Replacement channels for semiconductor devices and methods for forming the same using dopant concentration boost

A method for forming a FinFET semiconductor device, said method comprising:

• forming a fin over a substrate, at least a portion of said fin comprising a channel region and said fin formed of a semiconductor material;
• removing channel material from said channel region thereby forming a void in said fin in said channel region;
• forming replacement channel material within said void, said replacement channel material comprising one of Ge and SiGe, and including a dopant, and having an as-deposited average dopant concentration of less than 5E18 atoms/cm3;
• further doping said replacement channel material with said dopant thereby increasing said average dopant concentration to greater than 5E18 atoms/cm3 and forming a gradient of dopant concentration in said replacement channel material such that an upper portion of said replacement channel material has a higher dopant concentration than a lower portion of said replacement channel material.

A method for forming a semiconductor transistor, said method comprising:

• defining a channel region in a semiconductor substrate by forming a dummy gate material within a singular dielectric material and conterminous with sidewalls comprised entirely of said dielectric material, said channel region associated with a transistor;
• removing channel material from said channel region by successively removing said dummy gate then said channel material, thereby forming an opening having said sidewalls, and a recessed portion comprising a void in said semiconductor substrate in said channel region;
• forming replacement channel material within said void, said replacement channel material comprising one of Ge and SiGe, and including a dopant, and having an as-deposited average dopant concentration less than a first dopant concentration;
• further doping said replacement channel material with said dopant using beam line ion implantation thereby increasing said average dopant concentration to greater than said first dopant concentration and forming a gradient of dopant concentration in said replacement channel material such that an upper portion of said replacement channel material has a higher dopant concentration than a lower portion of said replacement channel material;
• and
• further comprising forming a metal transistor gate over said replacement channel material and conterminous with said sidewalls.