JPH0448725A - Wafer diffusion treatment method and wafer heat treatment method - Google Patents

Abstract

PURPOSE:To get a diffusion method which can produce a desired pure film on a wafer without fixed pressure gas atmosphere including air by vacuumizing a reactor, and filling up it with nitrogen gas to fixed pressure. CONSTITUTION:A wafers is loaded on the boat inside a load lock room, and the load lock room 9 is sealed airtightly, and further a reactor 1 is blockaded by a gate valve 10. When the vacuumization of the reactor 1 and the load lock 9 is completed, the boat 7 loaded with a wafer is charged in the reactor 1. In this condition, the inside of the reactor is highly vacuumized secondarily. And, nitrogen gas is supplied. Pure oxygen gas is mixed in the nitrogen gas to be supplied, and in the reactor 1, a pure oxide film is produced on a wafer. Since the air inside the reactor is exhausted completely and further nitrogen gas is supplied this way, wafer treatment can be done in the condition that the air inside the reactor is completely replaced with nitrogen gas.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a diffusion method in diffusion, which is one of the semiconductor manufacturing processes, and an apparatus therefor.

[Prior Art] One of the processes for manufacturing semiconductors from wafers, which are materials for semiconductor elements, is a diffusion process for producing a highly pure oxide film on the surface of the wafer.

A conventional vertical diffuser will be briefly described with reference to FIG.

In the figure, reference numeral 1 denotes a reactor, and a heater (not shown) is provided inside the reactor 1 to form a high-temperature soaking area inside the reactor. Further, a gas supply pipe 3 is connected to the upper part of the reactor 1, and a gas exhaust port 4 is provided in the lower part of the reactor 1.

Wafers are charged into the reactor 1 from below. The wafers are loaded horizontally in multiple stages into a boat 7 provided via a pedestal 6 to a 115 that closes the lower surface of the reactor 1.

The formation of an oxide film on the wafer is carried out by supplying pure oxygen (0□) in a nitrogen gas (N2) atmosphere at normal pressure, and the replacement of the atmosphere with nitrogen gas has been carried out as follows.

Nitrogen gas 8 was supplied from the gas supply pipe 3, and the atmosphere inside the reactor 1 was replaced by the nitrogen gas 8 from the upper part of the reactor 1 by pushing it out from the gas vent 4 below.

[Problems to be Solved by the Invention] However, in the above-described conventional replacement by extruding the atmosphere with nitrogen gas, complete replacement is difficult, and it is inevitable that the atmosphere remains in the reactor.

In addition to oxygen, sulfur, etc., and various metal atoms are mixed in the atmosphere, and if a wafer is diffused while left in the atmosphere, an oxide film containing impurities will be generated, resulting in a highly pure wafer. There was a problem in that the formation of an oxide film was inhibited and product quality was degraded.

In view of these circumstances, the present invention aims to make it possible to completely replace the atmosphere inside the reaction tube with nitrogen gas.

[Means for Solving the Problems] The present invention provides a diffusion method in which diffusion treatment is performed in a constant pressure nitrogen gas atmosphere, which is characterized in that a reaction furnace is evacuated and then filled with nitrogen gas to a constant pressure. A method and a diffusion device implementing the diffusion method.

[Operation] The reactor is evacuated to remove the internal atmosphere, and then filled with nitrogen gas to a constant pressure. This prevents atmospheric air from being mixed in the constant pressure nitrogen gas atmosphere, making it possible to form a desired pure film on the wafer.

[Actual example] An embodiment of the present invention will be described below with reference to the drawings.

Components in FIG. 1 that are the same as those shown in FIG. 2 are given the same reference numerals.

The reactor 1 is airtightly connected to the upper part of the load lock chamber 9.
A gate valve 1 is installed between the reactor 1 and the load lock chamber 9.
0 is set.

The gas supply pipe 3 is connected via a first air valve 11 to a nitrogen gas supply a (not shown), and also to a source of pure oxygen. The oxygen supply source has a flow rate regulator and a concentration regulator so that the amount or concentration of oxygen to be supplied can be adjusted.

The gas exhaust port 4 communicates with the atmosphere via a second air pulp 12 and communicates with the air intake pipe 2 via a third air valve 13.
Connected to 0. The intake pipe 20 has a branch pipe 21 in the middle.
．． 22, and is connected to a mechanical booster pump 23 via branch pipes 21 and 22, and the mechanical booster pump 23 is further connected to a vacuum pump 24.

One branch pipe 21 is provided with a fourth air valve 14, and the other branch pipe 22 is provided with a fifth air valve 14 from the third air valve 13 side.
An air valve 15, a turbo molecular pump 25, and a sixth air valve 16 are provided.

The inside of the load lock chamber 9 and the intake pipe 20 are connected to the exhaust pipe 2.
6, and a seventh air valve 17, an eighth air valve 18, and a ninth air valve 19 whose capacities are gradually increased are provided in parallel in the middle of the exhaust pipe 26.

