Rear-face illuminated solid state image sensors

• US 8,624,342 B2
• Filed: 11/05/2010
• Issued: 01/07/2014
• Est. Priority Date: 11/05/2010
• Status: Active Grant

• Current Assignee: Adeia Semiconductor Technologies LLC (f/k/a Invensas Corporation) (Adeia Inc.)
• Original Assignee: Adeia Semiconductor Technologies LLC (f/k/a Invensas Corporation) (Adeia Inc.)
• Inventors: Humpston, Giles, Kriman, Moshe
• Primary Examiner(s): ARMAND, MARC ANTHONY
• Application Number:
  US12/940,326
• Publication Number:
  US 20120112301A1
• Time in Patent Office: 1,159 Days
• Field of Search: 257/774, 257/773, 257/E23.011, 257/E31.11, 257/433
• US Class Current: 257/433
• CPC Class Codes: H01L 21/76898 formed through a semiconductor substrate
• CPC Class Codes: H01L 2224/13024 the bump connector being disposed on a redistribution layer on the semiconductor or solid-state body
• CPC Class Codes: H01L 27/14618 Containers
• CPC Class Codes: H01L 27/14632 Wafer-level processed structures
• CPC Class Codes: H01L 27/14636 Interconnect 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 27/14687 Wafer level processing
• CPC Class Codes: H01L 27/14806 Structural or functional details thereof

Abstract

A microelectronic unit includes a semiconductor element having a front surface to which a packaging layer is attached, and a rear surface remote from the front surface. The element includes a light detector including a plurality of light detector element arranged in an array disposed adjacent to the front surface and arranged to receive light through the rear surface. The semiconductor element also includes an electrically conductive contact at the front surface connected to the light detector. The conductive contact includes a thin region and a thicker region which is thicker than the thin region. A conductive interconnect extends through the packaging layer to the thin region of the conductive contact, and a portion of the conductive interconnect is exposed at a surface of the microelectronic unit.

Claims

1. A microelectronic unit comprising:

a semiconductor element having a front surface and a rear surface remote from the front surface;

a packaging layer attached to the front surface of the semiconductor element,

wherein the semiconductor element includes a light detector disposed adjacent to the front surface and aligned with a portion of the rear surface to receive light through the rear surface portion, and a conductive contact at the front surface connected to the light detector, wherein the light detector includes a plurality of light detector elements arranged in an array, wherein the conductive contact is at least partially within the semiconductor element and has a first surface and a second surface remote from the first surface, wherein the conductive contact includes a thin region having a first thickness and thicker region having a second thickness that is thicker than the first thickness, wherein the conductive contact has a hole extending from the first surface through the conductive contact towards the second surface, the hole defining a wall surface extending within the conductive contact from the first surface towards the second surface; and

a conductive interconnect extending through the packaging layer and the hole of the conductive contact from the first surface towards the second surface so as to contact the wall surface in at least the thicker region of the conductive contact, at least a portion of the conductive interconnect being exposed at a surface of the microelectronic unit.

2. The microelectronic unit of claim 1, wherein the first thickness is ninety percent of the second thickness.

3. The microelectronic unit of claim 1, wherein the first thickness is fifty percent of the second thickness.

4. The microelectronic unit of claim 1 further comprising:

a packaging assembly attached at the rear surface of the semiconductor element and defining a cavity aligned with the light detector in a direction normal to the rear surface.

5. The microelectronic unit of claim 1, wherein the packaging layer has a thickness of about thirty to one thousand microns.

6. The microelectronic unit of claim 1, wherein the light detector includes a plurality of light elements defining one or more pixels, wherein each pixel has a lateral dimension in a lateral direction along the front surface substantially equal to the thickness of the semiconductor element.

7. The microelectronic unit of claim 1 further comprising:

a layer including adhesive material attaching the semiconductor element to the packaging layer.

8. The microelectronic unit of claim 1,

wherein the conductive contact includes a plurality of layers disposed within the semiconductor element and having a third thickness, wherein the semiconductor element has a fourth thickness that is greater than the third thickness,

wherein the conductive interconnect extends into the conductive contact a depth less than the third thickness, and the conductive interconnect connects to a metal layer of the plurality of layers of the conductive contact.

9. The microelectronic unit of claim 4 further comprising:

a first dielectric layer disposed on the rear surface of the semiconductor element and to which the packaging assembly is attached through a second dielectric layer.

