Epitaxial silicon wafer with intrinsic gettering and a method for the preparation thereof

A single crystal silicon wafer comprising:

• (a) two major generally parallel surfaces, one of which is a front surface of the wafer and the other of which is a back surface of the wafer;
• (b) a central plane between and parallel to the front and back surfaces;
• (c) a front surface layer comprising the region of the wafer extending a distance of no greater than about 100 μm from the front surface toward the central plane;
• and (d) a bulk layer comprising the region of the wafer extending from the central plane to the front surface layer, wherein
• the bulk layer has a substantially uniform oxygen concentration and a concentration of crystal lattice vacancies such that upon subjecting the wafer to an oxygen precipitation heat treatment consisting essentially of annealing the wafer at 800° C. for about 4 hours and then at 1000° C. for 16 hours, the wafer will contain oxygen precipitates having a concentration profile in which the peak density of the precipitates in the bulk layer is at or near the central plane with the concentration of the precipitates in the bulk layer generally decreasing toward the front surface layer;
• and
• the front surface of the wafer has an epitaxial layer deposited thereon, the epitaxial layer having a thickness of at least about 0.1 μm.

A process for the preparation of a silicon wafer comprising a surface having an epitaxial layer deposited thereon, the process comprising:

• heating a surface of a wafer starting material in an essentially oxidant-free atmosphere to remove a silicon oxide layer from the surface;
• within about 30 seconds after removing the silicon oxide layer from the surface, exposing the surface to an atmosphere comprising silicon to deposit a silicon epitaxial layer onto the surface to form an epitaxial wafer;
• heating the epitaxial wafer to a soak temperature of at least about 1175° C. while exposing the epitaxial layer to an oxidizing atmosphere comprising an oxidant;
• and
• cooling the heated epitaxial wafer at a rate of at least about 10° C./sec.

A process for the preparation of a silicon wafer comprising a surface having an epitaxial layer deposited thereon, the process comprising:

• heating a surface of a wafer starting material to a temperature of at least about 1100° C. in an essentially oxidant-free atmosphere to remove a silicon oxide layer from the surface,
• within about 30 seconds after the surface reaches 1100° C., exposing the surface to an atmosphere comprising silicon to deposit a silicon epitaxial layer onto the surface to form an epitaxial wafer,
• heating the epitaxial wafer to a soak temperature of at least about 1175° C. while exposing the epitaxial layer to an oxidizing atmosphere comprising an oxidant, and
• cooling the heated epitaxial wafer at a rate of at least about 10° C./sec.

A process for the preparation of a silicon wafer comprising a surface having an epitaxial layer deposited thereon, the process comprising:

• depositing an epitaxial layer onto a surface of a wafer to form an epitaxial wafer,
• heating the epitaxial wafer to a soak temperature of at least about 1175° C. while exposing the epitaxial layer to an oxidizing atmosphere comprising an oxidant, and
• cooling the heated epitaxial wafer at a rate of at least about 10° C. /sec.,
• wherein the epitaxial layer is not contacted with a post-epitaxial-deposition cleaning solution before the epitaxial wafer is heated to the soak temperature.

A process for the preparation of a silicon wafer comprising a surface having an epitaxial layer deposited thereon, the process comprising:

• depositing an epitaxial layer onto a surface of a wafer starting material to form an epitaxial wafer,
• heating the epitaxial wafer to a soak temperature of at least about 1175° C. while exposing the epitaxial layer to an oxidizing atmosphere comprising an oxidant, and
• cooling the heated epitaxial wafer at a rate of at least about 10° C. /sec.,
• wherein the surface of the wafer starting material, before deposition of the epitaxial layer thereon, has an average light scattering event concentration of at least about 0.5/cm2 as measured by a laser-based auto inspection tool configured to detect light scattering events corresponding to polystyrene spheres having diameters of no less than about 0.12 μm.

A process for the preparation of a silicon wafer comprising a surface having an epitaxial layer deposited thereon, the process comprising:

• heating a surface of a wafer starting material to a temperature of at least about 1150° C. in an atmosphere consisting essentially of H2 to remove a silicon oxide layer from the surface,
• within about 10 seconds after the surface reaches 1150° C., exposing the surface to an atmosphere comprising SiHCl3 to deposit a silicon epitaxial layer onto the surface to form an epitaxial wafer,
• heating the epitaxial wafer to a soak temperature of at least about 1175° C. while exposing the epitaxial layer to an oxidizing atmosphere comprising O2, and
• cooling the heated epitaxial wafer from the soak temperature to 250° C. below the soak temperature at an average rate of at least about 20° C./sec,
• wherein the epitaxial layer has a thickness of from about 0.65 to 1.0 μm, and the concentration of the O2 in the oxidizing atmosphere is from about 300 to about 500 ppm.