Layout Dependence Modeling for 45-nm CMOS With Stress-Enhanced Technique

Layout dependences for stress-enhanced MOSFETs including contact positioning, the second neighboring poly effect, and bent diffusion are modeled in 45-nm CMOS logic technology. It is found that the sensitivity of contact position in the channel direction is larger for PMOS with a higher stress liner than for NMOS. The effect of contact positions is modeled by using the distance of contact to gate (x) and the number of contacts (N). In terms of the gate-space effect, it is concluded that, in addition to the neighboring gates, second neighboring gates affect the channel stress. The effect of bent-shape diffusion is analyzed for NMOS and PMOS. For NMOS, the channel profile is affected by the bent shape. This can be described by the change of V _th. For PMOS, the channel stress is modulated by the bent diffusion. The stress effect in bent-shape diffusion for PMOS is modeled with three geometrical parameters. The compact model is applied to the characterization of actual 45-nm cell libraries. It is confirmed that, with the constructed models and design flow, a saturation current (I _dsat) change of -12%-14% is removed from the uncertain margin in 45-nm corner libraries.