Sb-Doped S/D Ultrathin Body Ge-On Insulator nMOSFET Fabricated by Improved Ge Condensation Process

We report the demonstration of ultrathin Ge-on-insulator (GOI) inversion-type nMOSFETs, fabricated by the optimized Ge condensation technique and solid-phase diffusion of Sb. The GOI structures with low hole concentration of 10¹⁷ cm^-3 or less are realized by optimizing oxidation temperature and inserting annealing process for enhancement of intermixing in the Ge condensation process recipe. The hole concentration in the GOI body has been systematically analyzed with different oxidation temperature and insertion of annealing process. Highly doped n⁺ source/drain regions are formed in 16-nm-thick GOI layers by Sb solid-phase diffusion doping from spin-on-glass at 650°C. The high I_ON/IO_FF ratio of 104 is observed in the fabricated nMOSFETs. The peak electron mobility of 107 cm²/Vs is obtained for the inversion-type GOI nMOSFETs.