JPS59137396A - Synthetic method of p type semiconductor diamond - Google Patents

Abstract

PURPOSE:To grow a uniform p type semiconductor film on a base substance by a vapor-phase depositing method by supplying volatile hydrocarbons, hydrogen, a volatile boric compd. to a plasma generating chamber, and making a high-frequency wave or a microwave incident thereto. CONSTITUTION:A base substance 5 is arranged on a supporter 6 in a plasma generating chamber 4, which is evacuated by operating an exhauster 7. From a reaction gas supplying apparatus 1 through controlling valves 9, 11, volatile hydrocarbons such as hydrogen, methane, and volatile boric compds. such as B2H6 are supplied by controlling the flow rate of the mixed gases at a prescribed pressure. Then, a microwave nonpolar discharge is induced by operating a microwave oscillator 2. In this manner, hydrocarbons and hydroborides in a excited state are formed and a p type semiconductor thin film of diamond containing boric ions is grown on the surface of the base substance. Instead of the microwave oscillator 2, a high-frequency oscillator is used, and a diamond thin film is grown by inducing the plasma.

Description

[Detailed description of the invention] The present invention relates to a method for synthesizing P-type semiconductor diamond.

The conventional two-synthesis method for P-type semiconductor diamond is (
1) A high-pressure synthesis method using a metal catalyst, and (2) a synthesis method by implanting boron ions into a diamond single crystal are known.

The above method (1) not only requires a high-pressure device, but also has the disadvantage that a metal catalyst and nitrogen are mixed. In addition, the grown crystal is polyhedral and the amount of boron doped is different for each face, making it difficult to obtain a P-type semiconductor diamond that is homogeneously doped with boron.Furthermore, it becomes a lumpy single crystal, and a film-like product is better. .

The method (2) requires implantation of boron ions with an energy of 20 k, eV or more, which causes defects due to radiation damage caused by ion implantation. The disadvantage is that it requires a construction device, is troublesome to operate, and requires a high level of skill.

The present invention has been made to eliminate the drawbacks of conventional methods, and its purpose is to provide a method for synthesizing a homogeneous P-type semiconductor diamond thin film by plasma chemical vapor deposition without requiring expensive synthesis equipment. It is in.

The gist of the present invention is to provide a diamond single crystal or polycrystalline filH containing volatile hydrocarbons, hydrogen, and volatile boron compounds in a plasma generation chamber in which a substrate is installed.

A method for synthesizing P-type semiconductor diamond is characterized by growing a thin film of P-type semiconductor.

To explain this based on the drawings, Fig. 1 is a schematic diagram showing four methods using plasma induced by microwaves, and Fig. 2 is a schematic diagram showing one method using plasma induced by radio frequency waves.

'・1轡1Figure K >I"i・1 is the reaction"
2+"1' microwave oscillator, 3 is a waveguide, 4 is a plasma generation chamber, 5 is a base, 6 is a support, 7 is an exhaust device, 8゜9.10.11 is a regulating valve. Plasma generation After placing the substrate 5 on the support stand 6 in the chamber 4, the exhaust device 7 is activated and the regulating valve 8 is adjusted to reduce the pressure in the plasma generation chamber 4, and the pressure is adjusted from the reaction gas supply bag fil 1. Valve 9, 1
0 and 11 to adjust the flow rates of hydrogen gas, volatile hydrocarbons, and volatile boron compounds, and maintain them at a predetermined pressure. Next, the microwave oscillator 2 is activated to induce microwave non-polar discharge. As a result, excited state hydrocarbons and hydrogen borides are generated, and diamond P containing boron ions is formed on the surface of the substrate.
type semiconductor thin film is grown.

FIG. 2 shows a schematic diagram of the method using plasma induced by radio frequency plasma. Microwave oscillator 2 in Figure 1
Instead, a high frequency oscillator 15 is used, and an output diamond thin film is grown on the parallel electrode plate 13 through the coaxial cable 12.

Examples of volatile hydrocarbons used in the present invention include hydrocarbons such as methane, ethane, acetylene, and butane. Methane is preferable since high purity gas can be easily obtained. Examples of volatile boron compounds include B2H6 and BCl3, with B2H6 being preferred. The ratio of volatile hydrocarbon to hydrogen is preferably 1°:100 or less. The specific resistance value of the P-type semiconductor varies depending on the boron doping ratio and is 50 Torr. 100 Tor
If it exceeds r, granular crystals and graphitic carbon will precipitate, which is not preferable.

