Imaging device having microlens array adhered to wafer-level lens

• US 8,610,815 B2
• Filed: 01/12/2009
• Issued: 12/17/2013
• Est. Priority Date: 01/12/2009
• Status: Active Grant

• Current Assignee: Aptina Imaging Corporation (ON Semiconductor Corporation)
• Original Assignee: Aptina Imaging Corporation (ON Semiconductor Corporation)
• Inventors: Duparre, Jacques, Boettiger, Ulrich C.
• Primary Examiner(s): SPINKS, ANTOINETTE T
• Application Number:
  US12/352,479
• Publication Number:
  US 20100177235A1
• Time in Patent Office: 1,800 Days
• Field of Search: 348/345, 348/335, 348/336
• US Class Current: 348/345
• CPC Class Codes: H01L 27/14627 Microlenses
• CPC Class Codes: H01L 27/14632 Wafer-level processed structures
• CPC Class Codes: H01L 27/14685 Process for coatings or optical elements
• CPC Class Codes: H04N 23/57 Mechanical or electrical details of cameras or camera modules specially adapted for being embedded in other devices
• CPC Class Codes: H04N 25/134 based on three different wavelength filter elements

Abstract

Methods and apparatuses having imaging structures that include a focusing lens structure, a pixel array, and a transparent material arranged between the focusing lens and the pixel array. A color filter array may be located between the transparent material and the pixels of the pixel array.

Claims

1. An imaging structure, comprising:

a wafer-level focusing lens structure;

a pixel array for capturing an image focused by the focusing lens structure, wherein the pixel array comprises a plurality of dry-etched microlenses adhered to the wafer-level focusing lens structure;

a transparent material arranged between the focusing lens structure and the pixel array, wherein the transparent material comprises a thermal curable adhesive configured to adhere the plurality of microlenses to the wafer-level focusing lens structure, wherein the focusing lens structure has a first index of refraction at an interface with the transparent material, wherein the transparent material has a second index of refraction that is substantially the same as the first index of refraction, and wherein the second index of refraction is between about 1.38 and 1.45; and

a color filter array, wherein the color filter array is arranged above the plurality of microlenses and comprises a planar top surface and a bottom surface shaped conformally to the plurality of microlenses, wherein the planar top surface is adjacent to the transparent material, and wherein the transparent material is adjacent to the wafer-level focusing lens structure.

2. The imaging structure of claim 1, wherein the plurality of microlenses has a third index of refraction that is different from the second index of refraction by about 0.5 or more.

3. The imaging structure of claim 2, wherein the third index of refraction is greater than the second index of refraction by about 0.5 or more.

4. The imaging structure of claim 3, wherein the plurality of microlenses are convex microlenses.

5. The imaging structure of claim 2, wherein the third index of refraction is less than the second index of refraction by about 0.5 or more.

6. The imaging structure of claim 5, wherein the plurality of microlenses are concave microlenses.

7. The imaging structure of claim 1, wherein the microlenses have a third index of refraction, and wherein the third index of refraction is about 2.0.

8. The imaging structure of claim 1, wherein the plurality of microlenses is formed of a material selected from the group consisting of silicon nitride, silicon oxynitrides, carbon, and titanium oxide.

9. The imaging structure of claim 1, wherein the pixel array further comprises a plurality of photosensors.

10. The imaging structure of claim 1, wherein the second index of refraction is less than 20% different from the first index of refraction.

11. The imaging structure of claim 1, wherein the second index of refraction is less than 5% different from the first index of refraction.

12. A camera system employing the imaging structure of claim 1.

13. An imaging module, comprising:

an imager die comprising a plurality of pixel cells, a plurality of dry-etched microlenses arranged over the pixel cells, and a color filter array arranged over the microlenses, wherein the color filter array comprises a planar top surface and a bottom surface shaped conformally to the plurality of microlenses;

a wafer-level focusing lens structure adhered to the plurality of microlenses and configured to focus an image onto the imager die, the focusing lens structure comprising a substrate; and

a transparent material arranged between the substrate and the imager die, the transparent material having an index of refraction that is substantially the same as an index of refraction of the wafer-level focusing lens structure, wherein the planar top surface of the color filter array is adjacent to the transparent material, wherein the transparent material is adjacent to the wafer-level focusing lens structure, wherein the transparent material comprises a thermal curable adhesive configured to adhere the wafer-level focusing lens structure to the plurality of microlenses, and wherein the index of refraction of the wafer-level focusing lens structure is between about 1.38 and 1.45.

14. The imaging module of claim 13, wherein the plurality of microlenses are convex and have an index of refraction that is about 0.5 or greater than the index of refraction of the transparent material.

15. The imaging module of claim 13, wherein the plurality of microlenses are concave and have an index of refraction that is about 0.5 or less than the index of refraction of the transparent material.

16. A method of forming an imager module, comprising:

providing a first wafer, wherein providing the first wafer comprises forming a microlens array above an array of pixel cells and forming a color filter array above the microlens array, wherein the color filter array has a planar top surface and a bottom surface shaped conformally to the microlens array;

applying a transparent material between the first wafer containing a plurality of imager dies and a second wafer containing a plurality of wafer-level lens structures, the transparent material having an index of refraction that is less than 20% different from an index of refraction of the plurality of wafer-level lens structures, wherein the planar top surface of the color filter array is adjacent to the transparent material and wherein the transparent material is adjacent to the plurality of wafer-level lens structures;

coupling the first wafer to the second wafer; and

dividing the structure into a plurality of imager modules, each module comprising an imager die, a wafer-level lens structure, and a transparent material.

17. The method of claim 16, wherein the transparent material is an adhesive that couples the first wafer to the second wafer.

18. The method of claim 16, wherein the first wafer comprises a microlens array, and wherein microlenses of the microlens array have an index of refraction that is at least 0.5 different from an index of refraction of the transparent material.

19. The method of claim 18, wherein the index of refraction of the transparent material is less than 5% different from the index of refraction of the plurality of lens structures.