US-12628440-B2 - Photodiode devices, photodetectors, and methods of forming photodiode devices

Abstract

A photodiode device may include a semiconductor substrate, a multiplication layer disposed in the semiconductor substrate and having a first width, a dielectric layer disposed over the multiplication layer, a charge layer coupled to the multiplication layer and having a second width, and an absorption layer disposed over the charge layer and having a third width. The second width of the charge layer may be smaller than the first width of the multiplication layer, and the third width of the absorption layer may be greater than the second width of the charge layer.

Inventors

• Khee Yong Lim
• Kiok Boone Elgin Quek
• Kian Ming Tan
• Wei Sin PHANG
• Xiaoping Wang

Assignees

• GLOBALFOUNDRIES SINGAPORE PTE. LTD.

Dates

Publication Date

20260512

Application Date

20221222

Claims (18)

1. 1 . A photodiode device, comprising: a semiconductor substrate; a multiplication layer disposed in the semiconductor substrate and having a first width; a dielectric layer disposed over the multiplication layer; a charge layer coupled to the multiplication layer and having a second width smaller than the first width of the multiplication layer; and an absorption layer disposed over the charge layer and having a third width greater than the second width of the charge layer, wherein the dielectric layer has an opening with a fourth width, and the fourth width is smaller than the third width of the absorption layer, and wherein the absorption layer and the multiplication layer are separated from each other by the charge layer and the dielectric layer.
2. 2 . The photodiode device of claim 1 , wherein the charge layer is disposed in the opening of the dielectric layer.
3. 3 . The photodiode device of claim 1 , further comprising a guard ring disposed in the multiplication layer, wherein the charge layer is disposed in the multiplication layer and is wrapped around by the guard ring.
4. 4 . The photodiode device of claim 3 , wherein the absorption layer includes a lower portion disposed in the opening of the dielectric layer and an upper portion disposed over the lower portion.
5. 5 . The photodiode device of claim 1 , wherein the charge layer includes dopants of a first conductivity type, the photodiode device further comprising: a first doped region of a second conductivity type spaced apart from the charge layer by a distance sufficient to prevent breakdown at an edge of the charge layer.
6. 6 . The photodiode device of claim 5 , further comprising: a second doped region of the second conductivity type disposed farther from the charge layer than the first doped region; and a well region of the second conductivity type over which the multiplication layer, the first doped region, and the second region are disposed.
7. 7 . The photodiode device of claim 6 , wherein the well region has a retrograde doping profile.
8. 8 . The photodiode device of claim 1 , wherein the absorption layer is an epitaxial SiGe layer, the charge layer is a silicon epitaxial layer, and the multiplication layer is an intrinsic silicon epitaxial layer.
9. 9 . The photodiode device of claim 1 , wherein the multiplication layer has the first width in a first direction, the charge layer has the second width in the first direction, the absorption layer has the third width in the first direction, and the multiplication layer, the charge layer, and the absorption layer are stacked in a second direction orthogonal to the first direction, and wherein a ratio of the third width of the absorption layer to the second width of the charge layer is in a range from 1.5 to 2.5.
10. 10 . The photodiode device of claim 1 , wherein the device is a single-photon avalanche diode (SPAD).
11. 11 . A photodetector, comprising: a photodiode device configured to detect near-infrared (NIR) photons; and a control circuit configured to control an operation of the photodiode device, wherein the photodiode device includes: a semiconductor substrate; a multiplication layer disposed in the semiconductor substrate and having a first width; a dielectric layer disposed over the multiplication layer; a charge layer coupled to the multiplication layer and having a second width smaller than the first width of the multiplication layer; and an absorption layer disposed over the charge layer and having a third width greater than the second width of the charge layer, wherein the dielectric layer has an opening with a fourth width, and the fourth width is smaller than the third width of the absorption layer, and wherein the charge layer is disposed in the opening of the dielectric layer.
12. 12 . The photodetector of claim 11 , wherein the charge layer includes dopants of a first conductivity type, the photodetector further comprising a doped region of a second conductivity type spaced apart from the charge layer by a distance sufficient to prevent breakdown at an edge of the charge layer.
13. 13 . A method of forming a photodiode device, the method comprising: providing a substrate; forming a multiplication layer that has a first width in the substrate; forming a dielectric layer over the multiplication layer; forming a charge layer that has a second width smaller than the first width of the multiplication layer; and forming an absorption layer over the charge layer, the absorption layer having a third width greater than the second width of the charge layer, wherein forming the dielectric layer includes: forming a dielectric material layer over the multiplication layer; and forming an opening in the dielectric material layer to form a dielectric layer, the opening having a fourth width smaller than the third width of the absorption layer, and wherein the absorption layer and the multiplication layer are separated from each other by the charge layer and the dielectric layer.
14. 14 . The method of claim 13 , wherein forming the charge layer includes performing silicon epitaxial growth over a portion of the multiplication layer exposed by the opening with in-situ doping of a first conductivity type.
15. 15 . The method of claim 14 , further comprising: forming a first doped region of a second conductivity type that is spaced apart from the charge layer by a distance sufficient to prevent breakdown at an edge of the charge layer; and forming a second doped region of the second conductivity type that is disposed farther from the charge layer than the first doped region.
16. 16 . The method of claim 13 , wherein dopants of a first conductivity type are injected into the multiplication layer to form the charge layer in the multiplication layer.
17. 17 . The method of claim 16 , further comprising forming a guard ring by diffusing the dopants of the first conductivity type in the charge layer.
18. 18 . The photodiode device of claim 1 , wherein the dielectric layer has an opening with a fourth width, and the fourth width is smaller than the third width of the absorption layer, and wherein the absorption layer includes a lower portion disposed in the opening of the dielectric layer and an upper portion disposed over the lower portion.

