Strained Ge mosfet technology

Strained Ge (ε-Ge) on relaxed Si _1-xGe _x possesses extremely high hole mobility and can be used as a channel material for high-performance p-MOSFETs. In one configuration, referred to as a dual-channel heterostructure, the ε-Ge channel is epitaxially capped with strained Si (ε-Si) in order to allow the use of an SiO ₂ gate dielectric. In an alternate configuration, a high-κ gate dielectric is deposited directly onto the ε-Ge, allowing surface-channel operation. We earlier reported on the optimization of dual-channel ε-Ge p-MOSFETs, demonstrating hole mobility enhancements over bulk Si as high as 10 times. More recently, we reported surface-channel ε-Ge p-MOSFETs with an HfO ₂/TaN gate stack exhibiting a 2x mobility enhancement over similarly processed bulk Si devices. In this paper, we review the current progress in both dual-channel and surface-channel ε-Ge p-MOSFETs. Some results on the integration of n-MOSFETs will also be presented.