WO2022041550A1 - 一种雪崩光电探测器及其制备方法 - Google Patents

一种雪崩光电探测器及其制备方法 Download PDF

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WO2022041550A1
WO2022041550A1 PCT/CN2020/134059 CN2020134059W WO2022041550A1 WO 2022041550 A1 WO2022041550 A1 WO 2022041550A1 CN 2020134059 W CN2020134059 W CN 2020134059W WO 2022041550 A1 WO2022041550 A1 WO 2022041550A1
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layer
semiconductor material
electrode contact
region
transition
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French (fr)
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胡晓
肖希
陈代高
王磊
张宇光
李淼峰
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武汉光谷信息光电子创新中心有限公司
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Priority to EP20951218.5A priority Critical patent/EP4207318A4/en
Publication of WO2022041550A1 publication Critical patent/WO2022041550A1/zh

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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
    • H01L31/02—Details
    • H01L31/0232—Optical elements or arrangements associated with the device
    • H01L31/02327—Optical elements or arrangements associated with the device the optical elements being integrated or being directly associated to the device, e.g. back reflectors
    • 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
    • H01L31/0256—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 the material
    • H01L31/0264—Inorganic materials
    • H01L31/028—Inorganic materials including, apart from doping material or other impurities, only elements of Group IV of the Periodic Table
    • 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
    • H01L31/035272—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 characterised by at least one potential jump barrier or surface barrier
    • H01L31/035281—Shape of the body
    • 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
    • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
    • H01L31/1804—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof comprising only elements of Group IV of the Periodic Table
    • 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
    • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
    • H01L31/20—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof such devices or parts thereof comprising amorphous semiconductor materials
    • H01L31/202—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof such devices or parts thereof comprising amorphous semiconductor materials including only elements of Group IV of the Periodic Table
    • H01L31/204—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof such devices or parts thereof comprising amorphous semiconductor materials including only elements of Group IV of the Periodic Table including AIVBIV alloys, e.g. SiGe, SiC
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
    • G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
    • G02B2006/12083—Constructional arrangements
    • G02B2006/121—Channel; buried or the like
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present application relates to the technical field of photonic integrated chip detection, in particular to an avalanche photodetector and a preparation method thereof.
  • Photodetector is one of the key optoelectronic devices in optical communication, optical interconnection and optoelectronic integration technology. It is widely used in various fields of military and national economy, and avalanche photodetector is subject to high responsivity and sensitivity. The market welcomes.
  • the current avalanche photodetectors have shortcomings such as high dark current and low responsivity, so further improvement is needed.
  • the embodiments of the present application provide an avalanche photodetector and a manufacturing method thereof to solve at least one problem existing in the background art.
  • an embodiment of the present application provides an avalanche photodetector, including: a substrate, and a device structure layer on the substrate; the device structure layer at least includes a vertical direction of the substrate, and the device structure layer is arranged in sequence upward in a direction perpendicular to the plane of the substrate The charge layer, the transition layer, the absorption layer and the first electrode contact layer; wherein,
  • the charge layer is a first semiconductor material layer with a first doping type
  • the transition layer is epitaxially grown on the charge layer, and the transition layer is an intrinsic layer;
  • the absorption layer is epitaxially grown on the first region of the transition layer, and the absorption layer is an intrinsic second semiconductor material layer;
  • the first electrode contact layer is epitaxially grown on the second region of the transition layer, and the height of the first electrode contact layer is higher than the height of the absorber layer so that the first electrode contact layer covers the an absorption layer, the first electrode contact layer is a first semiconductor material layer;
  • the material of the transition layer is a composite material of the first semiconductor material and the second semiconductor material.
  • the first semiconductor material is silicon; the second semiconductor material is germanium; and the composite material of the first semiconductor material and the second semiconductor material is germanium silicon.
  • the first doping type is P-type.
  • the avalanche photodetector further includes: a first electrode contact region located in the first electrode contact layer, the first electrode contact region having a first doping type of first semiconductor material region.
  • the second area surrounds the first area; or, the second area includes two sub-areas separated by the first area.
  • Another aspect of the embodiments of the present application provides a method for preparing an avalanche photodetector, and the method includes the following steps:
  • first epitaxial layer on the substrate, where the first epitaxial layer is a first semiconductor material layer; performing ion doping of a first doping type on the first epitaxial layer to form a charge layer;
  • a second epitaxial layer is grown on the charge layer to form an intrinsic transition layer;
  • the material of the second epitaxial layer is a composite material of the first semiconductor material and the second semiconductor material;
  • the third epitaxial layer is a second semiconductor material layer
  • a fourth epitaxial layer is grown on the second region of the transition layer, the fourth epitaxial layer having a height higher than the third epitaxial layer to form a first electrode contact layer overlying the absorber layer ;
  • the fourth epitaxial layer is a first semiconductor material layer.
  • the first semiconductor material is silicon; the second semiconductor material is germanium; and the composite material of the first semiconductor material and the second semiconductor material is germanium silicon.
  • the first doping type is P-type.
  • the method further includes: performing ion doping of a first doping type on the fourth epitaxial layer to form a first electrode in the first electrode contact layer contact area.
  • the second area surrounds the first area; or, the second area includes two sub-areas separated by the first area.
  • Embodiments of the present application provide an avalanche photodetector and a method for fabricating the same, wherein the avalanche photodetector includes: a substrate, and a device structure layer on the substrate; the device structure layer at least includes A charge layer, a transition layer, an absorption layer, and a first electrode contact layer are arranged in order in a direction perpendicular to the plane of the substrate; wherein, the charge layer is a first semiconductor material layer with a first doping type; the transition layer Epitaxially grown on the charge layer, the transition layer is an intrinsic layer; the absorption layer is epitaxially grown on the first region of the transition layer, and the absorption layer is an intrinsic second semiconductor material layer; The first electrode contact layer is epitaxially grown on the second region of the transition layer, and the height of the first electrode contact layer is higher than the height of the absorber layer so that the first electrode contact layer covers the absorber The first electrode contact layer is a first semiconductor material layer; the material of the transition layer is a composite material of
  • the transition layer is provided, and the material of the transition layer is a composite material of the first semiconductor material and the second semiconductor material, so that the transition layer and the charge layer, the absorption layer and the first electrode contact layer are all formed. It can have better lattice matching; thus, on the one hand, the transition layer can grow well on the charge layer, avoiding the lattice mismatch problem caused by growing the absorber layer directly on the charge layer; on the other hand, By epitaxially growing the absorber layer in the first region of the transition layer, and by epitaxially growing the first electrode contact layer in the second region of the transition layer, both the absorber layer and the first electrode contact layer can have better growth quality. The dark current is reduced, the responsivity of the detector is improved, the device structure is simple, and the process cost is low.
  • FIG. 1 is a side cross-sectional view of an avalanche photodetector in the related art
  • FIG. 2 is a side cross-sectional view of an avalanche photodetector provided by an embodiment of the present application
  • FIG. 3 is a top view of an avalanche photodetector provided by an embodiment of the present application.
  • FIG. 4 is a top view of another embodiment of the transition layer of the avalanche photodetector provided by the embodiment of the present application;
  • FIG. 5 is a schematic flowchart of a method for preparing an avalanche photodetector according to an embodiment of the present application
  • 6a-6h are schematic cross-sectional views of the device structure of the avalanche photodetector provided in the embodiment of the present application during the fabrication process.
  • 113-top silicon layer silicon slab layer
  • 1131-first doped region 1132-second doped region (second electrode contact region); 1133-second metal electrode;
  • 140-transition layer (interface layer); 141, 141'-first region; 142, 142'-second region;
  • Silicon photonics technology is a new generation technology for the development and integration of optical devices based on silicon and silicon-based substrate materials (such as SiGe/Si, silicon-on-insulator, etc.) using existing complementary metal-oxide-semiconductor (CMOS) processes.
  • CMOS complementary metal-oxide-semiconductor
  • Silicon photonics technology combines the ultra-large-scale and ultra-high-precision manufacturing characteristics of integrated circuit technology with the advantages of ultra-high speed and ultra-low power consumption of photonic technology. It is a disruptive technology to deal with the failure of Moore's Law. This combination is enabled by the scalability of semiconductor wafer fabrication, thereby reducing costs.
  • the photodetector has the function of realizing the conversion of optical signals to electrical signals.
  • III-V semiconductor materials are more suitable for photodetectors, III-V semiconductor materials are incompatible with silicon technology and cannot be used with silicon. Effective monolithic integration is carried out; considering the compatibility of germanium material with CMOS process, a technology of using germanium material as a light absorbing layer material to form a germanium-silicon photodetector has been proposed in the art.
  • Silicon photonic integrated chips can use germanium-silicon materials compatible with CMOS technology to realize avalanche photodetection. It uses silicon materials as optical waveguides and at the same time as avalanche gain regions, and germanium materials absorb photons.
  • FIG. 1 is a side cross-sectional view of an avalanche photodetector in the related art.
  • an absorption layer 50 needs to be epitaxially grown on the charge layer 30.
  • the charge layer 30 is used to regulate the electric field distribution inside the detector.
  • the absorption layer 50 is used to absorb the target detection light, and the target detection light The photons are converted into photo-generated carrier pairs, thereby converting optical signals into electrical signals; wherein, the charge layer 30 is a doped silicon layer, and the absorption layer 50 is a germanium layer.
  • the charge layer 30 and the absorption layer 50 are different semiconductor material layers, and the charge layer 30 has doping ions, during epitaxial growth, due to the lattice mismatch between the charge layer 30 and the absorption layer 50, the As a result, the growth quality of the absorption layer 50 is poor, and the responsivity of the detector is reduced.
  • a heavily doped first electrode contact region needs to be provided on one side of the absorption layer 50 to form an electric field between the second electrode contact region and the electric field to extract photo-generated carriers.
