High Ge Content SiGe Selective Processes for Manufacturing Source/Drain in the Next Generations of pMOS Transistors

Abstract

Selectivity of different SiGe processes towards oxide and nitride has been studied on both: blanket and patterned Si wafers. Three different precursors: silane, dichlorosilane and disilane were used for SiGe growth. It was found that growth of SiGe with Ge content higher than 35% is intrinsically selective towards SiO2; SiGe with any Ge content, up to pure Ge, could not be grown selectively towards nitride; in order to get selectivity towards nitride an etching gas should be used and its amount in the gas phase decreases with the Ge content increase.