Fabricating CMOS image sensor
View Patent ↗A CMOS image sensor and a fabricating method thereof are provided. The method includes forming a nitride layer over a boundary region between a device isolation region and a pixel region, forming a silicide barrier layer in the pixel region and performing a silicide process. A boundary portion of the silicide barrier layer formed in the pixel region can be prevented from being wet-etched while the silicide barrier layer is removed by the wet etching process.
1. A method comprising:
preparing a semiconductor substrate in which a device isolation region and a pixel region are defined and over which a polyline is formed;
forming a first type photodiode;
forming a second type photodiode at an upper portion of the first type photodiode;
depositing a nitride layer over the semiconductor substrate;
patterning the nitride layer to form a first nitride layer over a sidewall of the polyline and a second nitride layer overlapping the pixel region and the device isolation region by a predetermined length from a boundary between the pixel region and the device isolation region;
depositing a silicide barrier layer over the semiconductor substrate;
patterning the deposited silicide barrier layer to form silicide barrier layer patterns in the pixel region;
performing a silicide process on the semiconductor substrate; and
removing the silicide barrier layer patterns from a periphery region and the device isolation region.
2. The method of claim 1 , wherein said method is used to fabricate a complementary metal oxide semiconductor image sensor.
3. The method of claim 1 , wherein said forming a first type photodiode comprises ion-implanting first type impurities into the pixel region of the semiconductor substrate.
4. The method of claim 1 , wherein said forming a second type photodiode at an upper portion of the first type photodiode comprises ion-implanting second type impurities into the first type photodiode.
5. The method of claim 1 , wherein the second nitride layer overlaps the pixel region and the device isolation region equidistantly by about 0.2 μm from the boundary between the pixel region and the device isolation region.
6. The method of claim 1 , wherein the second nitride layer overlaps the pixel region and the device isolation region equidistantly from about 0.1 μm to 0.6 μm from the boundary between the pixel region and the device isolation region.
7. The method of claim 1 , wherein the silicide barrier layer comprises plasma-enhanced tetra-ethyl-ortho-silicate.
8. A method comprising:
preparing a semiconductor substrate in which a device isolation region and a pixel region are defined and over which a polyline is formed;
forming a first type photodiode by ion-implanting first type impurities into the pixel region of the semiconductor substrate;
forming a first nitride layer used as a spacer of the polyline;
forming a second nitride layer overlapping the pixel region and the device isolation region by a predetermined length from a boundary between the pixel region and the device isolation region;
forming a second type photodiode at an upper portion of the first type photodiode by ion-implanting second type impurities into the first type photodiode;
forming a silicide barrier layer over the semiconductor substrate;
patterning the formed silicide barrier layer to form silicide barrier layer patterns in the pixel region;
performing a silicide process to the semiconductor substrate; and
removing the silicide barrier layer patterns from a periphery region and the device isolation region by using a wet etching process.
9. The method of claim 8 , wherein the second nitride layer overlaps the pixel region and the device isolation region equidistantly by 0.2 μm from the boundary between the pixel region and the device isolation region over each region.
10. The method of claim 8 , wherein the second nitride layer overlaps the pixel region and the device isolation region equidistantly from about 0.1 μm to 0.6 μm from the boundary between the pixel region and the device isolation region.
11. The method of claim 8 , wherein the second nitride layer remains without being substantially etched by the wet etching process.
12. The method of claim 8 , wherein the silicide barrier layer comprises plasma-enhanced tetra-ethyl-ortho-silicate.
13. The method of claim 8 , wherein, in the forming of the second type photodiode, an implantation angle of the second type impurities is 7 degrees greater than that of the first type impurities from a line perpendicular to a top surface of the semiconductor substrate.