CN109742093B - Enhanced blue light type silicon-based avalanche photodiode array and preparation method thereof - Google Patents
Enhanced blue light type silicon-based avalanche photodiode array and preparation method thereof Download PDFInfo
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Abstract
The invention discloses an enhanced blue light type silicon-based avalanche photodiode array, wherein the avalanche photodiode is a SACM type APD, and comprises a substrate and an anode arranged at the bottom of the substrate, the upper surface of the substrate is provided with a groove, and the groove sequentially comprises: a cathode, a non-depletion layer, a multiplication layer and a field control layer, wherein the cathode, the non-depletion layer, the multiplication layer and the field control layer are insulated from the substrate; the field control layer is covered with an absorption layer, and the absorption layer is connected with the substrate; the surface of the absorption layer is covered with a sub-wavelength structure layer which is regularly arranged; the substrate is a p + type silicon wafer; the non-depletion layer is n + type high doping concentration and high defect polysilicon; the multiplication layer is a pi-type silicon epitaxial layer; the field control layer is a p-type silicon epitaxial layer; the absorption layer is a pi-type silicon epitaxial layer. Compared with the prior art, the invention provides the silicon-based APD which can improve the quantum efficiency and the sensitivity of blue light and has high gain.
Description
Technical Field
The invention relates to the field of photoelectricity, in particular to an enhanced blue light type silicon-based avalanche photodiode array and a preparation method thereof.
Background
VLC technology is receiving increasing attention internationally, and many research institutions in europe, america, and japan have invested a lot of funds to develop research in this area, and its main work is focused on theoretical research. Because silicon-based Avalanche Photodiodes (APDs) have the characteristics of high sensitivity, small volume, good modulation, high gain, easy integration and the like, and the spectral response range of the silicon-based APDs is wide (380-1100 nm), the silicon-based APDs are a common detector for VLC systems.
However, the absorption coefficient of the silicon material for blue light is about 10 -4cm-1, and the propagation distance of blue light in the silicon material is about 1 μm, so that blue light cannot propagate in the absorption layer in the conventional silicon-based APD and is absorbed, resulting in low sensitivity and low quantum efficiency of blue light. That is, APD detectors with high sensitivity to blue light are a bottleneck problem for visible light detection.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a silicon-based avalanche photodiode array capable of improving the blue light quantum efficiency and the sensitivity and a preparation method thereof.
In order to achieve the purpose of the invention, the following technical scheme is adopted:
An enhanced blue light type silicon-based avalanche photodiode, which is a SACM type APD, comprises a substrate and an anode arranged at the bottom of the substrate, wherein the upper surface of the substrate is provided with a groove, and the groove sequentially comprises: the cathode, the non-depletion layer, the multiplication layer and the field control layer are respectively insulated from the substrate; the field control layer is covered with an absorption layer, and the absorption layer is connected with the substrate; the surface of the absorption layer is covered with a sub-wavelength structure layer which is regularly arranged; the substrate is a p + type silicon wafer; the non-depletion layer is an n + -type silicon epitaxial layer; the multiplication layer is a pi-type silicon epitaxial layer; the field control layer is a p-type silicon epitaxial layer; the absorption layer is a pi-type silicon epitaxial layer.
Because of the self-characteristics of silicon materials, the absorption rate of silicon to blue light increases with thickness, and for traditional silicon-based APDs, blue light is difficult to reach the absorption layer and is absorbed due to the fact that the absorption layer is positioned at the bottom layer of the device, so that the quantum efficiency of blue light is low. Based on the reasons, the invention provides a device which adopts a flip-chip structure to arrange the absorption layer on the surface layer of the device, so that the incident blue light is fully absorbed on the surface layer, and the absorption rate of the absorption layer to the blue light is greatly improved; meanwhile, a sub-wavelength structural layer is added on the surface layer of the absorption layer, so that plasmon resonance effect can be generated when blue light incident light irradiates the photosensitive surface of the device, and the sensitivity of the device to blue light is greatly enhanced.
