AUTO-FOCUS IMAGE SENSOR

• US 20170047363A1
• Filed: 08/10/2016
• Published: 02/16/2017
• Est. Priority Date: 08/11/2015
• Status: Abandoned Application

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Choi, Hyuk Soon, Lee, Kyungho
• Application Number:
  US15/233,378
• Publication Number:
  US 20170047363A1
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H01L 27/14605 Structural or functional details relating to the position of the pixel elements, e.g. smaller pixel elements in the center of the imager compared to pixel elements at the periphery
• CPC Class Codes: H01L 27/1462 Coatings
• CPC Class Codes: H01L 27/1463 Pixel isolation structures
• CPC Class Codes: H01L 27/14636 Interconnect structures
• CPC Class Codes: H01L 27/1464 Back illuminated imager structures
• CPC Class Codes: H01L 27/14643 Photodiode arrays; MOS imagers
• CPC Class Codes: H01L 27/14689 MOS based technologies

Abstract

An auto-focus image sensor includes a substrate including unit pixels and having first and second surfaces facing each other, a pixel separation part passing through the substrate from the first surface to the second surface and separating the unit pixels from each other, at least one pair of photoelectric conversion parts provided in each of the unit pixels of the substrate, and a sub-pixel separation part provided in the substrate and interposed between the at least one pair of the photoelectric conversion parts. The second surface serves as a light-receiving surface.

Claims

1. An auto-focus image sensor, comprising:

a substrate with unit pixels, the substrate having a first surface and a second surface facing the first surface and serving as a light-receiving surface;

a pixel separation part provided in the substrate to separate the unit pixels from each other;

at least one pair of photoelectric conversion parts provided in each of the unit pixels of the substrate; and

a sub-pixel separation part interposed between the at least one pair of the photoelectric conversion parts that are positioned adjacent to each other,

wherein at least a portion of the pixel separation part comprises a material whose refractive index is different from that of the substrate, and

the sub-pixel separation part comprises a portion that is configured to allow photo charges generated in the at least one pair of the photoelectric conversion parts to be transmitted therethrough.

2. The auto-focus image sensor of claim 1, wherein the pixel separation part is configured to penetrate the substrate from the first surface to the second surface,

the pixel separation part comprises a first doped region adjacent to the first surface and a first deep device isolation layer adjacent to the second surface and in contact with the first doped region,

the first doped region is doped to have a first conductivity type, and

the first deep device isolation layer comprises a material whose refractive index is different from that of the substrate.

3. The auto-focus image sensor of claim 2, wherein each of the at least one pair of the photoelectric conversion parts comprises:

a first impurity region, which is formed adjacent to the first surface and is doped to have the first conductivity type; and

a second impurity region, which is formed spaced apart from the first surface and is doped to have a second conductivity type different from the first conductivity type,

wherein a top surface of the second impurity region adjacent to the second surface is farther from the first surface than an interface between the first doped region and the first deep device isolation layer.

4. The auto-focus image sensor of claim 2, wherein the sub-pixel separation part comprises a second doped region, which is disposed adjacent to the first surface and is doped to have the first conductivity type, and

at least a portion of the second doped region has a lower concentration of impurities of the first conductivity type than the first doped region.

5. The auto-focus image sensor of claim 4, wherein the sub-pixel separation part further comprises a second deep device isolation layer disposed adjacent to the second surface and in contact with the second doped region, and

the second deep device isolation layer comprises substantially a same material as the first deep device isolation layer.

6. The auto-focus image sensor of claim 4, wherein the sub-pixel separation part further comprises a third doped region disposed adjacent to the second surface and in contact with the second doped region, and

the third doped region is doped to have the first conductivity type and has a higher concentration of impurities of the first conductivity type than the at least a portion of the second doped region.

13. The auto-focus image sensor of claim 1, wherein the pixel separation part comprises a first deep device isolation layer adjacent to the second surface and a third deep device isolation layer adjacent to the first surface and in contact with the first deep device isolation layer.

