Solid-State Image Sensors

• US 20090225205A1
• Filed: 05/17/2006
• Published: 09/10/2009
• Est. Priority Date: 07/08/2005
• Status: Active Grant

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Takagi, Toru
• Granted Patent: US 8,013,927 B2
• Time in Patent Office: Days
• US Class Current: 348/294
• 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 3/0037 characterized by the distribution or form of lenses
• 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: G02B 5/201 in the form of arrays
• CPC Class Codes: H01L 27/14605 Structural or functional details relating to the position of the pixel elements, e.g. smaller pixel elements in the center of the imager compared to pixel elements at the periphery
• CPC Class Codes: H01L 27/14627 Microlenses
• CPC Class Codes: H01L 27/14685 Process for coatings or optical elements

Abstract

Solid-state image sensors are disclosed that include one or more pixels formed on a semiconductor substrate. Each pixel includes a photoelectric converter to convert light to an electric signal, and a microlens above the photoelectric converter. The microlens has a plan profile in which the direct distance from a center to a lens edge is variable. The microlens has first base regions and second base regions not including the first base regions. The first base regions are provided near n positions (n being a natural number) of the lens edge from which the direct distance is relatively long. The vertical height of the first base regions from an upper surface of the photoelectric converter is less than the vertical height of the second base regions from the upper surface of the photoelectric converter.

Claims

1. A solid-state image sensor, comprising:

a pixel on a semiconductor substrate;

a photoelectric converter provided in the pixel to convert incident light to an electric signal; and

a microlens situated above the photoelectric converter,

wherein the microlens has a plan profile in which a direct distance from a center of the microlens to a lens edge is variable;

the microlens comprises a first base region and a second base region not including the first base region, the first base region being situated near n locations (n being a natural number) of the lens edge, from which the direct distance is relatively long; and

a vertical height of the first base region from an upper surface of the photoelectric converter is less than a vertical height of the second base region from the upper surface of the photoelectric converter.

2. The solid-state image sensor according to claim 1, wherein the vertical height from the upper surface of the photoelectric converter decreases stepwise from the second base region toward the first base region.

3. The solid-state image sensor according to claim 1, wherein the vertical height from the upper surface of the photoelectric converter continuously decreases from the second base region to the first base region.

4. A solid-state image sensor, comprising:

a pixel formed on a semiconductor substrate;

a photoelectric converter provided in the pixel to convert incident light to an electric signal;

a planarizing layer situated above the photoelectric converter; and

a microlens situated on the planarizing layer,

wherein the microlens has a plan profile with a direct distance from a center of the microlens to an edge of the microlens being variable;

the planarizing layer has a first region and a second region not including the first region, the first region being provided near n locations (n being a natural number) on the edge, from which the direct distance is relatively long in the plan profile of the microlens as vertically projected on the planarizing layer; and

a thickness of the planarizing layer is greater in the second region toward a microlens side than in the first region.

5. The solid-state image sensor according to claim 4, wherein the thickness of the planarizing layer decreases stepwise from the second region toward the first region.

6. The solid-state image sensor according to claim 4, wherein the thickness of the planarizing layer continuously decreases from the second region toward the first region.

7. A solid-state image sensor, comprising:

a pixel situated on a semiconductor substrate;

a photoelectric converter provided in the pixel to convert incident light to an electric signal; and

a microlens situated above the photoelectric converter,

wherein the microlens has a plan profile with a direct distance from a center of the microlens to an edge of the microlens being variable;

the microlens has a first region and a second region not including the first region, the first region being provided near n locations (n being a natural number), of the lens edge, from which the direct distance is relatively long; and

a difference between a maximum film thickness and a first minimum film thickness is larger than a difference between the maximum film thickness and a second minimum film thickness, the maximum film thickness being defined as a greatest lens thickness near the center of the microlens, the first minimum film thickness being defined as a smallest lens thickness in the first region, and the second minimum film thickness being defined as a smallest lens thickness in the second region.

8. A solid-state image sensor, comprising:

a pixel situated on a semiconductor substrate;

a photoelectric converter provided in said pixel to convert incident light to an electric signal;

a planarizing layer situated above the photoelectric converter; and

a microlens situated on the planarizing layer,

wherein in said planarizing layer, a second lens is provided substantially parallel to the photoelectric converter, with an optical axis of the second lens being aligned with an optical axis of the microlens; and

the second lens has a plan profile with a direct distance from a center to a lens edge being variable and being made of a member having a greater refractive index than the planarizing layer.

9. The solid-state image sensor according to claim 8, wherein:

the second lens has a first region and a second region not including the first region;

the first region is provided near n locations (n being a natural number) of the lens edge, from which the direct distance is relatively long; and

the second lens is sloped so as to become thinner from the second region to the first region.

10. The solid-state image sensor according to claim 9, wherein:

the second region is substantially planar; and

the first region in the second lens is sloped so as to have reduced thickness from portions adjacent to the second region toward the lens edge in the first region.