JPH0334650B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel laminate comprising gallium arsenide and boron arsenide thin films, and a novel method for producing the same.

Gallium arsenide is a useful material used to manufacture semiconductor devices, etc., but in order to manufacture semiconductor devices etc. from gallium arsenide, for example, wafers cut from a single crystal of gallium arsenide in a specific plane direction are used. They are often used in the form of wafers and are therefore often traded or transported in the form of wafers. Wafers are usually polished to a smooth surface, but oxygen in the air easily forms an oxide layer. However, since the oxide film on the surface of a gallium arsenide wafer is not necessarily mechanically strong, great care must be taken when handling it to avoid damaging the surface.

The present inventor conducted research on the modification of the surface of gallium arsenide wafers, and by bringing a gas containing boron chloride and/or boron bromide into contact with the surface of gallium arsenide, a coating of boron arsenide was formed on the surface of gallium arsenide. It has been found that a novel laminate having the following properties can be obtained. The thin film of boron arsenide thus obtained is dense and mechanically strong, hard and scratch resistant, chemically and thermally durable, and resistant to oxidation. Since it is stable and stable, it can be used as a protective coating to prevent scratches and oxidative deterioration when gallium arsenide wafers are distributed or otherwise handled.

To obtain such a boron arsenide thin film, boron chloride, boron bromide, or a mixture thereof is applied to the heated gallium arsenide surface with an inert gas such as argon or helium, or a carrier gas mixed with hydrogen. When brought into contact with or without combination, the gallium in gallium arsenide becomes chloride or bromide and vaporizes, while the remaining arsenic combines with the reduced and isolated boron and forms the surface of gallium arsenide. A method of precipitating boron arsenide can be used.

At this time, when the carrier gas is an inert gas or is not used, the composition of boron arsenide produced is approximately 1:1 in molar ratio, but when the carrier gas contains hydrogen, the content of hydrogen in the carrier gas is approximately 1:1. The boron content increases as
In particular, as the film thickness increases, the boron content tends to increase, and a film with a molar ratio of 1:6 is also produced.

There is no particular restriction on the concentration of boron chloride or boron bromide contained in the carrier gas, but it is usually suitable to be 5% by volume or more.

Further, the pressure of the gas when bringing the gas into contact is not particularly limited, but it is preferably atmospheric pressure or lower.

The temperature of the surface of gallium arsenide that is in contact with the gas is
If the temperature is too low, the formation of the film will be slow, and if it is too high, the sublimation of arsenic will be significant. Therefore, the temperature is preferably in the range of 300°C to 700°C, and particularly preferably around 500°C to 600°C.

In addition, the surface of gallium arsenide often combines with oxygen in the air and forms an oxide film, but if treated in the same way as when there is no oxide film, the oxide will be removed along with the formation of gallium chloride, etc. Since it is removed and discharged to the outside of the system together with the carrier gas, there is no problem at all with the formation of the boron arsenide thin film.

The resulting boron arsenide film is a semiconductor when the molar ratio is 1:1, and an insulator when the molar ratio is 1:6. The thickness of the film can also be freely selected by changing the reaction time. Therefore, the boron arsenide thin film can also be used as a semiconductor layer or an insulator layer as a member constituting a semiconductor device, especially as a dielectric layer provided on the gate of a field effect transistor, etc. The new semiconductor device is also new.

Embodiments of the present invention will be described below based on the drawings.

The figure is a schematic diagram showing an example of an apparatus for carrying out the present invention, in which 1 is a reaction tube made of quartz glass with a diameter of 3 cm and a length of 60 cm, with a carrier gas introduction tube 3 and boron trichloride at one end 2. A gas introduction pipe 4 is welded. The other end of the reaction tube 1 becomes a flange,
It is connected to a vacuum pump 5 via a nozzle. A quartz glass jig 7 is placed inside the reaction tube, and gallium arsenide single crystal wafers 6 are arranged on it. 9 is a heating furnace, and 8 is a temperature measurement sensor. 10 is a container storing boron trichloride 11, a flow rate regulator 12 for carrier gas, a flow rate regulator 13 for boron trichloride, and a pressure gauge 1.
4 are provided.

Using this device, the present invention was carried out in the following manner. First, the inside of the reaction tube was evacuated using a vacuum pump, and while maintaining the temperature at 10 Torr, argon containing 6% by volume of hydrogen (hereinafter referred to as carrier gas) was introduced at a rate of 50 ml per minute (converted to standard conditions) for 0.5 hours, and then the carrier gas was evacuated. Stop the supply and adjust the reaction tube internal pressure.
It was lowered to 10 ^-3 Torr. Next, boron trichloride was introduced at a rate of 50 ml per minute (converted to standard conditions), and the wafer was heated in a heating furnace at approximately 50°C per minute while adjusting the vacuum pump exhaust so that the internal pressure of the reaction tube was 10 Torr.
After about 30 minutes, raise the temperature to 600℃, and then heat for another 20 minutes.
It was maintained at 600°C. Next, while maintaining the internal pressure of the reaction tube at 10 Torr, the carrier gas is pumped every minute (converted to standard conditions).
After introducing boron trichloride for 6 minutes at a rate of 100 ml, the introduction of boron trichloride and evacuation by the vacuum pump were stopped, and after the internal pressure reached normal pressure, the introduction of carrier gas was stopped.
After maintaining this state at 600°C for an additional 30 minutes, heating was stopped and the mixture was allowed to cool.

When the surface of the thus obtained treated wafer was examined, it was found that the surface was boron arsenide containing 1 mole of arsenic and 6 moles of boron. According to observation using an electron microscope, the surface is smooth and uniform, and it can be heated to 500℃ in the atmosphere.
Almost no change was observed even after heating for 30 minutes. The surface layer exhibits electrical insulation, and the film thickness is approximately
It was 2600 angstroms.

[Brief explanation of the drawing]

The figure is a schematic diagram showing an example of an apparatus for carrying out the invention.

Claims (1)

[Scope of Claims] 1. A laminate of gallium arsenide and boron arsenide, which comprises a gallium arsenide substrate and an insulating boron arsenide thin film having a surface composition in which the molar ratio of boron to arsenic is greater than 1:1. 2. A method for producing a laminate of gallium arsenide and boron arsenide, which comprises contacting a gallium arsenide substrate or a gallium arsenide substrate having a thin oxide film on the surface with a gas containing boron chloride or bromide. 3. The production method according to claim 2, wherein the gas containing boron chloride or bromide contains hydrogen.