The working process of the invention specifically comprises the following steps: under the action of reverse bias voltage, light irradiates on an APD photosensitive surface, incident light generates a phenomenon of plasmon resonance on the surface of a sub-wavelength structure layer, electrons are bound around the plasmon structure and permeate into an absorption layer, the electrons drift towards n type under the action of an built-in electric field, and avalanche phenomenon occurs in a multiplication layer to form large reverse current; photons which do not generate plasmon resonance phenomenon on the surface of the APD can be incident into the absorption layer, when the photon energy of the incident light is larger than the forbidden bandwidth of silicon, the photon energy incident in the absorption layer is absorbed to generate electron-hole pairs, electrons diffuse to n type along the electric field direction, holes diffuse to p type, and when reverse bias voltage is large enough, avalanche multiplication of carriers is caused, so that large reverse current is formed; by the combined action of the plasmon resonance effect and the effect of the photo-generated carriers of the absorption layer, a larger reverse current can be generated, so that the conversion of the photoelectric signal can be amplified.
Wherein the doping concentration of the substrate is 10 15～1030cm-3; the non-depletion layer is polysilicon with high doping concentration and high defect, and the doping concentration is 10 15～1030cm-3; the doping concentration of the multiplication layer is 10 12～1015cm-3; the doping concentration of the field control layer is 10 16～1018cm-3; the doping concentration of the absorption layer is 10 12～1015cm-3. Preferably, the cathode and the anode can be one or more alloy layers such as Au, ag, cu, al, cr, ni, ti.
Further, the material of the sub-wavelength structure layer is Au, ag or Al; and/or the thickness of the sub-wavelength structure layer is 10 nm-500 nm; and/or the shape of the sub-wavelength structure layer is square, rectangle, round or cross.
Further, the insulation between the cathode, the non-depletion layer, the multiplication layer and the field control layer and the substrate is specifically: insulating fillers are filled among the cathode, the non-depletion layer, the multiplication layer, the field control layer and the substrate; the insulation filler comprises a first insulation layer arranged at the bottom of the groove; the insulating filler also comprises a second insulating layer which is arranged on the side surface of the groove and isolates the side surfaces of the cathode, the non-depletion layer, the multiplication layer and the field control layer from the substrate. Preferably, the first insulating layer is an organic or inorganic material such as polydimethylsiloxane, polyimide, or SiO 2, and the second insulating layer is an insulating material such as air, polydimethylsiloxane, polyimide, or SiO 2. Preferably, the first insulating layer is SiO 2.
Further, the area of the non-depletion layer is smaller than the area of the multiplication layer. Preferably, the area of the non-depletion layer is slightly smaller than the area of the multiplication layer, so that the protection ring is formed to reduce leakage current. Further preferably, the area of the non-depletion layer is 50% to 99% of the area of the multiplication layer.
In order to further increase the gain of the device, the high-gain enhanced blue-light silicon-based avalanche photodiode array is obtained, and the APD array is arranged. That is, a plurality of arrays of grooves may be provided on the upper surface of the substrate; each groove is covered with a corresponding absorption layer, the absorption layers are respectively connected with the field control layer and the substrate, and meanwhile, the absorption layers corresponding to the grooves are disconnected. When light is incident, the arrayed APDs trigger a plurality of unit APDs simultaneously, so that the APDs have high gain, and the sensitivity of the device is further improved.
