JPS62223095A - Production of diamond semiconductor - Google Patents

Abstract

PURPOSE:To obtain the titled semiconductor extremely useful as an electronic element material, having improved thermal conductivity, etc., by reacting a mixed gas of an oxygen-containing compound containing O, C and H and a dopant and precipitating. CONSTITUTION:A reaction tube 9 is packed with diamond or a material 12 except the diamond, valves 6-8 are closed and the reaction tube is exhausted to <=about 10<-4>Torr by a high vacuum exhaust device 14. The valves 6 and 8 are opened. As a given amount of a H2 gas as a carrier gas is sent from a carrier gas feeder 1, a given amount of an oxygen-containing compound such as butanol, etc., containing O, C and H as a carbon source is fed from an oxygen-containing compound feeder 2 to the reaction tube. Microwave having given output is sent from a microwave oscillator 11 to the reaction tube and plasma is generated in the reaction tube 9 while controlling gas pressure at given pressure. The valve 7 is successively opened, a given amount of a dopant such as B2H6, etc. is fed from a dopant feeder to the reaction tube, temperature of the substrate 12 is measured by a thermocouple 13, a mixed gas is reacted at a given temperature for a fixed time and the titled semiconductor is precipitated from the gaseous phase on the substrate 12 and grown.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing a diamond semiconductor having excellent properties as an electronic device material.

[Prior Art] Recently, attempts have been made to add boron or phosphorus when synthesizing diamond from a gas phase.

For example, in JP-A-59-1:17396, an attempt is made to synthesize a P-type diamond semiconductor by causing a gas phase reaction between a hydrocarbon and a boron compound in plasma. JP-A-59-213126 attempts to synthesize an N-type diamond semiconductor by causing a gas phase reaction between a hydrocarbon and P]13 or 8SI+3 in plasma.

[Problems to be Solved by the Invention] However, these methods have problems such as the growth rate of diamond being as low as 1 μm/hr or less, and the diamond tending to become amorphous on substrates other than diamond substrates. However, it has not yet been put into practical use.

The present inventors have developed a diamond manufacturing method using an oxygen-containing compound containing oxygen, carbon, and hydrogen as a raw material. Although this method contained oxygen in the raw material, the growth rate of diamond was fast, and it was a highly practical method for producing diamond.

In researching the synthesis of diamond using this oxygen-containing compound as a raw material, the present inventors further examined various effects of adding dopants such as phosphorus-containing compounds, and found that the electrical resistance of diamond decreased at a certain amount of dopant added. discovered that it exhibits semiconductivity and can easily form a crystalline semiconductor on substrates other than diamond substrates.
As a result of intensive research, we have arrived at the present invention.

That is, an object of the present invention is to provide a method for manufacturing a diamond semiconductor that can increase the growth rate of diamond and can also obtain a crystalline diamond semiconductor on a substrate other than a diamond substrate.

[Means for Solving the Problems] That is, in the present invention, a diamond semiconductor is manufactured by causing a mixed gas of a dopant and an oxygen-containing compound containing oxygen, carbon, and hydrogen to react to precipitate diamond from the gas phase.

The oxygen-containing compound containing oxygen, carbon, and hydrogen used in the present invention may be entrained in gaseous, solid, or liquid form by hydrogen or a carrier gas such as argon or helium, or under reduced pressure, and supplied to the reaction system. Good, but
It is preferable to supply it in an extremely minute amount, preferably in a gaseous state.

In particular, it is a compound with a carbon number of 30 or less, and a compound with a carbon number of 15 or less is preferred for ease of handling.

These oxygen-containing compounds are compounds containing oxygen, carbon, and hydrogen, but may also contain sulfur, halogen, and the like.

