JPS58173837A - Forming method for thermal oxide film - Google Patents

Abstract

PURPOSE:To obtain the thermal oxide film with uniform thickness by bending a H2 gas introducing nozzle and ejecting H2 gas while being opposed to O2 gas when a semiconductor wafer is arranged into a core pipe, while H2 gas and O2 gas are burnt and steam is generated and the thermal oxide film is formed to the wafer. CONSTITUTION:A boat 13 on which a large number of the semiconductor wafers 12 are erected at intervals is encased into the core pipe 11, and a nozzle blowing O2 in and the nozzle 14 blowing H2 in are set up to one side of the core pipe 11. In the constitution, the nozzle for O2 is not protruded in long size in the core pipe 11, only the nozzle 14 for H2 is protruded up to the inside of the core pipe 11, and the nose is bent previously in the direction of the nozzle for O2 at 180 deg.C. According to such constitution, the temperature of the blow-off section of O2 gas is brought to approximately 100 deg.C, the temperature of the blow-off section of H2 gas is elevated up to approximately 800 deg.C, and gases are mixed sufficiently in the section of H2 gas, and forwarded to the wafers 12. Accordingly, a mixed gas collides directly with the wafers 12, and the oxide film with uniform film thickness is obtained.

Description

[Detailed description of the invention] The present invention relates to a method for forming a thermal oxide film.

In the conventional method, semiconductor wafers [2] are placed inside the reactor core tube (1).
...(2) are placed directly in line with the port (3) Kill, and the nozzle +4 extends in parallel from one side of the reactor core tube (1).
1 +4) using hydrogen gas (■2) and oxygen gas (
02) is introduced and burned at the tip of the adjacent nozzle +4>+4).

In this method, the tip of the nozzle +41 +41 is approximately 2000
'C also reached, and the flame directly touched the semiconductor wafer (2)
The disadvantage is that the semiconductor urchin (2) may be distorted or the furnace core tube (1) or quartz board (3) may be severely damaged.

In addition, since the water vapor pressure generated is non-uniform within the reactor core tube (1), there is a large variation in the thickness of the saponified film, resulting in defects in which quartz deterioration products caused by the above damage adhere to the surface of the semiconductor wafer (2). was also occurring.

The present invention has been made in view of this point, and is intended to realize a method for forming a thermally saponified film that completely eliminates the conventional drawbacks. An embodiment of the present invention will be described in detail below with reference to FIG.

According to the present invention, semiconductor wafers (up to) and
... A large number of @ are arranged vertically on board a3, one nozzle a- is extended from one side of the furnace core tube (2), and its tip is bent into a U-shape. Hydrogen gas (H
2) is ejected, and the oxygen gas (02) is ejected without using a nozzle extending from the vicinity of the introduction end of the furnace tube αn. In this state, it is combusted at the tip of the nozzle α- to generate water vapor. This water vapor is supplied to semiconductor wafers (11) along the tube wall as shown by arrows to form a thermally oxidized film of uniform thickness.

In the present invention, the reaction temperature is about 100° C. at the oxygen gas ejection port, and about 800° C. at the first tip of the nozzle where hydrogen gas is ejected. Further, since hydrogen gas and oxygen gas are ejected in opposition to each other, the reaction is promoted and water vapor can be stably generated. Furthermore, this water vapor is not directly blown onto the semiconductor wafers ql...□□□, but is indirectly uniformly supplied to the semiconductor wafers t13 along the tube wall as shown by the arrow, so that the water vapor pressure inside the tube can be kept uniform. Can be done.

FIG. 3 shows a film thickness distribution diagram of thermal oxide films of the present invention and a conventional example. The solid line is the characteristic according to the present invention, and the set needle value is 850.
Approximately 70% of semiconductor wafers (2) for AK are 840~
It is clear that the film thickness falls within 880 μm and that a uniform film thickness can be obtained. On the other hand, in the conventional example shown by the dotted line, only about 40% of the semiconductor wafers are distributed in the same range.

As detailed above, the present invention has the advantage that a thermally oxidized film having a uniform thickness can be easily formed with high yield. Furthermore, since the combustion temperature at the tip of nozzle I is lowered, damage to equipment can also be prevented.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view for explaining the conventional example, FIG. 2 is a cross-sectional view for explaining the present invention, and FIG. 3 is a film thickness distribution diagram for the present invention and the conventional example. fill is the reactor core tube, (to) is the semiconductor Ueno 1-1 (to)
is the board, and US is the nozzle. Engineering 1; l+1 2 2 1 11 71 IIts
/4 Figure 8

Claims (1)

[Claims] 1. A method of placing a semiconductor wafer in a reactor core tube, burning hydrogen gas and oxygen gas to generate water vapor, and forming a thermal oxide film on the semiconductor wafer, bending the hydrogen gas introduction nozzle. A method for forming a thermal oxide film, characterized by ejecting oxygen gas in the opposite direction.