The preparation method of the enhanced blue light type silicon-based avalanche photodiode specifically comprises the following steps:
S1: firstly, selecting a p + type silicon wafer as a substrate material, cleaning the silicon wafer, and preparing a layer of metal with the thickness of 10 nm-5000 nm on the back surface of the silicon wafer as an anode of a device, wherein the metal is one or more alloys such as Au, ag, cu, al, cr, ni, ti;
s2: cleaning the surface of a silicon wafer, then drying, coating photoresist on the surface of the silicon wafer, and preparing a mask pattern through a photoetching process;
S3: preparing a SiO 2 mask layer, removing photoresist on the surface of the silicon wafer, and removing part of the silicon wafer to form a groove with the depth of 0.1-20 mu m;
S4: carrying out surface cleaning treatment on a silicon wafer, then drying, coating photoresist on the surface of the silicon wafer, and preparing a mask pattern of a cathode through a photoetching process;
S5: preparing a SiO 2 mask layer, and then preparing a layer of metal with the thickness of 10 nm-5000 nm on the surface of a silicon wafer as a cathode of a device, wherein the metal is one or more alloys in Au, ag, cu, al, cr, ni, ti;
S6: removing photoresist and SiO 2 layer on the surface of the silicon wafer, then performing surface cleaning treatment, coating photoresist on the surface of the silicon wafer again, and preparing a mask pattern of a non-depletion layer through a photoetching process; sequentially depositing a non-depletion layer, a multiplication layer and a field control layer on the surface of the cathode (preferably, the area of the non-depletion layer can be slightly smaller than that of the multiplication layer, so that a protection ring is formed to reduce leakage current);
S7: removing the surface photoresist, cleaning the surface of the epitaxial wafer, and drying; coating photoresist on the surface of the epitaxial wafer again, and preparing a mask pattern of the absorption layer through a photoetching process; depositing a pi-type silicon epitaxial layer on the surface of the silicon wafer to serve as an absorption layer;
S8: cleaning and drying the epitaxial wafer, coating photoresist on the surface of the epitaxial wafer, and preparing a mask pattern with a sub-wavelength structure through a photoetching process; preparing a sub-wavelength structure layer on the surface of the epitaxial wafer by sputtering or electron beam evaporation;
S9: and packaging the device.
Further, after step S1 and before step S2, the method further includes the following steps:
s10: performing surface cleaning treatment on a silicon wafer, drying, coating photoresist on the surface of the silicon wafer, exposing and developing to obtain a mask pattern, preparing a SiO 2 mask layer, and removing the photoresist on the surface of the silicon wafer;
S11: coating photoresist on the SiO 2 mask layer, preparing a mask pattern by a photoetching process, and preparing an isolation channel;
S12: and selecting an insulating filler to fill the isolation channel, and removing photoresist and a SiO 2 layer on the surface of the silicon wafer.
Further, the step S6 specifically includes:
(1) Removing photoresist and SiO 2 layer on the surface of the silicon wafer, performing surface cleaning treatment, coating photoresist on the surface of the silicon wafer again, preparing a mask pattern of a non-depletion layer through a photoetching process, and depositing the non-depletion layer on the surface of a cathode;
(2) Then removing photoresist on the surface of the epitaxial wafer, carrying out surface cleaning treatment on the epitaxial wafer, coating the photoresist on the surface of the epitaxial wafer, preparing a mask pattern of the multiplication layer through a photoetching process, and then depositing the multiplication layer;
(3) Finally, a field control layer is deposited.
Preferably, the depth of the isolation channel is 1-20 μm and the width is 0.1-1000 μm.
Compared with the prior art, the invention provides the silicon-based APD which can improve the quantum efficiency and the sensitivity of blue light and has high gain, and the surface layer of the APD is prepared into a layer of sub-wavelength structural layer, so that the incident blue light generates plasmon resonance effect on the surface layer, the blue light is fully absorbed on the surface layer, weak light can be induced, the sensitivity and the quantum efficiency of the APD on the blue light are improved, and the thickness of the absorption layer can be reduced; meanwhile, the anode and the cathode of the device are positioned at the bottom of the same side of the device, so that the influence of the electrode is avoided, the induction area of incident light is reduced, and meanwhile, the size of the electrode can reach the size of an array unit, thereby increasing the response speed and the quantum efficiency; when incident light irradiates the surface of the APD, the array device drives a plurality of cells to work simultaneously, so that the gain of the APD is improved, the photosensitive area of the array cells is reduced, and the cut-off frequency of the device is improved.
Drawings
FIG. 1 is a perspective view of an enhanced blue-light type silicon-based avalanche photodiode array provided by the present invention;
FIG. 2 is a longitudinal cross-sectional view of an enhanced blue-light type silicon-based avalanche photodiode array provided by the present invention;
FIG. 3 is a flow chart of the preparation of the present invention.
Description of the drawings: 1. a sub-wavelength structural layer; 2. an absorption layer; 3. a field control layer; 4. a multiplication layer; 5. a non-depletion layer; 6. a cathode; siO 2 oxide layer; 8. a trench filler; 9. a substrate; 10. an anode; 11. and (3) photoresist.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in further detail with reference to the accompanying drawings.
