Silicon wafer

Abstract

A silicon wafer which has DZ layers formed on both sides thereof by heat treatment in an atmosphere of reducing gas (such as hydrogen) or rare gas (such as argon) with a specific temperature profile for heating, holding, and cooling, and which also has a gettering site of BMD in the bulk inside the DZ layer. A silicon wafer which has a silicon epitaxial layer formed on one side thereof. The DZ layer and the silicon epitaxial layer contain dissolved oxygen introduced into their surface parts, with the concentration and distribution of dissolved oxygen properly controlled. Introduction of oxygen into the surface part is accomplished by heat treatment and ensuing rapid cooling in an atmosphere of oxygen-containing gas.

1 . A silicon wafer formed from a single-crystal silicon ingot grown by pulling, the silicon wafer having a DZ layer formed in the surface layer thereof and a specific amount of BMD inside the DZ layer, such that oxygen is introduced into the surface part of the DZ layer, with the concentration of dissolved oxygen in the surface part being no lower than 1×10 17  atoms/cm 3 , as the result of heat treatment at 1100° C. to 1300° C. in an atmosphere of reducing gas or rare gas or a mixture thereof. 
   
   
       2 . A silicon wafer formed from a single-crystal silicon ingot grown by pulling, the silicon wafer being a silicon epitaxial wafer with a silicon epitaxial layer which has oxygen introduced into the surface part thereof, with the concentration of dissolved oxygen in the surface part being no lower than 1×10 17  atoms/cm 3 . 
   
   
       3 . The silicon wafer as defined in  claim 1  or  2 , wherein dissolved oxygen in the surface part has the concentration which is distributed in the depthwise direction of the surface part. 
   
   
       4 . The silicon wafer as defined in  claim 3 , wherein the concentration of the dissolved oxygen is so distributed as to have a minimum value and the BMD density is no higher than 2.5×10 7  pieces/cm 3  in the region of the silicon wafer from the surface to a depth of 2 μm. 
   
   
       5 . The silicon wafer as defined in  claim 4 , wherein the concentration of dissolved oxygen ranges from 1.2 to 6.0×10 17  atoms/cm 3  in the region from the surface to a depth of 2 μm of the silicon wafer and ranges from 2.8 to 5.2×10 17  atoms/cm 3  in the region from the surface to a depth of 9 μm of the silicon wafer. 
   
   
       6 . The silicon wafer as defined in  claim 1 , wherein oxygen is introduced into the surface part of the DZ layer and the surface part of the silicon epitaxial layer by heat treatment and ensuing cooling in an atmosphere of oxygen-containing gas.