Epitaxial silicon wafer free from autodoping and backside halo and a method and apparatus for the preparation thereof
First Claim
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1. A single crystal silicon wafer, the single crystal silicon wafer comprising:
- a silicon wafer substrate having a central axis, a front surface and a back surface which are generally perpendicular to the central axis, a circumferential edge, and a radius extending from the central axis to the circumferential edge of the wafer, the back surface being free of an oxide seal and substantially free of a chemical vapor deposition process induced halo, the silicon wafer substrate comprising P-type or N-type dopant atoms; and
an epitaxial silicon layer on the front surface of the silicon wafer substrate characterized by an axially symmetric region extending radially outwardly from the central axis toward the circumferential edge wherein the resistivity is substantially uniform, the radius of the axially symmetric region being at least about 80% of the length of the radius of the substrate, the epitaxial silicon layer comprising P-type or N-type dopant atoms.
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Abstract
A single crystal silicon wafer with a back surface free of an oxide seal and substantially free of a chemical vapor deposition process induced halo and an epitaxial silicon layer on the front surface, the epitaxial layer is characterized by an axially symmetric region extending radially outwardly from the central axis of the wafer toward the circumferential edge of the wafer having a substantially uniform resistivity, the radius of the axially symmetric region being at least about 80% of the length of the radius of the wafer.
50 Citations
35 Claims
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1. A single crystal silicon wafer, the single crystal silicon wafer comprising:
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a silicon wafer substrate having a central axis, a front surface and a back surface which are generally perpendicular to the central axis, a circumferential edge, and a radius extending from the central axis to the circumferential edge of the wafer, the back surface being free of an oxide seal and substantially free of a chemical vapor deposition process induced halo, the silicon wafer substrate comprising P-type or N-type dopant atoms; and
an epitaxial silicon layer on the front surface of the silicon wafer substrate characterized by an axially symmetric region extending radially outwardly from the central axis toward the circumferential edge wherein the resistivity is substantially uniform, the radius of the axially symmetric region being at least about 80% of the length of the radius of the substrate, the epitaxial silicon layer comprising P-type or N-type dopant atoms. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35)
the wafer substrate has a non-uniform distribution of crystal lattice vacancies wherein (a) the bulk layer has a crystal lattice vacancy concentration which is greater than in the front surface layer, (b) the crystal lattice vacancies have a concentration profile having a peak density of crystal lattice vacancies at or near the central plane, and (c) the concentration of crystal lattice vacancies generally decreases from the position of peak density toward the front surface of the wafer.
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33. The single crystal silicon wafer of claim 32 wherein D1, is from about 50 to about 100 μ
- m.
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34. The single crystal silicon wafer as set forth in claim 1 wherein the silicon wafer substrate further comprises a central plane between and parallel to the front and back surfaces;
- a front surface layer which comprises the region of the wafer extending a distance, D1, of at least about 10 μ
m from the front surface toward the central plane; and
a bulk layer which comprises the region of the wafer extending from the central plane to the front surface layer, the wafer substrate being characterized in that;the wafer substrate has a non-uniform distribution of oxygen precipitates wherein (a) the bulk layer has a oxygen precipitate concentration which is greater than in the front surface layer, (b) the oxygen precipitates have a concentration profile having a peak density of oxygen precipitates at or near the central plane, and (c) the concentration of oxygen precipitates generally decreases from the position of peak density toward the front surface of the wafer.
- a front surface layer which comprises the region of the wafer extending a distance, D1, of at least about 10 μ
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35. The single crystal silicon wafer of claim 34 wherein D1, is from about 50 to about 100 μ
- m.
Specification