satsuma-gun, Kagoshima Prefecture Kyushu Fujitsu Electronics Limited

Claims (2)

[Claims] 1. A reaction gas containing a substrate is introduced into the reaction tube from a plurality of gas introduction tubes at different timings, and a product produced by a chemical reaction between the reaction gases in the reaction tube is formed on the substrate. In the chemical vapor deposition method of depositing on the above, before introducing the reaction gas (15) into the reaction tube (22), a gas which first introduces the reaction gas (14) into the reaction tube (22). A chemical vapor deposition method characterized in that an inert gas (12) is introduced into the pipelines of the gas introduction pipe (25) excluding the introduction pipe (24). 2. The reaction gas is introduced into the reaction tube containing the substrate from a plurality of gas introduction tubes at different timings,
In a chemical vapor deposition apparatus for depositing a product generated by a chemical reaction between reaction gases in a reaction tube on a substrate, an inert gas (12) is provided in each of the gas introduction tubes (24, 25). (3) A chemical vapor deposition apparatus having an inert gas introducing pipe (31, 32).