Formation of high-mobility silicon—germanium structures by low-energy plasma enhanced chemical vapor deposition

摘要

Method for making a semiconductor structures comprising the steps:—forming a virtual substrate on a silicon substrate with a graded Si_1-xGe_x layer and a non-graded Si_1-xGe_x layer, using a high-density, low-energy plasma enhanced chemical vapor deposition (LEPECVD) process with a growth rate above 2 nm/s, a substrate temperature between 400° and 850° C., and a total reactive gas flow at the gas inlet between 5 sccm and 200 sccm;—forming an active region on the virtual substrate that comprises a Ge-channel and at least one modulation-doped layer using a low-density, low-energy plasma enhanced chemical vapor deposition (LEPECVD) process by introducing hydrogen (H₂) into the growth chamber, maintaining a substrate temperature between 400° and 500° C., and by introducing a dopant gas in a pulsed manner into the growth chamber to provide for the modulation-doped layer.