Interlevel conductive light shield
View Patent ↗A CMOS image sensor pixel includes a conductive light shield, which is located between a first dielectric layer and a second dielectric layer. At least one via extends from a top surface of the second dielectric layer to a bottom surface of the first dielectric layer is formed in the metal interconnect structure. The conductive light shield may be formed within a contact level between a top surface of a semiconductor substrate and a first metal line level, or may be formed in any metal interconnect via level between two metal line levels. The inventive CMOS image sensor pixel enables reduction of noise in the signal stored in the floating drain.
1. A semiconductor structure comprising:
at least one semiconductor device located on a top surface of a semiconductor substrate;
at least one first-level metal line separated from a top surface of said semiconductor substrate;
a first dielectric layer abutting a top surface of said at least one first-level metal line;
a conductive light shield located over said at least one semiconductor device and abutting a top surface of said first dielectric layer; and
a second dielectric layer located over said conductive light shield, wherein said first dielectric layer and said second dielectric layer encapsulate an entirety of said conductive light shield.
2. The semiconductor structure of claim 1 , further comprising:
a second level metal line embedded in said second dielectric layer; and
a contact via abutting a bottom surface of said at least one second level metal line and a top surface of said at least one first level metal line.
3. The semiconductor structure of claim 2 , wherein said contact via is of integral construction without any physically manifested interface therein.
4. The semiconductor structure of claim 2 , further comprising:
a metal plate having a same material composition and a same thickness as said conductive light shield and abutting said top surface of said first dielectric layer and disjoined from said conductive light shield; and
another contact via abutting a bottom surface of another second level metal line and a top surface of said metal plate.
5. The semiconductor structure of claim 4 , further comprising yet another contact via abutting a bottom surface of yet another second level metal line and said top surface of said metal plate.
6. The semiconductor structure of claim 4 , further comprising:
a first metal plate having a same material composition as, and a same thickness as, said conductive light shield and abutting said top surface of said dielectric layer and disjoined from said conductive light shield;
a first dielectric portion abutting a top surface of said conductive light shield and having sidewalls substantially vertically coincident with sidewalls of said conductive light shield;
a second dielectric portion having a same material composition as, and a same thickness as, said first dielectric portion, abutting a top surface of said first metal plate, and disjoined from said first dielectric portion; and
a second metal plate abutting a top surface of said second dielectric portion.
7. A design structure embodied in a machine readable medium for designing, manufacturing, or testing a design, said design structure comprising:
a first data representing a semiconductor device on a semiconductor substrate;
a second data representing a conductive light shield located in a local interconnect level and overlying said semiconductor device;
a third data representing a metal line located in a metal interconnect level which is located above said local interconnect level; and
a fourth data representing a contact via abutting said metal line and said semiconductor device.
8. The design structure of claim 7 , wherein said contact via is of integral construction without any physically manifested interface therein.
9. The design structure of claim 7 , further comprising:
a fifth data representing a dielectric substrate-capping layer abutting a top surface of said semiconductor substrate and located underneath a portion of said conductive light shield; and
a sixth data representing a middle-of-line (MOL) dielectric layer located over said dielectric substrate-capping layer and located underneath said at least one metal line.
10. The design structure of claim 9 , further comprising another data representing a middle-of-line (MOL) dielectric liner layer abutting a top surface of said dielectric substrate-capping layer and a non-planar bottom surface of said conductive light shield.
11. The design structure of claim 7 , wherein said fourth data includes another data representing at least one downward-protruding via portion located within said conductive light shield, wherein said at least one downward-protruding via portion vertically abuts a conductive structure located on said semiconductor substrate.
12. A design structure embodied in a machine readable medium for designing, manufacturing, or testing a design, said design structure comprising:
a first data representing a semiconductor device located on a top surface of a semiconductor substrate;
a second data representing a first-level metal line separated from a top surface of said semiconductor substrate;
a third data representing a first dielectric layer abutting a top surface of said at least one first-level metal line;
a fourth data representing a conductive light shield located over said at least one semiconductor device and abutting a top surface of said first dielectric layer; and
a fifth data representing a second dielectric layer located over said conductive light shield, wherein said first dielectric layer and said second dielectric layer encapsulate an entirety of said conductive light shield.
13. The design structure of claim 12 , further comprising:
a sixth data representing a second-level metal line embedded in said second dielectric layer; and
a seventh data representing a contact via abutting a bottom surface of said at least one second-level metal line and a top surface of said at least one first level metal line.