CN117038777A - Avalanche photodiode - Google Patents
Avalanche photodiode Download PDFInfo
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- CN117038777A CN117038777A CN202311170912.9A CN202311170912A CN117038777A CN 117038777 A CN117038777 A CN 117038777A CN 202311170912 A CN202311170912 A CN 202311170912A CN 117038777 A CN117038777 A CN 117038777A
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- 238000010521 absorption reaction Methods 0.000 claims abstract description 50
- 229910052710 silicon Inorganic materials 0.000 claims description 48
- 239000010703 silicon Substances 0.000 claims description 48
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 47
- 229910052751 metal Inorganic materials 0.000 claims description 30
- 239000002184 metal Substances 0.000 claims description 30
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 22
- 239000000758 substrate Substances 0.000 claims description 17
- 238000000034 method Methods 0.000 claims description 16
- 239000000377 silicon dioxide Substances 0.000 claims description 9
- 235000012239 silicon dioxide Nutrition 0.000 claims description 9
- 230000015556 catabolic process Effects 0.000 claims description 6
- 229910002601 GaN Inorganic materials 0.000 claims description 4
- JMASRVWKEDWRBT-UHFFFAOYSA-N Gallium nitride Chemical compound [Ga]#N JMASRVWKEDWRBT-UHFFFAOYSA-N 0.000 claims description 4
- 229910052732 germanium Inorganic materials 0.000 claims description 4
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 claims description 4
- 238000001514 detection method Methods 0.000 abstract description 19
- 230000005684 electric field Effects 0.000 abstract description 10
- 230000009286 beneficial effect Effects 0.000 abstract description 4
- 239000000463 material Substances 0.000 description 10
- 238000010586 diagram Methods 0.000 description 7
- 238000011049 filling Methods 0.000 description 4
- 229910052814 silicon oxide Inorganic materials 0.000 description 4
- 239000000969 carrier Substances 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 238000005530 etching Methods 0.000 description 3
- 238000000605 extraction Methods 0.000 description 3
- 230000005540 biological transmission Effects 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005538 encapsulation Methods 0.000 description 2
- 239000012212 insulator Substances 0.000 description 2
- 238000005468 ion implantation Methods 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 238000000206 photolithography Methods 0.000 description 2
- 238000005498 polishing Methods 0.000 description 2
- 239000002210 silicon-based material Substances 0.000 description 2
- 108091006149 Electron carriers Proteins 0.000 description 1
- 229910052581 Si3N4 Inorganic materials 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 238000001459 lithography Methods 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000002161 passivation Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 1
- 229910010271 silicon carbide Inorganic materials 0.000 description 1
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 1
- 230000003595 spectral effect Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/08—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors
- H01L31/10—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors characterised by potential barriers, e.g. phototransistors
- H01L31/101—Devices sensitive to infrared, visible or ultraviolet radiation
- H01L31/102—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier
- H01L31/107—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier the potential barrier working in avalanche mode, e.g. avalanche photodiodes
- H01L31/1075—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier the potential barrier working in avalanche mode, e.g. avalanche photodiodes in which the active layers, e.g. absorption or multiplication layers, form an heterostructure, e.g. SAM structure
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/0248—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies
- H01L31/0352—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by their shape or by the shapes, relative sizes or disposition of the semiconductor regions
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- Condensed Matter Physics & Semiconductors (AREA)
- Electromagnetism (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
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Abstract
The invention discloses an avalanche photodiode, comprising: a plurality of diode chips; the diode chip includes: the P-type heavily doped region, the P-type lightly doped absorption region, the N-type charge region, the N-type lightly doped avalanche region and the N-type heavily doped region are horizontally arranged in sequence from inside to outside, and the depth of the P-type lightly doped absorption region is larger than the width. The invention adopts horizontal arrangement, so that the electric field is transversely distributed, and the depth of the P-type lightly doped absorption region is larger than the width, thereby being beneficial to improving the photon detection efficiency.
Description
Technical Field
The invention relates to the technical field of photoelectric detectors, in particular to an avalanche photodiode.
