Cocktail Implants for Exotic Materials

In the past 30 years CMOS devices have improved dramatically due to dimension scaling. Scaling has led increasingly to smaller and faster devices facilitating higher component density on chips with improved performance at increasingly lower prices. This sustained the dramatic growth in the multi-billion semiconductors industry. However, as the scaling of conventional Si CMOS devices is reaching its limits, novel strained Si and SiGe materials are being applied to enhance the hole and electron mobilities in CMOS devices. Silicon on Insulator (SOI) substrates are increasingly becoming mainstream technology for CMOS and BiCMOS technologies and are the key for future triple gate MOS devices. These major advances come with very demanding challenges. The problem of transient enhanced boron diffusion in silicon has long been a limiting factor for conventional CMOS devices. This problem is even worse in strained Si as boron diffusion in strained Si is enhanced by a factor of two in comparison to unstrained silicon. The diffusion of both phosphorus and arsenic is enhanced in SiGe with increasing Ge content. The activation of phosphorus and arsenic after implants in Ge rich SiGe are limiting challenges yet to be resolved. Hence, there is an urgent need to find solutions for the problems of enhanced dopant diffusion and dopant activation in these novel materials in order to optimise and facilitate their commercial application. This proposal aims to investigate novel techniques using cocktail implants of light elements such as hydrogen and helium in order to optimize dopant diffusion suppression in high Ge content SiGe, Strained Si and SOI, for state of the art and future semiconductor device applications.