US-12628453-B2 - Quad photodiode microlens arrangements, and associated systems and methods

Abstract

Quad photodiode microlens arrangements, and associated systems and methods. In one embodiment, a plurality of pixels are arranged in rows and columns of a pixel array disposed in a semiconductor material. The plurality of pixels includes green (G) pixels, red (R) pixels, blue (B) pixels and clear (C) pixels. Each pixel comprises a plurality of photodiodes that are configured to receive incoming light through an illuminated surface of the semiconductor material. A plurality of small microlenses are distributed over individual photodiodes of clear (C) pixels. A plurality of large microlenses are distributed over individual green (G) pixels. A diameter of the small microlenses is smaller than a diameter of the large microlenses.

Inventors

• Xiaodong Yang
• Sylvia Shuoyu Zhang
• John Li
• Chengming Liu
• Guansong Liu

Assignees

• OMNIVISION TECHNOLOGIES, INC.

Dates

Publication Date

20260512

Application Date

20220603

Claims (16)

1. 1 . An image sensor, comprising: a plurality of pixels arranged in rows and columns of a pixel array disposed in a semiconductor material, wherein the plurality of pixels includes green (G) pixels, red (R) pixels, blue (B) pixels and clear (C) pixels, and wherein each green (G), red (R), blue (B), and clear (C) pixel comprises a plurality of photodiodes of the same color as the pixel, and wherein the photodiodes are configured to receive incoming light through an illuminated surface of the semiconductor material; a green (G) color filter configured for transmitting green light to a green (G) photodiode; a red (R) color filter configured for transmitting red (R) light to a red (R) photodiode; a blue (B) color filter configured for transmitting blue (B) light to a blue (B) photodiode; a clear (C) color filter configured for transmitting all light to a clear (C) photodiode; a plurality of small microlenses each distributed over individual photodiodes of a given clear (C) pixel, wherein an incident light enters the image sensor through the small microlens and the clear (C) color filter; and a plurality of large microlenses each distributed over individual green (G) pixels such that each large microlens covers a plurality of photodiodes of the individual green (G) pixels; wherein a diameter of the small microlenses is smaller than a diameter of the large microlenses.
2. 2 . The image sensor of claim 1 , further comprising: a plurality of large microlenses each distributed over individual red (R) pixels and individual blue (B) pixels such that each large microlens covers an entire plurality of photodiodes of a given individual red (R) or blue (B) pixel.
3. 3 . The image sensor of claim 1 , further comprising: a plurality of small microlenses each distributed over individual photodiodes of the red (R) pixels and the blue (B) pixels such that each red (R) and blue (B) pixel is covered by a plurality of small microlenses each distributed over individual photodiodes of a given red (R) and blue (B) pixel.
4. 4 . The image sensor of claim 1 , wherein each pixel comprises four photodiodes.
5. 5 . The image sensor of claim 1 , wherein the clear (C) pixels determine a resolution of the image sensor.
6. 6 . The image sensor of claim 1 , wherein the green (G) pixels determine an autofocusing of the image sensor.
7. 7 . An image sensor, comprising: a plurality of pixels arranged in rows and columns of a pixel array disposed in a semiconductor material, wherein the plurality of pixels includes green (G) pixels, red (R) pixels, blue (B) pixels and clear (C) pixels, and wherein each green (G), red (R), blue (B), and clear (C) pixel comprises a plurality of photodiodes of the same color as the pixel, and wherein the photodiodes are configured to receive incoming light through an illuminated surface of the semiconductor material; a green (G) color filter configured for transmitting green light to a green (G) photodiode; a red (R) color filter configured for transmitting red (R) light to a red (R) photodiode; a blue (B) color filter configured for transmitting blue (B) light to a blue (B) photodiode; a clear (C) color filter configured for transmitting all light to a clear (C) photodiode; a plurality of small microlenses each distributed over individual photodiodes of a given clear (C) pixel, wherein an incident light enters the image sensor through the small microlens and the clear (C) color filter; and a plurality of large microlenses each distributed over individual green (G) pixels, red (R) pixels, and blue (B) pixels such that each large microlens covers a plurality of photodiodes of the individual green (G), red (R), and blue (B), pixels, wherein a diameter of the small microlenses is smaller than a diameter of the large microlenses.
8. 8 . The image sensor of claim 7 , wherein each pixel comprises four photodiodes.
9. 9 . The image sensor of claim 7 , wherein the clear (C) pixels determine a resolution of the image sensor.
10. 10 . The image sensor of claim 7 , wherein the green (G) pixels determine an autofocusing of the image sensor.
11. 11 . A computer-implemented method for operating an image sensor, the method comprising: exposing at least a portion of an image sensor to incident electromagnetic radiation, the image sensor comprising: a plurality of pixels arranged in rows and columns of a pixel array disposed in a semiconductor material, wherein the plurality of pixels includes green (G) pixels, red (R) pixels, blue (B) pixels and clear (C) pixels, and wherein each green (G), red (R), blue (B), and clear (C) pixel comprises a plurality of photodiodes of the same color as the pixel, and wherein the photodiodes are configured to receive incoming light through an illuminated surface of the semiconductor material, a green (G) color filter configured for transmitting green light to a green (G) photodiode; a red (R) color filter configured for transmitting red (R) light to a red (R) photodiode, a blue (B) color filter configured for transmitting blue (B) light to a blue (B) photodiode, a clear (C) color filter configured for transmitting all light to a clear (C) photodiode, a plurality of small microlenses each distributed over individual photodiodes of a given clear (C) pixel, wherein an incident light enters the image sensor through the small microlens and the clear (C) color filter; and a plurality of large microlenses each distributed over individual green (G) pixels such that each large microlens covers a plurality of photodiodes of the individual green (G) pixels; wherein a diameter of the small microlenses is smaller than a diameter of the large microlenses.
12. 12 . The computer-implemented method of claim 11 , wherein the image sensor further comprises: a plurality of large microlenses each distributed over individual red (R) pixels and individual blue (B) pixels such that each large microlens covers an entire plurality of photodiodes of a given individual red (R) or blue (B) pixel.
13. 13 . The computer-implemented method of claim 11 , wherein the image sensor further comprises: a plurality of small microlenses each distributed over individual photodiodes of the red (R) pixels and the blue (B) pixels such that each red (R) and blue (B) pixel is covered by a plurality of small microlenses each distributed over individual photodiodes of a given red (R) and blue (B) pixel.
14. 14 . The computer-implemented method of claim 11 , wherein each pixel comprises four photodiodes.
15. 15 . The computer-implemented method of claim 11 , wherein the clear (C) pixels determine a resolution of the image sensor.
16. 16 . The computer-implemented method of claim 11 , wherein the green (G) pixels determine an autofocusing of the image sensor.