Examples
The embodiment provides a method for adopting a flip-chip structure with an absorption layer arranged on a surface layer and simultaneously arranging a sub-wavelength structure on the surface of the absorption layer, so as to obtain a blue light silicon-based avalanche photodiode array based on plasmon resonance enhancement. The embodiment can greatly improve the quantum efficiency and sensitivity of blue light and has high-gain silicon-based APD.
The enhanced blue light type silicon-based avalanche photodiode array provided in this embodiment includes a substrate 9 and an anode 10 disposed at the bottom of the substrate 9, a groove is disposed on the upper surface of the substrate 9, and the groove sequentially includes from bottom to top: a SiO 2 oxide layer 7, a cathode 6, a non-depletion layer 5, a multiplication layer 4 and a field control layer 3, and the cathode 6, the non-depletion layer 5, the multiplication layer 4 and the side surface of the field control layer 3 are insulated from the substrate 9; the field control layer 3 is covered with an absorption layer 2, and the absorption layer 2 is connected with the substrate 9; the surface of the absorption layer 2 is covered with a sub-wavelength structure layer 1 which is regularly arranged.
As another preferred embodiment, the SiO 2 oxide layer 7 may also be another insulating substance, which can separate the cathode 6 from the substrate and facilitate the subsequent growth of a non-depletion layer.
The substrate 9 is a p + type silicon wafer with high doping (the impurity is trivalent element such as B) and the doping concentration is 10 15～1030cm-3; the non-depletion layer 5 is n + type high doping concentration (the impurity is P, as and other pentavalent elements) and high defect polysilicon, and the doping concentration is 10 15～1030cm-3; the multiplication layer 4 is a pi-type silicon epitaxial layer, and the doping concentration is 10 12～1015cm-3; the field control layer 3 is a p-type silicon epitaxial layer, and the doping concentration is 10 16～1018cm-3; the absorption layer 2 is a pi-type silicon epitaxial layer, and the doping concentration is 10 12～1015cm-3; the material of the sub-wavelength structure layer 1 is Au, ag or Al, the thickness is 10 nm-500 nm, and the shape is square, rectangle, round or cross.
Preferably, isolation trenches are arranged on two sides of the groove, and trench filling materials 8 are filled in the isolation trenches to isolate the sides of the cathode 6, the non-depletion layer 5, the multiplication layer 4 and the field control layer 3 in the groove from the substrate 9. Further preferably, the trench filling 8 is made of an organic insulating material or an inorganic insulating material such as polydimethylsiloxane, polyimide, or SiO 2.
As a preferred embodiment, as shown in fig. 1-2, a plurality of grooves are arranged on the surface of the substrate in an array, each groove sequentially comprises an SiO 2 oxide layer 7, a cathode 6, a non-depletion layer 5, a multiplication layer 4 and a field control layer 3 from bottom to top, the bottom of the cathode 6 is isolated from the substrate 9 by the SiO 2 oxide layer 7, and the sides of the cathode 6, the non-depletion layer 5, the multiplication layer 4 and the field control layer 3 are isolated from the substrate 9 by channel fillers 8 filled in isolation channels; the surface of the field control layer 3 corresponding to each groove is covered with an absorption layer 2, and the absorption layers 2 are covered on the surface of the substrate 9 at the same time, but the absorption layers 2 corresponding to each groove are disconnected from each other. That is, the present embodiment employs a manner in which a plurality of individual APDs share the same substrate to obtain an arrayed APD. When light is incident, a plurality of unit APDs can be triggered simultaneously, thereby enabling the APDs to have high response speed and high gain.
As shown in fig. 3, the preparation method of the enhanced blue-light type silicon-based avalanche photodiode specifically includes the following steps (wherein, the graphs (1) to (18) in fig. 3 correspond to the following steps (1) to (18):
(1) A p + type silicon wafer with high doping (the impurities are trivalent elements such as B) and the thickness of 2-500 mu m is selected as a substrate material, the doping concentration is 10 15～1030cm-3, and the silicon wafer is subjected to wax removal, oil removal and surface impurity removal by a heat treatment, an active ion beam method, an optical cleaning treatment or a chemical cleaning treatment.
