Patent ID: 8158495

Claim:
A process for forming at least one substantially single-crystal silicon-based portion on a surface of a substrate, comprising: /a/ heating the substrate and forming a silicon-based layer on the surface of the substrate, under suitable conditions so that said silicon-based layer is selectively substantially single-crystal in a first substrate zone and amorphous in a second substrate zone, by bringing a first gas mixture comprising molecules of at least one non-chlorinated silicon hydride and molecules of a first carrier gas into contact with the substrate, at said surface in said first and second substrate zones, the molecules of silicon hydride having a partial pressure between 0.03 and 30 ton and the molecules of the first carrier gas having a partial pressure between 10 and 760 torr; and /b/ bringing a second gas mixture into contact with both the substantially single-crystal portion of the silicon-based layer and the amorphous portion of the silicon-based layer, the second gas mixture performing a dry gas chemical selective etch that selectively etches the silicon-based layer after formation in /a/ to completely remove the amorphous portion of said silicon-based layer formed in the second substrate zone while the substantially single-crystal portion of said silicon-based layer, formed in the first substrate zone, remains substantially intact; wherein the substrate is retained in a same treatment chamber during both /a/ heating the substrate and forming the silicon-based layer and /b/ performing the dry gas chemical selective etch that selectively etches said silicon-based layer; and wherein said dry gas chemical selective etch selectively etches the substantially single-crystal portion of said silicon-based layer at a rate at least equal to ten times lower than a rate for etching said amorphous portion of said silicon-based layer.