Molybdenum gate technology for ultrathin-body MOSFETs and FinFETs

Damage-free sputter deposition and highly selective dry-etch processes have been developed for molybdenum (Mo) metal gate technology, for application to fully depleted silicon-on-insulator ( devices such as the ultrathin body (UTB) MOSFET and double-gate FinFET. A plasma charge trap effectively eliminates high-energy particle bombardment during Mo sputtering; hence the gate-dielectric integrity (TDDB, Q_BD) is significantly improved and the field-effect mobility in Mo-gated MOSFETs follows the universal mobility curve. The effects of etch process parameters such as chlorine (Cl₂) and oxygen (O₂) gas flow rate, and source and bias radio frequence powers, were investigated in order to optimize the Mo etch rate and selectivity to SiO₂. A highly selective etch process was successfully applied to pattern Mo gate electrodes for UTB MOSFETs and FinFETs without leaving any residue or stringers. Measured electrical characteristics and physical analysis results are discussed.