Examples of the oxygen-containing compounds of the present invention include ethanol,
Methanol, propatool, butanol, 5ec-butyl alcohol, tert-butyl alcohol, pentanol, hexanol, octatool, 4-methyl-2-
Pentanol, adamantanol, 2,3-dimethyl-
Saturated alcohols such as 2-butanol, furfuryl alcohol, cyclohexanol, acetone, acetylacetone, methylpropyl ketone, acetonylacetone, ethylmethylketone, diethylketone, diisobutylketone, dibutylketone, dipropylketone, 3.3 −
Dimethyl-2-butanone, butyl methyl ketone, methyl isopropyl ketone, isobutyl methyl ketone, ketones such as cyclohexanone, acetaldehyde, propionaldehyde, butyraldehyde, formaldehyde,
Aldehydes such as propionaldehyde, 2-ethylhexylaldehyde, propylaldehyde, methyl vinyl ether, ethyl ether, methyl ethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, dipropyl ether, diisopropyl ether, trimethoxydimethane, ethyl vinyl ether, Ethers such as butyl ether, methylene glycol dimethyl ether, furan, citric acid, succinic acid, acetic acid, 3,3-dimethylglutaric acid, 2-ketopropionic acid, fumaric acid, propionic acid, maleic acid, caproic acid, glutaric acid, etc. Carboxylic acids, methyl acetate, ethyl acetate, trimethyl acetate, methyl formate, ethyl formate,
Propyl formate, isopropyl formate, trimethyl citrate, triethyl citrate, dimethyl succinate, diethyl succinate, dimethyl oxalate, diethyl oxalate, methyl methacrylate, ethyl methacrylate, trimethyl acetate,
Methyl 2-ketopropionate, dimethyl fumarate, diethyl fumarate, ethyl propionate, methyl propionate, butyl propionate, propyl acetate, isopropyl acetate, ethyl maleate, methyl maleate, dimethyl malonate, ethyl malonate, malon These include esters such as acid methyl, polyhydric alcohols such as triethylene glycol, 2-tetramethylethylene glycol, butanediol, butylene glycol, and cyclohexane dimetatool, as well as ether alcohols, ester ethers, and esters. Alcohols, ester ketones, ketone alcohols, etc. are also included, as well as aromatic compounds and unsaturated compounds.

Furthermore, these oxygen-containing compounds have a ratio of the number of oxygen atoms to the number of carbon atoms (0/C) of 1/1 to 1/lo.

A preferred compound is 1/1 to 1/3
It is 0. Furthermore, a mixture of these oxygen-containing compounds and a hydrocarbon consisting basically of carbon and hydrogen may be used. At that time, the hydrocarbons used are
Alternatively, it may be entrained in a gaseous, liquid, or solid state under reduced pressure and supplied to the reaction system, but in an extremely minute state,
Preferably, it is supplied in sublimated or gaseous form.

In particular, it is a hydrocarbon with a carbon number of 30 or less, and a hydrocarbon with a carbon number of 15 or less is preferred from the viewpoint of ease of handling.

In the present invention, the amount of oxygen-containing compound supplied varies depending on the type of oxygen-containing compound, the gas phase reaction method and apparatus, and the use of carrier gas, but for example, in the case of a reaction tube with a tube diameter of 2 cm, the amount of the oxygen-containing compound supplied is 0. When using a carrier gas at 001g/hr to 100g/hr, the carrier gas is 1°C.
0.001g/j2~Long/u,
Preferably it is o, otg/i to 50 g/l.

Below 0.001g/42, the growth rate is slow;
If g71 or more, black carbon is produced as a by-product, which is not preferable.

In the present invention, the dopant is a III-III compound such as boron, aluminum, gallium, indium, thallium, etc.
Compounds of Group B, compounds of Group VB such as nitrogen, phosphorus, arsenic, antimony, bismuth, etc. can be used.

Preferably, boron compounds, phosphorus compounds, and arsenic compounds are used.

For example, the boron compound is B2116,84111
0゜BSH9+B5HIl+ B6HI0.81011
Boron hydride such as BF3. BCI13, BBr
3, BI3, I]2Cj2a, B2Br4.

