1. Field of the Invention
The present invention relates to a method for dry etching a surface of diamond which is used in the production of semiconductor devices.
2. Description of the Related Art
A diamond semiconductor device attracts attention since is functions stably under severe conditions such as high temperature or under irradiation, and can function at a high output. A reason for that the diamond device functions at high temperature may be that the band gap of diamond is as large as 5.5 eV, which may be attributed to the fact that a temperature at which carriers of the semiconductor cannot be controlled is higher than 1400.degree. C.
When a device comprising diamond is produced, an etching technique is necessary in addition to epitaxy growth of diamond, electrode formation and wiring techniques. With silicon which is most widely used in electronic devices, the etching technique is well developed, and very complicated devices have been produced. It can be said that the etching technique makes it possible to produce the high performance electronic devices.
It is known that diamond can be etched with oxygen (see, for example, Japanese Patent Kokai Publication No. 220524/1988).
When diamond is etched with oxygen, etch pits tend to be formed or unevenness appears on the surface of diamond. Therefore, the etched surface of diamond cannot be smooth enough for the production of electronic devices.
When the surface of diamond is etched with argon, the diamond surface can be smoothly etched, but a masking material is also etched. That is, the diamond surface is not etched with sufficient selection between the diamond and the masking material. Therefore, argon cannot be used for etching diamond in the production of electronic devices.
Further, Japanese Patent Kokai Publication No. 220525/1988 discloses the use of a mixture of oxygen and argon for etching diamond. But, this Kokai Publication describes that, when a mixture of oxygen and argon in a ratio of 1:1 was used, the etched diamond surface was rough.
None of the above prior arts is succeeded in etching the diamond surface selectively when it is masked.