Pixel for CMOS image sensor and image sensor including the same

A semiconductor device comprising:

• a semiconductor substrate having a trench extending from a first surface to a second surface of the semiconductor substrate;
• a photoelectric conversion element in an active region of the semiconductor substrate configured to generate charges in response to light incident on one of the first and second surfaces of the semiconductor substrate;
• an isolation material disposed in a first portion of the trench, the isolation material extending vertically with respect to the first and second surfaces of the substrate, the isolation material having a vertically extending void;
• and
• a capping material disposed in a second portion of the trench and on the isolation material,
• wherein a top surface of the capping material has a concaved contour over the trench, and wherein the vertically extending void is isolated from the capping material within the trench by a top portion of the isolation material.

A method of forming a complementary metal-oxide-semiconductor (CMOS) image sensor device having a photoelectric conversion element, the method comprising:

• forming a vertically extending trench in a semiconductor substrate;
• disposing an isolation material in the trench, the isolation material including a vertically extending void;
• recessing a portion of the isolation material at a first surface of the semiconductor substrate;
• disposing a capping material in the trench and on a top surface the isolation material so that the vertically extending void is isolated from the capping material;
• and
• removing a bottom portion of the semiconductor substrate to expose a bottom surface of the isolation material.