  • the first electrode contact region is formed by doping directly on the absorption layer 50, since the absorption layer 50 serves as a light absorption region, the doping will cause light absorption loss and reduce the quantum efficiency of the detector. Therefore, generally, a first electrode contact layer 60 is epitaxially grown on the absorber layer 50, and the first electrode contact layer 60 is doped to form the first electrode contact region 61; the first electrode contact layer 60 is usually for the silicon layer.
  • a transition layer can be added between every two semiconductor layers with different materials. One layer of transition layer will make the process complicated and the cost higher.
  • FIG. 2 is a side cross-sectional view of an avalanche photodetector provided by an embodiment of the present application
  • FIG. 3 is a top view of an avalanche photodetector provided by an embodiment of the present application. It should be noted that FIG. 2 is a side cross-sectional view along the dotted line in FIG. 3 .
  • the structure of the avalanche photodetector at least includes: a substrate, and a device structure layer located on the substrate; the device structure layer at least includes The charge layer 130, the transition layer 140, the absorption layer 150 and the first electrode contact layer 160 are arranged in sequence upward in the plane direction of the substrate; wherein, the charge layer 130 is a first semiconductor material layer with a first doping type;
  • the transition layer 140 is epitaxially grown on the charge layer 130, and the transition layer 140 is an intrinsic layer;
  • the absorption layer 150 is epitaxially grown on the first region 141 of the transition layer 140, and the absorption layer 150 is Intrinsic second semiconductor material layer;
  • the first electrode contact layer 160 is epitaxially grown on the second region 142 of the transition layer 140 , and the height of the first electrode contact layer 160 is higher than that of the absorption layer 150 height so that the first electrode contact layer 160 covers the absorption layer 150, the first electrode contact layer 160 is a first semiconductor material layer;
  • the transition layer 140 is made of
  • a transition layer 140 is added between the charge layer 130 and the absorption layer 150 , the absorption layer 150 is located on the first region 141 of the transition layer 140 , and the first electrode contact layer 160 is located on the transition layer 140 .
  • the material of the transition layer is a composite material of the first semiconductor material and the second semiconductor material; in this way, the absorption layer 150 and the first electrode contact layer are improved.
  • the growth quality of 160 in this way, is not only conducive to reducing dark current and improving the responsivity of the detector, but also the device structure is simple and the process cost is low.
  • the substrate may be an elemental semiconductor material substrate (such as a silicon (Si) substrate, a germanium (Ge) substrate, etc.), a compound semiconductor material substrate (such as a silicon germanium (SiGe) substrate, etc.) substrate, etc.), or silicon-on-insulator (SOI) substrate, germanium-on-insulator (GeOI) substrate, etc.
  • elemental semiconductor material substrate such as a silicon (Si) substrate, a germanium (Ge) substrate, etc.
  • a compound semiconductor material substrate such as a silicon germanium (SiGe) substrate, etc.) substrate, etc.
  • SOI silicon-on-insulator
  • GeOI germanium-on-insulator
  • the substrate as an SOI substrate as an example, and the SOI substrate includes an underlying substrate 111, a buried oxide layer 112, and a top silicon layer 113; the underlying substrate 111 is an underlying silicon material; The buried oxide layer 112 is located on the underlying substrate 111 ; the buried oxide layer 112 is, for example, a silicon dioxide layer; the top silicon layer 113 is located on the buried oxide layer 112 .
  • the substrate may include a top surface on the front side and a bottom surface on the back side opposite to the front side; in the case of ignoring the flatness of the top and bottom surfaces, the direction perpendicular to the top and bottom surfaces of the substrate is defined as the second direction.
  • the second direction is also the stacking direction of each layer structure subsequently deposited on the substrate, or the height direction of the device.
  • the surface where the top surface and the bottom surface of the substrate are located, or strictly speaking, the central plane in the thickness direction of the substrate, is determined as the substrate plane; the direction parallel to the substrate plane is the direction along the substrate plane.
  • Two mutually intersecting first and third directions are defined in the plane direction of the substrate; for example, the first and third directions are two directions that are perpendicular to each other.
  • the direction of the dotted line in the figure is the first direction
  • the direction perpendicular to the direction of the dotted line is the third direction.
  • the top silicon layer 113 is formed with a first doped region 1131 and a second doped region 1132 arranged adjacently;
  • the doping types are the same, and both are second doping types different from the first doping type;
  • the doping concentration of the second doping region 1132 is greater than the doping concentration of the first doping region 1131;
  • the first doping region 1131 is, for example, an N+ doping region, and the second doping region 1132 is, for example, an N++ doping region;
  • the doping concentration of the first doping region 1131 is 2 ⁇ 10 17 /cm 3 ⁇ 8 ⁇ 10 18 /cm 3 ;
  • the doping concentration of the second doping region 1132 is 1 ⁇ 10 20 /cm 3 to 8 ⁇ 10 20 /cm 3 .
  • the charge layer 130 , the transition layer 140 , the absorption layer 150 and the first electrode contact layer 160 are disposed directly above the first doping region 1131 ; the second doping region 1132 is the the second electrode contact area of the avalanche photodetector.
  • FIG. 2 and FIG. 3 only illustrate that two second electrode contact regions are formed on the top silicon layer 113 1132; the two second electrode contact regions 1132 are located on both sides of the first doped region 1131, respectively.
  • the avalanche photodetector further includes an avalanche layer 120 epitaxially grown on the top silicon layer 113 , and the avalanche layer 120 is an intrinsic first semiconductor material layer.
  • the size range of the avalanche layer 120 in the first direction is 700 nm ⁇ 7000 nm; the size range in the second direction is 100 nm ⁇ 1500 nm; and the size range in the third direction is 4 ⁇ m ⁇ 30 ⁇ m.
  • the avalanche layer of the avalanche photodetector refers to a region where carrier avalanche multiplication occurs.
  • the absorption layer of the avalanche photodetector can convert the incident optical signal into multiple electron-hole pairs, and these hole-electron pairs flow to the electrode under the action of the electric field to form a photocurrent; the avalanche layer can absorb the absorption through the action of avalanche multiplication.
  • the photocurrent formed by the layer is further amplified; and then the photocurrent is conducted through a pair of metal electrodes to realize photodetection.
  • the charge layer 130 is located on the avalanche layer 120 , and the charge layer 130 is a first semiconductor material layer with a first doping type.
  • the charge layer 130 is used to regulate the electric field distribution inside the detector, so that the avalanche layer 120 has a high enough electric field, so that avalanche multiplication can occur, and at the same time, the absorption layer 150 has an appropriate electric field strength, so as to ensure the current carrying capacity. At the same time of high-speed drift of the electrons, the electric field in the absorption layer 150 is prevented from being too high, so as to prevent the excessively high electric field from generating excessive tunnel dark current or causing harmful avalanche multiplication.
  • the size of the charge layer 130 in the first direction is in the range of 700 nm to 7000 nm
  • the size in the second direction is in the range of 50 to 1000 nm
  • the size in the third direction is in the range of 4 ⁇ m to 30 ⁇ m.
  • the transition layer 140 is epitaxially grown on the charge layer 130 , and the transition layer 140 is an intrinsic layer; the material of the transition layer 140 is a composite of a first semiconductor material and a second semiconductor material. Material.
  • the transition layer 140 may also be referred to as an interface layer.
  • the size of the transition layer 140 in the first direction is in the range of 700 nm to 7000 nm
  • the size in the second direction is in the range of 20 to 100 nm
  • the size in the third direction is in the range of 4 ⁇ m to 30 ⁇ m.
  • the absorber layer 150 is epitaxially grown on the first region 141 of the transition layer 140 , and the absorber layer 150 is an intrinsic second semiconductor material layer.
  • the absorption layer 150 is used for absorbing the target detection light, converting the photons of the target detection light into photo-generated carrier pairs, so as to convert the optical signal into an electrical signal.
  • the lower surface of the absorption layer 150 is in direct contact with the first region 141 of the transition layer 140 ; a portion of the lower surface of the first electrode contact layer 160 is in direct contact with the second region 142 of the transition layer 140 In direct contact, the other part is in direct contact with the upper surface of the absorption layer 150 .
  • the first electrode contact layer 160 also covers the sidewall of the absorption layer 150 so as to be in direct contact with the sidewall.
  • the size of the absorption layer 150 in the first direction ranges from 450 nm to 5500 nm.
  • the size of the absorption layer 150 in the first direction is smaller than the size of the transition layer 140 in the first direction, and the size difference therebetween is, for example, in the range of 150 nm ⁇ 1500 nm.
  • the size of the absorption layer 150 in the second direction ranges from 150 nm to 600 nm.
  • the size of the absorption layer 150 in the third direction may be smaller than the size of the transition layer 140 in the third direction; the size difference between the two may be greater than 150 nm, for example.
  • the second area 142 surrounds the first area 141 ; the second area 142 is an area on the transition layer 140 other than the first area 141 .
  • the first area 141 is, for example, the area within the smaller dotted box in the figure
  • the second area 142 is, for example, the smaller dotted box and the larger dotted line in the figure. the area between the boxes.
  • the size of the absorption layer 150 in the third direction may also be equal to the size of the transition layer 140 in the third direction; in this case, the size of the absorption layer 150 in the third direction may be in the range of 4 ⁇ m ⁇ 30 ⁇ m.
  • the second region 142 ′ of the transition layer 140 is located on both sides of the first region 141 ′, so that the part of the first electrode contact layer 160 in contact with the transition layer 140 is described in the third direction
  • the absorber layer 150 is spaced; that is, the second region 142' includes two sub-regions separated by the first region 141'.
  • the second region 142' may also be a region on the transition layer 140 other than the first region 141'.