(2) Preparing a layer of metal with the thickness of 10 nm-5000 nm as an anode of the device on the back surface of the silicon wafer by a magnetron sputtering or evaporation coating or electroplating method, wherein the metal is one or more alloys such as Au, ag, cu, al, cr, ni, ti.
(3) And (3) carrying out surface cleaning treatment, wax removal, oil removal and surface impurity removal on the silicon wafer, then carrying out drying treatment, coating photoresist on the front surface of the silicon wafer, and obtaining a mask pattern after exposure and development.
(4) And preparing a SiO 2 mask layer by a thermal oxidation method, a vapor phase epitaxy growth method or a molecular beam epitaxy method, and then removing photoresist on the surface of the silicon wafer by using a photoresist removing solution.
(5) Coating photoresist on the SiO 2 layer, preparing a mask pattern by a photoetching process, and preparing an isolation channel by a dry etching method, a wet etching method, a mechanical method or the like, wherein the depth of the channel is 1-20 mu m, and the width of the channel is 0.1-1000 mu m.
(6) And selecting organic or inorganic materials such as polydimethylsiloxane, polyimide or SiO 2 as fillers of the channels to fill the isolation channels.
(7) Photoresist on the surface of the silicon wafer is removed by using the photoresist removing solution, and then the SiO 2 layer on the surface of the silicon wafer is removed by a wet etching method.
(8) And cleaning the surface of the silicon wafer, then drying, coating photoresist on the surface of the silicon wafer, and preparing a mask pattern through a photoetching process.
(9) And preparing a SiO 2 mask layer by a vapor phase epitaxy method or a molecular beam epitaxy method or a low-temperature evaporation method, and then removing photoresist on the surface of the silicon wafer.
(10) And removing part of the silicon wafer by wet etching or dry etching to form a groove with the depth of 0.1-20 mu m for the subsequent manufacturing of the cathode and the growth of the epitaxial layer.
(11) And (3) carrying out surface cleaning treatment on the silicon wafer, and then drying for standby. Coating photoresist on the surface of the silicon wafer, and preparing a mask pattern of the cathode through a photoetching process.
(12) The SiO 2 mask layer is prepared by a thermal oxidation method, a vapor phase epitaxy growth method, a molecular beam epitaxy method or a low-temperature evaporation method, a layer of metal film with the thickness of 10 nm-5000 nm is prepared on the surface of a silicon wafer by a magnetron sputtering method, an evaporation coating method or an electroplating method and the like to serve as a cathode of a device, and the metal is one or more alloys such as Au, ag, cu, al, cr, ni, ti and the like.
(13) Removing photoresist on the surface of the silicon wafer, removing the SiO 2 layer on the surface of the silicon wafer by a wet etching method, performing surface cleaning treatment, coating the photoresist on the surface of the silicon wafer again, and preparing a mask pattern of a non-depletion layer by a photoetching process.
(14) A silicon epitaxial layer is deposited on the surface of a cathode by a Vapor Phase Epitaxy (VPE) or Molecular Beam Epitaxy (MBE) technology and the like to serve as a non-depletion layer of an APD, and the grown epitaxial layer is n + type polycrystalline silicon with high doping concentration and high defect, and the doping concentration is 10 15～1030cm-3. And then sequentially depositing a multiplication layer and a field control layer on the non-depletion layer, wherein the multiplication layer is a pi-type silicon epitaxial layer, the doping concentration is 10 12～1015cm-3, the field control layer is a p-type silicon epitaxial layer, and the doping concentration is 10 16～1018cm-3.
(15) And removing the surface photoresist, then cleaning the surface of the epitaxial wafer, and drying. And coating photoresist on the surface of the epitaxial wafer again, and preparing a mask pattern of the absorption layer through a photoetching process.
(16) And depositing a pi-type silicon epitaxial layer on the surface of the epitaxial wafer by utilizing vapor phase epitaxy or molecular beam epitaxy to serve as an absorption layer, wherein the doping concentration is 10 12～1015cm-3.