Background
Avalanche photodiodes are used in a large number of applications in the sensor field, and in order to increase the spectral range of detection by such sensors, heterojunction structures are generally employed, in which non-silicon materials are used to absorb photons in the non-visible wavelength band, and silicon materials are used to transport and multiply the collected photons. The design can effectively expand the detection wave band of the sensor and ensure certain detection sensitivity, but the PN heterojunction of the conventional avalanche photodiode is mainly of a vertical structure, and if the thickness of a photosensitive material is increased for improving photon detection efficiency, a large number of defects are introduced, so that dark current or dark count is deteriorated.
Disclosure of Invention
In order to solve the technical problems, the invention provides an avalanche photodiode. The following presents a simplified summary in order to provide a basic understanding of some aspects of the disclosed embodiments. This summary is not an extensive overview and is intended to neither identify key/critical elements nor delineate the scope of such embodiments. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is presented later.
The invention adopts the following technical scheme:
the present invention provides an avalanche photodiode comprising: a plurality of diode chips; the diode die includes: the P-type heavy doping region, the P-type light doping absorption region, the N-type charge region, the N-type light doping avalanche region and the N-type heavy doping region are horizontally arranged in sequence from inside to outside;
the depth of the P-type lightly doped absorption region is larger than the width;
the N-type lightly doped avalanche region is formed by epitaxially growing silicon on a silicon wafer, a groove with a groove depth larger than a groove width is formed in the N-type lightly doped avalanche region, the N-type charge region and the P-type lightly doped absorption region are sequentially epitaxially grown at the bottom and the side wall of the groove and reserved with a central space, and the P-type heavily doped region is grown in the reserved central space.
Further, the avalanche photodiode further includes: a support silicon substrate, an N-type metal electrode region and a P-type electrode metal region; the P-type heavily doped region, the P-type lightly doped absorption region, the N-type charge region, the N-type lightly doped avalanche region and the N-type heavily doped region are positioned on the front surface of the supporting silicon substrate; the N-type metal electrode area is communicated with the N-type heavily doped area and is led out from the back surface of the support silicon substrate, and the P-type electrode metal area is communicated with the P-type heavily doped area and is led out from the back surface of the support silicon substrate.
Further, the avalanche photodiode further includes: an incident light anti-reflection layer and a microlens structure; the incident light anti-reflection layer is positioned on the front surface of the N-type lightly doped avalanche region, and the micro lens structure is grown on the front surface of the incident light anti-reflection layer.
Further, the avalanche photodiode further includes: a silicon dioxide layer; the N-type metal electrode region and the P-type electrode metal region are insulated and isolated from the support silicon substrate through the silicon dioxide layer.
Further, silicon is used as the N-type lightly doped avalanche region; germanium is used as the P-type lightly doped absorption region.
Further, silicon is used as the N-type lightly doped avalanche region; gallium nitride is used as the P-type lightly doped absorption region.
Further, the potential value of the N-type heavily doped region is lower than the potential value of the breakdown voltage of the N-type lightly doped avalanche region.
Further, the potential value of the N-type heavily doped region is higher than the potential value of the breakdown voltage of the N-type lightly doped avalanche region.
Further, the N-type lightly doped avalanche region has an N-type doping concentration ranging from 1×10 12 ～5×10 16 cm 3 The method comprises the steps of carrying out a first treatment on the surface of the The doping concentration of the N-type charge region is 1×10 16 ～5×10 17 cm 3 The method comprises the steps of carrying out a first treatment on the surface of the The P-type doping concentration range of the P-type lightly doped absorption region is 1 multiplied by 10 14 ～5×10 16 cm 3 The method comprises the steps of carrying out a first treatment on the surface of the The P type doping concentration range of the P type heavily doped region is 1 multiplied by 10 18 ～1×10 21 cm 3 。
Further, the thickness range of the N-type lightly doped avalanche region is 3-10 microns; the thickness range of the N-type charge region is 0.3-1.0 micrometers; the width of the groove ranges from 1 to 4 micrometers; the thickness range of the P-type lightly doped absorption region is 0.1-1.0 micrometers; the thickness of the P-type heavily doped region ranges from 0.02 microns to 0.5 microns.
