Charge release layer to remove charge carriers from dielectric grid structures in image sensors

A method for manufacturing a semiconductor structure, the method comprising:

• forming photodetectors within a semiconductor substrate;
• forming an interconnect structure on the semiconductor substrate, wherein the interconnect structure has a conductive wire layer;
• etching the semiconductor substrate to define a first opening in the semiconductor substrate;
• depositing an etch stop layer and a charge release layer over the semiconductor substrate and the interconnect structure, wherein the charge release layer overlies the etch stop layer, and wherein the charge release layer and etch stop layer line at least a portion of the first opening;
• forming a conductive contact in the first opening, wherein the conductive contact extends through the charge release layer and the semiconductor substrate to contact the conductive wire layer;
• depositing a grid dielectric layer over the photodetectors;
• etching the grid dielectric layer and the charge release layer until an upper surface of the etch stop layer is reached, wherein etching the grid dielectric layer defines a dielectric grid structure and a plurality of color filter openings overlying the photodetectors;
• and
• depositing a plurality of color filters in the plurality of color filter openings.

A method for manufacturing a semiconductor structure, the method comprising:

• forming an isolation structure on a front-side surface of a semiconductor substrate, wherein the semiconductor substrate comprises a back-side surface opposite the front-side surface;
• forming photodetectors within the semiconductor substrate;
• forming a stack of dielectric layers over the back-side surface of the semiconductor substrate;
• etching the back-side surface of the semiconductor substrate to define a first opening in the semiconductor substrate that exposes an upper surface of the isolation structure;
• depositing an etch stop layer and a charge release layer over the semiconductor substrate and the stack of dielectric layers, wherein the etch stop layer is disposed between the charge release layer and the stack of dielectric layers, and wherein the charge release layer and etch stop layer line at least a portion of the first opening;
• forming a ground contact in the first opening, wherein the ground contact extends through the charge release layer to a point below a top surface of the isolation structure, wherein the charge release layer and the etch stop layer directly contact a sidewall of the ground contact;
• depositing a grid dielectric layer over the photodetectors;
• and
• etching the grid dielectric layer to define a dielectric grid structure over the photodetectors such that the dielectric grid structure is laterally offset from the ground contact.