  • the first electrode contact layer 160 is epitaxially grown on the second region 142 of the transition layer 140, and the height of the first electrode contact layer 160 is higher than the height of the absorption layer 150 so that the The first electrode contact layer 160 covers the absorption layer 150, and the first electrode contact layer 160 is a first semiconductor material layer;
  • the first semiconductor material is silicon; the second semiconductor material is germanium; the composite material of the first semiconductor material and the second semiconductor material is silicon germanium (Si x Ge 1-x , where 0 ⁇ x ⁇ 1); the first doping type is P-type.
  • the doping concentration of the avalanche layer 120 is ⁇ 2 ⁇ 10 16 /cm 3 ; the doping concentration of the charge layer 130 is 2 ⁇ 10 17 /cm 3 to 6 ⁇ 10 18 /cm 3 ; the transition layer 140
  • the doping concentration of the absorbing layer 150 is ⁇ 2 ⁇ 10 15 /cm 3 ; the doping concentration of the absorption layer 150 is 2 ⁇ 10 17 /cm 3 to 6 ⁇ 10 18 /cm 3 .
  • the top silicon layer 113 may also be referred to as a silicon slab layer; the avalanche layer 120 and the charge layer 130 may also be referred to as a strip-shaped silicon waveguide layer; thus, the avalanche photodetector may include a silicon material region, so the The silicon material region may include the silicon slab layer and the strip-shaped silicon waveguide layer.
  • the avalanche photodetector further includes a first electrode contact region 161 located in the first electrode contact layer 160, and the first electrode contact region 161 is a first electrode contact region 161 with a first doping type.
  • the first electrode contact region 161 is a P+ doped region, such as a P+ doped silicon region.
  • the doping concentration of the first electrode contact region 161 is 1 ⁇ 10 19 /cm 3 to 2 ⁇ 10 20 /cm 3 .
  • first electrode contact regions 161 there may be one or more first electrode contact regions 161 on the first electrode contact layer 160 , and FIG. 2 and FIG. 3 only illustrate that the first electrode contact layer 160 has two The case of an electrode contact region 161 .
  • the first electrode contact area 161 is located on the absorber layer 150 ; in other words, the first electrode contact area 161 is located in the portion of the first electrode contact layer 160 that covers the absorber layer 150 .
  • the avalanche photodetector further includes an optical waveguide 180, and the optical waveguide 180 is disposed on the side of the absorption layer 150 along a direction parallel to the plane of the substrate; It transmits optical signals and couples the optical signals to the absorption layer 150 .
  • the material of the optical waveguide 180 may be silicon nitride, that is, the optical waveguide 180 may be a silicon nitride optical waveguide. In some other embodiments, the material of the optical waveguide 180 may also be silicon.
  • the upper surface of the optical waveguide 180 may be flush with or higher than the upper surface of the absorption layer 150 ; the lower surface of the optical waveguide 180 may be flush with or lower than the absorption layer 150 the lower surface.
  • the distance between the optical waveguide 180 and the absorption layer 150 is 100 nm ⁇ 500 nm.
  • the optical waveguide 180 includes an optical input port 181 and a first waveguide region 182, and the first waveguide region 182 is a straight waveguide region.
  • the optical signal transmitted by the optical waveguide 180 propagates along the direction from the optical input port 181 to the first waveguide region 182 .
  • the size of the optical waveguide 180 in the first direction ranges from 500 nm to 3000 nm
  • the size in the second direction ranges from 100 nm to 900 nm
  • the size in the third direction ranges from 5 ⁇ m to 32 ⁇ m.
  • a filling layer 170 is arranged between the optical waveguide 180 and the absorption layer 150 , and a filling layer 170 is arranged between the optical waveguide 180 and the top silicon layer 113 .
  • the filling layer 170 covers the top silicon layer 113 and the absorption layer 150
  • the optical waveguide 180 is disposed in the filling layer 170 and is connected with the top silicon layer 113 and the absorbing layer 150 .
  • the absorbing layers 150 are separated by a certain distance.
  • the filling layer 170 is used to support and fix the optical waveguide 180, and the filling layer 170 has a lower refractive index, so as to optically confine the transmitted optical signal.
  • the difference between the refractive index of the optical waveguide 180 and the refractive index of the absorption layer 150 is large, and the optical waveguide 180 is arranged on the side of the absorption layer 150 , thus improving the coupling efficiency of the optical signal from the optical waveguide 180 to the absorption layer 150
  • the length of the coupling region is equal to the length of the absorption layer 150 in the third direction. In this way, the gain-bandwidth product of the detector can be increased by reducing the size of the region of the absorption layer 150 .
  • the projection of the sidewall of the absorption layer 150 on the silicon flat layer 113 has a second shape.
  • the second shape may be a rectangle, and the rectangle has a shape along the third direction.
  • the extended long side and the short side extending along the first direction; wherein, the length of the second shape in the third direction is the length of the long side of the rectangle, and the length of the first shape in the first direction is a rectangle
  • the length of the short side It can be understood with reference to FIG. 3 that the length of the coupling region is the length of the second shape in the third direction.
  • the length of the absorption layer 150 in the third direction is 4 ⁇ m ⁇ 30 ⁇ m. That is, the length of the coupling region is 4 ⁇ m ⁇ 30 ⁇ m.
  • the optical waveguide 180 is designed as a lateral waveguide, which realizes the slow coupling of light into the absorption layer 150 and the strong interaction with the absorption layer 150, and at the same time benefits from the absorption layer 150 and the avalanche layer
  • the decoupling of 120 and the design of the intrinsic transition layer 140 can realize avalanche photodetection with low dark current, high gain, large bandwidth, and high quantum efficiency.
  • a first electrode contact region 161 is formed on the first electrode contact layer 160
  • a second electrode contact region 1132 is formed on the top silicon layer 113 ; on the first electrode contact region 161
  • a first metal electrode 162 and a second metal electrode 1133 are respectively provided on the contact region 1132 with the second electrode.
  • the distance between any one of the first metal electrode 162 and the second metal electrode 1133 and the optical waveguide 180 is greater than or equal to 700 nm.
  • the extraction of the The carriers generated in the absorption layer 150, and the electric field direction of the applied electric field is the same as the electric field direction of the built-in electric field formed in the absorption layer 150, so that the applied electric field can speed up the moving speed of the carriers, thereby improving the avalanche Responsiveness of the detector.
  • the avalanche photodetector is designed based on a vertical electrode structure, so that the electric field distribution in the absorption layer is uniform, and at the same time, the light transmission, light absorption, and light multiplication are decoupled, which facilitates the transport of photogenerated carriers and helps to improve Gain Bandwidth Product.
  • the embodiment of the present application also provides a method for preparing an avalanche photodetector, please refer to FIG. 5 for details. As shown in the figure, the method includes the following steps:
  • Step 501 providing a substrate
  • Step 502 Grow a first epitaxial layer on the substrate, where the first epitaxial layer is a first semiconductor material layer; perform ion doping of a first doping type on the first epitaxial layer to form a charge layer;
  • Step 503 growing a second epitaxial layer on the charge layer to form an intrinsic transition layer;
  • the material of the second epitaxial layer is a composite material of the first semiconductor material and the second semiconductor material;
  • Step 504 growing a third epitaxial layer on the first region of the transition layer to form an intrinsic absorption layer; the third epitaxial layer is a second semiconductor material layer;
  • Step 505 growing a fourth epitaxial layer on the second region of the transition layer, the height of the fourth epitaxial layer is higher than that of the third epitaxial layer, so as to form a first epitaxial layer covering the absorption layer an electrode contact layer; the fourth epitaxial layer is a first semiconductor material layer.
  • 6a-6h are schematic cross-sectional views of the device structure of the avalanche photodetector provided in the embodiment of the present application during the fabrication process.
  • step 501 is performed to provide a substrate;
  • the substrate may be a substrate of elemental semiconductor material (for example, a silicon (Si) substrate, a germanium (Ge) substrate, etc.), a compound semiconductor material substrate ( For example, a silicon germanium (SiGe) substrate, etc.), or a silicon-on-insulator (SOI) substrate, a germanium-on-insulator (GeOI) substrate, and the like.
  • elemental semiconductor material for example, a silicon (Si) substrate, a germanium (Ge) substrate, etc.
  • a compound semiconductor material substrate for example, a silicon germanium (SiGe) substrate, etc.
  • SOI silicon-on-insulator
  • GeOI germanium-on-insulator
  • the substrate includes an underlying substrate 111, a buried oxide layer 112, and a top silicon layer 113;
  • the underlying substrate 111 can be made of underlying silicon material ;
  • the buried oxide layer 112 is located on the underlying substrate 111 ;
  • the buried oxide layer 112 is, for example, a silicon dioxide layer;
  • the top silicon layer 113 is located on the buried oxide layer 112 .
  • a first doped region 1131 and a second doped region 1132 are formed on the top silicon layer 113 through photolithography, ion implantation, and other processes;
  • the doping type of the region 1131 and the second doping region 1132 are the same, and both are of the second doping type; the doping concentration of the second doping region 1132 is greater than the doping concentration of the first doping region 1131 ;
  • the first doping region 1131 is, for example, an N+ doping region, and the second doping region 1132 is, for example, an N++ doping region;
  • the doping concentration of the first doping region 1131 is 2 ⁇ 10 17 /cm 3 ⁇ 8 ⁇ 10 18 /cm 3 ;
  • the doping concentration of the second doping region 1132 is 1 ⁇ 10 20 /cm 3 to 8 ⁇ 10 20 /cm 3 .
  • one or more second doping regions 1132 may be formed on the top silicon layer 113
  • FIG. 6 a only illustrates the case where two second doping regions 1132 are formed on the top silicon layer 113 ;
  • the two second electrode contact regions 1132 are respectively located on both sides of the first doped region 1131 .
