Image sensor with high quantum efficiency

Abstract

The present disclosure describes an image sensor device and a method for forming the same. The image sensor device can include a semiconductor layer. The semiconductor layer can include a first surface and a second surface. The image sensor device can further include an interconnect structure formed over the first surface of the semiconductor layer, first and second radiation sensing regions formed in the second surface of the semiconductor layer, a metal stack formed over the second radiation sensing region, and a passivation layer formed through the metal stack and over a top surface of the first radiation sensing region. The metal stack can be between the passivation layer and an other top surface of the second radiation sensing region.

What is claimed is: 
     
         1 . An image sensor device, comprising:
 a semiconductor layer comprising a first surface and a second surface opposite to the first surface;   an interconnect structure formed over the first surface of the semiconductor layer;   first and second radiation sensing regions formed in the second surface of the semiconductor layer;   a metal stack formed over the second radiation sensing region; and   a passivation layer formed through the metal stack and over a top surface of the first radiation sensing region, wherein the metal stack is between the passivation layer and an other top surface of the second radiation sensing region.   
     
     
         2 . The image sensor device of  claim 1 , wherein the top surface of the first radiation sensing region comprises groove structures, and wherein the other top surface of the second radiation sensing region comprises a substantially planar surface. 
     
     
         3 . The image sensor device of  claim 1 , wherein a thickness of a portion of the metal stack over the other top surface of the second radiation sensing region is greater than zero and less than an other thickness of an other portion of the metal stack that is vertically above and laterally displaced from the other top surface of the second radiation sensing region. 
     
     
         4 . The image sensor device of  claim 1 , wherein the metal stack comprises a first metal layer and a second metal layer, wherein the first metal layer is formed over the other top surface of the second radiation sensing region, and wherein the second metal layer is formed above and laterally displaced from the other top surface of the second radiation sensing region. 
     
     
         5 . The image sensor device of  claim 1 , further comprising a trench structure formed between the first and second radiation sensing regions. 
     
     
         6 . The image sensor device of  claim 1 , further comprising a grid structure with an aperture formed over the first radiation sensing region. 
     
     
         7 . The image sensor device of  claim 6 , wherein the grid structure is configured to reflect incident light through the aperture and onto the first radiation sensing region. 
     
     
         8 . A structure, comprising:
 a semiconductor layer having a first surface and a second surface opposite to the first surface;   a first radiation sensing region disposed within the second surface of the semiconductor layer;   a second radiation sensing region disposed within the second surface of the semiconductor layer;   a metal layer having a groove structure over the first radiation sensing region; and   a passivation layer over the groove structure, wherein the metal layer is between the passivation layer and the first radiation sensing region.   
     
     
         9 . The structure of  claim 8 , comprising an interconnect structure formed over the first surface of the semiconductor layer. 
     
     
         10 . The structure of  claim 9 , wherein the interconnect structure comprises:
 a dielectric layer disposed on the first surface of the semiconductor layer;   a vertical conductive structure disposed in the dielectric layer and connected to the semiconductor layer; and   a horizontal conductive structure disposed in the dielectric layer and connected to the vertical conductive structure.   
     
     
         11 . The structure of  claim 8 , wherein a top surface of the first radiation sensing region comprises groove structures, and wherein an other top surface of the second radiation sensing region comprises a substantially planar surface. 
     
     
         12 . The structure of  claim 8 , wherein the metal layer comprises:
 an opening through the metal layer, wherein the opening is laterally overlapped with a top surface of the first radiation sensing region; and   a metal mask disposed in the opening through the metal layer.   
     
     
         13 . The structure of  claim 8 , wherein the passivation layer comprises a dielectric. 
     
     
         14 . An image sensing device, comprising:
 a semiconductor layer having a first surface and a second surface opposite to the first surface;   an interconnect structure disposed over the first surface of the semiconductor layer;   first and second radiation sensing regions disposed within the second surface of the semiconductor layer;   a metal stack, over the second surface of the semiconductor layer, to mask the second radiation sensing region; and   a passivation layer over the second surface of the semiconductor layer, wherein the metal stack is disposed between the passivation layer and the first and second radiation sensing region.   
     
     
         15 . The image sensing device of  claim 14 , wherein the metal stack comprises an opening through the metal stack and over the first radiation sensing region. 
     
     
         16 . The image sensing device of  claim 14 , wherein the interconnect structure comprises:
 a dielectric layer disposed on the first surface of the semiconductor layer;   a vertical conductive structure disposed in the dielectric layer and connected to the semiconductor layer; and   a horizontal conductive structure disposed in the dielectric layer and connected to the vertical conductive structure.   
     
     
         17 . The image sensing device of  claim 14 , further comprising a grid structure with an aperture formed over the first radiation sensing region. 
     
     
         18 . The image sensor of  claim 17 , wherein the grid structure is configured to reflect incident light through the aperture and onto the first radiation sensing region. 
     
     
         19 . The image sensing device of  claim 14 , wherein the first radiation sensing region comprises a grooved top surface. 
     
     
         20 . The image sensing device of  claim 14 , wherein the second radiation sensing region comprises a substantially planar top surface.