Photodiode with deep trench isolation structures

A photodetector, comprising:

• a photodiode device;
• and
• a control circuit configured to control an operation of the photodiode device,
• wherein the photodiode device includes:
• a semiconductor substrate;
• a plurality of pixels, each of the pixels including a diode structure on a first side of the semiconductor substrate and a conductive layer on a second side of the semiconductor substrate;
• deep trench isolation (DTI) structures isolating adjacent pixels from one another, the DTI structures including a conductive material electrically coupled to the conductive layer on the second side of the substrate and a metal line on the first side of the semiconductor substrate;
• an anti-reflective layer over the conductive layer;
• and
• an insulation liner layer disposed over sidewalls of trenches within the DTI structures, wherein conductive material includes a first shoulder that overlaps upper edges of the insulation liner layer,
• wherein the conductive material extends through an entire thickness of the conductive layer, and a sidewall of the first shoulder contacts the conductive layer, and
• wherein the conductive material further comprises a second shoulder above the first shoulder, and the second shoulder overlaps a portion of the anti-reflective coating layer.

A method of forming a photodiode device, the method comprising:

• providing a semiconductor substrate with first and second sides, the semiconductor substrate including a plurality of diode structures on the first side of the substrate respectively associated with a plurality of pixels, and a conductive layer on the second side of the substrate;
• and
• forming deep trench isolation (DTI) structures isolating adjacent pixels from one another, the DTI structures including a conductive material that electrically couples the conductive layer on the second side of the substrate and a metal line on the first side of the semiconductor substrate;
• and
• forming an anti-reflective layer over the conductive layer,
• wherein forming the DTI structures includes:
• forming trenches in the semiconductor substrate;
• and
• depositing an insulation liner layer over sidewalls of the trenches,
• wherein an upper portion of the trenches is exposed by the insulation layer so that the conductive material is electrically coupled to the conductive layer in the upper portion of the trenches, and
• wherein a portion of the conductive material includes a first shoulder that overlaps upper edges of the insulation liner layer,
• wherein the conductive material further comprises a second shoulder above the first shoulder, and the second shoulder overlaps a portion of the anti-reflective coating layer, and
• wherein the conductive material extends through an entire thickness of the conductive layer, and a sidewall of the first shoulder contacts the conductive layer.