Applications of SiGe Material for CMOS and Related Processing

Despite the fact that the main commercial heterostructure based on SiGe is the HBT, the CMOS R&D has also focused on the use of SiGe material for boosting the performances. SiGe alloys are indeed extensively used for their electrical properties (band gap engineering by adjusting the Ge content, carriers' mobility improvement...). New applications for CMOS are emerging that are based on the crystalline properties of the SiGe material: strained devices, high-mobility SiGe channel transistors or architectures where it is used as a sacrificial layer. The selective SiGe/Si etching can be used in several advanced microelectronics architectures that require a thin single-crystal Si film isolated from the substrate by a cavity. The capability to perform sustained mono-Si areas over an empty tunnel opens a wide range of applications for this technique, in particular for the realization of localized single-gate fully depleted transistors, double-gate or multi-channel devices, MEMS in nanoscale dimensions...