Epitaxial silicon wafer and method for manufacturing epitaxial silicon wafer

Abstract

A manufacturing method of an epitaxial silicon wafer includes: an epitaxial-film formation step for forming an epitaxial film made of silicon on a surface of a silicon wafer in a trichlorosilane gas atmosphere; and a nitrogen-concentration setting step for setting the nitrogen concentration of the surface of the epitaxial film through inward diffusion from a nitride film on the epitaxial film, the nitride film being formed by subjecting the silicon wafer provided with the epitaxial film through the epitaxial-film formation step to a heat treatment in a nitrogen atmosphere.

1 . An epitaxial silicon wafer comprising:
 a silicon wafer; and   an epitaxial film made of silicon and formed on a surface of the silicon wafer, wherein   a nitrogen concentration of the surface of the epitaxial film is 5.0×10 13  atoms/cm 3  or more.   
     
     
         2 . The epitaxial silicon wafer according to  claim 1 , wherein
 the nitrogen concentration at a depth of 3 μm from the surface of the epitaxial film is 5.0×10 13  atoms/cm 3  or more.   
     
     
         3 . The epitaxial silicon wafer according to  claim 1 , further comprising:
 a strain layer provided on the surface of the epitaxial film, the strain layer causing a film stress ranging from 10 MPa to 1000 MPa.   
     
     
         4 . The epitaxial silicon wafer according to  claim 1 , wherein
 an oxygen concentration of the silicon wafer ranges from 10×10 17  atoms/cm 3  to 15×10 17  atoms/cm 3  according to ASTM 1979.   
     
     
         5 . A manufacturing method of an epitaxial silicon wafer, the method comprising
 forming an epitaxial film made of silicon on a surface of a silicon wafer in a trichlorosilane gas atmosphere; and   setting a nitrogen concentration of the surface of the epitaxial film through inward diffusion from a nitride film on the epitaxial film, the nitride film being formed by subjecting the silicon wafer provided with the epitaxial film through the forming of the epitaxial film to a heat treatment in a nitrogen atmosphere.   
     
     
         6 . The manufacturing method of an epitaxial silicon wafer according to  claim 5 , further comprising:
 removing a native oxide on the surface of the epitaxial film before the nitride film is formed, wherein   the setting of the nitrogen concentration is conducted on the silicon wafer after removing the native oxide.   
     
     
         7 . The manufacturing method of an epitaxial silicon wafer according to  claim 6 , wherein
 the native oxide is removed by subjecting the silicon wafer to a heat treatment in one of an argon atmosphere, an ammonia atmosphere, and a hydrogen atmosphere by using the same heat treatment equipment as used in the setting of the nitrogen concentration.   
     
     
         8 . The manufacturing method of an epitaxial silicon wafer according to  claim 5 , further comprising:
 entirely removing the nitride film.   
     
     
         9 . The manufacturing method of an epitaxial silicon wafer according to  claim 8 , further comprising:
 forming a strain layer on the surface of the epitaxial film exposed after the removing of the nitride film, the strain layer causing a film stress ranging from 10 MPa to 1000 MPa.   
     
     
         10 . The manufacturing method of an epitaxial silicon wafer according to  claim 5 , wherein
 in the setting of the nitrogen concentration, the heat treatment is conducted so that a temperature X (degrees C.) is in a range from 850 degrees C. to 1400 degrees C., a heat treatment time Y (seconds) second or more and a formula (1),
     Y≥ 1×10 34  exp(−0.084X)   (1) is satisfied.