Processes for production of silicon ingot, silicon wafer and epitaxial wafer, and silicon ingot
A process for production of a silicon ingot, by which a silicon ingot exhibiting a low resistivity even in the top portion can be produced. The process for the production of a silicon ingot includes withdrawing a silicon seed crystal from a silicon melt to grow a silicon single crystal, with the silicon seed crystal and the silicon melt containing dopants of the same kind. The process includes the dipping step of dipping a silicon seed crystal containing a dopant in a specific concentration in a silicon melt in such a manner that the temperature difference between both falls within the range of 50 to 97K, and the growing step of growing a silicon single crystal withdrawn after the dipping to form a silicon ingot, the growing step being conducted by using a single crystal puller provided with a thermal shield plate for shielding against radiant heat emitted from the silicon melt and controlling the distance between the thermal shield plate and the silicon melt within a specific range.
1. A process for manufacturing a silicon ingot, comprising:
dipping a seed crystal in a melt in a crucible in a hot zone, wherein:
the seed crystal and the melt containing dopants of the same kind,
a concentration of the dopant contained in the seed crystal is: 2.0×10 19 to 4.0×10 19 atoms/cm 3 in a case of arsenic; 5.0×10 19 to 7.0×10 19 atoms/cm 3 in a case of phosphorous; and 5.0×10 19 to 7.0×10 19 atoms/cm 3 of phosphorous and 4.0×10 19 to 8.0×10 19 atoms/cm 3 of germanium in a case of a combination of phosphorous and germanium,
the temperature difference between the seed crystal and the melt, when dipping the seed crystal in the melt, is 50 to 97 K; and
growing the silicon single crystal pulled after the dipping obtain the silicon ingot, wherein the growing comprises using a single crystal puller provided with a thermal shield plate for shielding the silicon ingot against radiant heat from the melt; wherein
a distance between the thermal shield plate and a surface of the melt is 20 to 30 mm at the beginning of growing a straight body portion of the silicon ingot, in the growing,
a distance between the thermal shield plate and the surface of the melt is 6 to 15 mm in growing the straight body portion from a position of 200 mm away from a boundary between a shoulder portion and the straight body portion in a direction opposite to a pulling direction of the silicon ingot, in the growing,
a diameter of the produced silicon ingot is 200 mm; and
a length of a region of the produced silicon ingot having resistivity of no greater than 1.6 mΩcm is no less than 200 mm in a longitudinal direction in a case of arsenic; a length of a region of the produced silicon ingot having resistivity of no greater than 0.8 mΩcm is no less than 100 mm in a longitudinal direction in a case of phosphorous; a length of a region of the produced silicon ingot having resistivity of no greater than 0.8 mΩcm is no less than 50 mm in a longitudinal direction in a case of a combination of phosphorous and germanium.
2. A silicon ingot that is produced by the process for manufacturing a silicon ingot according to claim 1 and satisfies any one of the following conditions A to C:
Condition A: the dopant is arsenic and resistivity of a region in the silicon ingot of 5 to 15% solidification ratio is 1.6 to 2.0 mΩcm;
Condition B: the dopant is phosphorous and resistivity of a region in the silicon ingot of 5 to 15% solidification ratio is 0.95 to 1.1 mΩcm; and
Condition C: the dopant is a combination of phosphorous and germanium and resistivity of a region in the silicon ingot of 5 to 15% solidification ratio is 1.0 to 1.2 mΩcm.
3. The silicon ingot according to claim 2 that further satisfies any one of the following conditions D to F:
Condition D: the dopant is arsenic and resistivity of a region in the silicon ingot of 80 to 90% solidification ratio is 1.3 to 1.6 mΩcm;
Condition E: the dopant is phosphorous and resistivity of a region in the silicon ingot of 80 to 90% solidification ratio is 0.70 to 0.80 mΩcm; and
Condition F: the dopant is a combination of phosphorous and germanium and resistivity of a region in the silicon ingot of 80 to 90% solidification ratio is 0.70 to 0.90 mΩcm.
4. The process according to claim 1 , further comprising obtaining a silicon wafer by slicing the silicon ingot.
5. A The process according to claim 4 , further comprising obtaining an epitaxial wafer by forming an epitaxial layer on a surface of the silicon wafer.
