Ellipsoidal gapless micro lenses for imagers

• US 7,643,213 B2
• Filed: 04/15/2008
• Issued: 01/05/2010
• Est. Priority Date: 10/09/2003
• Status: Active Grant

• Current Assignee: Aptina Imaging Corporation (ON Semiconductor Corporation)
• Original Assignee: Aptina Imaging Corporation (ON Semiconductor Corporation)
• Inventors: Li, Jin, Boettiger, Ulrich C.
• Primary Examiner(s): Harrington; Alicia M
• Application Number:
  US12/081,374
• Publication Number:
  US 20080192357A1
• Time in Patent Office: 630 Days
• Field of Search: 359619-626
• US Class Current: 359/619
• CPC Class Codes: B29D 11/00278 Lenticular sheets B29D11/00269 takes precedence
• CPC Class Codes: B29D 11/00365 Production of microlenses lenticular sheets B29D11/00278
• CPC Class Codes: G02B 3/0018 Reflow, i.e. characterized by the step of melting microstructures to form curved surfaces, e.g. manufacturing of moulds and surfaces for transfer etching
• CPC Class Codes: G02B 3/0056 arranged along two different directions in a plane, e.g. honeycomb arrangement of lenses G02B3/0043 takes precedence; miniaturised objectives for electronic devices employing wafer level optics G02B13/0085
• CPC Class Codes: H01L 27/14627 Microlenses
• CPC Class Codes: H01L 27/14685 Process for coatings or optical elements

Abstract

Ellipse-shaped microlenses focus light onto unbalanced photosensitive areas, increase area coverage for a gapless layout of microlenses, and allow pair-wise or other individual shifts of the microlenses to account for asymmetrical pixels and pixel layout architectures. The microlenses may be fabricated in sets, with one set oriented differently from another set, and may be arranged in various patterns, for example, in a checkerboard pattern or radial pattern. The microlenses of at least one set may be substantially elliptical in shape. To fabricate a first set of microlenses, a first set of microlens material is patterned onto a support, reflowed under first reflow conditions, and cured. To fabricate a second set of microlenses, a second set of microlens material is patterned onto the support, reflowed under second reflow conditions, which may be different from the first conditions, and cured.

Claims

1. A microlens array for an array of photosensitive areas, the microlens array comprising:

a plurality of first microlenses; and

a plurality of elliptically-shaped second microlenses, each second microlens having a longitudinal axis that parallels a surface of said array of photosensitive areas, wherein said plurality of first and second microlenses are arranged adjacent to each other and have first and second focal lengths for corresponding photosensitive areas, said array of photosensitive areas including asymmetrical photosensitive areas.

2. The microlens array of claim 1, wherein said microlens array is substantially gapless.

3. The microlens array of claim 1, wherein said second microlenses have a longitudinal axis which is offset by an angle from a vertical axis of said microlens array.

4. The microlens array of claim 1, wherein each of the plurality of first microlenses has a different shape than each of said plurality of second microlenses.

5. The microlens array of claim 1, wherein each of the plurality of first microlenses has an elliptical shape.

6. The microlens array of claim 5, wherein each of the plurality of first microlenses has a longitudinal axis which is offset by a same angle from the vertical axis of said microlens array as a longitudinal axis of each of the plurality of second microlenses.

7. The microlens array of claim 5, wherein each of the plurality of first microlenses has a longitudinal axis which is offset by a different angle from the vertical axis of said microlens array as a longitudinal axis of each of the plurality of second microlenses.

8. The microlens array of claim 1, further comprising a plurality of third microlenses.

9. The microlens array of claim 8, wherein said third microlenses are elliptically-shaped.

10. The microlens array of claim 8, wherein said first, second, and third microlenses are arranged in a radial configuration about a center point.