Solid-state imaging element, manufacturing method, and electronic device

• US 9,437,636 B2
• Filed: 11/21/2014
• Issued: 09/06/2016
• Est. Priority Date: 11/29/2013
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Kuboi, Nobuyuki
• Primary Examiner(s): Pasiewicz, Daniel M
• Application Number:
  US14/550,625
• Publication Number:
  US 20150155327A1
• Time in Patent Office: 655 Days
• US Class Current: 1/1
• CPC Class Codes: H01L 27/14612 involving a transistor
• CPC Class Codes: H01L 27/14621 Colour filter arrangements
• CPC Class Codes: H01L 27/14623 Optical shielding
• CPC Class Codes: H01L 27/14627 Microlenses
• CPC Class Codes: H01L 27/1463 Pixel isolation structures
• CPC Class Codes: H01L 27/14638 Structures specially adapted for transferring the charges across the imager perpendicular to the imaging plane
• CPC Class Codes: H01L 27/1464 Back illuminated imager structures
• CPC Class Codes: H01L 27/14685 Process for coatings or optical elements
• CPC Class Codes: H01L 27/14689 MOS based technologies
• CPC Class Codes: H04N 25/62 Detection or reduction of noise due to excess charges produced by the exposure, e.g. smear, blooming, ghost image, crosstalk or leakage between pixels
• CPC Class Codes: H04N 25/77 Pixel circuitry, e.g. memories, A/D converters, pixel amplifiers, shared circuits or shared components

Abstract

A solid-state imaging element includes a semiconductor substrate where a plurality of photodiodes are arranged in a plane, and a separation section which separates the photodiodes, in which the separation section has a photoelectric conversion section formed by filling a material which has a high light absorption coefficient and a high quantum efficiency in trenches which are formed in the semiconductor substrate.

Claims

1. A solid-state imaging element comprising:

a semiconductor substrate where a plurality of photodiodes are arranged in a plane; and

a separation section which separates the photodiodes,

wherein the separation section has a photoelectric conversion section formed by filling a material which has a high light absorption coefficient and a high quantum efficiency in trenches which are formed in the semiconductor substrate.

2. The solid-state imaging element according to claim 1,

wherein the material which is filled in the trenches is a compound semiconductor which has a chalcopyrite structure or a group III-V compound semiconductor.

3. The solid-state imaging element according to claim 1,

wherein the separation section also has a transparent electrode which is laminated on an upper section of the photoelectric conversion section and a P-type doped layer which is provided so as to cover side surfaces and a bottom surface of the photoelectric conversion section, and

the transparent electrode and the P-type doped layer are both connected with the ground.

4. The solid-state imaging element according to claim 3, further comprising:

a driving device where photoelectrons which are generated in the photoelectric conversion section by photoelectric conversion using the incident light which is incident onto the separation section are taken out via the transparent electrode and positive holes which are generated in the photoelectric conversion section are taken out via the P-type doped layer at the same time, and which uses photovoltaic power taken out from the photoelectric conversion section for driving.

5. The solid-state imaging element according to claim 3,

wherein the separation section further has a buffer layer which is laminated between the photoelectric conversion section and the transparent electrode.

6. The solid-state imaging element according to claim 1,

wherein the photoelectric conversion section is formed in a portion which is shallower than a predetermined depth of the trenches, and

any of an insulation film, a metal film, or an organic film is filled in a portion which is deeper than the predetermined depth of the trenches.

7. The solid-state imaging element according to claim 6,

wherein the depth of the portion where the photoelectric conversion section is formed is 400 nm or more.

8. The solid-state imaging element according to claim 1,

wherein the separation section further has a metal thin film which covers side surfaces of the photoelectric conversion section in a portion which is deeper than a predetermined depth of the photoelectric conversion section.

9. The solid-state imaging element according to claim 1,

wherein an insulation layer and a color filter are laminated on the semiconductor substrate, and

the separation section is formed to protrude from the semiconductor substrate up to the middle of the color filter in the thickness direction so as to extend from the semiconductor substrate toward a color filter side, or to protrude from the semiconductor substrate until the color filter is divided.

10. The solid-state imaging element according to claim 1,

wherein the separation section further has

a transparent electrode which is arranged above the photoelectric conversion section and applies a negative bias,

an electrode which is arranged below the photoelectric conversion section and applies a positive bias,

a memory section which is arranged between the photoelectric conversion section and the electrode and which stores photoelectrons which are generated in the photoelectric conversion section by photoelectric conversion using the incident light which is incident onto the separation section, and

a gate electrode which configures a transfer transistor which takes out the photoelectrons which are stored in the memory section as a signal.

11. The solid-state imaging element according to claim 10, further comprising:

a signal processing circuit which performs signal processing which, based on a signal strength ratio which is the ratio of a photodiode signal which is a signal read out from the photodiode and a pixel separation signal which is a signal read out from the photoelectric conversion section and a database where a degree of mixing which corresponds to the signal strength ratio is predicted beforehand by simulation or actual measurement and registered, determines the mixing ratio when the pixel separation signal is added to the photodiode signal and adds the pixel separation signal to the photodiode signal at a ratio in accordance with the degree of mixing.

12. A method for manufacturing a solid-state imaging element which is provided with a semiconductor substrate where a plurality of photodiodes are arranged in a plane and a separation section which separates the photodiodes, the method comprising:

forming trenches in the semiconductor substrate when forming the separation section; and

forming a photoelectric conversion section by filling a material which has a high light absorption coefficient and a high quantum efficiency in the trenches.

13. An electronic device comprising:

a solid-state imaging element which is provided with a semiconductor substrate where a plurality of photodiodes are arranged in a plane, and a separation section which separates the photodiodes,

wherein the separation section has a photoelectric conversion section formed by filling a material which has a high light absorption coefficient and a high quantum efficiency in trenches which are formed in the semiconductor substrate.

14. The electronic device according to claim 13,

wherein the material which is filled in the trenches is a compound semiconductor which has a chalcopyrite structure or a group III-V compound semiconductor.

15. The electronic device according to claim 13,

wherein the separation section also has a transparent electrode which is laminated on an upper section of the photoelectric conversion section and a P-type doped layer which is provided so as to cover side surfaces and a bottom surface of the photoelectric conversion section, and

the transparent electrode and the P-type doped layer are both connected with the ground.

16. The electronic device according to claim 15, further comprising:

a driving device where photoelectrons which are generated in the photoelectric conversion section by photoelectric conversion using incident light which is incident onto the separation section are taken out via the transparent electrode and positive holes which are generated in the photoelectric conversion section are taken out via the P-type doped layer at the same time, and which uses photovoltaic power taken out from the photoelectric conversion section for driving.

17. The electronic device according to claim 16, further comprising:

a charging section which charges photovoltaic power taken out from the photoelectric conversion section; and

a driving circuit which drives an optical system which focuses the incident light with respect to the solid-state imaging element such that the photovoltaic power is maximized in the photoelectric conversion section when a mode for performing charging is specified in the charging section.