Patent ID: 6541329
Filing Date: 2003-04-01
Classification: H01L

Abstract:
A method for making a plurality of active pixel sensors on a surface of a semiconductor wafer, the semiconductor wafer comprises a P-type substrate, an active pixel sensor region, and a periphery circuit region, the method comprising:forming a first active pixel sensor block mask (APSB mask) on the surface of the semiconductor wafer by performing a first photolithography process to cover the active pixel sensor region; performing a first ion implantation process to form at least one first type well on the surface of the semiconductor wafer not covered by the first active pixel sensor block mask; removing the first active pixel sensor block mask; forming a second active pixel sensor block mask (APSB mask) and at least one first type well mask on the surface of the semiconductor wafer by performing a second photolithography process to cover the active pixel sensor region and the region outside a second type well in the periphery circuit region, respectively; performing a second ion implantation process to form at least one second type well on the surface of the semiconductor wafer not covered by the second active pixel sensor block mask and the first type well mask; removing the second active pixel sensor block mask and the first type well mask; forming a sensor mask on the surface of the semiconductor wafer by performing a third photolithography process to define a photodiode region in the active pixel sensor region; performing a third ion implantation process to form at least one sensor implantation region on the surface of the semiconductor wafer not covered by the sensor mask; removing the sensor mask; forming a source/drain mask on the surface of the semiconductor wafer by performing a fourth photolithography process to expose at least one source/drain region in the active pixel sensor region; performing a fourth ion implantation process to form at least one source/drain region on the surface of the semiconductor wafer not covered by the source/drain mask to form at least one photodiode and at least one metal-oxide semiconductor (MOS) transistor of a complementary metal-oxide semiconductor (CMOS) transistor on the surface of the active pixel sensor region; and removing the source/drain mask; wherein the third ion implantation process and the fourth ion implantation process are both N-type ion implantation processes, the dosage for the third ion implantation is lower than the dosage for the fourth ion implantation, the implantation depth for the third ion implantation process is deeper than the fourth ion implantation process, the drain does not join with the P-type substrate, and the sensor implantation region joins with the P-type substrate.