US company Silicon Genesis Corporation (SiGen) says it has developed a wafer-level strained substrate technology, called “Next-Generation Strain” or NGS. NGS features uniaxial instead of biaxial strain. It is said to avoid the mobility degradation and high defect levels associated with current silicon-germanium- (SiGe) based biaxially strained silicon or strained silicon on insulator (S-SOI).
Several chip manufacturers, including Intel and Texas Instruments, have successfully demonstrated the benefits of uniaxial strain, but until now only local transistor-level strain has been available.
“Uniaxial strain is now being recognised as the preferred strain type for deep-submicron device applications, and its local variant has displaced global biaxial strain as the mobility enhancer of choice,” explains Dr Scott Thompson, an associate professor at the University of Florida and former Intel fellow director.
“Biaxial strain has been plagued with process integration issues such as high defect levels and germanium inter-diffusion, but more importantly it’s much less efficient in boosting PMOS transistor performance.
“The availability of a global uniaxially strained substrate can work with these existing approaches to substantially improve total transistor performance and has scaling advantages over local strain at the 45nm node and beyond,” concludes Dr Thompson.