Halides such as B214, or trimethyl borate, triethyl borate, diphenyl borate.

These include boric acid esters such as triphenyl borate.

Phosphorus compounds are hydrogen compounds such as PH3, PF3.

Halides such as PCfL3, PBr+, PI3, )13PO2°JPOi, 11. +P2O5,H
4P2O6, t13P04,)14P20? .

Oxides such as +1SP3010.113PO5, 114P208, (C)130)3PO.

(C21150) 3PO, (CatlsO) 3PO
, (CH30) 3P , (C2H5O) 3P
.

(C611SO) 3I'011, (in 1130)
Esters such as 3POH, (C81150) 2POH, or (Ca)Is) 2PH, (CaHs)
These include alkyl phosphines such as 3P.

Arsenic compounds include AsH3 and ^sF3. AsCA,
, halides such as AsBr5-As+3, or ^
It is an oxide such as 52o3+113As03.

In these mixed gases of boron compounds, phosphorus compounds, or arsenic compounds and oxygen-containing compounds, each atom of boron, phosphorus, or arsenic is ,1
0-2 to 1O-8 (atom/atom), preferably 10-
'~10-'. These gases may be mixed in advance and supplied, or each may be supplied independently. 1o
If it is more than -2, it tends to become amorphous, and if it is less than lo-8, it is difficult to become a semiconductor, which is not preferable.

The gas pressure is generally 1 atmosphere or less,
In the case of plasma gas phase reaction, it is 100 Torr or less.

These dopants may be supplied to the reaction system in a gaseous, liquid, or solid state using a carrier gas or under reduced pressure, but it is preferable to supply them in a very minute state, preferably by sublimation or in a gaseous state.

Furthermore, it is preferable to install a base material as a place for diamond to precipitate, and examples of such base materials include diamond, graphite, carbonaceous materials such as glassy carbon, single crystal silicon wafers, quartz, silicon carbide, and silicon nitride. silicon compounds, stainless steel, molybdenum, iron, nickel, etc.
Metals consisting of copper, tungsten, niobium, tantalum, vanadium, chromium, hafnium, and alloys based on these components, or sapphire, alumina,
Oxides such as zirconia are used, and these base materials are
Various shapes can be used, such as plate-like, flaky 2-grain, powder, and filament-like shapes.

These substrates may be heated by gas or by external or internal heaters. Generally, the temperature of the base material is 100°C to 1200°C, for example, in the case of plasma gas phase reaction, 300°C to 1000°C is preferable.
At temperatures below 100°C, carbon tends to become amorphous;
C or higher, black carbon is also produced as a by-product, which is not preferable.

[Function] According to the present invention, it is possible to provide a method for manufacturing a diamond semiconductor in which diamond grows at a high rate, and is extremely useful industrially.

The diamond semiconductor thus produced according to the present invention has an electrical resistance of 10 8 ΩC+U to 10 Ωcm, and has excellent thermal conductivity and heat resistance, so it is extremely useful as a material for electronic devices.

[Actual 7i color example] The present invention will be described in detail below with reference to the drawings.

Example-1 In this example, the apparatus shown in FIG. 1 was used. In FIG. 1, 1 is a carrier gas supply device, 2 is an oxygen-containing compound supply device, and 3 is a dopant supply device. The carrier gas from the supply device 1 is led from the flow meter 4 to the supply device 2 via the valve 6. The dopant from the supply device 3 is transferred to the flowmeter 5
The oxygen-containing compound from the supply device 2 is combined with the oxygen-containing compound from the supply device 2 through the valve 7, and further led to the reaction tube 9 through the valve 8. A microwave waveguide IO is arranged around the reaction tube 9, and microwave power generated by a microwave oscillator IO is guided to the waveguide IO. Reference numeral 12 denotes a base material disposed within the reaction tube 9, and a diamond semiconductor is deposited and grown on this base material 12. 13 is a thermocouple for measuring the temperature of the base material 12, and 14 is a high vacuum evacuation device for maintaining the inside of the reaction tube 9 in a predetermined vacuum state.

