Method of manufacturing silicon wafer and silicon wafer

Abstract

This invention provides a method for manufacturing silicon wafers that can simultaneously avoid the risks of metal contamination and suppress BMD precipitation. The silicon wafer manufacturing method of this invention includes the following steps: a first RTO (Regenerative Thermal Oxidation) step, in which a planarized silicon wafer W, made from a single-crystal silicon ingot grown by the CZ (Chemical Z-Oxygenation) method, is heated to a first maximum temperature of 1300°C to 1380°C in an oxidizing atmosphere with an oxygen partial pressure of 25% to 100%, and held at the first maximum temperature for at least 5 seconds; an oxide film stripping step, in which the silicon wafer W obtained by the first RTO step is cleaned with hydrofluoric acid; and a second RTO step, in which the silicon wafer W obtained by the oxide film stripping step is heated to a second maximum temperature of 1050°C to 1300°C in an oxidizing atmosphere with an oxygen partial pressure of 25% to 100%, and held at the second maximum temperature for at least 5 seconds.

Claims

1. A method for manufacturing a silicon wafer, comprising the following steps: a first heat treatment step, wherein a silicon wafer obtained by slicing and planarizing a single-crystal silicon ingot grown by the Tchaikovsky (CZ) method is heated to a first maximum temperature of 1300°C to 1380°C in an oxidizing atmosphere with an oxygen partial pressure of 25% to 100%, and held at the first maximum temperature for at least 5 seconds; an oxide film stripping step, wherein the silicon wafer obtained by the first heat treatment step is cleaned with hydrofluoric acid; and a second heat treatment step, wherein the silicon wafer obtained by the oxide film stripping step is heated to a second maximum temperature of 1050°C to 1300°C in an oxidizing atmosphere with an oxygen partial pressure of 25% to 100%, and held at the second maximum temperature for at least 5 seconds.

2. The method for manufacturing a silicon wafer as described in claim 1, which further includes a grinding process, wherein the surface and outer layer of the silicon wafer obtained by the aforementioned second heat treatment process are ground.

3. The method for manufacturing a silicon wafer as described in claim 1, wherein in the aforementioned first heat treatment step and the aforementioned second heat treatment step, the oxygen partial pressure in the aforementioned oxidizing atmosphere is 100%.

4. The method for manufacturing a silicon wafer as described in claim 1, wherein in the aforementioned oxide film stripping process, the surface of the silicon wafer obtained by the aforementioned first heat treatment process is washed with a hydrofluoric acid aqueous solution of 10% or more for more than 10 seconds.

5. The method for manufacturing a silicon wafer as described in claim 1, wherein the oxygen concentration of the silicon wafer prior to the aforementioned first heat treatment step is 1.0 × 10¹⁸ / cm³ to 1.5 × 10¹⁸ / cm³.

6. A silicon wafer subjected to a two-stage rapid thermal oxidation (RTO), wherein the two-stage rapid thermal oxidation includes a step of stripping an oxide film formed on the surface; after being held at 780°C for 3 hours in an oxidizing atmosphere and then at 1000°C for 16 hours, the defect density above 20 nm observed by infrared (IR) tomography is less than 1×10⁸ / cm³.

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