(17) And (3) carrying out surface cleaning treatment on the epitaxial wafer, then drying for standby, coating photoresist on the surface of the epitaxial wafer, and preparing a mask pattern with a sub-wavelength structure through a photoetching process.
(18) The subwavelength structure layer is prepared on the surface of the epitaxial wafer by sputtering, electron beam evaporation or other methods, the subwavelength structure layer is made of Au, ag, al or the like, the thickness is about 10 nm-500 nm, and the shape of the plasmon structure can be square, rectangular, round, cross-shaped or the like.
(19) And packaging the device.
The isolation channel is deeper, and meanwhile, the isolation channel is narrow in width, large in depth and high in depth-to-width ratio, and the silicon surface is easy to damage during ICP (Inductively Coupled Plasma) etching, so that the preparation method adopts a mode of a SiO 2 mask layer and a photoresist mask layer (double layers) (see steps (3) to (5)) in detail; the depth of the groove is only about twenty micrometers or less, the depth-to-width ratio of the groove is small, and the etching is easy, so that a layer of protection is manufactured (see steps (8) - (10)).
As a preferred embodiment, the area of the non-depletion layer 5 may be slightly smaller than the area of the multiplication layer 4, so that the formation of a guard ring reduces leakage current. Based on this, in the above preparation scheme, the step (14) is modified as follows; depositing a silicon epitaxial layer on the surface of a cathode to serve as a non-depletion layer of an APD (avalanche photo diode) by using technologies such as Vapor Phase Epitaxy (VPE) or Molecular Beam Epitaxy (MBE), wherein the grown epitaxial layer is n + type polycrystalline silicon with high doping concentration and high defect, and the doping concentration is 10 15～1030cm-3; then removing photoresist on the surface of the epitaxial wafer, performing surface cleaning treatment, coating the photoresist on the surface of the epitaxial wafer again, preparing a mask pattern of the multiplication layer through a photoetching process, and then depositing the multiplication layer; then depositing a field control layer; the multiplication layer is a pi-type silicon epitaxial layer, the doping concentration is 10 12～1015cm-3, the field control layer is a p-type silicon epitaxial layer, and the doping concentration is 10 16～1018cm-3.
The above examples are provided for the purpose of clearly illustrating the invention and are not to be construed as limiting the invention in any way. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. Any modification, equivalent replacement, improvement, etc. which come within the spirit and principles of the invention are desired to be protected by the following claims.
Claims (9)
1. The utility model provides an enhancement blue light type silicon-based avalanche photodiode array which characterized in that, avalanche photodiode is SACM type APD, including the substrate and locate the positive pole of substrate bottom, the substrate upper surface is equipped with the recess, include from bottom to top in proper order in the recess: the cathode, the non-depletion layer, the multiplication layer and the field control layer are respectively insulated from the substrate; the field control layer is covered with an absorption layer, and the absorption layer is connected with the substrate; the surface of the absorption layer is covered with a sub-wavelength structure layer;
the substrate is a p + type silicon wafer; the non-depletion layer is an n + -type silicon epitaxial layer; the multiplication layer is a pi-type silicon epitaxial layer; the field control layer is a p-type silicon epitaxial layer; the absorption layer is a pi-type silicon epitaxial layer;
The doping concentration of the substrate is 10 15～1030cm-3; the doping concentration of the non-depletion layer is 10 15～1030cm-3; the doping concentration of the multiplication layer is 10 12～1015cm-3; the doping concentration of the field control layer is 10 16～1018cm-3; the doping concentration of the absorption layer is 10 12～1015cm-3.
2. The enhanced blue-light type silicon-based avalanche photodiode array of claim 1 wherein the cathode and anode are alloy layers of one or more of Au, ag, cu, al, cr, ni, ti;
And/or the insulation between the cathode, the non-depletion layer, the multiplication layer and the field control layer and the substrate is specifically:
insulating fillers are filled among the cathode, the non-depletion layer, the multiplication layer, the field control layer and the substrate;
the insulation filler comprises a first insulation layer arranged at the bottom of the groove; the insulating filler also comprises a second insulating layer which is arranged on the side surface of the groove and isolates the side surfaces of the cathode, the non-depletion layer, the multiplication layer and the field control layer from the substrate.
