CMOS image sensor and method for fabricating the same
View Patent ↗A CMOS image sensor and a method for fabricating the same is disclosed, to improve reliability of a driving part transistor and to improve an output voltage of a photodiode, which includes a semiconductor substrate defined as a photodiode transistor region and a driving part transistor region; a first gate insulating layer on the photodiode transistor region of the semiconductor substrate; a second gate insulating layer on the driving part transistor region of the semiconductor substrate, wherein the second gate insulating layer is thicker than the first gate insulating layer; and gate electrodes on the respective first and second gate insulating layers.
1. A method for fabricating a CMOS image sensor comprising:
forming a first conductive-type epitaxial layer on a first conductive-type semiconductor substrate;
preparing the semiconductor substrate to have a photodiode transistor region and a driving part transistor region defined thereon;
forming a first gate insulating layer on the driving part transistor region;
forming a second gate insulating layer on the first gate insulating layer and on the photodiode transistor region; and
forming respective gate electrodes of a photodiode transistor and a driving part transistor by coating a conductive layer on the first and second gate insulating layers, and selectively removing the coated conductive layer and the first and second gate insulating layers.
2. The method of claim 1 , wherein the photodiode transistor region forms a reset transistor therein, or a reset transistor and a transfer transistor therein.
3. The method of claim 1 , wherein the driving part transistor region forms a drive transistor and a select transistor therein.
4. The method of claim 1 , wherein the first gate insulating layer is formed at a thickness between 15Å and 40Å.
5. The method of claim 1 , wherein the second gate insulating layer is formed at a thickness between 15Å and 40Å.
6. The method of claim 1 , further comprising the process of forming source/drain regions by implanting impurity ions to the semiconductor substrate at both sides of the respective gate electrodes in the photodiode transistor region and the driving part transistor region.