In an apparatus having such a configuration, the base material 12 is
is loaded into the reaction tube 9, then all valves 6 to 8 are closed, and the inside of the reaction tube 9 is heated to 10'''' by the exhaust device 9.
Evacuate to around Torr. Then valves 6 and 8
, and while supplying a predetermined amount of carrier gas from the supply device 1, a predetermined amount of the oxygen-containing compound is supplied from the supply device 2.

While adjusting the gas pressure in the reaction tube 9 to a predetermined pressure, the microwave oscillator 11 oscillates microwaves with a predetermined output,
Plasma is generated within the reaction tube 9. Continue with valve 7
is opened, a predetermined amount of dopant is supplied from the supply device 2 to the reaction tube 9, and in this state, a reaction is carried out for a predetermined time to deposit and grow a diamond semiconductor on the base material 12.

For example, in the apparatus shown in FIG. 1, hydrogen is supplied from the carrier gas supply device 1, butanol is used as the carbon source in the oxygen-containing compound supply device 2, and 82116 is used as the dopant in the dopant supply device 3. there was. Diamond was used as the base material 12.

Prior to the experiment, after closing the valve 8 and evacuating the inside of the reaction tube 9 to around 10-'Torr using the high vacuum evacuation device 14, valves 6 and 8 were opened and hydrogen gas was pumped in at 100 cc/cm from the carrier gas supply bag ffi+. Butanol was supplied to the reaction tube 9 from the oxygen-containing compound supply device 2 at a supply rate of 0.5 g/hr while the oxygen-containing compound was flowing at a rate of 0.5 g/hr. The valve 7 was opened, and a gas containing 1100 pp of diborane (B211a) mixed with hydrogen was supplied from the dopant supply device 3 at a supply rate of 0.1 cc/min.

2450M1 oscillated in microwave oscillator 11
Plasma was generated for one hour using a 0.5 KW output of a 1z microwave. During this time, the gas pressure in the reaction tube 9 was 3 Torr, and the temperature of the substrate 12 was 800° C. as measured by the thermocouple 13.

The base material 12 was taken out and its surface and cross section were observed using an electron microscope. As a result, a uniform thin film with a thickness of 4 μm was deposited on the base material 12.

As a result of measuring an X-ray diffraction image of this thin film, a diamond diffraction pattern was obtained, and it was found that there were 200 crystallites. In addition, as a result of measuring the electrical resistance, 5X102Ω
It was cm.

Example 2 In this example, the apparatus shown in FIG. 2 was used. In FIG. 2, the same parts as in FIG. 1 are given the same reference numerals. In this example, a work coil 15 is arranged around the reaction tube 9,
High frequency power is supplied from a high frequency oscillator 16 to this work coil 15 .

In this example as well, as in the case of the apparatus shown in FIG. Generates induced plasma.

In this example, in the apparatus shown in FIG. 2, argon gas is supplied from the carrier gas supply device 1, acetic acid is used as a carbon source in the oxygen-containing compound supply device 2, Pll3 is used as a dopant in the dopant supply device 3, A Si wafer was used as the base material 12.

100c of argon gas from carrier gas supply device 1
Acetic acid was supplied from the oxygen-containing compound supply device 2 at a rate of 0.3 g/hr while flowing at a rate of c/min. From the dopant supply device 3, a gas containing loop ppm of hydrogen and Pll was supplied at a supply rate of 0.1 cc/min.

A high frequency wave of 13.56 MHz was oscillated at an output of 0.4 KW from the high frequency oscillator 16, and was guided into the reaction tube 9 by the work coil 15 to generate plasma for one hour. During this time, the gas pressure was 5 Torr and the gas temperature was 85
Cooled down to 0°C. It was found from electron microscope observation and X-ray diffraction measurements that a diamond thin film with a thickness of 3 μm was formed on the St wafer 12. The resistance of this thin film is 2×lO
It was 0 cm.

