CN-122002936-A - Image sensor, imaging system and method of operating image sensor

Abstract

An image sensor, an imaging system, and a method of operating an image sensor are disclosed. The image sensor includes a plurality of image pixels. Each image pixel includes a semiconductor region having a photodiode and a photosensitive electrical element. Each image pixel also includes a primary superlens. The primary superlens includes a dielectric layer and a plurality of nanostructures disposed within the dielectric layer. Each nanostructure of the plurality of nanostructures has a first refractive index that is greater than a second refractive index of the dielectric layer. The plurality of nanostructures are patterned within the dielectric layer to direct light received by the image pixels away from the photosensitive electrical element.

Inventors

• LI BINGXI
• A - E - Pakejinsi

Assignees

• 半导体元件工业有限责任公司

Dates

Publication Date

20260508

Application Date

20250117

Priority Date

20241104

Claims (20)

1. 1. An image sensor comprising a plurality of image pixels, each image pixel comprising a semiconductor region and a primary superlens, The semiconductor region includes a photodiode and a photosensitive element; the primary superlens includes a dielectric layer and a plurality of nanostructures, The plurality of nanostructures are disposed within the dielectric layer, wherein: each nanostructure of the plurality of nanostructures having a first refractive index greater than a second refractive index of the dielectric layer, and The plurality of nanostructures are patterned within the dielectric layer to direct light received by the image pixels away from the photosensitive electrical elements.
2. 2. The image sensor of claim 1, wherein: each image pixel further comprises a local readout circuit including at least the photosensitive element, and The photosensitive element is one of an NMOS transistor, a PMOS transistor, and a capacitor of the local readout circuit.
3. 3. The image sensor of claim 1, wherein the plurality of nanostructures are patterned to asymmetrically direct light received by the image pixels.
4. 4. The image sensor of claim 1, wherein the plurality of nanostructures are patterned to transmit light in a first wavelength band and filter light in a second wavelength band.
5. 5. The image sensor of claim 1, wherein: The dielectric layer comprises silicon dioxide, and Each nanostructure of the plurality of nanostructures disposed within the dielectric layer comprises one of silicon nitride and titanium dioxide.
6. 6. The image sensor of claim 1, wherein a diameter of a focal region of the primary superlens for a wavelength of light is less than the wavelength.
7. 7. The image sensor of claim 1, wherein each image pixel further comprises a diffusion layer positioned over the primary superlens and configured to normalize angled light received by the image pixel.
8. 8. The image sensor of claim 7, wherein the diffusion layer comprises a secondary superlens comprising: a second dielectric layer, and A second plurality of nanostructures disposed within the second dielectric layer, the second plurality of nanostructures patterned to normalize the angled light received by the image pixels.
9. 9. The image sensor of claim 8, wherein: The second dielectric layer of the secondary superlens comprises the same dielectric material as the dielectric layer of the primary superlens, and The second plurality of nanostructures of the secondary superlens comprise the same nanostructure material as the plurality of nanostructures of the primary superlens.
10. 10. An imaging system includes an imaging controller and a camera module, The camera module includes a lens system and an image sensor; The lens system is coupled to the imaging controller; The image sensor is communicatively coupled to the imaging controller and includes a plurality of image pixels, each image pixel of the plurality of image pixels including a semiconductor region and a primary superlens; The semiconductor region includes a photodiode and a photosensitive element; the primary superlens includes a dielectric layer and a plurality of nanostructures; The plurality of nanostructures are disposed within the dielectric layer, wherein: each nanostructure of the plurality of nanostructures having a first refractive index greater than a second refractive index of the dielectric layer, and The plurality of nanostructures are patterned within the dielectric layer to direct light received by the image pixels away from the photosensitive electrical elements.
11. 11. The imaging system of claim 10, wherein the plurality of nanostructures are patterned to asymmetrically direct light received by the image pixels.
12. 12. The imaging system of claim 10, wherein: The dielectric layer comprises silicon dioxide, and Each nanostructure of the plurality of nanostructures disposed within the dielectric layer comprises one of silicon nitride and titanium dioxide.
13. 13. The imaging system of claim 10, wherein a diameter of a focal region of the primary superlens for a wavelength of light is less than the wavelength.
14. 14. The imaging system of claim 10, wherein each image pixel further comprises a diffusion layer positioned over the primary superlens and configured to normalize angled light received by the image pixel.
15. 15. The imaging system of claim 14, wherein the diffusing layer comprises a secondary superlens comprising: a second dielectric layer, and A second plurality of nanostructures disposed within the second dielectric layer, the second plurality of nanostructures patterned to normalize the angled light received by the image pixels.
16. 16. The imaging system of claim 15, wherein: The second dielectric layer of the secondary superlens comprises the same dielectric material as the dielectric layer of the primary superlens, and The second plurality of nanostructures of the secondary superlens comprise the same nanostructure material as the plurality of nanostructures of the primary superlens.
17. 17. A method of operating an image sensor, the method comprising: receiving light from a scene at image pixels of the image sensor; Diffracting the light into a semiconductor region comprising a photodiode and a photosensitive electrical element using a primary superlens; Directing the light into a focal region within the semiconductor region separate from the photosensitive electrical element using the primary superlens, and An electrical signal is generated with the photodiode in response to absorption of the light in the semiconductor region.
18. 18. The method of claim 17, further comprising normalizing an inclination of the light received by the image pixels prior to passing through the primary superlens with a diffusing layer.
19. 19. The method of claim 17, wherein the light is directed asymmetrically by the primary superlens.
20. 20. The method of claim 17, wherein directing the light with the primary superlens comprises transmitting a first wavelength band of the light and filtering a second wavelength band of the light.