Description

BACKGROUND INFORMATION Field of the Disclosure This disclosure relates generally to the design of image sensors, and in particular, relates to image sensors that use different arrangements of microlenses to improve balance between autofocusing and resolution of the image sensor. Background Image sensors have become ubiquitous. They are widely used in digital still cameras, cellular phones, security cameras, as well as medical, automotive, and other applications. The technology for manufacturing image sensors continues to advance at a great pace. For example, the demands for higher image sensor resolution and lower power consumption motivate further miniaturization and integration of image sensors into digital devices. In some applications, auto focusing of the image sensor depends on dedicated groups of pixels that engage in phase detection auto focus (PDAF). It is known that autofocusing improves with the size of lens that covers photodiodes of the pixels. On the other hand, large size of lens tends to degrade the resolution of the pixels. Therefore, systems and methods that can provide both good autofocusing and good resolution of the image sensor are needed. BRIEF DESCRIPTION OF THE DRAWINGS Non-limiting and non-exhaustive embodiments of the present invention are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified. FIG. 1 is a diagram of an example image sensor in accordance with an embodiment of the present technology. FIG. 2 is a cross-sectional side view of an example image sensor in accordance with embodiments of the present technology. FIG. 3 is a top schematic view of an arrangement of microlenses over pixels in accordance with an embodiment of the present technology. FIG. 4 is a top schematic view of an arrangement of microlenses over pixels in accordance with an embodiment of the present technology. FIG. 5 is a top schematic view of an arrangement of microlenses over pixels in accordance with an embodiment of the present technology. Corresponding reference characters indicate corresponding components throughout the several views of the drawings. Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention. DETAILED DESCRIPTION Image sensors, and in particular, image sensors with microlenses that are arranged to improve resolution and autofocusing of the image sensor are disclosed. In the following description, numerous specific details are set forth to provide a thorough understanding of the embodiments. One skilled in the relevant art will recognize, however, that the techniques described herein can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring certain aspects. Reference throughout this specification to “one example” or “one embodiment” means that a particular feature, structure, or characteristic described in connection with the example is included in at least one example of the present invention. Thus, the appearances of the phrases “in one example” or “in one embodiment” in various places throughout this specification are not necessarily all referring to the same example. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more examples. Spatially relative terms, such as “beneath”, “below”, “lower”, “under”, “above”, “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” or “under” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary terms “below” and “under” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. In addition, it will also be understood that when a layer is referred to as being “between” two