Nitrogen doped and vacancy dominated silicon ingot and thermally treated wafer formed therefrom having radially uniformly distributed oxygen precipitation density and size
Nitrogen-doped CZ silicon crystal ingots and wafers sliced therefrom are disclosed that provide for post epitaxial thermally treated wafers having oxygen precipitate density and size that are substantially uniformly distributed radially and exhibit the lack of a significant edge effect. Methods for producing such CZ silicon crystal ingots are also provided by controlling the pull rate from molten silicon, the temperature gradient and the nitrogen concentration. Methods for simulating the radial bulk micro defect size distribution, radial bulk micro defect density distribution and oxygen precipitation density distribution of post epitaxial thermally treated wafers sliced from nitrogen-doped CZ silicon crystals are also provided.
1. A nitrogen-doped CZ silicon crystal ingot, the ingot having a diameter of from about 150 mm to about 450 mm and having a nitrogen concentration of from 1*10 14 nitrogen atoms per cm 3 to about 1*10 15 nitrogen atoms per cm 3 , wherein a wafer sliced from the nitrogen-doped CZ silicon crystal ingot and thermally treated at 780° C. for 3 hours and then at 1000° C. for 16 hours is characterized by having an edge band in a region extending from about 4000 μm from the edge of said wafer to the edge of said wafer, wherein the bulk micro defect density of the edge band region differs from the remainder of the wafer by no more than 200% and an increase in radial bulk micro defect size in a region extending from the center of said wafer to the edge of said wafer of less than 20%, and further wherein the edge band of the wafer sliced from the nitrogen-doped CZ silicon crystal ingot and thermally treated at 780° C. for 3 hours and then at 1000° C. for 16 hours is characterized by oxygen precipitates having an average diameter from about 80 nm to about 90 nm and an oxygen precipitate density of 1*10 8 per cm 3 to about 1*10 10 per cm 3 .
2. The nitrogen-doped CZ silicon crystal ingot of claim 1 wherein the wafer has an increase in radial bulk micro defect size in a region extending from about 10 mm from the edge of said wafer to the edge said wafer of less than 15%.
3. The nitrogen-doped CZ silicon crystal ingot of claim 1 wherein the wafer has an increase in radial bulk micro defect density in a region extending from about 10 mm from the edge of said wafer to the edge of said wafer of less than 100%.
4. The nitrogen-doped CZ silicon crystal ingot of claim 1 wherein the edge band comprises voids having an average radius of from about 1 nm to about 50 nm.
5. The nitrogen-doped CZ silicon crystal ingot of claim 1 wherein the diameter is about 300 mm.
6. The nitrogen-doped CZ silicon crystal ingot of claim 1 wherein the thermally treated wafer is a post epitaxial thermally treated wafer.
7. A nitrogen-doped CZ silicon crystal ingot having a diameter of about 300 mm and having a nitrogen concentration of from 1*10 14 nitrogen atoms per cm 3 to about 1*10 15 nitrogen atoms per cm 3 , wherein a wafer sliced from the nitrogen-doped CZ silicon crystal ingot comprises a front surface, a back surface, a central plane between the front and back surfaces, a circumferential edge joining the front and back surface, a central axis perpendicular to the central plane, a bulk layer which comprises the region of the wafer between the central plane and front surface, and further wherein the wafer sliced from the nitrogen-doped CZ silicon crystal ingot that is thermally treated at 780° C. for 3 hours and then at 1000° C. for 16 hours is characterized by bulk micro defects having an average diameter from about 80 nm to about 90 nm from the central axis of the wafer to the circumferential edge of the wafer, wherein the average diameter decreases by about 6% from the central axis of the wafer to the circumferential edge of the wafer and is further characterized by a bulk micro defect density of 1*10 9 per cm 3 to about 1*10 10 per cm 3 from the center of the wafer to the edge of the wafer, wherein the bulk micro defect density decreases by about 6% from the central axis of the to the circumferential edge of the wafer.
8. The nitrogen-doped CZ silicon crystal ingot of claim 7 wherein the average diameter decreases by about 3% from the central axis of the wafer to the circumferential edge of the wafer.
9. The nitrogen-doped CZ silicon crystal ingot of claim 7 wherein the average diameter decreases by about 1% from the central axis of the wafer to the circumferential edge of the wafer.