CMOS image sensor and method for fabricating the same
View Patent ↗A CMOS image sensor and fabricating method can reduce leakage current of a photodiode reduced by configuring a triangular shape of a photodiode area to minimize an interface contacting the STI or performing deuterium annealing to remove dangling bonds from an interface contacting with oxide. The CMOS image sensor includes a semiconductor substrate, a device isolation layer on the semiconductor substrate, and a plurality of diodes, each having a shape minimizing an area of a boundary contacting with the device isolation layer.
1. A method of fabricating a CMOS image sensor, comprising:
forming a shallow trench isolation layer on a semiconductor substrate to define an active area and peri area;
forming a photodiode on the semiconductor substrate in the active area and peri area, wherein a length of the photodiode formed in the active area to contact with the shallow trench isolation layer is shorter than a length of a photodiode formed in the peri area to contact with the shallow trench isolation layer; and
annealing the semiconductor substrate in the presence of deuterium, to remove dangling bonds from an interface between the semiconductor substrate and the shallow trench isolation layer.
2. The method of claim 1 , wherein the annealing step is carried out in the presence of nitrogen.
3. The method of claim 2 , wherein a composition ratio of deuterium to nitrogen is 2:8.
4. The method of claim 2 , wherein the deuterium having a concentration of about 10 to 25%.
5. The method of claim 1 , wherein the annealing step is carried out for 30 minutes at 400° C.
6. The method of claim 1 , wherein the photodiode has a triangular shape.