JPS6047424A - Laminated body of gallium arsenide and boron arsenide and manufacture thereof - Google Patents

Abstract

PURPOSE:To prevent the generation of damages and the change of quality due to oxidation during transportation or any other handlings of the wafers of gallium arsenide by composing the protective layer formed on a surface of the gallium arsenide out of a thin film of boron arsenide. CONSTITUTION:One end of the tube reactor 1 made of crystal glass surrounded by a heating furnace 9 is provided with a carrier gas introducing pipe 3 and a boron trichloride gas introducing pipe 4 and another end is provided with a vacuum pump 5 having a pressure gage 14. Also, a container 10 containing boron trichloride 11 is connected to the introducing pipe 4 through a valve 13 and the wafer 6 of gallium arsenide single crystal put on a jig 7 made of crystal glass is contained in the reactor 1. In this constitution, the reactor is firstly kept at 10Torr and the Ar gas including 6 volume % hydrogen is introduced. Then the gas is stopped to reduce the pressure to 10<-3>Torr and boron trichloride is introduced to restore the pressure. After that, the temperature of the wafer 6 is increased to about 60 deg.C and is kept for 20min and then 600 deg.C is kept for 20min. Then the carrier gas is introduced and cooling is done to produce boron arsenide thin film on the wafer 6.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel laminate comprising gallium arsenide and an arsenic thin film, 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. Although wafers are usually polished smooth, they easily develop an oxide layer due to oxygen in the air.

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 discovered that boron chloride and/or
Alternatively, it has been found that a novel laminate having a boron arsenide coating on the surface can be obtained by contacting with a gas containing boron bromide. 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 or boron bromide, or a mixture thereof, is applied to the surface of the heated gallium arsenide using an inert gas such as argon or helium, or a carrier gas containing hydrogen mixed therewith. When the gallium in the gallium arsenide is brought into contact with or without the combination of 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 boron content tends to increase, especially as the film thickness increases, 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.

If the temperature of the surface of the gallium arsenide that is in contact with the gas is too low, the formation of a film will be slow, and if it is too high, the sublimation of arsenic will be significant. Preferably, the temperature is around ℃.

In short, the surface of gallium arsenide often combines with oxygen in the air, forming an oxide film, but if it is treated in the same way as when there is no oxide film, gallium chloride etc. will be formed and the oxide will be removed. 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. Semiconductor devices are also new.

Hereinafter, the present invention will be described in detail 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 5 Q cm, with a carrier gas introduction tube 3 and a quartz glass reaction tube at one end 2. A boron chloride gas introduction pipe 4 is in explosive contact. Reaction tube 1
The other end becomes a flange and passes through the nozzle to the vacuum pump 5.
It is connected to the. 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. A container 10 stores boron trichloride 1j, and is equipped with a carrier gas flow regulator 12, a boron trichloride flow regulator 13, and a pressure gauge 14.

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 the pressure was increased to 10T.
Argon containing 6% by volume of hydrogen (hereinafter referred to as carrier gas) is heated at 50rr+ per minute in standard conditions while maintaining the
42 for 0.5 hour, and then the supply of carrier gas was stopped and the internal pressure of the reaction tube was lowered to 10' Torr. Next, apply boron trichloride at a rate of 50% per minute in standard conditions.
The wafer was heated in a heating furnace while adjusting the exhaust of the vacuum pump so that the internal pressure of the reaction tube was 10 Torr, and after about 30 minutes at a heating rate of 50°C per minute,
The temperature was set to 00°C, and the temperature was further maintained at 600°C for 20 minutes. Next, while maintaining the internal pressure of the reaction tube at 10 Torr, the carrier gas was pumped at 100 nnj/min (converted to standard conditions). Then, the introduction of boron trichloride and the evacuation by the vacuum pump were stopped, and when the internal pressure reached normal pressure, the introduction of the carrier gas was stopped. After maintaining this state at 600° C. for another 30 minutes, heating was stopped and 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 was smooth and uniform, and almost no change was observed even after heating at 500° C. for 130 minutes in the air. The surface layer was electrically insulating and the film thickness was about 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)

[Claims] (11) A laminate consisting of gallium arsenide and a boron arsenide thin film provided on its surface. A method for producing a laminate comprising gallium arsenide and a boron arsenide thin film provided on its surface, characterized by contacting with a gas containing boron bromide and/or boron bromide.