A CMOS sensor. The CMOS sensor comprises a substrate, a gate electrode formed on the substrate, a source/drain region formed in the substrate on one side of the gate electrode, and a sensor region formed in the substrate on another side of the gate electrode. The impurity in the source/drain region is arsenic. The source/drain further comprises a lightly doped drain region. The sensor region comprises a first doped region and a second doped region which together have a dentoid profile. The impurity in the first doped region and the second doped region is phosphorus.