10. The microelectronic unit of claim 8, wherein the plurality of layers of the conductive contact includes a layer including dielectric material.

11. The microelectronic unit of claim 8, wherein the conductive contact includes a conductive via interconnecting adjacent layers of the plurality of layers.

12. The microelectronic unit of claim 8, wherein the plurality of layers of the conductive contact includes alternating layers of dielectric material and metal.

13. The microelectronic unit of claim 8, wherein the third thickness is a maximum of about 10 microns.

14. The microelectronic unit of claim 9, wherein the first dielectric layer has a thickness of about one to five microns and the second dielectric layer includes an adhesive material.

15. A microelectronic unit comprising:

a semiconductor element having a front surface and a rear surface remote from the front surface;

a packaging layer attached to the front surface of the semiconductor element,

wherein the semiconductor element includes a light detector disposed adjacent to the front surface and aligned with a portion of the rear surface to receive light through the rear surface portion, and a conductive contact at the front surface connected to the light detector, wherein the light detector includes a plurality of light detector elements arranged in an array, wherein the conductive contact includes a thin region having a first thickness and thicker region having a second thickness that is thicker than the first thickness; and

and at least a portion of the thicker region of the conductive contact, at least a portion of the conductive interconnect being exposed at a surface of the microelectronic unit,

wherein the thin and thicker regions of the conductive contact extend from the front surface toward the packaging layer,

wherein the conductive interconnect extends into the conductive contact a depth less than the second thickness.

16. The microelectronic unit of claim 15, wherein the conductive contact includes a first metal layer adjacent the front surface and at least one second metal layer disposed between the first metal layer and the packaging layer.

17. The microelectronic unit of claim 15 further comprising:

a packaging assembly attached at the rear surface of the semiconductor element and defining a cavity aligned with the light detector in a direction normal to the rear surface.

18. The microelectronic unit of claim 16, wherein the first metal layer includes aluminum and the second metal layer includes at least one of nickel, copper, silver or gold.

19. The microelectronic unit of claim 16, wherein the second metal layer is formed by electrode-less plating.

20. The microelectronic unit of claim 16, wherein the second metal layer has a thickness greater than that of the first metal layer.

21. The microelectronic unit of claim 16, wherein the second metal layer has a thickness of about 0.5 to 30 microns.

22. The microelectronic unit of claim 16, wherein the conductive interconnect extends into the conductive contact to a depth so as to terminate between the first metal layer and the packaging layer.

23. A microelectronic unit comprising:

a semiconductor element having a front surface, a rear surface remote from the front surface and a region consisting essentially of semiconductor material disposed between the front and rear surfaces; and

a first packaging layer attached to the front surface of the semiconductor element,

wherein the semiconductor element includes a light detector disposed adjacent to the front surface and aligned with a portion of the rear surface to receive light through the rear surface portion, and a conductive contact at the front surface connected to the light detector, wherein the light detector includes a plurality of light detector elements arranged in an array; and

a packaging assembly having a second packaging layer attached to the rear surface of the semiconductor element,

a conductive interconnect extending through the first packaging layer, through the conductive contact and into the second packaging layer and connected to the conductive contact, wherein the conductive interconnect is electrically isolated from the semiconductor region and at least a portion of the conductive interconnect is exposed at a surface of the microelectronic unit.

24. The microelectronic unit of claim 23, wherein the second packaging layer is attached to a portion of a rear surface of the conductive contact.

25. The microelectronic unit of claim 23 further comprising:

a layer of dielectric material contacting the rear surface portion of the conductive contact and electrically isolating the semiconductor region from the conductive interconnect.

26. The microelectronic unit of claim 23, wherein the semiconductor element includes an isolation region completely circumscribing the conductive contact, the isolation region electrically isolating the conductive contact from the semiconductor region.

27. The microelectronic unit of claim 25, wherein the dielectric layer includes adhesive material.

28. The microelectronic unit of claim 25, wherein the dielectric layer contacts the rear surface of the semiconductor element.

29. The microelectronic unit of claim 26, wherein the isolation region includes dielectric material.

30. The microelectronic unit of claim 26, wherein the isolation region includes semiconductor material having a doping different than a doping of semiconductor material in a region of the semiconductor element adjacent to and circumscribed by the isolation region.