Abstract: A nitride semiconductor substrate includes: a heat-resistant support substrate having a core including nitride ceramic enclosed in an encapsulating layer; a planarization layer provided on the heat-resistant support substrate; a silicon single crystal layer having a carbon concentration of 1×1017 atoms/cm3 or higher provided on the planarization layer; a carbonized layer containing silicon carbide as a main component and having a thickness of 4 to 2000 nm provided on the silicon single crystal layer; and a nitride semiconductor layer provided on the carbonized layer. This provides a high-quality nitride semiconductor substrate (a nitride semiconductor substrate particularly suitable for GaN-based high mobility transistors (HEMT) for high-frequency switches, power amplifiers, and power switching devices); and a method for producing the same.

Abstract: A method for manufacturing a carbon-doped silicon single crystal wafer, including steps of: preparing a silicon single crystal wafer not doped with carbon; performing a first RTA treatment on the silicon single crystal wafer in an atmosphere containing compound gas; performing a second RTA treatment at a higher temperature than the first RTA treatment; cooling the silicon single crystal wafer after the second RTA treatment; and performing a third RTA treatment. The crystal wafer is modified to a carbon-doped silicon single crystal wafer, sequentially from a surface thereof: a 3C-SiC single crystal layer; a carbon precipitation layer; a diffusion layer of interstitial carbon and silicon; and a diffusion layer of vacancy and carbon. A carbon-doped silicon single crystal wafer having a surface layer with high carbon concentration and uniform carbon concentration distribution to enable wafer strength enhancement; and a method for manufacturing the carbon-doped silicon single crystal wafer.

Abstract: A silicon single crystal substrate for vapor phase growth, having the silicon single crystal substrate being made of an FZ crystal having a resistivity of 1000 ?cm or more, wherein the surface of the silicon single crystal substrate is provided with a high nitrogen concentration layer having a nitrogen concentration higher than that of other regions and a nitrogen concentration of 5×1015 atoms/cm3 or more and a thickness of 10 to 100 ?m.

Abstract: A method for manufacturing a silicon single-crystal substrate having a carbon diffusion layer on a surface, proximity gettering ability, and high strength near the surface, and hardly generating dislocation or extending dislocation, includes: a step of adhering carbon on a surface of a silicon single-crystal substrate by an RTA treatment of the silicon single-crystal substrate in a carbon-containing gas atmosphere; a step of forming a 3C-SiC single-crystal film on the surface of the silicon single-crystal substrate by reacting the carbon and the silicon single-crystal substrate; a step of oxidizing the 3C-SiC single-crystal film to be an oxide film and diffusing carbon inward the silicon single-crystal substrate by an RTA treatment of the silicon single-crystal substrate on which the 3C-SiC single-crystal film is formed, the RTA treatment being performed in an oxidative atmosphere; and a step of removing the oxide film.

Abstract: A method for manufacturing a carbon-doped silicon single crystal wafer, including steps of: preparing a silicon single crystal wafer not doped with carbon; performing a first RTA treatment on the silicon single crystal wafer in an atmosphere containing compound gas; performing a second RTA treatment at a higher temperature than the first RTA treatment; cooling the silicon single crystal wafer after the second RTA treatment; and performing a third RTA treatment. The crystal wafer is modified to a carbon-doped silicon single crystal wafer, sequentially from a surface thereof: a 3C-SiC single crystal layer; a carbon precipitation layer; a diffusion layer of interstitial carbon and silicon; and a diffusion layer of vacancy and carbon. A carbon-doped silicon single crystal wafer having a surface layer with high carbon concentration and uniform carbon concentration distribution to enable wafer strength enhancement; and a method for manufacturing the carbon-doped silicon single crystal wafer.

Abstract: A silicon wafer is produced by growing a silicon single crystal ingot having a resistivity of 100 &OHgr;·cm or more and an initial interstitial oxygen concentration of 10 to 25 ppma by the Czochralski method, processing the silicon single crystal ingot into a wafer, and subjecting the wafer to an oxygen precipitation heat treatment so that a residual interstitial oxygen concentration in the wafer should become 8 ppma or less. A silicon wafer produced as described above shows little decrease in resistivity even after a heat treatment in device production etc. Further, if a silicon wafer is produced and heat-treated so that the wafer should have the above-defined initial interstitial oxygen concentration and residual interstitial oxygen concentration, slip dislocations in a subsequent heat treatment process are prevented irrespective of resistivity.