Image sensor with vertically integrated thin-film photodiode

A method for forming an image sensor with a vertically integrated thin-film photodiode, comprising:

• providing a substrate;
• forming an interconnection structure adjacent to the substrate, wherein the interconnection structure includes a top metal layer comprising a plurality of first metal pads for thin-film photodiodes and a second metal pad for a ground pad;
• forming a dielectric layer on the interconnection structure;
• forming a plurality of first openings and a second opening in the dielectric layer;
• forming a plurality of bottom doped layers with a first conductive type in the first openings and the second opening, wherein each bottom doped layer contacts the corresponding first metal pad without extending outside the surface of the corresponding first metal pad;
• forming a stacked layer of an I-type layer and an upper doped layer with a second conductive type over at least one bottom doped layer and the dielectric layer;
• removing the bottom doped layer in the second opening;
• forming a transparent electrode over the upper doped layer and contacting the second metal pad through the second opening in the dielectric layer.

A method for forming an image sensor with a vertically integrated thin-film photodiode, comprising:

• providing a substrate having a ground pad region, a pixel array region and a ASIC circuit region;
• forming an interconnection structure adjacent to the substrate, wherein the interconnection structure includes a top metal layer comprising a plurality of pixel electrodes in the pixel array region, a ground pad in the ground pad region and a circuit pad in the ASIC circuit region;
• forming a dielectric layer on the interconnection structure;
• forming a plurality of first openings and a second opening in the dielectric layer, wherein a bottom of each first opening is a surface of the corresponding pixel electrode;
• forming a plurality of bottom doped layers with a first conductive type in the first openings and the second opening, wherein each bottom doped layer contacts the corresponding pixel electrode;
• forming a stacked layer of an I-type layer and an upper doped layer with a second conductive type over at least one bottom doped layer and the dielectric layer;
• removing the bottom doped layer in the second opening;
• forming a light transmitting electrode over the upper doped layer and contacting the second metal pad through the second opening in the dielectric layer.