Imaging device, imaging apparatus, and electronic device
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 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.
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,
wherein the charge accumulating unit is provided in a plane beneath the plurality of photodiodes in a cross-sectional view; and
a light shielding wall including top segments provided around an entire perimeter of a top surface of each of the plurality of photodiodes in a plan view and vertical segments extending from the top segments in the cross-sectional view,
wherein the light shielding wall separately light-shields the photodiodes and the charge accumulation unit, and
wherein the light shielding wall is configured to surround the charge accumulation unit, with one of the vertical segments having a first depth and another of the vertical segments 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 charge accumulation unit is shared by the plurality of photodiodes, and a charge transfer path for transferring the electric charge from each of the photodiodes to the charge accumulation unit is formed between the plurality of photodiodes.
3. 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.
4. The imaging device according to claim 3 , 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.
5. The imaging device according to claim 4 , 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.
6. The imaging device according to claim 5 , wherein
the annular structure is circular, rhombic, rectangular, or polygonal.
7. The imaging device according to claim 1 , wherein
the charge accumulation unit includes a floating diffusion region and a memory.
8. 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.
9. The imaging device according to claim 1 , wherein a portion of one of the top segments has a width narrower than a width of a remainder of the one of the top segments.
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,
wherein the charge accumulating unit is provided in a plane beneath the plurality of photodiodes in a cross-sectional view; and
a light shielding wall including top segments provided around an entire perimeter of a top surface of each of the plurality of photodiodes in a plan view and vertical segments extending from the top segments in the cross-sectional view,
wherein the light shielding wall separately light-shields the photodiodes and the charge accumulation unit, and
wherein the light shielding wall is configured to surround the charge accumulation unit, with one of the vertical segments having a first depth and another of the vertical segments 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. The imaging apparatus according to claim 10 , wherein
the charge accumulation unit is shared by the plurality of photodiodes, and a charge transfer path for transferring the electric charge from each of the photodiodes to the charge accumulation unit is formed between the plurality of photodiodes.
12. The imaging apparatus according to claim 10 , wherein
the charge accumulation unit includes a floating diffusion region and a memory.
13. The imaging apparatus according to claim 10 , 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.
14. The imaging apparatus according to claim 10 , wherein a portion of one of the top segments has a width narrower than a width of a remainder of the one of the top segments.
15. 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,
wherein the charge accumulating unit is provided in a plane beneath the plurality of photodiodes in a cross-sectional view; and
a light shielding wall including top segments provided around an entire perimeter of a top surface of each of the plurality of photodiodes in a plan view and vertical segments extending from the top segments in the cross-sectional view,
wherein the light shielding wall separately light-shields the photodiodes and the charge accumulation unit, and
wherein the light shielding wall is configured to surround the charge accumulation unit, with one of the vertical segments having a first depth and another of the vertical segments 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.
16. The electronic device according to claim 15 , wherein
the charge accumulation unit is shared by the plurality of photodiodes, and the charge transfer path for transferring the electric charge from each of the photodiodes to the charge accumulation unit is formed between the plurality of photodiodes.
17. The electronic device according to claim 15 , wherein
the charge accumulation unit includes a floating diffusion region and a memory.
18. The electronic device according to claim 15 , 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.
19. The electronic device according to claim 15 , wherein a portion of one of the top segments has a width narrower than a width of a remainder of the one of the top segments.