3X hole mobility enhancement in epitaxially grown SiGe PMOSFETs on (110) Si substrates with high k / metal gate for hybrid orientation technology

MOSFETs were fabricated on both thick and thin epi SiGe films. An ultra thin (~ 1- 2 nm) epi Si cap grown on the SiGe layers serves to separate the Ge from the high k dielectric as well as form a SiO₂ interfacial layer between the SiGe channel and the high k gate dielectric. There is evidence that this cap layer is completely oxidized during the ozone based ALD high k deposition process. Both epitaxial Si as well as SiO₂ based capping layers are reported to improve the interface for pure Ge devices. PMOSFETs were fabricated using a conventional 4 mask step process flow using a deposited field isolation oxide, ALD high k, metal gate electrode and implanted source/drain regions.