Search

EP-4742861-A1 - ELECTRONIC DEVICE

EP4742861A1EP 4742861 A1EP4742861 A1EP 4742861A1EP-4742861-A1

Abstract

The present description relates to an electronic device comprising a single-photon avalanche diode (22), the single-photon avalanche diode (22) comprising a PN junction (26-28a), the PN junction having a first dimension (R) less than 1.2 µm, the single-photon avalanche diode (22) being surrounded by an insulating wall (30), the first dimension (R) being the smallest dimension of the junction.

Inventors

  • BIANCHI, RAUL ANDRES
  • PLACE, SEBASTIEN
  • BUJ, CHRISTEL MARIE-NOËLLE
  • GOLANSKI, DOMINIQUE
  • NICHOLSON, ISOBEL

Assignees

  • STMicroelectronics International N.V.

Dates

Publication Date
20260513
Application Date
20251028

Claims (15)

  1. Electronic device comprising a single-photon avalanche diode (22), the single-photon avalanche diode (22) comprising a PN junction, the PN junction having a first dimension less than 1.2 µm, the single-photon avalanche diode (22) being surrounded by an insulating wall (30), the first dimension being the smallest dimension of the junction.
  2. Method of manufacturing an electronic device comprising a single-photon avalanche diode (22), the single-photon avalanche diode (22) comprising a PN junction, the method comprising a doping step to fabricate at least a part of the anode of the single-photon avalanche diode (22), the PN junction having a first dimension less than 1.2 µm, the single-photon avalanche diode (22) being surrounded by an insulating wall (30), the first dimension being the smallest dimension of the junction.
  3. Device according to claim 1 or method according to claim 2, wherein the insulating wall (30) comprises a conductive core (30b) and an insulating sheath (30a).
  4. Device according to claim 1 or 3 or method according to claim 2 or 3, wherein the cathode (26) of the single-photon avalanche diode (22) comprises an N-doped region located in a substrate (24), the anode of the single-photon avalanche diode (22) comprising: - a first part (28a) located directly above the cathode; and - a second part (28b) surrounding a region of the substrate (24), said region of the substrate (24) being separated from the cathode by the first part (28a).
  5. Device or method according to claim 4, wherein the PN junction is formed by the first part (28a) of the anode, the cathode (26) and the portion (27) of the substrate located between the first part (28a) of the anode and the cathode (26).
  6. Device or method according to claim 4 or 5, wherein a second dimension is less than 0.5 µm, the second dimension being the smallest dimension of the overlap between the first part (28a) and the second part (28b).
  7. Device according to any one of claims 1, 3 to 6 or method according to any one of claims 2 to 6, wherein the first dimension is less than 150%, for example less than 130%, of the lateral spatial resolution of the doping method used to form at least a part of the anode (28a) of the single-photon avalanche diode (22).
  8. Device or method according to claim 7, wherein the doping method used is an ionic implantation of doping elements.
  9. Device according to any one of claims 1, 3 to 8 or method according to any one of claims 2 to 8, wherein the first dimension is greater than 90% of the lateral spatial resolution of the doping method.
  10. A device or method according to any one of claims 6 to 9, wherein the lateral spatial resolution of a doping method is, during the doping of a region having the shape of a rectangular parallelepiped, the smallest value of the smallest dimension of the upper surface of the region allowing the upper surface of the region to be flat.
  11. Device according to any one of claims 1, 3 to 10 or method according to any one of claims 2 to 10, wherein the first dimension is less than 1 µm.
  12. Device according to any one of claims 1, 3 to 10 or method according to any one of claims 2 to 10, wherein the first dimension is between 0.7 µm and 1.2 µm.
  13. Device according to any one of claims 1, 3 to 12 or method according to any one of claims 2 to 12, wherein the device comprises a time-of-flight device, the single-photon avalanche diode (22) being part of the time-of-flight device.
  14. A method according to any one of claims 2 to 13, wherein the method comprises the formation of a hard mask, the hard mask comprising an aperture, at least one of the dimensions of the aperture being less than 150% of the lateral spatial resolution of the doping method.
  15. A method according to any one of claims 2 to 14, wherein the doping is carried out from the face closest to the cathode.