  • step 502 is performed, a selective epitaxial growth process is performed, and a first epitaxial layer is grown on the top silicon layer 113 to form an avalanche layer 120; the first epitaxial layer is a first semiconductor material layer; Next, a selective doping process is performed to perform ion doping of the first doping type on the first epitaxial layer to form the charge layer 130 .
  • the size range of the avalanche layer 120 in the first direction is 700 nm ⁇ 7000 nm; the size range in the second direction is 100 nm ⁇ 1500 nm; and the size range in the third direction is 4 ⁇ m ⁇ 30 ⁇ m.
  • the size of the charge layer 130 in the first direction is in the range of 700 nm to 7000 nm
  • the size in the second direction is in the range of 50 to 1000 nm
  • the size in the third direction is in the range of 4 ⁇ m to 30 ⁇ m.
  • step 503 is performed, a selective epitaxial growth process is performed, a second epitaxial layer is grown on the charge layer 130, and an intrinsic transition layer 140 is formed; the material of the second epitaxial layer is the first A composite of a semiconductor material and a second semiconductor material.
  • the size of the transition layer 140 in the first direction is in the range of 700 nm to 7000 nm
  • the size in the second direction is in the range of 20 to 100 nm
  • the size in the third direction is in the range of 4 ⁇ m to 30 ⁇ m.
  • step 504 is performed, and a selective epitaxial growth process is performed again to grow a third epitaxial layer on the first region 141 of the transition layer 140 to form an intrinsic absorption layer 150 ; the third epitaxial layer
  • the material is the second semiconductor material.
  • the size of the absorption layer 150 in the first direction ranges from 450 nm to 5500 nm.
  • the size of the absorption layer 150 in the first direction is smaller than the size of the transition layer 140 in the first direction, and the size difference therebetween is, for example, in the range of 150 nm ⁇ 1500 nm.
  • the size of the absorption layer 150 in the second direction ranges from 150 nm to 600 nm.
  • the size of the absorption layer 150 in the third direction may be smaller than the size of the transition layer 140 in the third direction; the size difference between the two may be greater than 150 nm, for example.
  • the second area 142 surrounds the first area 141 ; the second area 142 is an area on the transition layer 140 other than the first area 141 .
  • the first area 141 is, for example, the area within the smaller dotted box in the figure
  • the second area 142 is, for example, the smaller dotted box and the larger dotted line in the figure. the area between the boxes.
  • the size of the absorption layer 150 in the third direction may also be equal to the size of the transition layer 140 in the third direction; in this case, the size of the absorption layer 150 in the third direction may be in the range of 4 ⁇ m ⁇ 30 ⁇ m.
  • the second region 142 ′ of the transition layer 140 is located on both sides of the first region 141 ′, so that the part of the first electrode contact layer 160 in contact with the transition layer 140 is described in the third direction
  • the absorber layer 150 is spaced; that is, the second region 142' includes two sub-regions separated by the first region 141'.
  • the second region 142' may also be a region on the transition layer 140 other than the first region 141'.
  • the doping concentration of the avalanche layer 120 is ⁇ 2 ⁇ 10 16 /cm 3 ; the doping concentration of the charge layer 130 is 2 ⁇ 10 17 /cm 3 to 6 ⁇ 10 18 /cm 3 ; the transition layer 140
  • the doping concentration of the absorption layer 150 is ⁇ 2 ⁇ 10 15 /cm 3 ; the doping concentration of the absorption layer 150 is 2 ⁇ 10 17 /cm 3 to 6 ⁇ 10 18 /cm 3
  • step 505 is performed, a selective epitaxial growth process is performed, and a fourth epitaxial layer is grown on the second region 142 of the transition layer 140 , and the height of the fourth epitaxial layer is higher than that of the third epitaxial layer.
  • the lower surface of the absorption layer 150 is in direct contact with the first region 141 of the transition layer 140 ; a portion of the lower surface of the first electrode contact layer 160 is in direct contact with the second region 142 of the transition layer 140 The other part is in direct contact with the upper surface of the absorption layer 150; the first electrode contact layer 160 also covers the sidewall of the absorption layer 150, so as to be in direct contact with the sidewall.
  • the first semiconductor material is silicon; the second semiconductor material is germanium; the composite material of the first semiconductor material and the second semiconductor material is germanium silicon; the first doping type is P-type.
  • the method further includes performing ion doping of the first doping type on the fourth epitaxial layer by using processes such as photolithography and ion implantation doping, so as to perform ion doping of the first doping type on the fourth epitaxial layer.
  • a first electrode contact region 161 is formed in an electrode contact layer 160 , that is, the first electrode contact region 161 is a P+ doped silicon region.
  • the doping concentration of the first electrode contact region 161 is 1 ⁇ 10 19 /cm 3 to 2 ⁇ 10 20 /cm 3 .
  • the number of first electrode contact regions 161 on the first electrode contact layer 160 may be one or more, and in this embodiment, the number of first electrode contact regions 161 may be two.
  • the first electrode contact area 161 is located on the absorber layer 150; in other words, the first electrode contact area 161 is located in a portion of the first electrode contact layer 160 that covers the absorber layer 150.
  • the top silicon layer 113 may also be referred to as a silicon slab layer; the avalanche layer 120 and the charge layer 130 may also be referred to as a strip-shaped silicon waveguide layer; thus, the avalanche photodetector may be A silicon material region is included, and the silicon material region may include the silicon slab layer and the strip-shaped silicon waveguide layer.
  • the method further includes forming an optical waveguide 180 , and the optical waveguide 180 is disposed on the side of the absorption layer 150 along a direction parallel to the plane of the substrate.
  • a filling layer 170 is formed on the substrate, specifically on the top silicon layer 113 .
  • the material of the filling layer 170 may include silicon dioxide.
  • the filling layer 170 may be formed by depositing a certain thickness of silicon dioxide material and performing a planarization process.
  • a patterned mask layer (not shown in the figure) may be used to define a region where an optical waveguide needs to be formed on the filling layer 170; an optical waveguide material is grown in the region, for example, by depositing silicon nitride. material or growing silicon material to form the optical waveguide 180 .
  • the upper surface of the optical waveguide 180 may be flush with or higher than the upper surface of the absorption layer 150 ; the lower surface of the optical waveguide 180 may be flush with or lower than the absorption layer 150 the lower surface.
  • the material of the optical waveguide 180 may be silicon nitride, that is, the optical waveguide 180 may be a silicon nitride optical waveguide. In some other embodiments, the material of the optical waveguide 180 may also be silicon.
  • the optical waveguide 180 is used to transmit and couple optical signals to the absorption layer 150.
  • the distance between the optical waveguide 180 and the absorption layer 150 is 100 nm ⁇ 500 nm.
  • the optical waveguide 180 includes an optical input port 181 and a first waveguide region 182, and the first waveguide region 182 is a straight waveguide region.
  • the optical signal transmitted by the optical waveguide 180 propagates along the direction from the optical input port 181 to the first waveguide region 182 .
  • the size of the optical waveguide 180 in the first direction ranges from 500 nm to 3000 nm
  • the size in the second direction ranges from 100 nm to 900 nm
  • the size in the third direction ranges from 5 ⁇ m to 32 ⁇ m.
  • the method further includes forming vertical electrode contact regions 161 on the first electrode contact region 161 and on the second electrode contact region 1132 of the top silicon layer 113 respectively.
  • the first metal electrode 162 and the second metal electrode 1133 are arranged in the plane direction of the substrate (ie, the second direction).
  • the above two metal electrodes can be fabricated by using processes such as photolithography and inductive plasma etching to open windows, and magnetron sputtering to deposit metal materials.
  • the distance between any one of the first metal electrode 162 and the second metal electrode 1133 and the optical waveguide 180 is greater than or equal to 700 nm.
  • the upper surfaces of the first metal electrode 162 and the second metal electrode 1133 should be higher than the upper surface of the optical waveguide 180 .
  • it also includes forming a filling layer 170 on the optical waveguide 180, and using photolithography and etching (such as inductive plasma etching) processes to form and expose the first electrode contact region 161 and the first electrode contact region 161 in the filling layer 170.
  • a window of the second electrode contact region 1132 filling the window with an electrode material (eg, a metal material deposited by magnetron sputtering) to form the first metal electrode 162 and the second metal electrode 1133 .
  • avalanche photodetectors provided in the embodiments of the present application and the embodiments of the methods for preparing avalanche photodetectors belong to the same concept; the technical features in the technical solutions described in the embodiments are not in conflict with each other. , can be combined arbitrarily, and will not be repeated here.

