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.