6. A silicon ingot, wherein the silicon ingot is manufactured by the following process:
dipping a seed crystal in a melt in a crucible in a hot zone, wherein:
the seed crystal and the melt each contain an arsenic dopant,
a concentration of the arsenic dopant contained in the seed crystal is: 2.0×10 19 to 4.0×10 19 atoms/cm 3 , and
the temperature difference between the seed crystal and the melt, when dipping the seed crystal in the melt, is 50 to 97 K; and
growing the silicon single crystal pulled after the dipping obtain the silicon ingot, wherein the growing comprises using a single crystal puller provided with a thermal shield plate for shielding the silicon ingot against radiant heat from the melt; wherein
a distance between the thermal shield plate and a surface of the melt is 20 to 30 mm at the beginning of growing a straight body portion of the silicon ingot, in the growing,
a distance between the thermal shield plate and the surface of the melt is 6 to 15 mm in growing the straight body portion from a position of 200 mm away from a boundary between a shoulder portion and the straight body portion in a direction opposite to a pulling direction of the silicon ingot, in the growing,
a diameter of the silicon ingot is 200 mm, and
a length of a region having resistivity of no greater than 1.6 mΩcm is no less than 200 mm in a longitudinal direction.
7. A silicon wafer, wherein the silicon wafer is obtained by slicing the silicon ingot according to claim 6 .
8. An epitaxial wafer, wherein the epitaxial wafer is obtained by forming an epitaxial layer on a surface of the silicon wafer according to claim 7 .
9. The silicon ingot according to claim 6 , wherein the silicon ingot is a single crystal silicon ingot.
10. A silicon ingot, wherein the silicon ingot is manufactured by the following process:
dipping a seed crystal in a melt in a crucible in a hot zone, wherein:
the seed crystal and the melt each contain a phosphorous dopant,
a concentration of the phosphorous dopant contained in the seed crystal is: 5.0×10 19 to 7.0×10 19 atoms/cm 3 , and
the temperature difference between the seed crystal and the melt, when dipping the seed crystal in the melt, is 50 to 97 K; and
growing the silicon single crystal pulled after the dipping obtain the silicon ingot, wherein the growing comprises using a single crystal puller provided with a thermal shield plate for shielding the silicon ingot against radiant heat from the melt; wherein:
a distance between the thermal shield plate and a surface of the melt is 20 to 30 mm at the beginning of growing a straight body portion of the silicon ingot, in the growing, and
a distance between the thermal shield plate and the surface of the melt is 6 to 15 mm in growing the straight body portion from a position of 200 mm away from a boundary between a shoulder portion and the straight body portion in a direction opposite to a pulling direction of the silicon ingot, in the growing,
a diameter of the silicon ingot is 200 mm; and
a length of a region having resistivity of no greater than 0.8 mΩcm is no less than 100 mm in a longitudinal direction.
11. The silicon ingot according to claim 10 , wherein the silicon ingot is a single crystal silicon ingot.
12. A silicon wafer, wherein the silicon wafer is obtained by slicing the silicon ingot according to claim 10 .
13. An epitaxial wafer, wherein the epitaxial wafer is obtained by forming an epitaxial layer on a surface of the silicon wafer according to claim 12 .
14. A silicon ingot, wherein the silicon ingot is manufactured by the following process:
dipping a seed crystal in a melt in a crucible in a hot zone, wherein:
the seed crystal and the melt each contain a phosphorous dopant and a germanium dopant,
a concentration of the phosphorous dopant contained in the seed crystal is: 5.0×10 19 to 7.0×10 19 atoms/cm 3 ,
a concentration of the germanium dopant contained in the seed crystal is: 4.0×10 19 to 8.0×10 19 atoms/cm 3 , and
the temperature difference between the seed crystal and the melt, when dipping the seed crystal in the melt, is 50 to 97 K; and
growing the silicon single crystal pulled after the dipping obtain the silicon ingot, wherein the growing comprises using a single crystal puller provided with a thermal shield plate for shielding the silicon ingot against radiant heat from the melt; wherein:
a distance between the thermal shield plate and a surface of the melt is 20 to 30 mm at the beginning of growing a straight body portion of the silicon ingot, in the growing,
a distance between the thermal shield plate and the surface of the melt is 6 to 15 mm in growing the straight body portion from a position of 200 mm away from a boundary between a shoulder portion and the straight body portion in a direction opposite to a pulling direction of the silicon ingot, in the growing,
a diameter of the silicon ingot is 200 mm; and
a length of a region having resistivity of no greater than 0.8 mΩcm is no less than 50 mm in a longitudinal direction.
15. The silicon ingot according to claim 14 , wherein the silicon ingot is a single crystal silicon ingot.
16. A silicon wafer, wherein the silicon wafer is obtained by slicing the silicon ingot according to claim 14 .
17. An epitaxial wafer, wherein the epitaxial wafer is obtained by forming an epitaxial layer on a surface of the silicon wafer according to claim 16 .