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CN-116169198-B - Single photon avalanche photodiode and preparation method thereof

CN116169198BCN 116169198 BCN116169198 BCN 116169198BCN-116169198-B

Abstract

The invention provides a single photon avalanche photodiode and a preparation method thereof, wherein the photodiode comprises a semiconductor substrate and a deep trench region, wherein the deep trench region extends from a first main surface of the semiconductor substrate to the inside of the semiconductor substrate; the semiconductor device comprises a semiconductor substrate, a cathode region, an anode region and a photoelectric signal conversion region, wherein the semiconductor substrate comprises a first main surface, a deep trench region and a second main surface, the deep trench region is arranged on the semiconductor substrate, the deep trench region is arranged on the first main surface, the second main surface is arranged on the outer periphery of the semiconductor substrate, the second main surface is arranged on the deep trench region and extends to the inside of the semiconductor substrate along the deep trench region, the buffer region comprises a first buffer part arranged on the outer periphery of the first main surface and below the first cathode region and a second buffer part arranged on the outer periphery of the second main surface, an avalanche region is formed in a contact region between the buffer region and the cathode region, the anode region is arranged on the upper part of the semiconductor substrate, and the photoelectric signal conversion region is arranged in the semiconductor substrate. The single photon avalanche photodiode has the advantage of low time jitter, and the time-of-flight sensor detection adopting the single photon avalanche photodiode has higher ranging precision.

Inventors

  • GUO TONGHUI

Assignees

  • 思特威(上海)电子科技股份有限公司

Dates

Publication Date
20260512
Application Date
20211125

Claims (17)