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Abstract

本申请实施例公开了一种雪崩光电探测器及其制备方法。其中，所述雪崩光电探测器包括：衬底，以及位于衬底上的器件结构层；器件结构层至少包括沿垂直衬底平面方向向上依次设置的电荷层、过渡层、吸收层以及第一电极接触层；其中，电荷层为具有第一掺杂类型的第一半导体材料层；过渡层外延生长于电荷层上，过渡层为本征层；吸收层外延生长于过渡层的第一区域上，吸收层为本征的第二半导体材料层；第一电极接触层外延生长于过渡层的第二区域上，第一电极接触层的高度高于吸收层的高度以使第一电极接触层包覆吸收层，第一电极接触层为第一半导体材料层；过渡层的材料为第一半导体材料和第二半导体材料的复合材料。

Description

一种雪崩光电探测器及其制备方法
相关申请的交叉引用
本申请基于申请号为202010901268.8、申请日为2020年8月31日的中国专利申请提出，并要求该中国专利申请的优先权，该中国专利申请的全部内容在此引入本申请作为参考。
技术领域
本申请涉及光子集成芯片探测技术领域，具体涉及一种雪崩光电探测器及其制备方法。
背景技术
光电探测器是光通信、光互连和光电集成技术中关键的光电器件之一，目前在军事和国民经济的各个领域都有广泛的用途，而雪崩光电探测器又以高响应度和灵敏度受到市场欢迎。
然而，目前的雪崩光电探测器具有暗电流高、响应度低等缺点，因此有待进一步的改进。
发明内容
有鉴于此，本申请实施例为解决背景技术中存在的至少一个问题而提供一种雪崩光电探测器及其制备方法。
为达到上述目的，本申请的技术方案是这样实现的：
本申请实施例一方面提供了一种雪崩光电探测器，包括：衬底，以及位于所述衬底上的器件结构层；所述器件结构层至少包括沿垂直所述衬底平面方向向上依次设置的电荷层、过渡层、吸收层以及第一电极接触层； 其中，
所述电荷层为具有第一掺杂类型的第一半导体材料层；
所述过渡层外延生长于所述电荷层上，所述过渡层为本征层；
所述吸收层外延生长于所述过渡层的第一区域上，所述吸收层为本征的第二半导体材料层；
所述第一电极接触层外延生长于所述过渡层的第二区域上，所述第一电极接触层的高度高于所述吸收层的高度以使所述第一电极接触层包覆所述吸收层，所述第一电极接触层为第一半导体材料层；
所述过渡层的材料为第一半导体材料和第二半导体材料的复合材料。
在本申请的一种可选实施例中，所述第一半导体材料为硅；所述第二半导体材料为锗；所述第一半导体材料和第二半导体材料的复合材料为锗硅。
在本申请的一种可选实施例中，所述第一掺杂类型为P型。
在本申请的一种可选实施例中，所述雪崩光电探测器还包括：位于所述第一电极接触层内的第一电极接触区，所述第一电极接触区为具有第一掺杂类型的第一半导体材料区。
在本申请的一种可选实施例中，所述第二区域环绕所述第一区域；或者，所述第二区域包括被所述第一区域间隔的两个子区域。
本申请实施例另一方面提供了一种雪崩光电探测器的制备方法，所述方法包括以下步骤：
提供衬底；
在所述衬底上生长第一外延层，所述第一外延层为第一半导体材料层；对所述第一外延层进行第一掺杂类型的离子掺杂，形成电荷层；
在所述电荷层上生长第二外延层，形成本征的过渡层；所述第二外延层的材料为第一半导体材料和第二半导体材料的复合材料；
在所述过渡层的第一区域上生长第三外延层，形成本征的吸收层；所述第三外延层为第二半导体材料层；
在所述过渡层的第二区域上生长第四外延层，所述第四外延层的高度高于所述第三外延层的高度，以形成一包覆所述吸收层的第一电极接触层；所述第四外延层为第一半导体材料层。
在本申请的一种可选实施例中，所述第一半导体材料为硅；所述第二半导体材料为锗；所述第一半导体材料和第二半导体材料的复合材料为锗硅。
在本申请的一种可选实施例中，所述第一掺杂类型为P型。
在本申请的一种可选实施例中，所述方法还包括：对所述第四外延层进行第一掺杂类型的离子掺杂，以在所述第一电极接触层内形成第一电极接触区。
在本申请的一种可选实施例中，所述第二区域环绕所述第一区域；或者，所述第二区域包括被所述第一区域间隔的两个子区域。
本申请实施例提供了一种雪崩光电探测器及其制备方法，其中，所述雪崩光电探测器包括：衬底，以及位于所述衬底上的器件结构层；所述器件结构层至少包括沿垂直所述衬底平面方向向上依次设置的电荷层、过渡层、吸收层以及第一电极接触层；其中，所述电荷层为具有第一掺杂类型的第一半导体材料层；所述过渡层外延生长于所述电荷层上，所述过渡层为本征层；所述吸收层外延生长于所述过渡层的第一区域上，所述吸收层为本征的第二半导体材料层；所述第一电极接触层外延生长于所述过渡层的第二区域上，所述第一电极接触层的高度高于所述吸收层的高度以使所述第一电极接触层包覆所述吸收层，所述第一电极接触层为第一半导体材料层；所述过渡层的材料为第一半导体材料和第二半导体材料的复合材料。本申请实施例中，通过设置过渡层，并且过渡层的材料为第一半导体材料 和第二半导体材料的复合材料，由此，过渡层与电荷层、吸收层和第一电极接触层之间都能够具有较好的晶格匹配度；从而，一方面，过渡层可以在电荷层上较好的生长，避免了直接在电荷层上生长吸收层而产生的晶格失配问题；另一方面，借助过渡层的第一区域外延生长吸收层，借助过渡层的第二区域外延生长第一电极接触层，可以使得吸收层和第一电极接触层均具有较好的生长质量，如此，不仅有利于降低暗电流、提高探测器的响应度，而且器件结构简单，工艺成本较低。
附图说明
图1为相关技术中雪崩光电探测器的侧面剖视图；
图2为本申请实施例提供的雪崩光电探测器的侧面剖视图；
图3为本申请实施例提供的雪崩光电探测器的俯视图；
图4为本申请实施例提供的雪崩光电探测器的过渡层的另一实施例的俯视图；
图5为本申请实施例提供的雪崩光电探测器的制备方法的流程示意图；
图6a-6h为本申请实施例提供的雪崩光电探测器在制备过程中的器件结构剖面示意图。
附图标记说明：
111-底层衬底；112-埋氧层；
113-顶硅层(硅平板层)；1131-第一掺杂区；1132-第二掺杂区(第二电极接触区)；1133-第二金属电极；
120-雪崩层；
30、130-电荷层；
140-过渡层(界面层)；141、141’-第一区域；142、142’-第二区域；
50、150-吸收层；
60、160-第一电极接触层(第四外延层)；61、161-第一电极接触区； 162-第一金属电极；
170-填充层；
180-光波导；181-光输入端口；182-第一波导区。
具体实施方式
下面将参照附图更详细地描述本申请公开的示例性实施方式。虽然附图中显示了本申请的示例性实施方式，然而应当理解，可以以各种形式实现本申请，而不应被这里阐述的具体实施方式所限制。相反，提供这些实施方式是为了能够更透彻地理解本申请，并且能够将本申请实施例公开的范围完整的传达给本领域的技术人员。
在下文的描述中，给出了大量具体的细节以便提供对本申请实施例更为彻底的理解。然而，对于本领域技术人员而言显而易见的是，本申请实施例可以无需一个或多个这些细节而得以实施。在其他的例子中，为了避免与本申请实施例发生混淆，对于本领域公知的一些技术特征未进行描述；即，这里不描述实际实施例的全部特征，不详细描述公知的功能和结构。
在附图中，为了清楚，层、区、元件的尺寸以及其相对尺寸可能被夸大。自始至终相同附图标记表示相同的元件。
应当明白，当元件或层被称为“在……上”、“与……相邻”、“连接到”或“耦合到”其它元件或层时，其可以直接地在其它元件或层上、与之相邻、连接或耦合到其它元件或层，或者可以存在居间的元件或层。相反，当元件被称为“直接在……上”、“与……直接相邻”、“直接连接到”或“直接耦合到”其它元件或层时，则不存在居间的元件或层。应当明白，尽管可使用术语第一、第二、第三等描述各种元件、部件、区、层和/或部分，这些元件、部件、区、层和/或部分不应当被这些术语限制。这些术语仅仅用来区分一个元件、部件、区、层或部分与另一个元件、部件、区、层或部分。因此，在不脱离本申请实施例教导之下，下面讨论的第一元件、部 件、区、层或部分可表示为第二元件、部件、区、层或部分。而当讨论的第二元件、部件、区、层或部分时，并不表明本申请实施例必然存在第一元件、部件、区、层或部分。
空间关系术语例如“在……下”、“在……下面”、“下面的”、“在……之下”、“在……之上”、“上面的”等，在这里可为了方便描述而被使用从而描述图中所示的一个元件或特征与其它元件或特征的关系。应当明白，除了图中所示的取向以外，空间关系术语意图还包括使用和操作中的器件的不同取向。例如，如果附图中的器件翻转，然后，描述为“在其它元件下面”或“在其之下”或“在其下”元件或特征将取向为在其它元件或特征“上”。因此，示例性术语“在……下面”和“在……下”可包括上和下两个取向。器件可以另外地取向(旋转90度或其它取向)并且在此使用的空间描述语相应地被解释。
在此使用的术语的目的仅在于描述具体实施例并且不作为本申请实施例的限制。在此使用时，单数形式的“一”、“一个”和“所述/该”也意图包括复数形式，除非上下文清楚指出另外的方式。还应明白术语“组成”和/或“包括”，当在该说明书中使用时，确定所述特征、整数、步骤、操作、元件和/或部件的存在，但不排除一个或更多其它的特征、整数、步骤、操作、元件、部件和/或组的存在或添加。在此使用时，术语“和/或”包括相关所列项目的任何及所有组合。
为了彻底理解本申请实施例，将在下列的描述中提出详细的步骤以及详细的结构，以便阐释本申请实施例的技术方案。本申请的可选实施例详细描述如下，然而除了这些详细描述外，本申请还可以具有其他实施方式。