Description

technical field This description relates generally to electronic devices and, in particular, to electronic devices comprising single-photon avalanche diodes and their manufacturing process. Previous technique A single-photon avalanche diode (SPAD) is a solid-state photodetector in the same family as photodiodes and avalanche photodiodes (APDs), while fundamentally sharing the basic behavior of diodes. Like photodiodes and APDs, a SPAD is based on a semiconductor PN junction that can be illuminated by ionizing radiation. The key difference between SPADs and APDs or photodiodes is that a SPAD is biased well beyond its reverse-bias breakdown voltage and has a structure that allows for operation without damage or excessive noise. Summary of the invention One embodiment provides for an electronic device comprising a single-photon avalanche diode, the single-photon avalanche diode comprising a PN junction, the PN junction having a first dimension less than 1.2 µm, the single-photon avalanche diode being surrounded by an insulating wall, the first dimension being the smallest dimension of the junction. Another embodiment provides a method for manufacturing an electronic device comprising a single-photon avalanche diode, the single-photon avalanche diode comprising a PN junction, the method comprising a doping step to fabricate at least part of the anode of the single-photon avalanche diode, the PN junction having a first dimension less than 1.2 µm, the single-photon avalanche diode being surrounded by an insulating wall, the first dimension being the smallest dimension of the junction. According to one embodiment, the insulating wall comprises a conductive core and an insulating sheath. According to one embodiment, the cathode of the single-photon avalanche diode comprises an N-doped region located in a substrate, the anode of the single-photon avalanche diode comprising: - a first part located directly above the cathode; and - a second part surrounding a region of the substrate, said region of the substrate being separated from the cathode by the first part. According to one embodiment, the PN junction is formed by the first part of the anode, the cathode and the portion of the substrate located between the first part of the anode and the cathode. According to one embodiment, a second dimension is less than 0.5 µm, the second dimension being the smallest dimension of the overlap between the first part and the second part. According to one embodiment, the first dimension is less than 150%, for example less than 130%, of the lateral spatial resolution of the doping process used to form at least part of the anode of the single-photon avalanche diode. According to one embodiment, the doping process used is an ionic implantation of dopant elements. According to one embodiment, the first dimension is greater than 90% of the lateral spatial resolution of the doping process. According to one embodiment, the lateral spatial resolution of a doping process is, during the doping of a region having the shape of a rectangular parallelepiped, the smallest value of the smallest dimension of the top face of the region allowing the top face of the region to be flat. According to one embodiment, the first dimension is less than 1 µm. According to one embodiment, the first dimension is between 0.7 µm and 1.2 µm. According to one embodiment, the device includes a time-of-flight device, the single-photon avalanche diode being part of the time-of-flight device. According to one embodiment, the process includes the formation of a hard mask, the hard mask comprising an aperture, at least one of the dimensions of the aperture being less than 150% of the lateral spatial resolution of the doping process. According to one embodiment, the doping is carried out from the face closest to the cathode. Brief description of the drawings These features and advantages, as well as others, will be described in detail in the following description of particular embodiments, given by way of non-limiting example, in relation to the attached figures, among which: there figure 1 represents the definition of the lateral spatial resolution of doping; there figure 2 represents an embodiment of an electronic device comprising a single-photon avalanche diode; there figure 3 represents an example of breakdown probabilities in different single-photon avalanche diodes; and there figure 4 represents an embodiment of an electronic device comprising a single-photon avalanche diode. Description of the implementation methods The same elements have been designated by the same reference numerals in the different figures. In particular, structural and/or functional elements common to the different embodiments may have the same reference numerals and may have identical structural, dimensional and material properties. For the sake of clarity, only the steps and elements useful for understanding the implementation methods described have been represented and are detailed. Unl