Implant-free quantum-well SiGe pFETs for future high-performance CMOS architectures

Next-generation multimedia applications will require ICs that are at the same time very powerful and low power. One attractive option is to use high-mobility channels, for example using SiGe (silicon-germanium) with a high Ge content. However, further scaling of the gate length will require a better electrostatic gate control, and a low variability of the key electrical parameters. Imec and its partners have recently shown that the IF-QW concept with a buried SiGe channel meets these requirements while significantly improving the device performance.

Imec now presents the 2^nd generation of SiGe_45% IF-QW pFETs, processed on standard 300mm STI wafers. Compared to earlier IF-QW devices, the raised SiGe and Si substrate are recessed and replaced with a thick SiGe_25% epi-layer to form the source/drain electrodes. Also, imec has developed process modules that minimize local variations and maximize the device performance.

This has resulted in an excellent short channel control, with a drain induced barrier lowering of ~110mV/V at 35nm-L_G and a record 1mA/µm-I_on at -1V. For lower operating voltages, an increased performance was demonstrated. The devices were benchmarked at various operating voltages against state-of-the-art technologies such as SOI nFETs or SiGe-FET, showing at least equivalent results. These results show that SiGe IF-QW devices with embedded source drain form a promising architecture for integration on bulk Si, from the 16nm node onwards.