硅光子技术是基于硅和硅基衬底材料(如SiGe/Si、绝缘体上硅等)，利用现有互补金属氧化物半导体(CMOS)工艺进行光器件开发和集成的新一代技术。硅光子技术结合了集成电路技术的超大规模、超高精度制造的特 性和光子技术超高速率、超低功耗的优势，是应对摩尔定律失效的颠覆性技术。这种结合得力于半导体晶圆制造的可扩展性，因而能够降低成本。光电探测器作为硅光子架构的核心器件之一，具有实现光信号到电信号转换的功能。但晶体硅材料的能带结构决定其在光通信波段探测效率很低，虽然III-V族半导体材料更适合用于光电探测器，但是III-V族半导体材料与硅工艺不兼容，无法与硅进行有效的单片集成；考虑到锗材料与CMOS工艺的兼容性，本领域提出了采用锗材料作为光吸收层材料而形成锗硅光电探测器的技术。
硅光子集成芯片中可采用兼容CMOS工艺的锗硅材料实现雪崩光电探测，它是利用硅材料作为光波导，同时作为雪崩增益区，锗材料吸收光子。
图1为相关技术中雪崩光电探测器的侧面剖视图。在相关技术中，需要在电荷层30上外延生长一层吸收层50，所述电荷层30用于调控探测器内部电场分布，所述吸收层50用于吸收目标探测光，将目标探测光的光子转化为光生载流子对，从而将光信号转化为电信号；其中，电荷层30为掺杂硅层，吸收层50为锗层。但是，由于电荷层30和吸收层50为不同的半导体材料层，并且电荷层30中具有掺杂离子，故在外延生长时，因电荷层30和吸收层50之间存在晶格不匹配，会导致吸收层50生长质量差，进而导致探测器响应度降低。此外，在雪崩光电探测器中，需要在吸收层50的一侧提供一个重掺杂的第一电极接触区，以便与第二电极接触区之间形成电场抽取光生载流子。如果直接在吸收层50上掺杂形成第一电极接触区，由于吸收层50作为光吸收区，进行掺杂会造成光吸收损耗，降低探测器量子效率。因此，一般采用先在吸收层50上外延生长一层第一电极接触层60的方式，在第一电极接触层60内进行掺杂，形成第一电极接触区61；第一电极接触层60通常为硅层。但是，吸收层50和第一电极接触层60之间又会因为材料的不同，在外延生长时，出现晶格不匹配的情况，从而导致第 一电极接触层60生长质量差。为改善生长质量问题，可以在每两层材料不同的半导体层之间加一层过渡层，但若电荷层30和吸收层50之间、吸收层50和第一电极接触层60之间都加一层过渡层，又会使工艺复杂，成本较高。
基于此，提出了本申请实施例的以下技术方案。
图2为本申请实施例提供的雪崩光电探测器的侧面剖视图，图3为本申请实施例提供的雪崩光电探测器的俯视图，需要说明的是，图2为沿图3中虚线方向的侧面剖视图，如图2和图3所示，本申请实施例提供的雪崩光电探测器的结构至少包括：衬底，以及位于所述衬底上的器件结构层；所述器件结构层至少包括沿垂直所述衬底平面方向向上依次设置的电荷层130、过渡层140、吸收层150以及第一电极接触层160；其中，所述电荷层130为具有第一掺杂类型的第一半导体材料层；所述过渡层140外延生长于所述电荷层130上，所述过渡层140为本征层；所述吸收层150外延生长于所述过渡层140的第一区域141上，所述吸收层150为本征的第二半导体材料层；所述第一电极接触层160外延生长于所述过渡层140的第二区域142上，所述第一电极接触层160的高度高于所述吸收层150的高度以使所述第一电极接触层160包覆所述吸收层150，所述第一电极接触层160为第一半导体材料层；所述过渡层140的材料为第一半导体材料和第二半导体材料的复合材料。
在本申请实施例中，在电荷层130和吸收层150之间加了一层过渡层140，吸收层150位于过渡层140的第一区域141上，第一电极接触层160位于过渡层140的第二区域142以及吸收层150上，且过渡层140为本征层，过渡层的材料为第一半导体材料和第二半导体材料的复合材料；如此，改善了吸收层150和第一电极接触层160的生长质量，如此，不仅有利于降低暗电流、提高探测器的响应度，而且器件结构简单，工艺成本较低。
在一实施例中，所述衬底可以为单质半导体材料衬底(例如为硅(Si)衬底、锗(Ge)衬底等)、复合半导体材料衬底(例如为锗硅(SiGe)衬底等)，或绝缘体上硅(SOI)衬底、绝缘体上锗(GeOI)衬底等。本实施例以所述衬底为SOI衬底为例进行说明，所述SOI衬底包括底层衬底111、埋氧层112和顶硅层113；所述底层衬底111为可以底层硅材料；所述埋氧层112位于所述底层衬底111上；所述埋氧层112例如为二氧化硅层；所述顶硅层113位于所述埋氧层112上。
这里，衬底可以包括处于正面的顶表面以及处于与正面相对的背面的底表面；在忽略顶表面和底表面的平整度的情况下，定义垂直衬底顶表面和底表面的方向为第二方向。第二方向也为后续在衬底上沉积各层结构的层叠方向，或称器件的高度方向。而衬底顶表面和底表面所在的面，或者严格意义上讲衬底厚度方向上的中心面，即确定为衬底平面；平行衬底平面的方向即为沿衬底平面方向。在所述衬底平面方向上定义两彼此相交的第一方向和第三方向；所述第一方向和所述第三方向例如为彼此垂直的两个方向。在本实施例中，如图3所示，图中虚线方向为第一方向，与虚线方向垂直的方向为第三方向。
在一实施例中，所述顶硅层113内形成有邻接布置的第一掺杂区1131和第二掺杂区1132；所述第一掺杂区1131和所述第二掺杂区1132的掺杂类型相同，均为不同于所述第一掺杂类型的第二掺杂类型；所述第二掺杂区1132的掺杂浓度大于所述第一掺杂区1131的掺杂浓度；所述第一掺杂区1131例如为N+掺杂区，所述第二掺杂区1132例如为N++掺杂区；所述第一掺杂区1131的掺杂浓度为2×10 17/cm 3～8×10 18/cm 3；所述第二掺杂区1132的掺杂浓度为1×10 20/cm 3～8×10 20/cm 3。
所述电荷层130、所述过渡层140、所述吸收层150以及所述第一电极接触层160设置于所述第一掺杂区1131的正上方；所述第二掺杂区1132 作为所述雪崩光电探测器的第二电极接触区。
需要说明的是，所述顶硅层113上的第二电极接触区1132可以为一个或多个，图2和图3仅示例出所述顶硅层113上形成有两个第二电极接触区1132的情况；两个所述第二电极接触区1132分别位于所述第一掺杂区1131的两侧。
所述雪崩光电探测器还包括外延生长于所述顶硅层113上的雪崩层120，所述雪崩层120为本征的第一半导体材料层。
所述雪崩层120在第一方向上的尺寸范围为700nm～7000nm；在第二方向上的尺寸范围为100nm～1500nm；在第三方向上的尺寸范围为4μm～30μm。
这里，所述雪崩光电探测器的雪崩层是指发生载流子雪崩倍增的区域。雪崩光电探测器的吸收层能够将入射的光信号转换成多个电子-空穴对，这些空穴-电子对在电场作用下流向电极从而形成光电流；雪崩层能够通过雪崩倍增的作用将吸收层形成的光电流进一步放大；进而通过一对金属电极传导光电流，实现光电探测。
在一实施例中，所述电荷层130位于所述雪崩层120上，所述电荷层130为具有第一掺杂类型的第一半导体材料层。
所述电荷层130用于调控探测器内部电场分布，使所述雪崩层120内有足够高的电场，从而可以发生雪崩倍增，同时使所述吸收层150有适当的电场强度，在保证载流子高速漂移的同时防止所述吸收层150内电场过高，以防止过高的电场产生过大的隧道暗电流或产生有害的雪崩倍增。
所述电荷层130在第一方向上的尺寸范围为700nm～7000nm，在第二方向上的尺寸范围为50～1000nm，在第三方向上的尺寸范围为4μm～30μm。
在一实施例中，所述过渡层140外延生长于所述电荷层130上，所述过渡层140为本征层；所述过渡层140的材料为第一半导体材料和第二半 导体材料的复合材料。
所述过渡层140又可以称为界面层。
所述过渡层140在第一方向上的尺寸范围为700nm～7000nm，在第二方向上的尺寸范围为20～100nm，在第三方向上的尺寸范围为4μm～30μm。
在一实施例中，所述吸收层150外延生长于所述过渡层140的第一区域141上，所述吸收层150为本征的第二半导体材料层。
所述吸收层150用于吸收目标探测光，将目标探测光的光子转化为光生载流子对，从而将光信号转化为电信号。
所述吸收层150的下表面与所述过渡层140的所述第一区域141直接接触；所述第一电极接触层160的下表面的一部分与所述过渡层140的所述第二区域142直接接触，另一部分与所述吸收层150的上表面直接接触。所述第一电极接触层160还覆盖所述吸收层150的侧壁，从而与所述侧壁直接接触。
所述吸收层150在第一方向上的尺寸范围为450nm～5500nm。所述吸收层150在第一方向上的尺寸小于所述过渡层140在第一方向上的尺寸，并且二者之间的尺寸差值例如在150nm～1500nm的范围内。
所述吸收层150在第二方向上的尺寸范围为150nm～600nm。
所述吸收层150在第三方向上的尺寸可以小于所述过渡层140在第三方向上的尺寸；二者之间的尺寸差值例如大于150nm。所述第二区域142环绕所述第一区域141；所述第二区域142为所述过渡层140上除所述第一区域141以外的区域。具体地，如图3所示，所述第一区域141例如为图中较小的虚线方框以内的区域，所述第二区域142例如为图中较小的虚线方框和较大的虚线方框之间的区域。
在其他一些实施例中，所述吸收层150在第三方向上的尺寸也可以等于所述过渡层140在第三方向上的尺寸；此时，所述吸收层150在第三方 向上的尺寸范围可以为4μm～30μm。具体地，如图4所示，过渡层140的第二区域142’位于第一区域141’的两侧，从而第一电极接触层160与过渡层140相接触的部分在第三方向上被所述吸收层150间隔；也即，第二区域142’包括被第一区域141’间隔的两个子区域。所述第二区域142’同样可以为所述过渡层140上除所述第一区域141’以外的区域。
