JPS63200537A - Silicon oxide film forming equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a silicon oxide film forming technique designed to improve yield, quality, and uniformity when forming a silicon oxide film on a silicon surface.

[Prior art] Silicon oxide film forming methods include thermal oxidation method, vacuum deposition method, C
Although there are VD methods and the like, thermal oxidation methods are generally used.

This thermal oxidation method forms a silicon oxide film on the surface of a silicon substrate by heating the silicon substrate to a predetermined high temperature in an oxidizing atmosphere.

As shown in Fig. 2, the apparatus for carrying out the conventional thermal oxidation method is composed of a heating section 3, a scorching tube section 2, and a quartz tube section l, and various gases are introduced into the quartz tube section l. A plurality of gas introduction pipes are connected to the quartz tube part l, which has a structure that allows for the introduction of other gases such that at least one of the introduction pipes is heated to a temperature higher than the ignition point of hydrogen at the heating furnace temperature. It has the role of burning hydrogen gas with high efficiency.

Conventionally, oxygen gas is flowed to fill the inside of the quartz tube with an oxygen atmosphere, and after 2 to 5 minutes, hydrogen gas is flowed to cause combustion. The flow of water vapor generated at this time oxidizes the surface of the silicon substrate placed inside the quartz tube. In this case, controlling the oxide film thickness by temperature and time is a common method.

[Problems to be solved by the invention] However, in the conventional method described above, the silicon substrate is kept in an oxygen atmosphere before flowing, so that the surface of the silicon substrate is oxidized not by water vapor but by oxygen. However, when forming a thin oxide film, there is a large variation with respect to the target value, and even when forming a thick oxide film, the number of levels formed at the interface between the oxide film and silicon is unstable. had.

Note that oxidation by oxidation alone (dry oxidation) is undesirable in a semiconductor process because the film quality is brittle and a film with low packing density (filling degree) is formed.

The present invention has been made in view of the above-mentioned conventional problems,
The purpose is to provide a method for forming a silicon oxide film in which the number of oxide film-silicon interface states is small and stable, and the film thickness can be stably supplied with little variation with respect to a target value.

[Means for Solving the Problems] In order to achieve the above object, the silicon oxide film forming apparatus according to the present invention includes a means for heating at least the inside of a quartz tube housing a silicon substrate, and a predetermined heating method in the quartz tube. In a silicon oxide film forming apparatus equipped with a means for selectively supplying and flowing gas, a mixer is disposed outside the quartz tube, and at least hydrogen gas and oxygen gas are disposed outside the quartz tube. The present invention is characterized in that a silicon oxide film is formed on the silicon substrate by uniformly mixing the gas in a mixer and flowing the mixed gas into the quartz tube to cause hydrogen combustion.

[Function] As described above, according to the present invention, hydrogen gas and oxygen gas can be uniformly mixed in a mixer provided outside the quartz tube, and then fed into the quartz tube and made to flow. Therefore,
By exposing the silicon substrate to an extremely stable flow of water vapor without exposing it to an oxygen atmosphere, the number of levels at the interface between the silicon and oxide films is reduced (Table 1), and the thickness of the oxide film is 11 times thinner with good reproducibility. (Table 2).

[Examples] Hereinafter, the present invention will be described by way of examples with reference to the accompanying drawings.
explain.

As shown in FIG. 1, the silicon oxide film forming apparatus according to the present invention includes a heater section 3 equipped with a means for heating a quartz tube l and controlling the heating temperature, It is composed of a heat soaking tube section 2 for enlarging the heat soaking section in both the direction and the axial direction, a quartz board 8 for installing a silicon substrate 9, and a quartz cap 10 for preventing outside air from entering.

Further, the nozzle portion 17 of the quartz tube l has a joint portion 14.
mixer 12 and gas inlet pipe 15.1 joined by
6 is provided, and has a structure in which a predetermined gas can be selectively introduced from the gas introduction hole 4 by opening and closing a pulp (not shown).

Further, a diffusion plate 13 is provided in the mixer 12 to uniformly mix the gases from the introduction pipes 15 and 16.

Since the cleanliness of the quartz tube 1 influences the quality of the silicon oxide film, a highly pure gas is always allowed to flow through the gas introduction hole 4.

Furthermore, the silicon substrate 9 on which the silicon oxide film is formed is
A plurality of quartz boards 8 are installed on top of the quartz tube 1, and a soft landing mechanism etc.
It is now being moved to

Next, the operation of the apparatus shown in FIG. 1 will be explained. Since the inside of the quartz tube 1 is filled in advance with a flowing nitrogen atmosphere from the gas introduction pipe 6,
A brittle silicon oxide film with low backing density is not formed.

After the silicon substrate 9 and the quartz board 8 are placed in a predetermined position, they are left in the apparatus for 30 seconds to 5 minutes until the humidity becomes uniform.

After that, after stopping the inflow of nitrogen gas, by opening the pulp (not shown), oxygen and hydrogen gas are respectively introduced into the mixing tube 12 from the gas introduction pipes 15 and 16.
The mixture is uniformly mixed by the diffusion plate 13. Furthermore, hydrogen and oxygen gases are introduced into the quartz tube l through the gas introduction hole 4 to cause hydrogen combustion.

According to the present invention, a silicon oxide film can be formed by a uniform water vapor flow generated by flowing and burning a gas in which hydrogen and oxygen gases are uniformly mixed simultaneously into a quartz tube. Therefore, as shown in Tables 1 and 2, good results are obtained in the reproducibility of the 5i-S i 02 interface state and film thickness.

The conditions used in the present invention are shown below.

After the silicon substrate 9 is left in the quartz tube l and heated, the supply of nitrogen is stopped and the oxygen 2 to 2 is directed to the mixer 12.
Simultaneously flow 8 fL/min and 1 to 5 liters/min of hydrogen.

At that time, the internal temperature of the quartz tube l is 5i-3i 0
2 In order to lower the interface level, 800
~900℃ is desirable, and in the case of a thick oxide film, the temperature is 900~1
100°C is desirable. The film thickness is controlled by the hydrogen combustion time by supplying and flowing hydrogen and oxygen. In addition, in order to stably lower the interface state, after hydrogen combustion has stopped, nitrogen is added to
~8 sentences/minute are passed, and the silicon oxide film formation is completed.

[Effects of the Invention] As described above, the method based on the present invention has better film quality and reproducibility of film thickness than silicon oxide films formed by conventional methods, and is an oxide film that can be fully used in semiconductor processes. A silicon film can be provided.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the present invention, and FIG. 2 is an explanatory diagram of a conventional technique. l...Quartz tube, 2...Soaking tube section, 3...Heater section, 4, 5...Gas introduction hole, 6゜7...Gas introduction tube, 8...φ quartz board, 9 ...Silicon substrate, 1
0...Quartz cap, 11...Soaking section, 12...
mixer, 13...diffusion plate, 14...junction, 15.
16... Gas introduction pipe, 17... Nozzle part.

Claims (1)

[Claims] In a silicon oxide film forming apparatus comprising means for heating the inside of a quartz tube housing a silicon substrate and means for selectively supplying and flowing a predetermined gas into the quartz tube, a mixer is provided outside the quartz tube. At least hydrogen gas and oxygen gas are uniformly mixed in a mixer disposed outside the quartz tube, and the mixed gas is fed and flowed into the quartz tube to cause hydrogen combustion. A silicon oxide film forming apparatus characterized by forming a silicon oxide film on a silicon substrate.