Example 3 The apparatus shown in FIG. 3 was used on the tree seed layer side. In FIG. 3, the same parts as in FIG. 1 are given the same reference numerals. In this example, an electric furnace 17 is disposed around the reaction tube 9, and a metal wire 18 as a heating element is disposed near the base material 12.

In this example, as in the case of the apparatus shown in FIG. 1, the inside of the reaction tube 9 is evacuated, and then the metal wire 18 is
Generate heat to around 0°C, and in that state, add carrier gas,
Predetermined amounts of an oxygen-containing compound and a dopant are each supplied and reacted, and a diamond semiconductor is precipitated and grown on the base material 12.

In this example, in the apparatus shown in FIG. 3, hydrogen gas was supplied from carrier gas supply device 1, acetic acid edyl ester was used as a carbon source in oxygen-containing supply device 2, and ASI+3 was used as a dopant in dopant supply device 3. . A silicon wafer was used as the substrate 12.

Add 150 ml of hydrogen gas to the carrier gas supply device 1.
Acetaldehyde was supplied from the oxygen-containing compound supply device 2 at a supply rate of 0.5 g/hr while flowing cc/min.

From the dopant supply device 3, 85l13 to hydrogen 1
A mixed gas of 100 pp was supplied at 1 cc/min.

While adjusting the gas pressure to 20 Torr, the reaction tube 9 was heated to 900° C. using an electric furnace 17, and the base material 12 was further heated using a tungsten wire 18 heated to 2000° C.

After one hour, it was found from electron microscope observation and X-ray diffraction measurements that a diamond thin film with a thickness of 6 μm had been formed on the silicon wafer 12. The resistance of the thin film was measured to be 8 x 102 Ωcm.

Comparative Example-1 In the apparatus shown in the first diagram used in Example-1, a hydrocarbon feeder was used instead of the oxygen-containing compound feeder 2, and 1 cc/ of methane was used as a raw material from this feeder.
1 c of hydrogen gas mixed with 1100 pp of diborane as a dopant while flowing hydrogen gas as a carrier gas at 100 cc/min.
c/n+in was supplied, and a reaction was attempted in the same manner as in Example-1. As a result, the thickness of the diamond formation layer confirmed was 0.5 μm, and it can be seen that the diamond growth rate was slower than in the above-mentioned examples. The crystallite size of this generated layer was 90, and the resistance was 1×10 3 Ωcm, and it was confirmed that the electrical resistance was higher than that of the above-mentioned example.

[Effects of the Invention] As is clear from the above, according to the present invention, it is possible to provide a method for manufacturing a diamond semiconductor in which diamond grows at a high rate, and is extremely useful industrially.

The diamond semiconductor produced according to the present invention has an electrical resistance of 10 8 Ωcm x lo Ωcan, and has excellent thermal conductivity and heat resistance, so it is extremely useful as a material for electronic devices, especially as a heat-resistant semiconductor.

[Brief explanation of drawings]

FIGS. 1, 2, and 3 are configuration diagrams showing three examples of devices used in embodiments of the present invention. DESCRIPTION OF SYMBOLS 1...Carrier gas supply device, 2...Oxygen-containing compound supply device, 3...Dopant supply device, 4.5.20...1 hour needle, 6.7, 8.19...Valve , 9... Reaction tube, IO... Waveguide, 11... Microwave oscillator, 12... Base material, 13... Thermocouple, 14... High vacuum pumping device, 15... - Work coil, 16... High frequency oscillator, 17... Electric furnace, 18... Metal wire.

Claims (1)

[Claims] (1) A method for producing a diamond semiconductor, which comprises forming a diamond semiconductor by reacting a mixed gas of an oxygen-containing compound containing oxygen, carbon, and hydrogen with a dopant to precipitate diamond from a gas phase.