The invention has the beneficial effects that: the P-type heavy doping region, the P-type light doping absorption region, the N-type charge region, the N-type light doping avalanche region and the N-type heavy doping region are horizontally distributed, so that the electric field is transversely distributed, the depth of the P-type light doping absorption region is larger than the width, and the photon detection efficiency is improved.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of an avalanche photodiode in accordance with the present invention;
FIG. 2 is a schematic diagram of another avalanche photodiode in accordance with the present invention;
FIG. 3 is a schematic diagram showing the lateral arrangement of a P-type heavily doped region, a P-type lightly doped absorption region, an N-type charge region, an N-type lightly doped avalanche region, and an N-type heavily doped region according to the present invention;
FIG. 4 is a schematic illustration of silicon after epitaxial growth on a silicon wafer;
FIG. 5 is a schematic illustration after etching trenches and growing N-type charge regions;
FIG. 6 is a schematic diagram of a P-type lightly doped absorption region and a P-type heavily doped region after growing;
FIG. 7 is a schematic diagram of a silicon wafer after surface planarization and preparation of an N-type heavily doped region;
FIG. 8 is a schematic diagram of wafer bonding;
FIG. 9 is a schematic illustration of wafer bonding after polishing;
fig. 10 is a schematic diagram after preparing an N-type metal electrode region and a P-type electrode metal region.
Detailed Description
Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the described embodiments are merely some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
As shown in fig. 1-3, in some illustrative embodiments, the present invention provides an avalanche photodiode for detection of weak photon signals, comprising: a plurality of diode chips; the avalanche photodiode is a single diode chip in the limit.
The diode chip includes: an N-type lightly doped avalanche region 104, an N-type charge region 105, a P-type lightly doped absorption region 106, a P-type heavily doped region 107, an N-type heavily doped region 109, an N-type metal electrode region 110, a P-type electrode metal region 111, an incident light anti-reflection layer 112, a microlens structure 113, a first silicon dioxide layer 116, a second silicon dioxide layer 203, and a supporting silicon substrate 202.
As shown in fig. 3, the P-type heavily doped region 107, the P-type lightly doped absorption region 106, the N-type charge region 105, the N-type lightly doped avalanche region 104 and the N-type heavily doped region 109 are sequentially arranged horizontally from inside to outside, so that the internal electric field of the avalanche photodiode is also horizontal in the operating state where the bias voltage is set.
The N-type lightly doped avalanche region 104 is formed by epitaxially growing silicon on a silicon wafer, specifically, by epitaxially growing silicon on a silicon wafer with a thickness ranging from 3 to 10 μm, and performing N-type lightly doping to finally form a N-type doped region with a concentration ranging from 1×10 12 ～5×10 16 cm 3 Is provided for the N-type lightly doped avalanche region 104.
The N-type lightly doped avalanche region 104 is provided with a trench, the depth of which is greater than the width, and the width of which ranges from 1 to 4 micrometers. The N-type charge region 105 is epitaxially grown on the surface of the N-type lightly doped avalanche region 104, wherein the surface of the N-type lightly doped avalanche region 104 includes a trench region, and only the N-type charge region 105 at the bottom and the sidewall of the trench remains after the polishing operation. The thickness of the N-type charge region 105 ranges from 0.3 to 1.0 μm, and the doping concentration of the N-type charge region 105 ranges from 1×10 16 ～5×10 17 cm 3 。
The P-type lightly doped absorption region 106 is epitaxially grown on the surface of the N-type charge region 105, i.e., the N-type charge region 105 and the P-type lightly doped absorption region 106 are sequentially epitaxially grown on the bottom and the sidewalls of the trench. Since the photosensitive material grows synchronously on the side wall and the bottom of the trench, and the depth of the trench is larger than the width of the trench, the P-type lightly doped absorption region 106 of the photosensitive material in the trench is also deeper than the width. The P-type lightly doped absorption region 106 has a P-type doping concentration in the range of 1×10 14 ～5×10 16 cm 3 The method comprises the steps of carrying out a first treatment on the surface of the The thickness of the P-type lightly doped absorption region 106 ranges from 0.1 to 1.0 microns.
N-type charge region 105 and P-type lightly doped absorption region 106 are sequentially epitaxially grownAt the bottom and side walls of the trench, a central space is reserved, and a P-type heavily doped region 107 grows in the reserved central space. The P-type heavily doped region 107 has a P-type doping concentration in the range of 1×10 18 ～1×10 21 cm 3 The method comprises the steps of carrying out a first treatment on the surface of the The thickness of the P-type heavily doped region 107 ranges from 0.02 to 0.5 microns.
