Process for controlling thermal history of Czochralski-grown silicon

摘要

A Czochralski method of producing a single crystal silicon ingot (26) having a uniform thermal history from a silicon melt (16) contained in a crucible (12) coaxial with the ingot (26). In the process the pulling rate of the end-cone (30) of the ingot (26) is maintained at a relatively constant rate which is comparable to the pulling rate for the second half of the main body (29) of the ingot (26). During the pulling of the end-cone (30) of the crystal (26) at a constant rate, the process may be further refined by, either independently or in combination, increasing the heat supplied to the melt (16), reducing the crystal rotation rate and/or reducing the crucible rotation rate. The second half of the main body (29) of a single crystal silicon ingot (26) grown in accordance with this process exhibits a relatively uniform axial concentration of flow pattern defects and amount of oxygen precipitated.