Description

BACKGROUND The present disclosure relates to a photodiode device, a photodetector including the photodiode device, and a method of forming the photodiode device. A photodetector including one or more photodiode devices may be used for detecting photons in various applications ranging from biosensing and imaging to optical communications and computing. Conventional photodiode devices, for example, avalanche photodiode devices, may be based on a PN junction that can be reverse biased to absorb photons in a depletion region across the PN junction. These conventional photodiode devices may have relatively high dark current rates, and thus it is desirable to provide an improved photodiode device with reduced dark count rates without sacrificing quantum efficiency. Conventional photodiode devices also may be susceptible to premature breakdown, and thus it is also desirable to provide an improved photodiode device with a reduced likelihood of premature breakdown. SUMMARY Embodiments of the present application relate to a photodiode device, a photodetector including the photodiode device, and a method of forming the photodiode device. In an embodiment, a photodiode device includes a semiconductor substrate, a multiplication layer disposed in the semiconductor substrate and having a first width, a dielectric layer disposed over the multiplication layer, a charge layer coupled to the multiplication layer and having a second width, and an absorption layer disposed over the charge layer and having a third width. The second width of the charge layer is smaller than the first width of the multiplication layer, and the third width of the absorption layer is greater than the second width of the charge layer. In an embodiment, a photodetector includes a photodiode device configured to detect near-infrared (NIR) photons and a control circuit configured to control an operation of the photodiode device. The photodiode device includes a semiconductor substrate, a multiplication layer disposed in the semiconductor substrate and having a first width, a dielectric layer disposed over the multiplication layer, a charge layer coupled to the multiplication layer and having a second width, and an absorption layer disposed over the charge layer and having a third width. The second width of the charge layer is smaller than the first width of the multiplication layer, and the third width of the absorption layer is greater than the second width of the charge layer. In an embodiment, a method of forming a photodiode device includes providing a substrate, forming a multiplication layer that has a first width in the substrate, forming a dielectric layer over the multiplication layer, forming a charge layer that has a second width, and forming an absorption layer that has a third width over the charge layer. The second width of the charge layer may be smaller than the first width of the multiplication layer, and the third width of the absorption layer may be greater than the second width of the charge layer. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates a schematic diagram of a photodetector according to an embodiment. FIG. 2 illustrates a simplified cross-sectional view of a photodiode device in FIG. 1 according to an embodiment. FIGS. 3A, 3B, 4A, 4B, 5A, 5B, 6A, 6B, 7A, 7B, 8A, 8B, 9A, and 9B illustrate a method of fabricating the photodiode device in FIG. 1 according to an embodiment. FIG. 10 illustrates a simplified cross-sectional view of a photodiode device according to another embodiment. FIGS. 11A, 11B, 12A, 12B, 13A, 13B, 14A, and 14B illustrate a method of fabricating the photodiode device in FIG. 10 according to an embodiment. FIG. 15 illustrates quantum efficiency of a photodiode device according to an embodiment. DETAILED DESCRIPTION Embodiments of the present application relate to a photodiode device, a photodetector including the photodiode device, and a method of forming the photodiode device. A detailed description of embodiments is provided below along with accompanying figures. The scope of this disclosure is limited by the claims and encompasses numerous alternatives, modifications and equivalents. Although steps of various processes are presented in a given order, embodiments are not necessarily limited to being performed in the listed order. In some embodiments, certain operations may be performed simultaneously, in an order other than the described order, or not performed at all. Numerous specific details are set forth in the following description. These details are provided to promote a thorough understanding of the scope of this disclosure by way of specific examples, and embodiments may be practiced according to the claims without some of these specific details. Accordingly, the specific embodiments of this disclosure are illustrative, and are not intended to be exclusive or limiting. For the purpose of clarity, technical material that is known in the technical fields related to this disclosure has not been de