JP2725069B2 - Method for producing diamond crystal - Google Patents

Description

The present invention relates to a method for producing a diamond crystal, and more particularly, to a method for producing a diamond crystal in a direction inclined to a substrate surface. The object of the present invention is to provide a method for growing a diamond crystal layer having a surface not parallel to the substrate surface, holding the substrate in a vacuum vessel, irradiating the substrate with a plasma jet, A method for producing a diamond crystal having a step of forming a diamond crystal layer, wherein the plasma jet is irradiated on the surface of the substrate while being inclined, and the diamond crystal layer is grown obliquely with respect to the substrate. I do.

[Industrial applications]

The present invention relates to a method for producing a diamond crystal, and more particularly, to a method for producing a diamond crystal in which a diamond crystal is grown in a direction inclined to a surface of a substrate.

[Prior art] Diamond crystal has a thermal conductivity of 2,000 W / mK and copper
Since it is twice as high, has high hardness, and has excellent insulation properties, it is an ideal material as a heat sink or circuit board material for semiconductor devices.

Further, since it has good translucency over a wide range of wavelengths, it is also excellent as an optical material. Further, diamond is a semiconductor having a wide band gap of 5.4 eV and a high carrier mobility, and has attracted attention for high-performance devices such as high-temperature transistors and high-speed transistors.

Conventionally, a chemical vapor deposition method (hereinafter, referred to as a CVD method) is used for forming a diamond crystal layer. Specifically, a raw material gas containing carbon is brought into contact with a heated tungsten filament to decompose the material, and the raw material gas is heated and decomposed by using a microwave in a hot filament method for growing a diamond crystal on a substrate or in a vacuum vessel. A microwave CVD method for growing a diamond crystal by using a plasma CVD method is known, and a DC plasma jet CVD method for irradiating a substrate with a plasma jet to grow a diamond crystal at a high speed (the details will be described later) is also new. Has been developed.

[Problems to be solved by the invention]

By the way, when the diamond crystal layer is grown using the above CVD method, the diamond crystal grows in a direction perpendicular to the substrate, and a diamond crystal layer having a surface parallel to the substrate surface is formed. .

An object of the present invention is to provide a method of growing a diamond crystal in a direction inclined to a substrate surface and growing a diamond crystal layer whose surface is not parallel to the substrate surface.

[Means for solving the problem]

The object is to hold a substrate (6) in a vacuum vessel (8), irradiate the substrate (6) with a plasma jet (5), and form a diamond crystal layer on the substrate (6). A step of irradiating the plasma jet (5) onto the surface of the substrate (6) at an inclined angle to grow the diamond crystal layer (12) obliquely with respect to the substrate. This is achieved by a method for producing a diamond crystal having the following.

[Action]

As a result of the experiment, when the plasma jet 5 generated by the DC plasma jet CVD apparatus was irradiated while being inclined with respect to the surface of the
Surface that grows in the irradiation direction and is orthogonal to the irradiation direction
It was confirmed that a diamond crystal layer 12 having 11 was formed. As an example, when a diamond crystal is grown on a silicon substrate having a (100) plane by irradiating a plasma jet 5 in a direction at an angle of 45 degrees with the substrate surface, a diamond crystal layer 12 is formed. The surface of (11
It was confirmed that 1) plane, (220) plane, and (311) plane existed.

Although the diamond crystal grows in the direction of irradiation of the plasma jet in earnest, the conclusion has not been reached at present.

〔Example〕

Hereinafter, a method for producing a diamond crystal according to one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a configuration diagram of a DC plasma jet CVD apparatus disclosed in Japanese Patent Application Laid-Open No. 64-33096. In the figure, 1
Is an anode, 2 is a cathode, 3 is a source gas supply port, 4 is a DC power supply, 5 is a plasma jet, 6 is a substrate, 7 is a substrate holder, and 8 is a vacuum. Numeral 9 denotes an XY stage, and numeral 10 denotes a vacuum pump.

A 5 cm square silicon substrate 6 having a (100) surface is placed on a substrate holder 7 such that the vertical distance between the silicon substrate 6 and the anode 1 is 10 mm. After the pressure in the chamber 8 was reduced to 1 × 10 ^-2 Torr, 40 SCCM of methane and 20 L / M of hydrogen were supplied from the raw material gas supply port 3, and a discharge power of 2 kW was applied between the anode 1 and the cathode 2. The raw material gas was supplied and turned into plasma, and the plasma jet 5 was irradiated on the silicon substrate 6 to grow diamond crystals on the silicon substrate 6 at a system pressure of 30 Torr for 10 hours.
At this time, the irradiation is performed so that the irradiation direction of the plasma jet forms an angle of 45 degrees with the substrate surface, and the silicon substrate 6 is irradiated.
The diamond crystal layer was uniformly formed on the silicon substrate 6 by moving using the XY stage 9.

See FIG. 2. As a result, a diamond crystal layer 12 having a surface 11 perpendicular to the direction at an angle of about 60 degrees with the substrate surface was formed on the silicon substrate 6 to a thickness of about 100 μm.
It was confirmed that (111) plane, (220) plane, and (311) plane exist on the surface of the diamond crystal layer 12.

It is needless to say that a similar result can be obtained even if the substrate is inclined instead of the plasma irradiation direction with respect to the substrate surface.

〔The invention's effect〕

As described above, in the method for producing a diamond crystal according to the present invention, the diamond crystal is grown in the irradiation direction of the plasma jet by irradiating the plasma jet generated by the DC plasma jet CVD apparatus at an inclined angle to the surface of the substrate. Therefore, by arbitrarily selecting the irradiation angle of the plasma jet, it becomes possible to form a diamond crystal layer having an arbitrary plane orientation different from the plane orientation of the substrate surface on a semiconductor device. Is expected to expand the field of application. In addition, when stress is applied obliquely to the surface of the substrate, if diamond crystals are grown in the direction in which the stress is applied, the durability against the stress can be improved. If the present invention is applied to coating of a cutting tool, a polishing tool or the like to which stress is applied, an improvement in the service life is expected.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a DC plasma jet CVD apparatus used in a method for producing a diamond crystal according to one embodiment of the present invention. FIG. 2 is a cross-sectional view of a diamond crystal layer formed using the diamond crystal manufacturing method according to one embodiment of the present invention. 1 ... Anode, 2 ... Cathode, 3 ... Source gas supply port, 4 ...
... DC power supply, 5 ... plasma jet, 6 ... substrate, 7
…… Substrate holder, 8… Vacuum container, 9 …… XY stage,
10 ... Vacuum pump.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akitomo Tejima 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Fujitsu Limited

Claims (1)

(57) [Claims] 1. A substrate (6) is held in a vacuum vessel (8),
Irradiating the substrate (6) with a plasma jet (5) to form a diamond crystal layer on the substrate (6); A method for producing a diamond crystal, comprising the step of: irradiating the crystal with a tilt to the surface of (6) to grow the diamond crystal layer (12) with respect to the substrate.