DEVICE HAVING A 2D IMAGE SENSOR AND DEPTH SENSOR

• US 20180084238A1
• Filed: 03/23/2017
• Published: 03/22/2018
• Est. Priority Date: 09/21/2016
• Status: Active Grant

• Current Assignee: STMicroelectronics SAS (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SAS (STMicroelectronics NV)
• Inventors: Chossat, Jerome, Le-Briz, Olivier
• Granted Patent: US 10,455,213 B2
• Time in Patent Office: Days
• CPC Class Codes: H01L 27/14607 Geometry of the photosensitive area
• CPC Class Codes: H01L 27/14636 Interconnect structures
• CPC Class Codes: H01L 27/14645 Colour imagers
• CPC Class Codes: H01L 27/14649 Infrared imagers
• CPC Class Codes: H01L 27/1469 Assemblies, i.e. hybrid integration
• CPC Class Codes: H04N 13/207 using a single 2D image sensor
• CPC Class Codes: H04N 13/254 in combination with electromagnetic radiation sources for illuminating objects
• CPC Class Codes: H04N 13/271 wherein the generated image signals comprise depth maps or disparity maps
• CPC Class Codes: H04N 25/702 SSIS architectures characterised by non-identical, non-equidistant or non-planar pixel layout

Abstract

A three dimensional (3D) device is formed from a first level and a second level that are attached together. The first level includes a backside illuminated two dimensional (2D) image sensor including an array of first pixels sensitive to visible light. The second level includes a frontside illuminated depth sensor including an array of second pixels sensitive to near infrared light. The first and second levels are attached in a manner such that radiation, in particular the near infrared light, received at the backside of the first level passes through the first level to reach the depth sensor in the second level.

Claims

1. A three dimensional (3D) device, comprising:

a first level having a two dimensional (2D) image sensor comprising an array of first pixels; and

a second level having a depth sensor comprising a plurality of second pixels sensitive to light in a near infrared wavelength range,

wherein the plurality of second pixels of the depth sensor are lit by radiation that passes through the first level.

2. The 3D device of claim 1, wherein the first level is superposed over the second level such that the 2D image sensor at least partially overlaps the depth sensor.

3. The 3D device of claim 1,

wherein the first level comprises:

an array of photosensitive elements forming the first pixels and arranged to be exposed to an image scene; and

a first electrical interconnection layer; and

wherein the second level comprises;

a second electrical interconnection layer bonded to the first electrical interconnection layer; and

an array of photosensitive elements forming the second pixels.

4. The 3D device of claim 3, wherein the first and second electrical interconnection layers are bonded together by molecular bonding.

5. The 3D device of claim 3, wherein the first and second electrical interconnection layers have one of a reduced density of interconnections or an absence of interconnections in zones that are aligned with locations of each second pixel in a direction of illumination to receive said radiation.

6. The 3D device of claim 1, wherein the array of first pixels of the 2D image sensor is a continuous array of pixels sensitive to light in the visible wavelength range.

7. The 3D device of claim 1, wherein the array of first pixels of the 2D image sensor comprises openings in which there are no first pixels present, the openings being aligned with each of the second pixels in a direction of illumination to receive said radiation.

8. The 3D device of claim 1, wherein the first and second levels are bonded together by molecular bonding.

9. The 3D device of claim 1, wherein the first and second levels each comprise a silicon substrate and wherein a silicon depth between a radiation receiving surface of the silicon substrate for the first level and the second pixels in the silicon substrate of the second level is in a range of 5 to 20 μ

m.

10. The 3D device of claim 9, wherein the silicon depth is in a range of 10 to 20 μ

m.

11. The 3D device of claim 1, wherein each depth pixel comprises one of:

a single-photon avalanche diode (SPAD); and

a photodiode configured to sample received light during three or more phases of a received light signal.

12. An image capturing device, comprising:

a three dimensional (3D) device, including;

a first level having a two dimensional (2D) image sensor comprising an array of first pixels; and

a second level having a depth sensor comprising a plurality of second pixels sensitive to light in a near infrared wavelength range,

wherein the plurality of second pixels of the depth sensor are lit by radiation that passes through the first level; and

a processing device coupled to the 3D device and configured to perform image processing on pixel information captured by both the 2D image sensor and the depth sensor in order to generate 2D images and depth maps.

13. The image capturing device of claim 12, wherein the processing device is configured to generate 2D images based on pixel information captured by the 2D image sensor and light intensity information captured by the second pixels of the depth sensor.

14. The image capturing device of claim 12, wherein the processing device is configured to generate the depth maps based on depth information determined based on signals provided by the second pixels of the depth sensor and on 2D pixel information captured by the 2D image sensor.

15. The image capturing device of claim 12, wherein the processing device is configured to adjust a sensitivity of the depth sensor based on 2D pixel information captured by the 2D image sensor.

16. The image capturing device of claim 12, wherein the first level is superposed over the second level such that the 2D image sensor at least partially overlaps the depth sensor,

said first level comprising:

an array of photosensitive elements forming the first pixels and arranged to be exposed to an image scene; and

a first electrical interconnection layer; and

said second level comprising;

a second electrical interconnection layer bonded to the first electrical interconnection layer; and

an array of photosensitive elements forming the second pixels.

17. The image capturing device of claim 16, wherein the first and second electrical interconnection layers are bonded together by molecular bonding.

18. The image capturing device of claim 16, wherein the first and second electrical interconnection layers have one of a reduced density of interconnections or an absence of interconnections in zones that are aligned with locations of each second pixel in a direction of illumination to receive said radiation.

19. The image capturing device of claim 16, wherein the first and second levels each comprise a silicon substrate and wherein a silicon depth between a radiation receiving surface of the silicon substrate for the first level and the second pixels in the silicon substrate of the second level is in a range of 5 to 20 μ

m.

23. The image capturing device of claim 15, wherein the processing device adjusts the sensitivity of the depth sensor in response to the 2D pixel information captured by the 2D image sensor by selectively actuating less than all of the plurality of second pixels when sensing light in the near infrared wavelength range.

24. The image capturing device of claim 15, wherein the processing device adjusts the sensitivity of the depth sensor in response to the 2D pixel information captured by the 2D image sensor by selectively actuating certain pixels of the plurality of second pixels when sensing light in the near infrared wavelength range based on aperture size.

20-22. -22. (canceled)