A high-sensitivity 1/4" 250k pixel Interline Transfer CCD (IT-CCD) image sensor has been developed. To achieve high-sensitivity, high-energy ion implantation process is adopted for photodiode (PD) formation. According to device simulation results, transfer gate (TG) and channel stop (CS) length are reduced to increase saturation signal. Sensitivity improvement of 35% are obtained, as well as 100mV saturation signal. Low smear level of -95dB is also achieved.