Imaging device, imaging apparatus, and electronic device

Abstract

The present disclosure relates to an imaging device, an imaging apparatus, and an electronic device capable of light-shielding a charge accumulation unit at low cost, while maintaining a charge transfer path from a photodiode to a charge accumulation unit. A depth of a trench that forms a trench buried film having a light-shielding characteristic for preventing color mixture of the photodiodes is adjusted according to a contact amount of a reactive gas by adjusting, among the shapes of a photomask pattern, a width of the trench through which the reactive gas flows or the number of intersections of the trenches at a portion forming a trench in which the trench buried film is formed. As a result, the trench buried films having a plurality of depths can be formed by a single dry etching with one mask pattern, and the manufacturing cost is reduced. Application to an imaging device is possible.

What is claimed is: 
     
         1 . An imaging device comprising:
 a plurality of photodiodes arranged in an array and generating an electric charge according to an amount of incident light;   a charge accumulation unit that accumulates the electric charge transferred from each of the photodiodes; and   a light shielding wall that separately light-shields the photodiode and the charge accumulation unit, wherein   the light shielding wall is configured to surround the charge accumulation unit, with a part of the light shielding wall having a first depth and other parts of the light shielding wall having a second depth, and the first depth and the second depth of the light shielding wall are formed by dry etching with a photomask pattern using a processing conversion difference caused by a microloading effect.   
     
     
         2 . The imaging device according to  claim 1 , wherein
 the light shielding wall is configured to surround the charge accumulation unit, in which a portion functioning as a charge transfer path for transferring the electric charge from each of the photodiodes to the charge accumulation unit is formed to have a first depth not reaching a substrate layer from a surface on which the photodiodes are arranged in an array, and other portions are formed to have a second depth reaching the substrate layer from the surface on which the photodiodes are arranged in an array, whereby the light shielding wall having the first depth and the second depth is formed by a single dry etching with one photomask pattern controlled using the processing conversion difference caused by the microloading effect   
     
     
         3 . The imaging device according to  claim 2 , wherein
 the charge accumulation unit is shared by the plurality of photodiodes, and the charge transfer path is formed between the plurality of photodiodes.   
     
     
         4 . The imaging device according to  claim 1 , wherein
 the photomask pattern controls a depth of a trench forming the light shielding wall by the dry etching by controlling a contact amount of a reactive gas, which is used in the dry etching, on a silicon substrate.   
     
     
         5 . The imaging device according to  claim 4 , wherein
 the photomask pattern controls the depth of the trench that forms the light shielding wall by the dry etching by controlling a contact area of the reactive gas, which is used in the dry etching, on the silicon substrate or controlling a contact amount of the reactive gas according to a number of flow paths of the reactive gas.   
     
     
         6 . The imaging device according to  claim 5 , wherein
 the photomask pattern is formed in an annular structure surrounding the charge accumulation unit and controls the contact amount of the reactive gas according to the number of the flow paths.   
     
     
         7 . The imaging device according to  claim 6 , wherein
 the annular structure is circular, rhombic, rectangular, or polygonal.   
     
     
         8 . The imaging device according to  claim 1 , wherein
 the charge accumulation unit includes a floating diffusion region and a memory.   
     
     
         9 . The imaging device according to  claim 1 , wherein
 the light shielding wall is formed by an insulating film having permeability and a refractive index lower than a refractive index of silicon, or the insulating film in which a light shielding metal is provided inside the insulating film.   
     
     
         10 . An imaging apparatus comprising:
 a plurality of photodiodes arranged in an array and generating an electric charge according to an amount of incident light;   a charge accumulation unit that accumulates the electric charge transferred from each of the photodiodes; and   a light shielding wall that separately light-shields the photodiode and the charge accumulation unit, wherein   the light shielding wall is configured to surround the charge accumulation unit, with a part of the light shielding wall having a first depth and other parts of the light shielding wall having a second depth, and the first depth and the second depth of the light shielding wall are formed by dry etching with a photomask pattern using a processing conversion difference caused by a microloading effect.   
     
     
         11 . An electronic device comprising:
 a plurality of photodiodes arranged in an array and generating an electric charge according to an amount of incident light;   a charge accumulation unit that accumulates the electric charge transferred from each of the photodiodes; and   a light shielding wall that separately light-shields the photodiode and the charge accumulation unit, wherein   the light shielding wall is configured to surround the charge accumulation unit, with a part of the light shielding wall having a first depth and other parts of the light shielding wall having a second depth, and the first depth and the second depth of the light shielding wall are formed by dry etching with a photomask pattern using a processing conversion difference caused by a microloading effect.