CN-121985611-A - Semiconductor device having optical structure for enhanced blue light detection

Abstract

The present disclosure relates to semiconductor devices having optical structures for enhanced blue light detection. A semiconductor device is disclosed. The semiconductor device includes a plurality of image pixels. Each image pixel includes a semiconductor region and a single photon avalanche diode formed in the semiconductor region. Each image pixel further includes an optical structure disposed in the semiconductor region and extending from an upper surface of the semiconductor region into an interior of the semiconductor region. Each image pixel also includes a microlens configured to focus light received by the image pixel into the optical structure.

Inventors

• LI BINGXI
• S. Bursack
• M.A. Sulfridge

Assignees

• 半导体元件工业有限责任公司

Dates

Publication Date

20260505

Application Date

20250113

Priority Date

20241031

Claims (20)

1. 1. A semiconductor device, the semiconductor device comprising: a plurality of image pixels, each image pixel of the plurality of image pixels comprising: A semiconductor region; A single photon avalanche diode formed in the semiconductor region; an optical structure disposed in the semiconductor region and extending from an upper surface of the semiconductor region into an interior of the semiconductor region, and A microlens configured to focus light received by the image pixel into the optical structure.
2. 2. The semiconductor device of claim 1, wherein the optical structure extends into a depletion region of the single photon avalanche diode.
3. 3. The semiconductor device of claim 1, wherein an absorption region for photons of blue light at least partially overlaps a depletion region of the single photon avalanche diode.
4. 4. The semiconductor device according to claim 1, wherein each image pixel comprises: A plurality of optical structures disposed in the semiconductor region and extending from the upper surface of the semiconductor region to the interior of the semiconductor region, and A plurality of microlenses configured to focus light received by the image pixels into the plurality of optical structures, respectively.
5. 5. The semiconductor device of claim 1, wherein the optical structure is symmetrically configured about a center of the image pixel.
6. 6. The semiconductor device of claim 1, wherein the optical structure has an inverted pyramid shape extending downward from the upper surface of the semiconductor region.
7. 7. The semiconductor device of claim 1, wherein the optical structure is formed along a crystal structure of the semiconductor region.
8. 8. The semiconductor device of claim 1, wherein each image pixel is a back-illuminated image pixel.
9. 9. The semiconductor device of claim 1, wherein each image pixel further comprises a blue-pass filter.
10. 10. An imaging system, the imaging system comprising: Image processing circuit, and A semiconductor device communicatively coupled to the image processing circuit and comprising a plurality of image pixels, each image pixel comprising: A semiconductor region; A single photon avalanche diode formed in the semiconductor region; an optical structure disposed in the semiconductor region and extending from an upper surface of the semiconductor region into an interior of the semiconductor region, and A microlens configured to focus light received by the image pixel into the optical structure.
11. 11. The imaging system of claim 10, wherein the optical structure extends into a depletion region of the single photon avalanche diode.
12. 12. The imaging system of claim 10, wherein an absorption region for photons of blue light at least partially overlaps a depletion region of the single photon avalanche diode.
13. 13. The imaging system of claim 10, wherein the optical structure has an inverted pyramid shape extending downward from the upper surface of the semiconductor region.
14. 14. A semiconductor device, the semiconductor device comprising: a plurality of image pixels, each image pixel of the plurality of image pixels comprising: A semiconductor region; A single photon avalanche diode formed in the semiconductor region, and A light pipe disposed in the semiconductor region above the single photon avalanche diode, and A lens layer configured to focus light received by the image pixels into the light pipe.
15. 15. The semiconductor device of claim 14, wherein each image pixel comprises a plurality of light pipes disposed in the semiconductor region above the single photon avalanche diode.
16. 16. The semiconductor device of claim 14, wherein the light pipe comprises the same material as the lens layer.
17. 17. The semiconductor device of claim 14, wherein the lens layer comprises a single microlens.
18. 18. The semiconductor device of claim 14, wherein the lens layer comprises a plurality of microlenses each configured to focus light received by the image pixels into the light pipe.
19. 19. The semiconductor device of claim 14, wherein the lens layer comprises a nanophotonic lens comprising a plurality of nanostructures disposed within a dielectric layer.
20. 20. The semiconductor device of claim 19, wherein the nanophotonic lens is configured as a blue pass filter.

Description

Semiconductor device having optical structure for enhanced blue light detection Technical Field The present disclosure relates generally to imaging systems, and in particular to imaging sensors including Single Photon Avalanche Diodes (SPADs) for single photon detection. Background Modern electronic devices, such as cellular telephones, cameras, and computers, often use digital image sensors. An image sensor (which may also be referred to as an imager) may be formed from a two-dimensional array of image sensing pixels. Each pixel typically includes a photosensitive element (such as a photodiode) that receives incident photons and converts the photons into an electrical signal. Each pixel often includes a microlens that focuses light onto the photosensitive element. The inventors of embodiments of the present disclosure have recognized that conventional image sensors having backside illuminated (BSI) image pixels may be affected by limited functionality in a variety of ways. For example, the inventors of embodiments of the present disclosure have recognized that since absorption of shorter wavelength light occurs primarily near the backside surface of BSI image pixels, while avalanche occurs primarily near the front side surface of BSI image pixels, the timing resolution of BSI image pixels for shorter wavelength light may be affected. The inventors of embodiments of the present disclosure have also recognized that the electric field at the backside surface may be weak, which may result in long delay times. Embodiments of the present disclosure may address one or more of these challenges. 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 circuit diagram showing an example Single Photon Avalanche Diode (SPAD) device in accordance with an embodiment of the present disclosure. Fig. 2 illustrates a circuit diagram of an example silicon photomultiplier according to an embodiment of the present disclosure. Fig. 3 illustrates a block diagram of a pixel array and associated readout circuitry for reading out image signals in an example SPAD-based semiconductor device, according to an embodiment of the present disclosure. Fig. 4 illustrates a schematic block diagram of an example imaging system with SPAD-based semiconductor devices in accordance with an embodiment of the present disclosure. Fig. 5 illustrates a schematic block diagram of an example Positron Emission Tomography (PET) imaging system with SPAD-based semiconductor devices, according to an embodiment of the present disclosure. Fig. 6 illustrates a side cross-sectional view of an image pixel according to an embodiment 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. 8A illustrates a side cross-sectional view of an image pixel according to an embodiment of the present disclosure. Fig. 8B illustrates a top view of an image pixel according to an embodiment of the present disclosure. Fig. 9A illustrates a side cross-sectional view of an image pixel according to an embodiment of the present disclosure. Fig. 9B illustrates a top view of an image pixel according to an embodiment of the present disclosure. Fig. 10A illustrates a side cross-sectional view of an image pixel according to an embodiment of the present disclosure. Fig. 10B illustrates a top view of an image pixel 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. The disclosed embodiments should not be interpreted, or otherwise used, as limiting the scope of the disclosure, including the claims. Furthermore, those skilled in the art will appreciate that the following description has broad application and that the discussion of any embodiment is meant to be exemplary of that embodiment, and not intended to intimate that the scope of the disclosure, including the claims, is limited to that embodiment. Various terms are used to refer to particular system components. Different companies may refer to a component by different names, and the present disclosure is not intended to distinguish between components that differ in name but not form and function. In the following discussion and in the claims, the terms "include" and "comprise" are used in an open-ended fashion, and thus, such terms should be interpreted to mean "include, but not limited to. In addition, the term "coupled" is intended to mean either an indirect connection or a direct connection. Thus, if a first device couples to a second device, that connection between the first device and the second device may be through a direct conn