Method for forming tabular diamond crystals

• US 5,445,851 A
• Filed: 08/29/1994
• Issued: 08/29/1995
• Est. Priority Date: 03/26/1992
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Hirose, Yoichi, Hirabayashi, Keiji
• Primary Examiner(s): King, Roy V.
• Application Number:
  US08/297,901
• Time in Patent Office: 365 Days
• Field of Search: 427/577, 427/573, 427/575, 427/249, 427/122, 427/314, 427/299, 427/450, 423/446, 423/408, 156/DIG. 68
• US Class Current: 427/450
• CPC Class Codes: C30B 25/02 Epitaxial-layer growth
• CPC Class Codes: C30B 29/04 Diamond
• CPC Class Codes: Y10T 428/30 Self-sustaining carbon mass or layer with impregnant or other layer

Abstract

A tabular diamond crystal is formed on a substrate by gas phase synthesis, wherein the diamond crystal has a ratio of thickness to width of from 1:4 to 1:1,000 and the surface of the substrate on which the diamond crystal has been formed and the top surface of the diamond crystal are at an angle ranging from 0° to 10°.

Claims

1. A method for forming diamond crystal comprising forming a diamond tabular crystal by combustion flame method carried out using oxygen and acetylene gas as a main starting material gas, wherein the oxygen and acetylene gas in the main starting material gas are controlled to be in a molar ratio of 0.9≦

O₂ /C₂ H₂ ≦

1, and the nucleation density of the diamond formed on a substrate is controlled to be 10² to 1×

10⁵ cm^-2.

4. The method for forming diamond crystal according to claim 1 or 2, wherein the substrate temperature is controlled to be from 400°

C. to 900°

C. to form said tabular diamond crystal whose top surface has a {111} plane.

5. The method for forming diamond crystal according to claim 1 or 2, wherein the substrate temperature is controlled to be from 950°

to 1,300°

C. to form said tabular diamond crystal whose top surface has a {100} plane.

6. The method for forming diamond crystal according to claim 1 or 2, wherein boron ions or carbons ions are implanted in the substrate at a preselected region and thereafter selectively forming said tabular diamond crystal at the preselected region on the substrate.

2. A method for forming diamond crystal comprising forming a tabular diamond crystal by a plasma CVD method or by a heat filament CVD method carried out using a starting material gas comprised of at least a carbon source gas and containing elements of hydrogen, carbon and oxygen, wherein the carbon source gas in the starting material gas is controlled to be in a concentration of 0.01 to 10%, as defined by the carbon source gas flow rate times the number of carbon atoms in the carbon source gas times 100/total starting material gas flow rate, the number of oxygen atoms and that of carbon atoms in the staring material gas to be in a ratio of 0.5≦

O/C≦

1.2, and the nucleation density of the diamond formed on a substrate is controlled to be 10⁴ to 2×

10⁶ cm^-2.

3. The method for forming diamond crystal according to claim 2, wherein said plasma CVD method is carried out using radio frequencies, direct currents or microwaves as a source of excitation, or said heat filament CVD method carried out using a heat filament as a source of excitation.