JP7478335B2 - How diamonds are processed - Google Patents

Description

Article 30, paragraph 2 of the Patent Act applies 1. Publication: 80th Autumn Meeting of the Japan Society of Applied Physics, Abstracts "20p-E312-1", published September 4, 2019 2. Meeting name: The 80th Autumn Meeting of the Japan Society of Applied Physics, held on September 20, 2019, at Hokkaido University Sapporo Campus (5-chome, Kita 8-jo Nishi, Kita-ku, Sapporo, Hokkaido 3. Publication: The 2nd International Forum on Quantum Metrology and Sensing PROCEEDINGS, page 40 4. Meeting name: The 2nd International Forum on Quantum Metrology and Sensing, held on December 17, 2019, at Kyoto Brighton Hotel (330, Shicho-cho, Kamigyo-ku, Kyoto, Kyoto Prefecture) 5. Publication: Hasselt Diamond Workshop 2020-SBDD XXV Proceedings, Publication date: March 10, 2020

The present invention relates to a method for processing diamonds, and in particular to a processing method that applies imprint technology.

Diamond is one of the hardest materials and is difficult to machine into desired shapes and structures.
Diamond has a large band gap and is therefore an excellent semiconductor material, and is therefore expected to be used in a variety of semiconductor and quantum devices and sensors.
It also has high value as jewelry.
In response to these needs, there is a demand for a highly accurate and inexpensive method for processing diamonds.
Conventionally, when diamond is patterned as a semiconductor device, the surface of the diamond is masked in a predetermined pattern and then dry etched with plasma or the like.
However, this method requires special equipment, which is expensive, and also does not provide high processing accuracy because it is difficult to etch the masking pattern in the vertical direction.
For example, Patent Document 1 discloses an inductively coupled plasma etching method, but since this technique is also an etching technique, it has the same technical problems as those mentioned above.

JP 2013-211562 A

The present invention aims to provide a method for processing diamonds by imprinting, which has high processing accuracy and enables low cost.

The method for processing diamonds by imprinting according to the present invention is characterized in that a carbon-soluble substrate, the surface of which has been formed into a predetermined structure, is heated while in contact with the surface of the diamond, so that the surface structure of the carbon-soluble substrate is transferred to the surface of the diamond.

Here, the carbon-soluble substrate refers to a substrate that, when heated in contact with the surface of a diamond, turns the carbon that constitutes the diamond into a solid solution at the contact area, and solid solution etching proceeds.
Examples of such carbon-solid-soluble substrates include nickel, iron, cobalt, titanium, chromium, copper, and oxides or alloys thereof.
Among these, nickel has a high maximum solid solution concentration of carbon of 2.7 at %, and has the excellent property of being resistant to the formation of carbides even at high temperatures.
In order to promote the formation of a solid solution of carbon in the substrate in contact with the surface of the diamond, heating to 800° C. or higher is preferred.
The higher the heating temperature, the faster the solution reaction will be. However, if the temperature is too high, carbides are likely to be formed on the surface of the base material, which in turn becomes an obstacle to solution formation, so the temperature is preferably 1200° C. or lower.

Heating is preferably carried out under an inert gas or vacuum to prevent carbonization of the substrate.
Examples of inert gases include argon, nitrogen, and helium. "Under vacuum" means that the pressure is reduced to a level that does not affect the formation of a solid solution on the surface of diamond.
As the surface of the diamond is solidified, a graphite layer is formed on this surface. After processing of the diamond, this graphite layer may be removed by washing with hot mixed acid.
Furthermore, when heating is performed in an inert gas or vacuum, if 2 to 10 vol % of hydrogen gas is contained in the heating atmosphere, graphite can be removed as methane gas.
Furthermore, if the heating atmosphere contains 2 to 10 vol % water vapor, an oxide film is formed on the surface of the nickel base material, which reacts with the dissolved carbon in the nickel and can be removed as carbon monoxide and/or carbon dioxide.
In the case of an inert gas, the pressure may be atmospheric pressure or higher, and solid solution etching is promoted.

In the present invention, the carbon-solid-soluble substrate is preferably any one of nickel, iron, cobalt, titanium, chromium, copper, and oxides or alloys thereof.
These carbon-soluble substrates are much easier to process than diamond, and can be used as a kind of transfer mold for imprint molding to process device patterns and complex microstructures.
It can also be processed into a transfer mold shape for jewelry diamonds.

The present invention utilizes a carbon solid solution reaction with a base material such as nickel, and the surface of the diamond is solid-solutioned and etched in accordance with the structure formed on the surface of the base material, thereby allowing the surface structure of the base material to be transferred and molded with high precision.
The present invention requires only a heating device capable of heating under an inert gas or under a vacuum, and has a simpler structure than conventional plasma devices and can be easily made large.

2 shows examples of the surface structure of the substrate used in the present invention. 2 shows an example of a diamond surface structure to which the structure of the substrate in FIG. 1 has been transferred.

Hereinafter, examples of the method for processing diamond by imprinting according to the present invention will be specifically described, but the present invention is not limited to these examples.
FIG. 1 shows an example of a transfer mold in which a nickel base material is used and minute recesses are formed on the surface.
In this embodiment, the surface of the nickel base material was subjected to a reduction treatment in hydrogen-containing argon gas at about 1100° C. for about 10 minutes.
Next, the diamond was stacked on top of the nickel substrate shown in FIG. 1 so that the surface of the diamond overlapped, and a weight of a predetermined weight was placed on top of the stack to maintain an appropriate contact state between the surface of the nickel substrate and the diamond.
In this state, the product was placed in an infrared heating annealing furnace, and argon gas was used as the inert gas, and about 4 vol % of hydrogen gas was mixed therein.
FIG. 2 shows a photograph of the surface of a diamond that has been heated to a temperature range of about 800° C. to 1200° C., taken out of the furnace after a predetermined time has elapsed, and then the nickel substrate has been removed.
It can be seen that the surface structure of the nickel base material shown in FIG. 1 has been precisely transferred.

Claims (2)

A carbon-dissolved substrate with a surface formed into a specific structure is heated in contact with the diamond surface,
a surface structure of the carbon-soluble substrate is transferred onto a surface of the diamond ;
The heating is carried out under an inert gas or vacuum, in a state containing a predetermined concentration of hydrogen gas and/or water vapor,
2. A method for processing diamond by imprinting, wherein the carbon-soluble substrate is a nickel substrate the surface of which has been subjected to reduction treatment in a hydrogen-containing inert gas . 2. The method for processing diamond by imprinting according to claim 1, wherein the heating is in the range of 800 to 1200°C .