在一实施例中，所述第一电极接触层160外延生长于所述过渡层140的第二区域142上，所述第一电极接触层160的高度高于所述吸收层150的高度以使所述第一电极接触层160包覆所述吸收层150，所述第一电极接触层160为第一半导体材料层；
这里，所述第一半导体材料为硅；所述第二半导体材料为锗；所述第一半导体材料和第二半导体材料的复合材料为锗硅(Si xGe 1-x，其中0<x<1)；所述第一掺杂类型为P型。
所述雪崩层120的掺杂浓度为≤2×10 16/cm 3；所述电荷层130的掺杂浓度为2×10 17/cm 3～6×10 18/cm 3；所述过渡层140的掺杂浓度为≤2×10 15/cm 3；所述吸收层150的掺杂浓度为2×10 17/cm 3～6×10 18/cm 3。
所述顶硅层113也可称为硅平板层；所述雪崩层120和所述电荷层130也可称为条形硅波导层；如此，所述雪崩光电探测器可以包括硅材料区，所述硅材料区可以包括所述硅平板层和所述条形硅波导层。
在一实施例中，所述雪崩光电探测器还包括，位于所述第一电极接触层160内的第一电极接触区161，所述第一电极接触区161为具有第一掺杂类型的第一半导体材料区；应当理解，所述第一电极接触层160内还可以包括未被掺杂的本征区域。在一具体实施例中，所述第一电极接触区161为P+掺杂区，例如为P+掺杂硅区。所述第一电极接触区161的掺杂浓度为1×10 19/cm 3～2×10 20/cm 3。
需要说明的是，所述第一电极接触层160上的第一电极接触区161可 以为一个或多个，图2和图3仅示例出所述第一电极接触层160上形成有两个第一电极接触区161的情况。
所述第一电极接触区161位于所述吸收层150上；换言之，所述第一电极接触区161位于所述第一电极接触层160的覆盖所述吸收层150上的部分内。
在一实施例中，所述雪崩光电探测器还包括光波导180，所述光波导180沿平行于所述衬底平面的方向设置于所述吸收层150的侧方；所述光波导180用于传输光信号，并将所述光信号耦合至所述吸收层150。
所述光波导180的材料具体可以为氮化硅，即所述光波导180可以为氮化硅光波导。在其他一些实施例中，所述光波导180的材料还可以为硅。
在一实施例中，所述光波导180的上表面可以齐平于或高于所述吸收层150的上表面；所述光波导180的下表面可以齐平于或低于所述吸收层150的下表面。
所述光波导180与所述吸收层150之间的距离为100nm～500nm。
所述光波导180包括光输入端口181和第一波导区182，所述第一波导区182为直形波导区。
所述光波导180传输的光信号沿所述光输入端口181至所述第一波导区182的方向传播。
所述光波导180在第一方向上的尺寸范围为500nm～3000nm，在第二方向上的尺寸范围为100nm～900nm，在第三方向上的尺寸范围为5μm～32μm。
所述光波导180与所述吸收层150之间具有填充层170，所述光波导180与所述顶硅层113之间具有填充层170。如图2所示，所述填充层170覆盖所述顶硅层113和所述吸收层150，所述光波导180设置在所述填充层170中，并与所述顶硅层113和所述吸收层150各间隔一定距离，所述填充层170用于支撑和固定所述光波导180，且所述填充层170具有较低的折射 率，从而可以对传输的光信号进行光约束。
所述光波导180的折射率和所述吸收层150的折射率的差较大，且光波导180设置在吸收层150的侧面，如此提高了光信号从光波导180到吸收层150的耦合效率；可以理解的是，耦合效率越高，耦合进入吸收层150中的光子数就越多，这样仅需要较短的耦合区长度就可以实现高响应速度。需要说明的是，耦合区长度等于所述吸收层150在第三方向上的长度。如此可以通过减少所述吸收层150区域的尺寸，进而提高探测器的增益带宽积。
所述吸收层150的侧壁在所述硅平板层113上的投影具有第二形状，在图3所示实施例中，该第二形状可以为矩形，所述矩形具有沿所述第三方向延伸的长边和沿所述第一方向延伸的短边；其中，所述第二形状在第三方向上的长度为矩形长边的长度，所述第一形状在第一方向上的长度为矩形短边的长度。结合图3可以理解的是，耦合区长度即为所述第二形状在第三方向上的长度。例如，所述吸收层150在第三方向上的长度为4μm～30μm。也就是说，耦合区的长度为4μm～30μm。通过控制所述吸收层150在第三方向上的长度，即可以控制耦合区的长度。
在一实施例中，所述光波导180为侧向波导的设计，实现了光缓慢耦合进入吸收层150，与吸收层150强相互作用，同时得益于所述吸收层150和所述雪崩层120的解耦以及增加本征的过渡层140的设计，能够实现低暗电流、高增益、大带宽、高量子效率雪崩光电探测。
在一实施例中，所述第一电极接触层160上形成有第一电极接触区161，所述顶硅层113上形成有第二电极接触区1132；在所述第一电极接触区161上和所述第二电极接触区1132上分别设有第一金属电极162和第二金属电极1133。
所述第一金属电极162和所述第二金属电极1133中任意一者与所述光 波导180之间的距离大于等于700nm。
在一实施例中，通过在所述顶硅层113上的第二金属电极1133和所述第一电极接触层160上的第一金属电极162之间施加外加电压以形成外加电场，抽取所述吸收层150内产生的载流子，且外加电场的电场方向与所述吸收层150内形成的内建电场的电场方向相同，从而所述外加电场可以加快载流子的移动速度，从而提高雪崩探测器的响应度。
在一实施例中，所述雪崩光电探测器基于垂直电极设计结构，使得吸收层内电场分布均匀，同时解耦光传输、光吸收、光倍增，易于光生载流子输运，有助于提高增益带宽积。
本申请实施例还提供了一种雪崩光电探测器的制备方法，具体请参见附图5，如图所示，所述方法包括以下步骤：
步骤501、提供衬底；
步骤502、在所述衬底上生长第一外延层，所述第一外延层为第一半导体材料层；对所述第一外延层进行第一掺杂类型的离子掺杂，形成电荷层；
步骤503、在所述电荷层上生长第二外延层，形成本征的过渡层；所述第二外延层的材料为第一半导体材料和第二半导体材料的复合材料；
步骤504、在所述过渡层的第一区域上生长第三外延层，形成本征的吸收层；所述第三外延层为第二半导体材料层；
步骤505、在所述过渡层的第二区域上生长第四外延层，所述第四外延层的高度高于所述第三外延层的高度，以形成一包覆所述吸收层的第一电极接触层；所述第四外延层为第一半导体材料层。
下面结合具体实施例对本申请的雪崩光电探测器的制备方法再作进一步详细的说明。
图6a-6h为本申请实施例提供的雪崩光电探测器在制备过程中的器件结构剖面示意图。
首先，参考图6a，执行步骤501，提供衬底；所述衬底可以为单质半导体材料衬底(例如为硅(Si)衬底、锗(Ge)衬底等)、复合半导体材料衬底(例如为锗硅(SiGe)衬底等)，或绝缘体上硅(SOI)衬底、绝缘体上锗(GeOI)衬底等。
本申请实施例以所述衬底为SOI衬底为例进行说明，所述SOI衬底包括底层衬底111、埋氧层112和顶硅层113；所述底层衬底111为可以底层硅材料；所述埋氧层112位于所述底层衬底111上；所述埋氧层112例如为二氧化硅层；所述顶硅层113位于所述埋氧层112上。
在一实施例中，通过光刻和离子注入掺杂等工艺，在所述顶硅层113上形成具有邻接布置的第一掺杂区1131和第二掺杂区1132；所述第一掺杂区1131和所述第二掺杂区1132的掺杂类型相同，均为第二掺杂类型；所述第二掺杂区1132的掺杂浓度大于所述第一掺杂区1131的掺杂浓度；所述第一掺杂区1131例如为N+掺杂区，所述第二掺杂区1132例如为N++掺杂区；所述第一掺杂区1131的掺杂浓度2×10 17/cm 3～8×10 18/cm 3；所述第二掺杂区1132的掺杂浓度为1×10 20/cm 3～8×10 20/cm 3。
需要说明的是，在所述顶硅层113上可以形成一个或多个第二掺杂区1132，图6a仅示例出在所述顶硅层113上形成两个第二掺杂区1132的情况；两个所述第二电极接触区1132分别位于所述第一掺杂区1131的两侧。
接下来，参考图6b，执行步骤502，执行选择性外延生长工艺，在所述顶硅层113上生长第一外延层，形成雪崩层120；所述第一外延层为第一半导体材料层；接着，执行选择性掺杂工艺，对所述第一外延层进行第一掺杂类型的离子掺杂，形成电荷层130。
所述雪崩层120在第一方向上的尺寸范围为700nm～7000nm；在第二方向上的尺寸范围为100nm～1500nm；在第三方向上的尺寸范围为4μm～30μm。
所述电荷层130在第一方向上的尺寸范围为700nm～7000nm，在第二方向上的尺寸范围为50～1000nm，在第三方向上的尺寸范围为4μm～30μm。
接下来，参考图6c，执行步骤503，执行选择性外延生长工艺，在所述电荷层130上生长第二外延层，形成本征的过渡层140；所述第二外延层的材料为第一半导体材料和第二半导体材料的复合材料。
所述过渡层140在第一方向上的尺寸范围为700nm～7000nm，在第二方向上的尺寸范围为20～100nm，在第三方向上的尺寸范围为4μm～30μm。
接着，参考图6d，执行步骤504，再次执行选择性外延生长工艺，在所述过渡层140的第一区域141上生长第三外延层，形成本征的吸收层150；所述第三外延层的材料为第二半导体材料。