  1. 1. A single photon avalanche photodiode is characterized in that, the single photon avalanche photodiode includes: a semiconductor substrate including opposed first and second major faces; A deep trench region extending from a first main surface of the semiconductor substrate to an inside of the semiconductor substrate, the deep trench region being filled with a filler; A cathode region including a first cathode portion disposed on a first main surface of the semiconductor substrate and a second cathode portion disposed on an outer peripheral side of the deep trench region and extending along the deep trench region to an inside of the semiconductor substrate; a buffer region including a first buffer portion provided on an outer peripheral side and a lower side of the first cathode portion and a second buffer portion provided on an outer peripheral side of the second cathode portion, the buffer region and a contact region of the cathode region forming an avalanche region; An anode region disposed on an upper portion of the semiconductor substrate at an outer peripheral side of the first buffer portion; and the photoelectric signal conversion area is arranged below the first buffer part and on the outer periphery side of the second buffer part.
  2. 2. The single photon avalanche photodiode according to claim 1, wherein said deep trench region has a width of 0.1-0.3 microns and a depth of greater than or equal to 0.5 microns, and wherein said filler in said deep trench region comprises one of an oxide, nitride, polysilicon and metal.
  3. 3. The single photon avalanche photodiode according to claim 1, wherein said cathode region has a thickness of 0.1 μm or more, an ion doping concentration of 1e18 atoms/cm 3 or more, and a doping ion comprising one or a mixture of two of arsenic ions and phosphorus ions.
  4. 4. The single photon avalanche photodiode according to claim 1, wherein said anode region has a width of 0.1 μm or more, a depth of 0.1 μm or more, an ion doping concentration of 1e18 atom/cm 3 or more, a doping ion including boron ion, and/or said buffer region has a thickness of 0.05 μm to 0.3 μm, an ion doping concentration of 1e15 atom/cm 3 ~1e19 atom/cm 3 , and a doping ion including boron ion.
  5. 5. The single photon avalanche photodiode according to claim 1, wherein said cathode region is circumscribed by a first voltage and said anode region is circumscribed by a second voltage, wherein a difference between said first voltage and said second voltage is greater than or equal to an avalanche voltage of said single photon avalanche photodiode.
  6. 6. The single photon avalanche photodiode according to claim 1, further comprising a pixel isolation region disposed in said semiconductor substrate below said anode region and in contact with said buffer region, said pixel isolation region being an ion doped isolation region having a doping type that is the same as a doping type of said buffer region and having a doping concentration that is greater than a doping concentration of said buffer region to form an additional driving electric field for movement of photoelectric charges in said semiconductor substrate to said buffer region.
  7. 7. The single photon avalanche photodiode according to claim 1, wherein said single photon avalanche photodiode receives optical signals in a manner comprising one of a first main surface incidence and a second main surface incidence, and/or wherein said planar structure of said deep trench region comprises one of a polygon, a circle, and an ellipse.
  8. 8. The single photon avalanche photodiode according to claim 1, wherein each of said single photon avalanche photodiodes comprises more than two of said deep trench regions, said more than two deep trench regions being centrally symmetric or axisymmetrically distributed in said single photon avalanche photodiode.
  9. 9. The single photon avalanche photodiode according to any of claims 1-8, wherein said semiconductor substrate has a target area, a horizontal distance of photoelectric charge generated by said target area to said second buffer portion is smaller than a vertical distance of said photoelectric charge to said first buffer portion, wherein an upper edge of said target area extends from a center of a vertical direction of said second cathode portion to a bottom end of an outer edge of said semiconductor substrate on a corresponding side.
  10. 10. A time-of-flight sensor comprising the single photon avalanche photodiode according to any one of claims 1 to 9.
  11. 11. A ranging apparatus comprising the time-of-flight sensor of claim 10.
  12. 12. A method of manufacturing a single photon avalanche photodiode according to any of claims 1 to 9, comprising the steps of: providing a semiconductor substrate, wherein the semiconductor substrate comprises a first main surface and a second main surface which are opposite, and a photoelectric signal conversion area and an anode area are formed in the semiconductor substrate; Forming a deep trench region in the semiconductor substrate; implanting first doping ions into a first main surface of the semiconductor substrate and the side wall of the deep trench region through a first inclined ion implantation process to form a buffer region, wherein the buffer region comprises a first buffer part arranged on the first main surface of the semiconductor substrate and a second buffer part arranged on the periphery side of the deep trench region and extending into the semiconductor substrate along the deep trench region; implanting second doping ions into the first main surface of the semiconductor substrate and the side wall of the deep trench region through a second inclined ion implantation process, wherein the implantation depth is smaller than that of the first doping ions so as to form a cathode region in the buffer region, the cathode region comprises a first cathode part arranged on the first main surface of the semiconductor substrate and a second cathode part arranged on the outer peripheral side of the deep trench region and extending to the inside of the semiconductor substrate along the deep trench region, and the contact region of the buffer region and the cathode region forms an avalanche region; And forming a filler in the deep groove region.
  13. 13. The method of making a single photon avalanche photodiode according to claim 12, wherein implanting first dopant ions into a first major surface of said semiconductor substrate and sidewalls of said deep trench region by a first angled ion implantation process comprises: forming a protective layer on the surface of the semiconductor substrate and the surface of the deep groove region; And performing multiple first inclined ion implantations on the first main surface of the semiconductor substrate and the side wall of the deep groove region, wherein the semiconductor substrate rotates by an angle when the first inclined ion implantations are performed twice adjacently, so that the first doping ions on the side wall of the deep groove region are uniformly distributed.
  14. 14. The method of claim 13, wherein the semiconductor substrate is rotated by an angle α during two adjacent first oblique ion implants, the first oblique ion implants are performed n times to the first main surface of the semiconductor substrate and the sidewall of the deep trench region, each time the ion implants have the same dose and energy, wherein n is a positive integer greater than or equal to 2, and the product of n and α is 360 degrees.
  15. 15. The method of claim 12, wherein implanting second dopant ions into the first main surface of the semiconductor substrate and the sidewalls of the deep trench region by a second angled ion implantation process comprises performing a plurality of second angled ion implants into the first main surface of the semiconductor substrate and the sidewalls of the deep trench region, wherein the semiconductor substrate is rotated by an angle such that the second dopant ions are uniformly distributed in the sidewalls of the deep trench region during two adjacent second angled ion implants.
  16. 16. The method of claim 15, wherein the semiconductor substrate is rotated by an angle β during two adjacent second angled ion implants, the first angled ion implants are performed k times on the first main surface of the semiconductor substrate and the sidewall of the deep trench region, each time the ion implants have the same dose and energy, wherein k is a positive integer greater than or equal to 2, and the product of k and β is 360 degrees.
  17. 17. The method for manufacturing a single photon avalanche photodiode according to any one of claims 12 to 16, wherein an included angle between an ion implantation direction of the first and second inclined ion implantation processes and the first main surface of the semiconductor substrate is 2 to 15 degrees.