Description

Image sensor, imaging system and method of operating image sensor Technical Field The present disclosure relates generally to image sensors, and in particular to techniques for improving parasitic light sensitivity of image sensors. Background Image sensors are used in electronic devices such as cellular telephones, cameras, and computers to capture images. The electronic device may be provided with an image sensor comprising an array of image pixels arranged in a grid pattern. Each image pixel may receive photons, such as light, and may convert the photons into electrical signals. The inventors of embodiments of the present disclosure have recognized that image pixels may include structures that are sensitive to parasitic light. The inventors of embodiments of the present disclosure have further recognized that the sensitivity of an image pixel structure to parasitic light can generally affect the parasitic light sensitivity of an image sensor. Embodiments of the present disclosure may address one or more of these challenges. Disclosure of Invention According to a first aspect, there is provided an image sensor comprising a plurality of image pixels, each image pixel comprising a semiconductor region comprising a photodiode and a photosensitive electrical element, and a primary superlens comprising a dielectric layer and a plurality of nanostructures arranged within the dielectric layer, wherein each nanostructure of the plurality of nanostructures has a first refractive index that is greater than a second refractive index of the dielectric layer, and the plurality of nanostructures is patterned within the dielectric layer to direct light received by the image pixel away from the photosensitive electrical element. According to a second aspect, there is provided an imaging system comprising an imaging controller and a camera module comprising a lens system and an image sensor, the lens system being coupled to the imaging controller, the image sensor being communicatively coupled to the imaging controller and comprising a plurality of image pixels, each of the plurality of image pixels comprising a semiconductor region and a primary superlens, the semiconductor region comprising a photodiode and a photosensitive electrical element, the primary superlens comprising a dielectric layer and a plurality of nanostructures, the plurality of nanostructures being arranged within the dielectric layer, wherein each of the plurality of nanostructures has a first refractive index that is greater than a second refractive index of the dielectric layer, and the plurality of nanostructures are patterned within the dielectric layer to direct light received by the image pixels away from the photosensitive electrical element. According to a third aspect there is provided a method of operating an image sensor, the method comprising receiving light from a scene at image pixels of the image sensor, diffracting the light into a semiconductor region comprising a photodiode and a light sensitive electrical element with a primary superlens, directing the light into a focal region within the semiconductor region separate from the light sensitive electrical element with the primary superlens, and generating an electrical signal with the photodiode in response to absorption of the light in the semiconductor region. Drawings A more complete understanding of the present embodiments may be obtained by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numbers indicate like features. Fig. 1 illustrates a block diagram of an imaging system according to an embodiment of the present disclosure. Fig. 2 illustrates a block diagram of an example image sensor, according to an embodiment of the disclosure. Fig. 3 illustrates a block diagram of exemplary components of an image pixel, according to an embodiment of the present disclosure. Fig. 4A to 4B illustrate side cross-sectional views of image pixels according to embodiments of the present disclosure. Fig. 5 illustrates a side cross-sectional view of an image pixel according to an embodiment of the present disclosure. Fig. 6A illustrates a top view of an example superlens according to embodiments of the present disclosure. Fig. 6B illustrates a top view of a focal region of an example superlens according to embodiments of the present disclosure. Fig. 7 illustrates a side cross-sectional view of an image pixel according to an embodiment of the present disclosure. Fig. 8 illustrates a side cross-sectional view of an image pixel according to an embodiment of the present disclosure. Fig. 9 illustrates a method of operating an image sensor according to an embodiment of the present disclosure. Detailed Description The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims. While one or more of these embod