所述吸收层150在第一方向上的尺寸范围为450nm～5500nm。所述吸收层150在第一方向上的尺寸小于所述过渡层140在第一方向上的尺寸，并且二者之间的尺寸差值例如在150nm～1500nm的范围内。
所述吸收层150在第二方向上的尺寸范围为150nm～600nm。
所述吸收层150在第三方向上的尺寸可以小于所述过渡层140在第三方向上的尺寸；二者之间的尺寸差值例如大于150nm。所述第二区域142环绕所述第一区域141；所述第二区域142为所述过渡层140上除所述第一区域141以外的区域。具体地，如图3所示，所述第一区域141例如为图中较小的虚线方框以内的区域，所述第二区域142例如为图中较小的虚线方框和较大的虚线方框之间的区域。
在其他一些实施例中，所述吸收层150在第三方向上的尺寸也可以等于所述过渡层140在第三方向上的尺寸；此时，所述吸收层150在第三方向上的尺寸范围可以为4μm～30μm。具体地，如图4所示，过渡层140的第二区域142’位于第一区域141’的两侧，从而第一电极接触层160与过渡层140相接触的部分在第三方向上被所述吸收层150间隔；也即，第二区 域142’包括被第一区域141’间隔的两个子区域。所述第二区域142’同样可以为所述过渡层140上除所述第一区域141’以外的区域。
所述雪崩层120的掺杂浓度为≤2×10 16/cm 3；所述电荷层130的掺杂浓度为2×10 17/cm 3～6×10 18/cm 3；所述过渡层140的掺杂浓度为≤2×10 15/cm 3；所述吸收层150的掺杂浓度为2×10 17/cm 3～6×10 18/cm 3
接着，参考图6e，执行步骤505，执行选择性外延生长工艺，在所述过渡层140的第二区域142上生长第四外延层，所述第四外延层的高度高于所述第三外延层的高度，以形成一包覆所述吸收层150的第一电极接触层160；所述第四外延层为第一半导体材料层。
所述吸收层150的下表面与所述过渡层140的所述第一区域141直接接触；所述第一电极接触层160的下表面的一部分与所述过渡层140的所述第二区域142直接接触，另一部分与所述吸收层150的上表面直接接触；所述第一电极接触层160还覆盖所述吸收层150的侧壁，从而与所述侧壁直接接触。
这里，所述第一半导体材料为硅；所述第二半导体材料为锗；所述第一半导体材料和第二半导体材料的复合材料为锗硅；所述第一掺杂类型为P型。
参考图6f，执行完步骤405后，所述方法还包括，利用光刻和离子注入掺杂等工艺，对所述第四外延层进行第一掺杂类型的离子掺杂，以在所述第一电极接触层160内形成第一电极接触区161，即所述第一电极接触区161为P+掺杂硅区。所述第一电极接触区161的掺杂浓度为1×10 19/cm 3～2×10 20/cm 3。
需要说明的是，所述第一电极接触层160上的第一电极接触区161可以为一个或多个，在本实施例中，所述第一电极接触区161可以为两个。
所述第一电极接触区161位于所述吸收层150上；换言之，所述第一 电极接触区161位于所述第一电极接触层160的覆盖所述吸收层150上的部分内。
应当理解，在上述执行选择性外延生长工艺后，均可以包括平坦化的步骤，这里未予详述。
在一实施例中，所述顶硅层113也可称为硅平板层；所述雪崩层120和所述电荷层130也可称为条形硅波导层；如此，所述雪崩光电探测器可以包括硅材料区，所述硅材料区可以包括所述硅平板层和所述条形硅波导层。
接下来，参考图6g及6h。首先，参考图6g，所述方法还包括，形成光波导180，所述光波导180沿平行于所述衬底平面的方向设置于所述吸收层150的侧方。
在一实施例中，在形成光波导180之前，先在所述衬底上，具体在所述顶硅层113上形成填充层170。
所述填充层170的材料可以包括二氧化硅。
在实际工艺中，可以通过沉积一定厚度的二氧化硅材料，并进行平坦化处理，以形成所述填充层170。
接下来，可以通过图案化的掩膜层(图中未示出)，在填充层170上定义出需要形成光波导的区域；在所述区域内生长光波导材料，具体例如为沉积氮化硅材料或者生长硅材料，以形成所述光波导180。
在一实施例中，所述光波导180的上表面可以齐平于或高于所述吸收层150的上表面；所述光波导180的下表面可以齐平于或低于所述吸收层150的下表面。
所述光波导180的材料具体可以为氮化硅，即所述光波导180可以为氮化硅光波导。在其他一些实施例中，所述光波导180的材料还可以为硅。
所述光波导180用于传输光信号，并将所述光信号耦合至所述吸收层 150。
所述光波导180与所述吸收层150之间的距离为100nm～500nm。
所述光波导180包括光输入端口181和第一波导区182，所述第一波导区182为直形波导区。
所述光波导180传输的光信号沿所述光输入端口181至所述第一波导区182的方向传播。
所述光波导180在第一方向上的尺寸范围为500nm～3000nm，在第二方向上的尺寸范围为100nm～900nm，在第三方向上的尺寸范围为5μm～32μm。
接下来，参考图6h，所述方法还包括，在所述第一电极接触层160的第一电极接触区161上和所述顶硅层113的第二电极接触区1132上分别形成垂直所述衬底平面方向(即第二方向)而设置的第一金属电极162和第二金属电极1133。
具体可以利用光刻与电感等离子刻蚀开窗口、磁控溅射沉积金属材料等工艺制作上述两个金属电极。
所述第一金属电极162和所述第二金属电极1133中任意一者与所述光波导180之间的距离大于等于700nm。
所述第一金属电极162和所述第二金属电极1133的上表面应当高于所述光波导180的上表面。具体地，还包括在所述光波导180上形成填充层170，利用光刻与刻蚀(如电感等离子刻蚀)等工艺在填充层170内形成暴露所述第一电极接触区161和所述第二电极接触区1132的窗口；在所述窗口内填充电极材料(如磁控溅射沉积金属材料)，以形成所述第一金属电极162和所述第二金属电极1133。
如此，基本完成了所述雪崩光电探测器的制备。后续可能还会涉及到一些互连工艺，这里不再展开论述。
需要说明的是，本申请实施例提供的雪崩光电探测器与雪崩光电探测 器的制备方法实施例属于同一构思；各实施例所记载的技术方案中各技术特征之间，在不冲突的情况下，可以任意组合，这里不再赘述。
以上所述，仅为本申请的可选实施例而已，并非用于限定本申请的保护范围，凡在本申请的精神和原则之内所作的任何修改、等同替换和改进等，均应包含在本申请的保护范围之内。

Claims (10)

  1. 一种雪崩光电探测器，包括：衬底，以及位于所述衬底上的器件结构层；所述器件结构层至少包括沿垂直所述衬底平面方向向上依次设置的电荷层、过渡层、吸收层以及第一电极接触层；其中，
    所述电荷层为具有第一掺杂类型的第一半导体材料层；
    所述过渡层外延生长于所述电荷层上，所述过渡层为本征层；
    所述吸收层外延生长于所述过渡层的第一区域上，所述吸收层为本征的第二半导体材料层；
    所述第一电极接触层外延生长于所述过渡层的第二区域上，所述第一电极接触层的高度高于所述吸收层的高度以使所述第一电极接触层包覆所述吸收层，所述第一电极接触层为第一半导体材料层；
    所述过渡层的材料为第一半导体材料和第二半导体材料的复合材料。
  2. 根据权利要求1所述的雪崩光电探测器，其中，
    所述第一半导体材料为硅；
    所述第二半导体材料为锗；
    所述第一半导体材料和第二半导体材料的复合材料为锗硅。
  3. 根据权利要求1所述的雪崩光电探测器，其中，
    所述第一掺杂类型为P型。
  4. 根据权利要求1所述的雪崩光电探测器，其中，还包括：
    位于所述第一电极接触层内的第一电极接触区，所述第一电极接触区为具有第一掺杂类型的第一半导体材料区。
  5. 根据权利要求1所述的雪崩光电探测器，其中，
    所述第二区域环绕所述第一区域；或者，所述第二区域包括被所述第一区域间隔的两个子区域。
  6. 一种雪崩光电探测器的制备方法，包括：
    提供衬底；
    在所述衬底上生长第一外延层，所述第一外延层为第一半导体材料层；对所述第一外延层进行第一掺杂类型的离子掺杂，形成电荷层；
    在所述电荷层上生长第二外延层，形成本征的过渡层；所述第二外延层的材料为第一半导体材料和第二半导体材料的复合材料；
    在所述过渡层的第一区域上生长第三外延层，形成本征的吸收层；所述第三外延层为第二半导体材料层；
    在所述过渡层的第二区域上生长第四外延层，所述第四外延层的高度高于所述第三外延层的高度，以形成一包覆所述吸收层的第一电极接触层；所述第四外延层为第一半导体材料层。
  7. 根据权利要求6所述的雪崩光电探测器的制备方法，其中，
    所述第一半导体材料为硅；
    所述第二半导体材料为锗；
    所述第一半导体材料和第二半导体材料的复合材料为锗硅。
  8. 根据权利要求6所述的雪崩光电探测器的制备方法，其中，
    所述第一掺杂类型为P型。
  9. 根据权利要求6所述的雪崩光电探测器的制备方法，其中，所述方法还包括：
    对所述第四外延层进行第一掺杂类型的离子掺杂，以在所述第一电极接触层内形成第一电极接触区。
  10. 根据权利要求6所述的雪崩光电探测器的制备方法，其中，
    所述第二区域环绕所述第一区域；或者，所述第二区域包括被所述第一区域间隔的两个子区域。
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