Description

Single photon avalanche photodiode and preparation method thereof Technical Field The invention belongs to the technical field of sensors, and particularly relates to a single photon avalanche photodiode with low time jitter in time-of-flight sensor equipment and a preparation method thereof. Background The flight time sensor is an important part of a distance measuring device, can capture three-dimensional (3D) distance information of a target object to obtain a 3D image, and is widely applied to the fields of behavior analysis, monitoring, automobile automatic driving, artificial intelligence, machine vision perception, image 3D enhancement and the like. The time-of-flight sensor adopts a time-of-flight method to measure the travel time of light from the light source transmitting end to the target object and then to the sensor receiving end after light pulses are reflected, so as to determine the distance information of the target object. The time-of-flight sensor can obtain the travel time of light by adopting a direct method, which is called a direct time-of-flight sensor, the direct time-of-flight sensor adopts a single photon avalanche photodiode to detect light pulse signals, the single photon avalanche photodiode converts the received light signals into photoelectric charges in a photoelectric signal conversion area, the photoelectric charges move to the avalanche area to trigger the photodiode to generate avalanche, and the generated high-current signals trigger a time-to-time digital converter to record the time from the emission to the receiving time period of the light pulse signals, and then the distance information is estimated by combining the light speed data. However, the existing single photon avalanche photodiode has a serious time jitter problem, and the ranging accuracy of the detection of the time-of-flight sensor is greatly reduced. It should be noted that the foregoing description of the background art is only for the purpose of providing a clear and complete description of the technical solution of the present application and is presented for the convenience of understanding by those skilled in the art. The above-described solutions are not considered to be known to the person skilled in the art simply because they are set forth in the background of the application section. Disclosure of Invention In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide a single photon avalanche photodiode and a method for manufacturing the same, which are used for solving the problem of serious time jitter of the single photon avalanche photodiode in the prior art, so as to greatly reduce the ranging accuracy of the detection of the time-of-flight sensor. To achieve the above and other related objects, the present invention provides a single photon avalanche photodiode including a semiconductor substrate including first and second opposite main surfaces, a deep trench region extending from the first main surface of the semiconductor substrate to the inside of the semiconductor substrate, the deep trench region being filled with a filler, a cathode region including a first cathode portion provided on the first main surface of the semiconductor substrate and a second cathode portion provided on an outer peripheral side of the deep trench region and extending into the semiconductor substrate along the deep trench region, a buffer region including a first buffer portion provided on an outer peripheral side and below the first cathode portion and a second buffer portion provided on an outer peripheral side of the second cathode portion, a contact region of the buffer region and the cathode region forming an avalanche region, an anode region provided on an upper portion of the semiconductor substrate on an outer peripheral side of the first buffer portion, and a signal conversion region provided under the first buffer portion and on an outer peripheral side of the second buffer portion. Optionally, the width of the deep trench region is 0.1-0.3 micrometers, and the depth is greater than or equal to 0.5 micrometers, and the filler in the deep trench region comprises one of oxide, nitride, polysilicon and metal. Optionally, the thickness of the cathode region is greater than or equal to 0.1 micrometer, the ion doping concentration is greater than or equal to 1e18atom/cm 3, and the doping ions comprise one or a mixture of two of arsenic ions and phosphorus ions. Optionally, the anode region has a width greater than or equal to 0.1 micrometer, a depth greater than or equal to 0.1 micrometer, an ion doping concentration greater than or equal to 1e18atom/cm 3, a doping ion comprising boron ions, and/or the buffer region has a thickness of 0.05 micrometer to 0.3 micrometer, an ion doping concentration of 1e15atom/cm 3～1e19atom/cm3, and a doping ion comprising boron ions. Optionally, the cathode region is externally connected with a first voltage, the anode regi