3. The enhanced blue light type silicon based avalanche photodiode array of claim 2 wherein said first insulating layer is polydimethylsiloxane, polyimide or SiO 2 and said second insulating layer is air, polydimethylsiloxane, polyimide or SiO 2.
4. The enhanced blue-light type silicon-based avalanche photodiode array of claim 1, wherein the material of said sub-wavelength structural layer is Au, ag or Al; and/or the thickness of the sub-wavelength structure layer is 10 nm-500 nm; and/or the shape of the sub-wavelength structure layer is square, rectangle, round or cross.
5. The enhanced blue light type silicon based avalanche photodiode array of claim 1 wherein,
The area of the non-depletion layer is smaller than the area of the multiplication layer.
6. The enhanced blue-light type silicon-based avalanche photodiode array of any one of claims 1-5, wherein a plurality of arrays of grooves are provided on an upper surface of said substrate; and each groove is covered with a corresponding absorption layer, the absorption layers are respectively connected with the field control layer and the substrate, and the absorption layers corresponding to the grooves are mutually disconnected.
7. The method for manufacturing an enhanced blue-light type silicon-based avalanche photodiode array according to any one of claims 1 to 6, comprising the steps of:
S1: firstly, selecting a p + type silicon wafer as a substrate material, cleaning the silicon wafer, and preparing a layer of metal with the thickness of 10 nm-5000 nm on the back surface of the silicon wafer as an anode of a device, wherein the metal is one or more alloys in Au, ag, cu, al, cr, ni, ti;
s2: cleaning the surface of a silicon wafer, then drying, coating photoresist on the surface of the silicon wafer, and preparing a mask pattern through a photoetching process;
S3: preparing a SiO 2 mask layer, removing photoresist on the surface of the silicon wafer, and removing part of the silicon wafer to form a groove with the depth of 0.1-20 mu m;
S4: carrying out surface cleaning treatment on a silicon wafer, then drying, coating photoresist on the surface of the silicon wafer, and preparing a mask pattern of a cathode through a photoetching process;
S5: preparing a SiO 2 mask layer, and then preparing a layer of metal with the thickness of 10 nm-5000 nm on the surface of a silicon wafer as a cathode of a device, wherein the metal is one or more alloy films in Au, ag, cu, al, cr, ni, ti;
S6: removing photoresist and SiO 2 layer on the surface of the silicon wafer, then performing surface cleaning treatment, coating photoresist on the surface of the silicon wafer again, and preparing a mask pattern of a non-depletion layer through a photoetching process; sequentially depositing a non-depletion layer, a multiplication layer and a field control layer on the surface of the cathode;
S7: removing the surface photoresist, cleaning the surface of the epitaxial wafer, and drying; coating photoresist on the surface of the epitaxial wafer again, and preparing a mask pattern of the absorption layer through a photoetching process; depositing a pi-type silicon epitaxial layer on the surface of the epitaxial wafer as an absorption layer, and removing photoresist;
S8: cleaning and drying the epitaxial wafer, coating photoresist on the surface of the epitaxial wafer, and preparing a mask pattern with a sub-wavelength structure through a photoetching process; preparing a sub-wavelength structure layer on the surface of the epitaxial wafer by sputtering or electron beam evaporation;
S9: and packaging the device.
8. The method of manufacturing an enhanced blue-light type silicon-based avalanche photodiode array according to claim 7, further comprising, after step S1 and before step S2, the steps of:
s10: performing surface cleaning treatment on a silicon wafer, drying, coating photoresist on the surface of the silicon wafer, exposing and developing to obtain a mask pattern, preparing a SiO 2 mask layer, and removing the photoresist on the surface of the silicon wafer;
s11: coating photoresist on the SiO 2 mask layer, preparing a mask pattern by a photoetching process, and preparing an isolation channel;
S12: and selecting an insulating filler to fill the isolation channel, and removing photoresist and a SiO 2 layer on the surface of the silicon wafer.
9. The method of manufacturing an enhanced blue-light type silicon-based avalanche photodiode array of claim 8, wherein said isolation channel has a depth of 1-20 μm and a width of 0.1-1000 μm.
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