Abstract: A method for manufacturing an SOI semiconductor substrate and a manufacturing apparatus therefor in which a mean implantation depth and a dose of each of a series of oxygen ion implantations are continuously or stepwise changed, a depthwise distribution of an oxygen atom concentration has a single peak and uniform in a plane at a predetermined depth, a maximum oxygen atom concentration is preferably no larger than 2.25.times.10.sup.22 atoms/cm.sup.3 and no smaller than 1.0.times.10.sup.22 atoms/cm.sup.3, a total oxygen dose is equal to a desired thickness of a buried oxide film multiplied by 4.48.times.10.sup.22 (in ions/cm.sup.3), and preferably a thermal process at a temperature of 1300.degree. C. or higher is applied after the completion of the oxygen ion implantation to form the buried oxide film.

Abstract: A process for producing a semiconductor substrate, including the phases of implanting oxygen ions into a semiconductor silicon substrate through one surface thereof to form a high oxygen concentration layer in the semiconductor silicon substrate, and then heat-treating the semiconductor substrate to cause a chemical reaction to occur between the implanted oxygen ions and the silicon, thereby forming an insulating silicon oxide film in the semiconductor silicon substrate, wherein the heat treatment phase includes at least a heat treatment step using an atmosphere having an oxygen partial pressure of 5.times.10.sup.3 Pa or more.

Abstract: A single silicon crystal wafer produced by the Czochvalski method and measuring not less than 100 mm in diameter, a single silicon crystal having low OSF density induced by oxidation, wherein regarding the local resistivity measured by the spread resistance method on the surface of said wafer subjected in advance to a heat treatment for extinction of oxygen donor, the proportion of the number of points of measurement registering errors exceeding .+-.1.0% of the mean value is not more than 35% of the total number of points of measurement, and regarding the distribution of oxygen concentration in solid solution in the wafer surface, the difference between the maximum and the minimum is not more than 2.0% of the maximum, and a method for production thereof.

Abstract: A silicon wafer comprising a substrate of single crystal silicon, a silicon oxide film 1 to 8 .ANG. in thickness formed on one surface of said substrate, and a polysilicon layer formed on said silicon oxide film and possessing an excellent gettering ability, is prepared by oxidizing single crystal silicon, thereby forming a silicon oxide film 1 to 8 .ANG. in thickness on said surface, and exposing said silicon oxide film to a gaseous silane at an elevated temperature, thereby forming a polysilicon layer on said silicon oxide film.