The surface of the silicon wafer is flattened, etched until the surface of the N-type lightly doped avalanche region 104 is exposed, and subjected to pattern lithography and ion implantation of the N-type heavily doped region 109. As shown in fig. 1, the N-type heavily doped region 109 may occupy only a portion outside of the N-type lightly doped avalanche region 104. As shown in fig. 2, the N-type heavily doped region 109 is a trench structure and extends to the surface of the N-type lightly doped avalanche region 104, as opposed to the structure shown in fig. 1. The structure can further improve the electric field distribution in the N-type lightly doped avalanche region 104, and avoid partial early breakdown caused by uneven electric field.
Because the photosensitive material grows synchronously at the bottom and the side wall in the groove, and finally the depth of the P-type lightly doped absorption region 106 is larger than the width, the effective detection depth 115 of incident light in the P-type lightly doped absorption region 106 is increased while the defect density of the P-type lightly doped absorption region 106 is not increased, and the photon detection efficiency is improved. In addition, the photo-generated carriers drift laterally under the drive of an electric field, and the drift distance is not increased, so that the jitter time of photon detection is not increased.
In the invention, the P-type lightly doped absorption region 106 grows on the side wall and the bottom of the groove, and the P-type lightly doped absorption region 106 is a P-type low doped photosensitive material, which is beneficial to the improvement of the triggering probability of electron carriers. Meanwhile, the electric field distribution is in the horizontal direction and is perpendicular to the growth direction of the side wall of the photosensitive material, so that the collection of photo-generated carriers is facilitated, and the jitter time of photon detection is not influenced. Therefore, the structural design of the invention realizes effective improvement of photon detection efficiency.
The P-type heavily doped region 107, the P-type lightly doped absorption region 106, the N-type charge region 105, the N-type lightly doped avalanche region 104, and the N-type heavily doped region 109 are located on the front surface of the supporting silicon substrate 202. The N-type metal electrode region 110 communicates with the N-type heavily doped region 109, and the N-type metal electrode region 110 is extracted from the back side of the support silicon substrate 202 using a through silicon via process. Meanwhile, the P-type electrode metal region 111 communicates with the P-type heavily doped region 107, and the P-type electrode metal region 111 is led out from the back surface of the support silicon substrate 202 using a through-silicon via process. The N-type metal electrode region 110 and the P-type electrode metal region 111 are insulated from the support silicon substrate 202 by the first silicon dioxide layer 116. The metal electrode of the avalanche photodiode realizes back extraction of the metal electrode through the through silicon via and wafer transfer and bonding technology, thereby improving the effective filling ratio of the sensor.
The incident light anti-reflection layer 112 is located on the front surface of the N-type lightly doped avalanche region 104, and the microlens structure 113 is grown on the front surface of the incident light anti-reflection layer 112. The micro lens structure 113 is added on the light incidence surface, so that the effective filling rate of the sensor can be further improved, and the effective filling rate of the photosensitive surface can be improved based on a back-illuminated detection mode, thereby being beneficial to metal electrode extraction and encapsulation.
If silicon is used as the N-type lightly doped avalanche region 104 and germanium is used as the P-type lightly doped absorption region 106, the avalanche photodiode is a germanium/silicon heterojunction avalanche photodiode for detecting short wave infrared light signals.
If silicon is used as the N-type lightly doped avalanche region 104 and gallium nitride is used as the P-type lightly doped absorption region 106, the avalanche photodiode is a gallium nitride/silicon (silicon carbide/silicon) heterojunction photodiode for detecting ultraviolet light signals.
If the potential of the N-type heavily doped region 109 is lower than the breakdown voltage of the N-type lightly doped avalanche region 104, the N-type lightly doped avalanche region 104 is operated in the linear multiplication mode. When the incident light enters the micro lens structure 113, the light transmission direction is changed based on the optical phase change, so that the incident light is converged to the P-type lightly doped absorption region 106 as much as possible. After the P-type lightly doped absorption region 106 and the P-type heavily doped region 107 receive photons and generate photoelectron hole pairs by the effective photoelectric effect, the photo-generated electrons drift towards the N-type lightly doped avalanche region 104 under the drive of a transverse electric field and are effectively collected and participate in linear multiplication, so that an electric signal for effective photon detection is output on the N-type metal electrode region 110.
