JPH118231A - Heat treatment equipment - Google Patents

Abstract

(57) Abstract: Provided is a heat treatment apparatus for forming a gate oxide film having good electric breakdown voltage. SOLUTION: A heat treatment apparatus 30 includes on-off valves 24A, B provided at a gas inlet end 20 and a gas outlet end 22 of a metal pipe 18, respectively, and a branch pipe branched and connected between the on-off valves 24A, B. 32, and a vacuum exhaust device 34 provided at the tip of the branch pipe 32. The branch pipe 32 has an on-off valve 36 near the metal pipe 18. In order to transport the corrosive gas into the chamber of the heat treatment apparatus 30, the corrosive gas is transported by opening both the open / close valves 24A and 24B. After the transportation, the on-off valves 24A and 24B are closed, and the evacuation device 3
4 is operated, the on-off valve 36 is opened, and the inside of the metal pipe 18 is evacuated. Thus, the corrosive gas does not remain in the metal pipe 18 after the transport of the corrosive gas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a heat treatment apparatus for processing a wafer, and more particularly, to a heat treatment apparatus for forming a high-quality gate oxide film.

[0002]

2. Description of the Related Art In a heat treatment apparatus used for manufacturing a semiconductor device, a wafer is often processed in a chamber using a corrosive gas. For example, a hydrogen chloride gas is introduced into a gas atmosphere in a chamber, and an oxidation step is performed in the gas atmosphere, or a heat treatment step is further performed in a hydrogen chloride gas atmosphere in the chamber after the oxidation step. Such a heat treatment apparatus generally includes a corrosive gas transport mechanism configured to transport a corrosive gas into a chamber by a metal pipe. FIG. 4 is a conceptual side view showing an example of a conventional heat treatment apparatus for forming a gate oxide film on a MOS type semiconductor device. The conventional heat treatment apparatus 10 includes a quartz glass tube 12 as a chamber for processing a wafer, and a corrosive gas transport mechanism 16 connected to the quartz glass tube 12 via a Teflon tube 14. The corrosive gas transport mechanism 16
A metal pipe 18 for transporting the corrosive gas, on-off valves 24A and 24B provided at a gas inlet 20 and a gas outlet 22 of the metal pipe 18, and a gas supply source such as a gas cylinder connected to the gas inlet 20. 26. The metal pipe 18 is usually made of stainless steel. In addition, metal piping 18
It is not preferable to replace all of them with Teflon tubes, since the pipes cannot be arranged in any shape.

[0003]

However, when wafer processing is performed using a conventional heat treatment apparatus, there is a problem that iron is taken in as an impurity in the gate oxide film and the electric breakdown voltage of the gate oxide film is reduced. . In view of the above circumstances, an object of the present invention is to provide a heat treatment apparatus that forms a gate oxide film having a good electric withstand voltage.

[0004]

Means for Solving the Problems The present inventor studied the cause of iron being taken in as an impurity when the conventional heat treatment apparatus 10 was used, and focused on the metal pipe 18. Further, the present inventor often finds that water droplets adhere to the metal pipe 18 due to various factors such as water vapor contained in the corrosive gas, so that a corrosive gas such as hydrogen chloride dissolves in the water droplets. Then, attention was paid to the fact that a corrosive liquid such as hydrochloric acid adhered to the metal pipe 18. Although the metal pipe 18 is made of stainless steel and has good corrosion resistance, when a part having low corrosion resistance such as the welded portion 28 is formed in the metal pipe 18, this part is corroded and iron is released into the pipe. And found that it is taken into the gate oxide film. In addition, in the welded portion, the corrosion resistance is weak because the metal composition is changed by the heat at the time of welding. Then, as a result of earnest examination, the present inventor considers that the corrosive gas is transported by the corrosive gas transport mechanism 16 and then the remaining corrosive gas is exhausted by vacuum-sucking the inside of the metal pipe 18. Thus, the present invention has been completed.

In order to achieve the above object, a heat treatment apparatus according to the present invention comprises a chamber for heat treating a wafer, a metal pipe for transporting a corrosive gas into the chamber, and a gas inlet and a gas outlet of the metal pipe. In a heat treatment apparatus having an on-off valve provided respectively, an exhaust pipe with an on-off valve is branched from between both on-off valves of a metal pipe and connected to a vacuum exhaust system.

