Effect of tilt angle variations in a halo implant on Vth values for 0.14-μm CMOS devices

Sensitivity of critical transistor parameters to halo implant tilt angle for 0.14-μm CMOS devices was investigated. V_th sensitivity was found to be 3% per tilt degree. A tilt angle mismatch between two serial ion implanters used in manufacturing was detected by tracking V_th performance for 0.14-μm production lots. Even though individual implanters may be within tool specifications for tilt angle control (±0.5° for our specific tool type), the relative mismatch could be as large as 1°, and therefore, result in a V_th mismatch of over 3% from nominal. The V_th mismatch results are in qualitative agreement with simulation results using SUPREM and MEDICI software.