Silicon wafer and silicon epitaxial wafer and production methods therefor
View Patent ↗The present invention provides a silicon wafer having a DZ layer near a surface and an oxide precipitate layer in a bulk portion, wherein interstitial oxygen concentrations of the DZ layer, the oxide precipitate layer and a transition region between the DZ layer and the oxide precipitate layer are all 8 ppma or less, and an epitaxial silicon wafer, wherein an epitaxial layer is formed on a surface of the silicon wafer, as well as a method for producing a silicon wafer, which comprises growing a silicon single crystal ingot having an initial interstitial oxygen concentration of 10 to 25 ppma by the Czochralski method, processing the silicon single crystal ingot into a wafer, and subjecting the wafer to a first heat treatment at 950 to 1050° C. for 2 to 5 hours, a second heat treatment at 450 to 550° C. for 4 to 10 hours, a third heat treatment at 750 to 850° C. for 2 to 8 hours, and a fourth heat treatment at 950 to 1100° C. for 8 to 24 hours. Thus, there is provided a method for producing a silicon wafer of which high resistivity can surely be maintained even when the wafer is subjected to a heat treatment for device production.
1. A silicon wafer having a DZ layer near a surface and an oxide precipitate layer in a bulk portion, wherein interstitial oxygen concentrations of the DZ layer, the oxide precipitate layer and a transition region between the DZ layer and the oxide precipitate layer are all 8 ppma or less.
2. The silicon wafer according to claim 1 , wherein the transition region between the DZ layer and the oxide precipitate layer has a width of 5 μm or less.
3. The silicon wafer according to claim 1 , wherein resistivity of the silicon wafer is 100 Ω·cm or more.
4. The silicon wafer according to claim 2 , wherein resistivity of the silicon wafer is 100 Ω·cm or more.
5. A silicon wafer having a DZ layer near a surface and an oxide precipitate layer in a bulk portion, wherein interstitial oxygen concentrations of the DZ layer and the oxide precipitate layer are both 8 ppma or less, and a transition region between the DZ layer and the oxide precipitate layer has a width of 5 μm or less.
6. An epitaxial silicon wafer, wherein an epitaxial layer is formed on a surface of the silicon wafer according to any one of claim 1 .
7. An epitaxial silicon wafer, wherein an epitaxial layer is formed on a surface of the silicon wafer according to any one of claim 2 .
8. An epitaxial silicon wafer, wherein an epitaxial layer is formed on a surface of the silicon wafer according to any one of claim 3 .
9. An epitaxial silicon wafer, wherein an epitaxial layer is formed on a surface of the silicon wafer according to any one of claim 4 .
10. An epitaxial silicon wafer, wherein an epitaxial layer is formed on a surface of the silicon wafer according to any one of claim 5 .
11. A method for producing a silicon wafer, which comprises growing a silicon single crystal ingot having an initial interstitial oxygen concentration of 10 to 25 ppma by the Czochralski method, processing the silicon single crystal ingot into a wafer, and subjecting the wafer to a first heat treatment at 950 to 1050° C. for 2 to 5 hours, a second heat treatment at 450 to 550° C. for 4 to 10 hours, a third heat treatment at 750 to 850° C. for 2 to 8 hours, and a fourth heat treatment at 950 to 1100° C. for 8 to 24 hours.
12. The method for producing a silicon wafer according to claim 11 , wherein the silicon single crystal ingot is grown so that the ingot should have a resistivity of 100 Ω·cm or more.
13. A method for producing an epitaxial silicon wafer, which comprises forming an epitaxial layer on a surface of a silicon wafer produced by the method for producing a silicon wafer according to claim 11 .
14. A method for producing an epitaxial silicon wafer, which comprises forming an epitaxial layer on a surface of a silicon wafer produced by the method for producing a silicon wafer according to claim 12 .