Issues and challenges of high-k dielectrics on high-mobility substrates

With the current trend in device scaling, for high speed and low power applications materials with high-k dielectric constant such as Hf-based dielectrics are being integrated into standard CMOS technologies. To attend the ITRS intended transistor drive current for sub-22 nm CMOS technology and beyond high mobility channel materials are required. Substrates such as germanium (Ge) and gallium arsenide (GaAs) are being considered for their high electron mobility. The interface between the high-k dielectrics and the high mobility substrates are not well understood. A strong interface passivation technique is, therefore, necessary to optimize the device performance. As it is clear from the electrical performance in these devices depends on the deposition process, precise selection of deposition parameters, predeposition surface treatments and subsequent annealing temperatures. This work reviews the recent developments of high-k/Ge interface and its characterization. To form an electrically passive interface, interface treatments such as surface nitridation of HfO ₂/Ge interface will be evaluated. In addition, electrical characteristics of high-k on HI-V substrates are also outlined.