The material of the metal pipe is often made of stainless steel, but is not particularly limited. In order to transport the corrosive gas by using the corrosive gas transport piping structure according to the present invention, the corrosive gas is transported by opening both of the on-off valves at the gas inlet and the gas outlet. After the transportation is completed, the on-off valves at the gas introduction end and the gas outlet end are closed, then the on-off valves of the vacuum exhaust system are opened, and the inside of the metal pipe is evacuated. Thus, the corrosive gas does not remain in the metal pipe after the transport of the corrosive gas.

[0007]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Embodiment This embodiment is an example of a heat treatment apparatus used for forming a gate oxide film on a MOS semiconductor device. FIG.
It is a side view of the heat processing apparatus of this example of an embodiment. In the present embodiment, the same components as those in the related art are denoted by the same reference numerals, and description thereof is omitted. The heat treatment apparatus 30 of the present embodiment is different from the conventional heat treatment apparatus 10 in that the open / close valve 24A of the metal pipe 18 is provided.
Further, there is further provided a branch pipe 32 connected between B and an evacuation device 34 provided at the tip of the branch pipe 32. The branch pipe 32 has an on-off valve 36 near the metal pipe 18. The on-off valves 24A and 24B and the on-off valve 36
It is closed when 0 is not used.

FIG. 2 and FIG. 3 are views showing the valve opening / closing state in this embodiment. In FIGS. 2 and 3, a black valve means closed, and a white valve means open. In order to supply the corrosive gas into the chamber using the heat treatment apparatus 30, as shown in FIG. 2, the on-off valves 24A and 24B are opened to transport the corrosive gas. When ending the transportation, close the on-off valves 24A and B,
The evacuation device 34 is operated, and the on-off valve 36 is opened (see FIG. 3). As a result, the corrosive gas remaining in the metal pipe 18 is exhausted.

[0009] Thus, after the corrosive gas is transported, no corrosive gas remains in the metal pipe 18.
The amount of corrosive gas that dissolves in water droplets adhering to the inside is greatly reduced, and the amount of corrosion in a portion having low corrosion resistance such as the welded portion 28 is greatly reduced. Therefore, the iron content released into the metal pipe 18 is greatly reduced, so that highly corrosive gas is transported. Therefore, the amount of iron mixed into the gate oxide film of the MOS type semiconductor element is significantly reduced, so that a gate oxide film having good electric breakdown voltage can be formed.
Preferably, immediately before transporting the corrosive gas, the on-off valve 36 is opened and the inside of the metal pipe 18 is exhausted. Thereby, a corrosive gas with higher purity can be transported.

[0010]

According to the present invention, the heat treatment apparatus is provided with a vacuum exhaust system with an on-off valve which is evacuated by vacuum suction between both on-off valves of a metal pipe for transporting corrosive gas. ing. As a result, it is possible to prevent the corrosive gas from remaining in the metal pipe after transporting the corrosive gas, so that the amount of the corrosive gas dissolved in water droplets adhering to the metal pipe is greatly reduced. In addition, the corrosive liquid generated in the metal pipe is greatly reduced. Therefore, the amount of the metal component released into the metal pipe is much reduced as compared with the conventional case. Therefore, a favorable gate oxide film can be formed by using the heat treatment apparatus according to the present invention. Further, since the amount of corrosion of the metal pipe is significantly reduced as compared with the conventional case, the frequency of replacing the metal pipe is reduced.

[Brief description of the drawings]

FIG. 1 is a side view of a heat treatment apparatus according to an embodiment.

FIG. 2 is a side view showing a valve opening and closing state in the embodiment.

FIG. 3 is a side view showing a valve opening and closing state in the embodiment.

FIG. 4 is a conceptual side view showing an example of a corrosive gas transport mechanism of a conventional heat treatment apparatus.

[Explanation of symbols]

10 ... heat treatment apparatus, 12 ... quartz glass tube, 14 ...
Teflon tube, 16 Corrosive gas transport mechanism, 1
8 metal pipe, 20 gas inlet end, 22 gas outlet end, 24A, B ... on-off valve, 26 gas supply source, 2
8 ... welded part, 30 ... heat treatment apparatus, 32 ... branch pipe,
34 ... evacuation device, 36 ... open / close valve.

Claims (1)

[Claims] 1. A heat treatment apparatus having a chamber for heat treating a wafer, a metal pipe for transporting a corrosive gas into the chamber, and on-off valves provided at a gas inlet end and a gas outlet end of the metal pipe. 3. The heat treatment apparatus according to claim 1, wherein an exhaust pipe with an on-off valve is branched from between the on-off valves of the metal pipe and connected to a vacuum exhaust system.