In order to grow a diamond single-crystal semiconductor film, it is desirable to use a diamond single-crystal substrate. (
111) plane, (100) plane, or (110) plane, but (110) plane is preferable.

The diamonds deposited on these substrate planes are oriented in the substrate crystal planes and are therefore homogeneously distributed in the pip layer to the doped boron. Also, zaphire and silicon are used to form polycrystalline semiconductor films.

Substrates such as tantalum and molybdenum are used.

Example 1 Using the apparatus shown in FIG. 1, a diamond (11,0) polished surface is placed as the substrate 5 on the substrate support 6 of the plasma generation chamber 4, and the inside of the plasma generation chamber 4 is operated by an exhaust device 7. After exhausting the gas with hydrogen and methane at 2% by volume,
A mixture of hydrogen and diborane (11,001)p each
Q,, z7 min, Q, 5 ml/mj-
The plasma was introduced into the plasma generation chamber 4 through the ion beam, and plasma was induced. Excitation of the reactive gas and heating of the diamond single crystal substrate were performed in a plasma space, and after 3 hours of precipitation, a P-type semiconductor diamond film with a thickness of 3 μm was obtained. The resistance of the membrane is 2X10' at room temperature in the apparatus shown in Figure 2.
After placing the diamond single crystal substrate 5 on the parallel electrode plate 13 of the plasma generation chamber 4, the plasma generation chamber 4 is evacuated by the exhaust device 7 to reduce the pressure, and the substrate 5 is placed on the parallel electrode plate 13 of the plasma generation chamber 4.
was raised to 800°C. Next, the regulating valves 9, 10, 1' 1 were prepared from the reaction gas supply device 1, and a gas containing 1% by volume of methane in hydrogen and 100% diborane in hydrogen were added.
ppm mixed gas at 50 cc/min, 0,
], cc at a rate of 4 cc, operating the exhaust system,
) 1 Adjust the bowl valves 8, 9, 10.11 to reduce the pressure of the plasma generation chamber to 40'I'orr and the flow rate of the mixed gas to 7/min.
Retained at 6cTIL. Next, the high frequency oscillator 15 was activated, and an output of 900 W was applied to the parallel electrode plate 13 through the coaxial cable 12 to induce plasma. Konaga, Sa1: (□) It has an excellent function and effect that allows epitaxial growth of a homogeneous thin film to be easily performed.

Example 3 Using the apparatus shown in FIG. 1, a sapphire plate was placed as the substrate 5 on the substrate support 6 of the plasma generation chamber 4, and after the inside of the plasma generation chamber 4 was evacuated by the exhaust device 7, it was replaced with hydrogen. 80 vl/m of a gas containing 0.3% by volume of methane and a gas containing 100 ppm of hydrogen and diborane.
in, at a rate of 0.5 ml/min, and the plasma generation chamber 4 was maintained at 4 Q Torr. Next, the microwave oscillator 2 is activated, and the output of 400W is transmitted to the waveguide 3.
It entered the plasma generation chamber 4 through the plasma and induced plasma. Excitation of gas in plasma space.

Dissociation and heating of the sapphire plate were carried out for 6 hours. 1 is a schematic diagram of a method using induced plasma; FIG.

1: Reaction gas supply device, 2: Microwave oscillator, 3: Waveguide, 4: Plasma generation chamber, 5: Substrate,
6: Support stand, 7: Exhaust device, 12: Coaxial cable, 13: Parallel electrode plate, 14: Heater, 8, 9, 10
, 11: Regulating valve.

Circle: Manpaku shallow burning ceremony.

Claims (1)

[Claims] Volatile hydrocarbons, hydrogen, and volatile boron compounds are supplied to a plasma generation chamber in which a substrate is installed, and high-frequency waves or microwaves are applied to the mixed residue to induce plasma and bring it into an excited state. 1. A method for synthesizing P-type semiconductor diamond, which is characterized in that a hydrocarbon, hydrogen chloride, is generated, and a P-type semiconductor sakaki film of diamond is grown on the surface of a substrate.・13)゛