BSI image sensor chips and methods for forming the same

摘要

A device includes semiconductor substrate having a front side and a backside. A polysilicon layer is disposed on the backside of the semiconductor substrate. The polysilicon layer includes a portion doped with a p-type impurity. A dielectric layer is disposed on the backside of the semiconductor substrate, wherein the polysilicon layer is between the semiconductor substrate and the polysilicon layer.

主权项

1. A device comprising:
a semiconductor substrate comprising a front side and a backside; a metal pad in a metallization layer and on the front side of the semiconductor substrate; a polysilicon layer on the backside of the semiconductor substrate, wherein the polysilicon layer comprises:
a bottom layer;a middle layer; andan upper layer, wherein the middle layer is between the bottom layer and the upper layer, wherein the middle layer is doped with a p-type impurity having a first concentration, and wherein second concentrations of the p-type impurity in the bottom layer and the upper layer are lower than the first concentration; a dielectric layer on the backside of the semiconductor substrate, wherein the polysilicon layer is between the semiconductor substrate and the dielectric layer; a recess extending from a back surface of the semiconductor substrate to penetrate through the semiconductor substrate, wherein the polysilicon layer extends to an edge of the recess; and an electrical pad extending into the recess, wherein the electrical pad contacts the metal pad on the front side of the semiconductor substrate.