The load lock chamber 9 is also provided with an elevator (not shown) for loading and unloading the boat 7 loaded with wafers into the reactor. The elevator arm 27 on which the boat 7 is placed via the pedestal 6 is configured to airtightly close the reactor 1 with the boat 7 inserted into the reactor 1.

The effect will be explained below.

A transfer device (not shown) loads wafers into a boat 9 in the load lock chamber, the load lock chamber 9 is hermetically sealed, and the reactor 1 is closed by a gate valve 10.

first air pulp 11, second air valve 12, fifth air valve 15, sixth air valve 16, seventh air valve 17,
The eighth air valve 18 and the ninth air valve 19 are closed, the third air valve 13 and the fourth air valve 14 are opened, and the inside of the reactor 1 is evacuated by the mechanical booster pump 23 and the vacuum pump 24.

Next, the third air valve 13 is closed and the seventh valve 17 is opened, and the load lock chamber 9 is evacuated while the other air valves are returned to their original states. As the pressure inside the load lock chamber 9 progresses, the seventh air valve 17 is closed, the eighth air valve 18 is opened, the eighth air valve 18 is further closed, and the ninth air valve 19 is opened to sequentially vacuum the chamber.

The reason why the capacity of the valves is gradually increased when the load lock chamber 9 is evacuated is to prevent an excessive load from being placed on the mechanical booster cylinder 123 and the vacuum pump 24 due to sudden evacuation.

Further, the reason why the reactor 1 and the load lock chamber 9 are individually evacuated is to prevent the inside of the reactor 1 from being contaminated with dust.

When the evacuation of the reactor 1 and the load lock chamber 9 is completed, the boat 7 loaded with wafers is loaded into the reactor 1.

In this state, the first air pulp 11, the second air valve 12
, close the fourth air pulp 14, seventh air valve 17, eighth air valve 18, and ninth air valve 19, open the third air valve 13, fifth air valve 15, and sixth air valve 16, and open the turbo molecular pump 25, mechanical booster pump 23, The inside of the reactor 1 is highly evacuated by a vacuum pump 24.

When the secondary evacuation inside the reactor 1 is completed, the third air valve 1
3. Close the fifth air valve 15 and the sixth air valve 16,
The first air pulp 11 is opened and the second air valve 12 is opened when the interior of the reactor 1 to which nitrogen gas is supplied is filled with nitrogen gas and the pressure becomes constant.

Pure oxygen gas is mixed into the supplied nitrogen gas, and reactor 1
In this process, a pure oxide film is formed on the wafer.

When the formation of the oxide film is completed, the boat 7 is taken out into the load lock chamber 9, all the air valves are closed, the gate valve 10 is closed, the wafer is sufficiently cooled, and the wafer is further removed from the load lock chamber 9. .

As explained above, the atmosphere inside the reactor is completely exhausted,
Furthermore, since nitrogen gas is supplied, the inside of the reactor is completely filled with nitrogen gas! The wafer can be processed in the changed state.

In the above embodiment, oxygen was supplied to form an oxide film, but it goes without saying that a nitride film or the like may be formed by combination with other gases.

[Effects of the Invention] As described above, according to the present invention, since the interior of the reactor is evacuated and then filled with nitrogen gas to a constant pressure, the atmosphere is not mixed with the nitrogen gas in the diffusion atmosphere, and the atmosphere is It can prevent the formation of oxide film containing impurities in the product, improve product quality,
It is possible to improve multilayer structure.

[Brief explanation of drawings]

FIG. 1 is a basic configuration diagram according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram of a conventional system. 1 is a reactor, 7 is a boat, 9 is a load lock chamber, 10 is a gate valve, 11, 12.13.14.15, 16.
17, 18 and 19 are air valves, 23 is a mechanical booster pump, 24 is a vacuum pump, and 25 is a turbo molecular pump.

Claims (1)

[Scope of Claims] 1) A diffusion method in which diffusion treatment is carried out in a constant pressure nitrogen gas atmosphere, which is characterized in that a reaction furnace is evacuated and then filled with nitrogen gas to a constant pressure. 2) Equipped with a load lock chamber connected to the reactor, the reactor,
After evacuating the load lock chamber individually, wafers are loaded into the reactor from the load lock chamber, and then only the reactor is evacuated.
2. The diffusion method according to claim 1, wherein the method is then evacuated. 3) A reactor is connected to the load-lock chamber, a gate valve is provided between the load-lock chamber and the reactor, and a loading device for loading a board onto which wafers are loaded into the reactor is connected to the load-lock chamber. 1. A diffusion device, characterized in that the reactor and the load lock chamber can be individually evacuated, and a nitrogen gas supply source is connected to the reactor. 4) The diffusion device according to claim 3, wherein only the reactor is evacuated by a turbo molecular pump while the boat is loaded into the reactor.