Patent ID: 7875117

Claim:
A method for manufacturing a nitrogen doped silicon wafer from a silicon single crystal doped with nitrogen, the method comprising the steps of: (1) evaluating a first relationship, said first relationship being a relationship of density of oxygen precipitates (as-grown precipitates) to a heating temperature of a silicon single crystal when a nitrogen concentration of the silicon single crystal is changed under a heat treatment condition that remains constant and at a predetermine oxygen concentration, said evaluating step including a numerical calculation to obtain a radius of each of the oxygen precipitates (as-grown precipitates) that can remain in a heating experiment based on the heat treatment condition; and (2) deriving a second relationship, said second relationship being a relationship for treating relational equations, using a variable of which at least the nitrogen concentration of the silicon single crystal and a cooling rate in a first temperature range in which the density of the oxygen precipitates (as grown precipitates) increases during crystal growth, the relationship relating the density to the radius of the oxygen precipitate (as grown precipitates), introduced in the silicon single crystal doped with nitrogen at the time of crystal growth, based on the step of evaluating a first relationship; wherein an oxygen concentration of the silicon single crystal and density of oxygen precipitates to be obtained after a heat treatment depending on each condition of a temperature process during epitaxial growth or annealing at a temperature of 1100° C. or more are determined by calculating and predicting the density of the oxygen precipitates using the numerical calculation of the evaluating step by using the first relationship, which relates the density to the radius of the oxygen precipitates, the first relationship having been obtained in the evaluating step, and wherein the density of the oxygen precipitates to be obtained after the heat treatment is controlled to a predetermined value by controlling the nitrogen concentration, the predetermined oxygen concentration and the temperature process of the heat treatment, and the density of the oxygen precipitates being obtained under conditions for obtaining a density of oxygen precipitates of 5×10 8 units/cm 3 after a heat treatment by using the nitrogen concentration, the predetermined oxygen concentration and each condition of the temperature process of the heat treatment.