15. The auto-focus image sensor of claim 13, wherein the sub-pixel separation part comprises a second doped region, which is disposed adjacent to the first surface and is doped to have a first conductivity type, and a second deep device isolation layer, which is disposed adjacent to the second surface and in contact with the second doped region, and

the second deep device isolation layer comprises substantially a same material as the first deep device isolation layer.

16. The auto-focus image sensor of claim 15, wherein an interface between the first deep device isolation layer and the third deep device isolation layer is closer to the second surface than a bottom surface of the second deep device isolation layer in contact with the second doped region.

7-11. -11. (canceled)

14. (canceled)

17-20. -20. (canceled)

21. An auto-focus image sensor, comprising:

a substrate having first and second surfaces facing each other, the substrate comprising unit pixels, each of which comprises at least one pair of sub-pixels configured to detect a difference in phase of light incident through the second surface;

a photoelectric conversion part in each of the at least one pair of the sub-pixels of the substrate;

a pixel separation part configured to penetrate the substrate from the first surface to the second surface and to separate the unit pixels from each other;

a sub-pixel separation part configured to penetrate the substrate from the first surface to the second surface and to separate the at least one pair of the sub-pixels from each other; and

a fixed charge layer on the second surface,

wherein at least a portion of the pixel separation part comprises a material whose refractive index is different from that of the substrate, and

each of the unit pixels is configured to collectively process electrical signals, which are respectively output from the at least one pair of the sub-pixels, to obtain image information.

22. The auto-focus image sensor of claim 21, wherein the pixel separation part comprises a first doped region adjacent to the first surface and a first deep device isolation layer adjacent to the second surface and in contact with the first doped region,

the first doped region is doped to have a first conductivity type, and

the first deep device isolation layer comprises a material whose refractive index is different from that of the substrate.

23. The auto-focus image sensor of claim 22, wherein the sub-pixel separation part comprises:

a second doped region, which is disposed adjacent to the first surface and is doped to have the first conductivity type; and

a second deep device isolation layer, which is disposed adjacent to the second surface and in contact with the second doped region,

wherein at least a portion of the second doped region has a lower concentration of impurities of the first conductivity type than the first doped region.

24. The auto-focus image sensor of claim 23, wherein the second deep device isolation layer comprises substantially a same material as the first deep device isolation layer.

25. The auto-focus image sensor of claim 23, wherein the sub-pixel separation part is configured to allow photo charges generated in the at least one pair of the photoelectric conversion parts to be transmitted through the at least a portion of the second doped region.

28. The auto-focus image sensor of claim 21, wherein the pixel separation part comprises a first deep device isolation layer adjacent to the second surface and a third deep device isolation layer adjacent to the first surface and in contact with the first deep device isolation layer, and

each of the first deep device isolation layer and the third device isolation layer comprises a material whose refractive index is different from that of the substrate.

29. The auto-focus image sensor of claim 28, wherein the sub-pixel separation part comprises a second doped region, which is disposed adjacent to the first surface and is doped to have a first conductivity type, and a second deep device isolation layer, which is disposed adjacent to the second surface and in contact with the second doped region, and

the second deep device isolation layer.

26-27. -27. (canceled)

30. An image sensor, comprising:

a substrate having a unit pixel disposed therein;

the unit pixel comprising first and second photoelectric conversion parts;

a separation part disposed between the first and second photoelectric conversion parts that is configured to provide a current path for charge to transfer between the first and second photoelectric conversion parts responsive to incident light received at the unit pixel; and

a unit pixel isolation region that surrounds the unit pixel when the substrate is viewed from a plan view,

wherein at least a portion of the unit pixel isolation region includes an insulating material.

31. The auto-focus image sensor of claim 30, wherein the separation part comprises:

a doped region; and

an isolation layer disposed on the doped region;

wherein the doped region is configured to provide the current path for the charge to transfer between the first and second photoelectric conversion parts.

32. The auto-focus image sensor of claim 31, wherein the doped region comprises:

a first portion; and

a second portion comprising a plurality of layers, the first portion being disposed between ones of the plurality of layers of the second portion;

wherein the first portion has a doping concentration that is less than a doping concentration of the second portion.

33-34. -34. (canceled)