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AssigneeMEMC Electronic Materials, Inc.
InventorsRobert Falster, Marco Cornara, Daniela Gambaro, Massimiliano Olmo
Estimating the term…
A process for heat-treating a single crystal silicon wafer to influence the precipitation behavior of oxygen in the wafer in a subsequent thermal processing step. The wafer has a front surface, a back surface, and a central plane between the front and back surfaces. In the process, the wafer is subjected to a heat-treatment to form crystal lattice vacancies in the wafer. During the heat-treatment, the front and back surfaces of the wafer are each exposed to either a nitriding or non-nitriding gas. The wafer is then cooled from the temperature of said heat treatment at a rate which allows some, but not all, of the crystal lattice vacancies to diffuse to the front surface to produce a wafer having a vacancy concentration profile determined in part by the gas that each surface is exposed to and in part by the cooling rate.
A single crystal silicon wafer having two major, generally parallel surfaces, one of which is the front surface of the wafer and the other of which is the back surface of the wafer, a central plane between the front and back surfaces, a circumferential edge joining the front and back surfaces, a front surface layer which comprises a first region of the wafer between the front surface and a distance, D1, of at least about 10 micrometers as measured from the front surface and toward the central plane, a back surface layer which comprises a second region of the wafer between the back surface and a distance D2, of at least about 10 micrometers as measured from the back surface and toward the central plane and a bulk layer which comprises a third region of the wafer between the front surface layer and the back surface layer, the wafer being characterized in that;
A single crystal silicon wafer having two major, generally parallel surfaces, one of which is the front surface of the wafer and the other of which is the back surface of the wafer, a central plane between the front and back surfaces, a circumferential edge joining the front and back surfaces, a front surface layer which comprises a first region of the wafer between the front surface and a distance, D1, of at least about 10 micrometers as measured from the front surface and toward the central plane, a back surface layer which comprises a second region of the wafer between the back surface and a distance D2, of at least about 10 micrometers as measured from the back surface and toward the central plane and a bulk layer which comprises a third region of the wafer between the front surface layer and the back surface layer, the wafer being characterized in that;
A single crystal silicon wafer having a front surface, a back surface, a central plane between the front and back surfaces, a circumferential edge joining the front and back surfaces, a surface layer which comprises the region of the wafer between the front surface and a distance, D1, of at least about 10 micrometers measured from the front surface and toward the central plane, a bulk layer which comprises a second region of the wafer between the central plane and the first region, and a non-uniform distribution of crystal lattice vacancies with the concentration of vacancies in the bulk layer being greater than the concentration of vacancies in the surface layer, such that upon being subjected to an oxygen precipitation heat-treatment a denuded zone is formed in the surface layer and oxygen precipitates are formed in the bulk layer wherein the formation of the denuded zone and the formation of the oxygen precipitates in the wafer bulk are not dependant upon differences in oxygen concentration in these regions of the wafer.
Dependencies are inferred from the claim text.