Silicon wafer manufacturing method, silicon epitaxial wafer manufacturing method, and silicon epitaxial wafer

A method for manufacturing a silicon wafer comprising the steps of:

• keeping the silicon wafer having grown-in precipitation nuclei generated in a growth step of a silicon single crystal at a temperature T4° C. in the range of from 500° C. to 700° C. for a prescribed time t1;
• then raising the temperature of the silicon wafer to a temperature T5° C. in the range of from 1000° C. to 1230° C. at a temperature raising rate of 5° C./min or less;
• and keeping the temperature thereof at the temperature T5° C. for a prescribed time t2, thereby the grown-in precipitation nuclei being grown into oxide precipitates each of a size equal to or larger than one having a gettering capability, and oxygen in the vicinity of a surface of the silicon wafer being out-diffused.

A method for manufacturing a silicon wafer wherein the silicon wafer having grown-in precipitation nuclei generated in a growth step of a silicon single crystal is subjected to heat treatment to impart a gettering capability thereto, comprising at least the following three steps of:

• a temperature raising step A1 for growing the grown-in precipitation nuclei;
• a temperature raising step B1 for further raising a temperature of the silicon wafer to a keeping temperature higher than that in the temperature raising step A1;
• and a constant temperature keeping step C1 for growing the grown-in precipitation nuclei into oxide precipitates each of a size equal to or larger than one having a gettering capability and for out-diffusing oxygen in the vicinity of a surface of the silicon wafer.

A silicon epitaxial wafer wherein density of oxide precipitates detected in the bulk thereof prior to heat treatment at 1000° C. for 2 hrs is less than 1×109/cm3 and density of oxide precipitates detected in the bulk thereof after the heat treatment at 1000° C. for 2 hrs is 1×109/cm3 or more.

A silicon epitaxial wafer wherein density of oxide precipitates detected in the bulk thereof in a non-heat treatment state after formation of an epitaxial layer is 1×109/cm3 or more.