Internal structure of image sensing element

• US 20050139750A1
• Filed: 12/10/2004
• Published: 06/30/2005
• Est. Priority Date: 12/12/2003
• Status: Active Grant

• Current Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Original Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Inventors: Nagano, Akihiko, Dobashi, Hideki, Okumura, Kouichirou
• Granted Patent: US 7,060,961 B2
• Time in Patent Office: Days
• US Class Current: 250/208.100
• CPC Class Codes: H01L 27/14621 Colour filter arrangements
• CPC Class Codes: H01L 27/14623 Optical shielding
• CPC Class Codes: H01L 27/14627 Microlenses
• CPC Class Codes: H01L 27/14629 Reflectors
• CPC Class Codes: H01L 27/14685 Process for coatings or optical elements

Abstract

An image sensing element having a high refractive index part that covers at least a portion of each of a plurality of photoelectric converters arranged in one or two dimensions and a low refractive index part provided on the periphery of the high refractive index part. The interface between the high refractive index part and the low refractive index part has a surface that is substantially parallel to the optical axis of an image sensing lens and a slanted surface having an angle that differs from that of the parallel surface. The slanted surface is disposed on a portion of a surface near the optical axis of the image sensing lens, the portion being on a side that light rays from the image sensing lens enters the image sensing element.

Claims

1. An image sensing element comprising:

a high refractive index part that covers at least a portion of each of a plurality of photoelectric converters arrayed in one dimension or two dimensions; and

a low refractive index part provided at a. periphery of said high refractive index part,

wherein an interface between said high refractive index part and said low refractive index part has a surface that is substantially parallel to the optical axis of an image sensing lens and a slanted surface of an angle different from that of the parallel surface,

and the slanted surface is disposed on a portion of a surface near the optical axis of the image sensing lens, the portion being on a side that light rays from the image sensing lens enter the image sensing element.

2. The image sensing element according to claim 1, wherein the angles of the slanted surfaces are essentially identical regardless of a distance from the optical axis of the image sensing lens to each of the plurality of photoelectric converters.

3. The image sensing element according to claim 1, further comprising a plurality of microlenses each corresponding to one of the plurality of photoelectric converters, for concentrating light rays from an external source,

wherein the optical axis of each of the plurality of microlenses offsets from a central axis of the photoelectric converter toward the optical axis of the image sensing lens by an amount that differs depending on a distance of the photoelectric converter from the optical axis of the image sensing lens.

4. An optical instrument equipped with the image sensing element according to claim 1, wherein the optical instrument is provided with an image sensing lens of a pupil distance from the image sensing element of 10 mm or less.

5. The optical instrument according to claim 4, wherein the focal length of the image sensing lens is variable and a ratio of the pupil distance at a maximum focal length to the pupil distance at a minimum focal length is 2 or greater.

6. A solid-state image sensing element composed of a plurality of pixels arranged on a projected image formation surface of an image sensing lens, each pixel comprising:

a microlens;

a photoelectric conversion unit that converts incident light into an electrical signal; and

a light-directing unit composed of a transparent, high refractive index material, disposed between said microlens and said photoelectric conversion unit and directing light from said microlens to said photoelectric conversion unit,

wherein said light-directing unit having a shape that differs depending on the position of each of the plurality of pixels in the solid-state image sensing element, such shape satisfying conditions for total reflection of light entering from said microlens within said light-directing unit.

7. The solid-state image sensing element according to claim 6, wherein:

said microlens is disposed so as to be offset toward the center of the solid-state image sensing element with respect to the optical axis of said photoelectric convertion unit depending on the position of a corresponding pixel in relation to the center of the solid-state image sensing element; and

said light-directing unit has an opening that accommodates '"'"'substantially all the light from said microlens.

8. The solid-state image sensing element according to claim 6, wherein said light-directing unit has a multilateral pyramidal prism shape or a truncated cone shape, a top surface of which is larger than a bottom surface.

9. The solid-state image sensing element according to claim 8, wherein said light-directing unit is formed so that an angle of a slanted surface positioned on a peripheral side of the solid-state image sensing element approaches the perpendicular the farther the pixel is positioned from the center of the solid-state image sensing element.

10. A solid-state image sensing element composed of a plurality of pixels arranged on a projected image formation surface of an image sensing lens, each pixel comprising:

a microlens;

a photoelectric conversion unit that converts incident light into an electrical signal; and

a light-directing unit composed of a transparent, high refractive index material, disposed between said microlens and said photoelectric conversion unit and directing light from said microlens to said photoelectric conversion unit,

wherein said light-directing unit having a shape such that a curvature on a periphery side of the solid-state image sensing element decreases the farther the pixel is positioned from the center of the solid-state image sensing element, and of such shape and light-gathering power as to gather light entering from the microlens substantially entirely within the area of said photoelectric conversion unit.

11. The solid-state image sensing element according to claim 10, wherein:

said microlens is disposed so as to be offset toward the center of the solid-state image sensing element with respect to the optical axis of said photoelectric conversion unit depending on the position of a corresponding pixel in relation to the center of the solid-state image sensing element; and

said light-directing unit has an opening that accommodates substantially all the light from said microlens.

12. A method of forming an asymmetrical light wave path, the method comprising:

a coating step of coating an interlayer insulation film containing a wiring layer with a resist;

a developing step of exposing and developing the resist using a photomask that forms a photomask pattern of gradually changing dot density on photo-permeable supporting body; and

a transferring step of transferring an asymmetrical shape to said interlayer insulation film by etching after patterning the resist to the asymmetrical shape.