If the potential of the N-type heavily doped region 109 is higher than the voltage of the N-type lightly doped avalanche region 104, the N-type lightly doped avalanche region 104 is operated in geiger-counting mode. When the incident light enters the micro lens structure 113, the light transmission direction is changed based on the optical phase change, so that the incident light is converged to the P-type lightly doped absorption region 106 as much as possible. After the P-type lightly doped absorption region 106 and the P-type heavily doped region 107 receive photons and generate photoelectron hole pairs by the effective photoelectric effect, the photo-generated electrons drift towards the N-type lightly doped avalanche region 104 under the drive of a transverse electric field and are effectively collected and rapidly trigger the avalanche multiplication process, so that an effective pulse signal is output on the N-type metal electrode region 110.
The specific process embodiment is as follows:
first, as shown in fig. 4, a silicon-on-insulator wafer is prepared, which includes a silicon substrate 102 and a third silicon oxide layer 103, and the thickness of the third silicon oxide layer 103 ranges from 0.1 to 5 μm. The thickness of epitaxial silicon is required to be 3-10 micrometers, and the N-type doping concentration is required to be 1X 10 12 ～5×10 16 cm 3 An N-type lightly doped avalanche region 104 is eventually formed.
In the second step, as shown in fig. 5, a nitride medium such as silicon oxide or silicon nitride is grown on top of the silicon wafer on the insulator, and after the patterned photolithography, the silicon epitaxial layer portion to be photoetched is exposed, and after the processes such as trench etching, trench sidewall oxidation, oxide layer etching, etc., an N-type charge region 105 is epitaxially grown. The thickness of the N-type charge region 105 is in the range of 0.3-1.0 μm, and the doping concentration of the N-type charge region 105 is in the range of 1×10 16 ～5×10 17 cm 3 The trench width ranges from 1 to 4 microns and the trench depth is greater than the trench width. A silicon oxide layer 120 is then grown thereon and the areas where the photosensitive material is grown are lithographically etched.
Third, as shown in fig. 6, after cleaning, the P-type lightly doped absorption region 106 of the photosensitive material is selectively epitaxially grown. In this process, the bottom and sidewalls of the trench are simultaneously grown with the P-type lightly doped absorption region 106, and thenP-type heavily doped region 107 continues to be grown. The thickness of the P-type lightly doped absorption region 106 is in the range of 0.1-1.0 μm, and the doping concentration is in the range of 1×10 14 ～5×10 16 cm 3 The method comprises the steps of carrying out a first treatment on the surface of the The thickness of the P-type heavily doped region 107 ranges from 0.02 to 0.5 microns, and the doping concentration ranges from 1X 10 18 ～1×10 21 cm 3 . Since the photosensitive material grows synchronously on the side wall and the bottom of the trench, and the depth of the trench is larger than the width of the trench, the P-type lightly doped absorption region 106 of the photosensitive material in the trench is also deeper than the width.
Fourth, as shown in fig. 7, the surface of the silicon wafer is planarized, etched until the surface of the N-type lightly doped avalanche region 104 is exposed, patterned photolithography and ion implantation are performed on the N-type heavily doped region 109, and after annealing activation, the superfluous passivation on the surface is etched away again, so as to ensure the surface to be flat.
Fifth, as shown in fig. 8, a second silicon wafer with the same size and the second silicon dioxide layer 203 is prepared, and then the silicon wafer in the previous step is turned over and bonded with the second silicon wafer at a low temperature.
Sixth, as shown in fig. 9, after bonding, the upper surface is etched, polished, and polished, so as to ensure that the surface of the N-type lightly doped avalanche region 104 is exposed, smooth and less defective.
Seventh, as shown in fig. 10, the P-type heavily doped region 107 and the N-type heavily doped region 109 are led out by a through-silicon-via process, respectively connected to the N-type metal electrode region 110 and the P-type electrode metal region 111, and isolated from the support silicon substrate 202 by the first silicon dioxide layer 116.
In the eighth step, as shown in fig. 1, an incident light anti-reflection layer 112 corresponding to the main detection light band and a microlens structure 113 are grown on the surface of the N-type lightly doped avalanche region 104.
