Single-crystal – oriented-crystal – and epitaxy growth processes; – Forming from vapor or gaseous state
Patent
1994-09-14
1996-03-19
Breneman, R. Bruce
Single-crystal, oriented-crystal, and epitaxy growth processes;
Forming from vapor or gaseous state
117921, 423446, C30B 2502
Patent
active
054996015
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a method for a vapor phase synthesis of diamond, particularly to a method for a vapor phase synthesis of a high-quality diamond crystal used for a cutting tool, an abrasion resistant tool, a precision tool, a semiconductor material, an electronic part, an optical part and the like.
RELATED ART
Since diamond has various excellent properties such as a high hardness, a high thermal conductivity and a good transparency, it is widely used as a material for various tools, an optical part, a semiconductor and an electronic part. The importance of the diamond seems to increase in feature.
In particular, when, among the above applications of the diamond, the diamond is used for a very precision tool, an optical part and a semiconductor in which a smooth abraded surface is needed or a highest level of the optical transparency or thermal conductivity is required, then a single crystal diamond or a diamond simple substance having a high crystal orientation must be used.
Hitherto, although a diamond film having a relatively large area has been artificially prepared on various substrates by a vapor phase synthesis, such diamond film is a polycrystal and a single crystal diamond film having a large area has not been prepared yet. Conditions for the epitaxial growth of the single crystal using the vapor phase synthesis have been studied and a method for preparing the single crystal having the large area by the vapor phase synthesis has been studied.
It has been known for a long time that a single crystal diamond layer can relatively easily grow through a homoepitaxial growth by using a diamond single crystal as a substrate in the diamond vapor phase synthesis. However, since a large diamond single crystal substrate which can act as a seed crystal has not been obtained, this method can give a single crystal having only a diameter of several millimeters. Various methods for the vapor phase synthesis have been proposed, since the vapor phase synthesis can easily give a homoepitaxial layer having a large area on the substrate if only a single crystal substrate having a large area is available.
Methods for growing the single crystal diamond having the large area by the vapor phase synthesis are generally classified into two classes of methods. The first class of methods utilizes a heteroepitaxial growth. Namely, the first class of methods is intended to give the single crystal having the large area by epitaxially growing the diamond layer on the single crystal substrate of a material which can give the large area single crystal substrate. For example, cubic boron nitride (cBN), silicon carbide, silicon, nickel, cobalt and the like have been reported as the substrate on which the diamond heteroepitaxially grows (cf. Japanese Patent Kokai Publication Nos. 224225/1988, 233591/1990 and 132687/1992).
However, a boron nitride cubic crystal which can be usually obtained has a size of only at most 0.5 mm, since a cubic boron nitride single crystal can be obtained with more difficulty than in the case of a diamond single crystal. Although a silicon carbide single crystal and a silicon single crystal having relatively large areas can be obtained, the diamond particles intend to have an orientation having no relationship with the orientation of the substrate so that it is difficult to obtain a large complete diamond single crystal. It is difficult to obtain a high-quality diamond single crystal by the use of nickel and cobalt, since nickel and cobalt not only have the same problems as in silicon carbide and silicon, but also they have the problem that the grown diamond reacts with nickel and cobalt to produce graphite.
Therefore, a second class of methods without the use of heteroepitaxy is considered. The second class of methods is a technique based on the growth of diamond on a diamond seed crystal, namely homoepitaxial growth. For example, the second class of methods includes a method which comprises shaping diamond single crystals in a constant shape, positioning the crystal
REFERENCES:
patent: 4034066 (1977-07-01), Strong et al.
Geis et al., "Large-Area Mosaic Diamond Films Approaching Single-Crystal Quality", Applied Physics Letter, vol. 58, No. 22, Jun. 3, 1991, pp. 2485-2487.
Lurie et al., "The Diamond Surface", Surface Science, vol. 65 (1977) pp. 453-475.
Patent Abstracts of Japan, vol. 15, No. 357 (C-0866), Oct. 24, 1989 & JP-A-03 141 193 (Fujitsu Ltd.) Jun. 17, 1991.
Narayan et al., "Enhancement of Nucleation and Adhesion of Diamond Films on Copper, Stainless Steel, and Silicon Substrates", Journal of Applied Physics, vol. 71, No. 2, Jan. 15, 1992, pp. 966-971.
Ramesham et al., "Selective Diamond Seed Deposition Using Elctroplated Copper", Diamond and Related Materials, vol. 1, No. 8, Jun. 25, 1992, pp. 907-910.
Fujimori Naoji
Imai Takahiro
Tsuno Takashi
Yamamoto Yoshiyuki
Breneman R. Bruce
Garrett Felisa
Sumitomo Electric Industries Ltd.
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