Method for producing semiconductor substrate, semiconductor substrate, and semiconductor device

A method for producing a semiconductor substrate, the method comprising the steps of:

• implanting an ion of at least one of silicon, carbon, or oxygen into a surface of a 4H—SiC substrate, to form, within the 4H—SiC substrate, an amorphous layer composed of amorphized silicon and carbon;
• bonding the surface of the 4H—SiC substrate and a bonding surface of another support substrate via a thin film formed on at least one of the surface of the 4H—SiC substrate that is subjected to the step of implanting the ion or the bonding surface of the support substrate, to obtain a bonded substrate;
• separating the 4H—SiC substrate at the amorphous layer from the bonded substrate, thereby dividing the bonded substrate into a joined substrate in which a surface layer of the 4H—SiC substrate is transferred as a 4H—SiC layer on the support substrate, and a separated substrate that is the 4H—SiC substrate after the surface layer has been separated;
• etching a separation surface of at least one of the joined substrate or the separated substrate, both of which have been subjected to the step of separating, by plasma etching;
• and
• performing epitaxial growth on at least one of the joined substrate or the separated substrate.

A semiconductor substrate comprising:

• a support substrate;
• and
• a 4H—SiC layer bonded onto a surface of the support substrate, wherein
• the support substrate is composed of SiC, and
• the 4H—SiC layer is bonded to the support substrate via a silicon thin film, and has a surface that is subjected to etching treatment.