The invention provides a structural design of a novel avalanche photodiode, and the depth of a photon absorption region in a groove is larger than the width, so that the effective detection depth of incident light in a P-type lightly doped absorption region 106 is increased while the defect density of the P-type lightly doped absorption region 106 is not increased, and the photon detection efficiency is improved. In addition, the photo-generated carriers drift laterally under the drive of an electric field, and the drift distance is not increased, so that the jitter time of photon detection is not increased. Finally, based on a back-illuminated detection mode, the effective filling rate of the photosensitive surface can be improved, and the extraction and encapsulation of the metal electrode are facilitated.
The foregoing is merely illustrative of the present invention, and the present invention is not limited thereto, and any changes or substitutions easily contemplated by those skilled in the art within the scope of the present invention should be included in the present invention. Therefore, the protection scope of the invention is subject to the protection scope of the claims.
Claims (10)
1. An avalanche photodiode comprising: a plurality of diode chips; the diode chip is characterized by comprising: the P-type heavy doping region, the P-type light doping absorption region, the N-type charge region, the N-type light doping avalanche region and the N-type heavy doping region are horizontally arranged in sequence from inside to outside;
the depth of the P-type lightly doped absorption region is larger than the width;
the N-type lightly doped avalanche region is formed by epitaxially growing silicon on a silicon wafer, a groove with a groove depth larger than a groove width is formed in the N-type lightly doped avalanche region, the N-type charge region and the P-type lightly doped absorption region are sequentially epitaxially grown at the bottom and the side wall of the groove and reserved with a central space, and the P-type heavily doped region is grown in the reserved central space.
2. The avalanche photodiode according to claim 1 further comprising: a support silicon substrate, an N-type metal electrode region and a P-type electrode metal region;
the P-type heavily doped region, the P-type lightly doped absorption region, the N-type charge region, the N-type lightly doped avalanche region and the N-type heavily doped region are positioned on the front surface of the supporting silicon substrate;
the N-type metal electrode area is communicated with the N-type heavily doped area and is led out from the back surface of the support silicon substrate, and the P-type electrode metal area is communicated with the P-type heavily doped area and is led out from the back surface of the support silicon substrate.
3. The avalanche photodiode according to claim 2 further comprising: an incident light anti-reflection layer and a microlens structure; the incident light anti-reflection layer is positioned on the front surface of the N-type lightly doped avalanche region, and the micro lens structure is grown on the front surface of the incident light anti-reflection layer.
4. The avalanche photodiode according to claim 3 further comprising: a silicon dioxide layer; the N-type metal electrode region and the P-type electrode metal region are insulated and isolated from the support silicon substrate through the silicon dioxide layer.
5. The avalanche photodiode according to claim 4 wherein silicon is used as said N-type lightly doped avalanche region; germanium is used as the P-type lightly doped absorption region.
6. The avalanche photodiode according to claim 4 wherein silicon is used as said N-type lightly doped avalanche region; gallium nitride is used as the P-type lightly doped absorption region.
7. The avalanche photodiode according to claim 4 wherein said N-type heavily doped region has a potential value lower than a potential value of a breakdown voltage of said N-type lightly doped avalanche region.
8. The avalanche photodiode according to claim 4 wherein said N-type heavily doped region has a potential value higher than a potential value of a breakdown voltage of said N-type lightly doped avalanche region.
9. The avalanche photodiode according to any of claims 1-4 wherein said N-type lightly doped avalanche region has an N-type doping concentration in the range of 1 x 10 12 ～5×10 16 cm 3 The method comprises the steps of carrying out a first treatment on the surface of the The N-type chargeThe doping concentration of the region ranges from 1X 10 16 ～5×10 17 cm 3 The method comprises the steps of carrying out a first treatment on the surface of the The P-type doping concentration range of the P-type lightly doped absorption region is 1 multiplied by 10 14 ～5×10 16 cm 3 The method comprises the steps of carrying out a first treatment on the surface of the The P type doping concentration range of the P type heavily doped region is 1 multiplied by 10 18 ～1×10 21 cm 3 。
10. The avalanche photodiode according to claim 9 wherein said N-type lightly doped avalanche region has a thickness in the range of 3 to 10 microns; the thickness range of the N-type charge region is 0.3-1.0 micrometers; the width of the groove ranges from 1 to 4 micrometers; the thickness range of the P-type lightly doped absorption region is 0.1-1.0 micrometers; the thickness of the P-type heavily doped region ranges from 0.02 microns to 0.5 microns.
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