Patent ID: 7781306

Claim:
A method for manufacturing a semiconductor substrate comprising the steps of: forming a first insulating film containing silicon and oxygen as its composition over a single-crystal semiconductor substrate; forming a second insulating film containing silicon and nitrogen as its composition over the first insulating film; irradiating the second insulating film with first ions to form a separation layer in the single-crystal semiconductor substrate; irradiating the second insulating film with second ions so that halogen is contained in the first insulating film, wherein the second ions are halogen ions; forming a bonding layer over the second insulating film; bonding the single-crystal semiconductor substrate and a supporting substrate with the bonding layer interposed therebetween; and performing heat treatment to separate the single-crystal semiconductor substrate with a single-crystal semiconductor film left over the supporting substrate, and accordingly the halogen is contained in the single-crystal semiconductor film.