All-dielectric metasurface enhanced broadband photoelectric response avalanche photoelectric detector

Abstract

The invention provides an all-dielectric metasurface enhanced broadband photoelectric response avalanche photodetector. The avalanche photodetector comprises an antireflection film, an upper / lower electrode, an oxide layer, a photosensitive surface, a protection ring, a cut-off ring, a multiplication layer, an intrinsic absorption layer and a contact layer. The all-dielectric metasurfaces are located on the antireflection film layer and the contact layer respectively. The photoelectric response characteristic of the avalanche photodetector is improved by means of the structural design of the material, the preparation process of the all-dielectric metasurface is compatible with the process of the detector, and the advantages of high structural controllability and device consistency are achieved. Finally, the long-term problems of incompatible process, uncontrollable metasurface structure and difficulty in large-scale preparation of the existing technical scheme are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to a full-dielectric metasurface enhanced wide-band photovoltaic response avalanche photodetector, and belongs to the field of semiconductor photodetectors. BACKGROUND

[0002] Avalanche photodetectors (APD) are widely used in laser guidance, optical communication and other fields due to their high photoresponsivity, large gain and fast speed. However, the spectral response range of photodetectors is closely related to the band gap of the device material. For example, gallium nitride APD is usually only used in the ultraviolet-near ultraviolet light band, silicon APD usually only has response in the visible-near infrared light band, and silicon germanium APD or indium gallium arsenide APD is mainly used in the field of near-infrared detectors. This results in a narrow spectral response range of traditional avalanche photodetectors, which is very limited in application scenarios. In addition, new materials such as gallium nitride, silicon germanium and indium gallium arsenide have poor compatibility in preparation process, making it difficult to be integrated and applied on a large scale. Therefore, it is of great significance to broaden the spectral response range of APD detectors with mature material and device process.

[0003] Optimizing four aspects is needed to achieve a wide-band photovoltaic response avalanche photodetector. First, optimizing the preparation process can significantly reduce the dark current of the detector by reducing the damage to the silicon material. Second, optimizing the antireflection film such as SiO2 and Si3N4 on the surface of the detector can reduce the reflectivity of the incident light on the surface of the detector. Third, optimizing the material band gap can expand the photovoltaic response characteristics of the detector in the long-wave range. Currently, the main method to solve these problems is to introduce microstructure design or impurity doping. It has been reported that a black silicon detector prepared by introducing microstructure design through femtosecond laser process and injecting chalcogen impurities can expand the response spectral range to 1200nm. In addition, introducing microstructure units into the photosensitive surface to form a metasurface can also enhance the wide-band photovoltaic response performance of the detector. Compared with black silicon design, metasurface structure has better controllability and advantages in device consistency. However, the mechanism of metasurface design to enhance the detection performance is still unclear, and the material system is complex and difficult to prepare, so this method has few applications in silicon photodetectors.

[0004] The existing technology mainly enhances the wide-band photovoltaic response characteristics of avalanche photodetectors by physically and chemically damaging the surface of the detector material and doping sulfur, titanium and tellurium impurities. The preparation process is not compatible, which is not conducive to large-scale application. SUMMARY

[0005] The technical solution of the present application is: the present application provides a full dielectric metasurface enhanced wide-band photovoltaic avalanche photodetector, which comprises a full dielectric antireflection film metasurface, which can reduce the reflection of the detector to the incident light; and a contact layer full dielectric metasurface, which can increase the absorption effect of the incident light that has entered the interior of the detector. The present application solves the problems of process incompatibility, uncontrollable metasurface structure and large-scale preparation in the existing metasurface preparation technology.

[0006] The technical solution adopted by the present application is: a full dielectric metasurface enhanced wide-band photovoltaic avalanche photodetector, comprising a full dielectric antireflection film metasurface, an upper electrode, a lower electrode, an oxidation layer, a photosensitive surface, a protection ring, a cutoff ring, a multiplication layer, an intrinsic absorption layer and a full dielectric contact layer metasurface.

[0007] The upper surface of the intrinsic absorption layer is etched to form a cutoff ring and a protection ring, and the protection ring is located in the inner ring of the cutoff ring; the upper and lower sides of the intrinsic absorption layer are respectively an oxidation layer and a full dielectric contact layer metasurface, and the upper surface of the intrinsic absorption layer is etched to form a multiplication layer and a photosensitive surface, and the multiplication layer is located below the photosensitive surface, and the full dielectric antireflection film metasurface is located above the photosensitive surface; the upper electrode is located above the protection ring, and the lower electrode is located below the full dielectric contact layer metasurface.

[0008] Further, the patterns for the full dielectric antireflection film metasurface and the full dielectric contact layer metasurface are periodic microstructure unit arrays, and the microstructure units are one or a combination of column type, hole type, cone type, spherical type, polygon type and slit ring type.

[0009] A processing method of a full dielectric metasurface enhanced wide-band photovoltaic avalanche photodetector, comprising:

[0010] The intrinsic silicon substrate is cleaned and dry oxygen oxidation is performed;

[0011] The intrinsic silicon substrate is etched to form a cutoff ring, and boron is injected at the cutoff ring;

[0012] First low-temperature thin layer oxidation is performed;

[0013] The multiplication layer region is etched and boron is injected;

[0014] Second low-temperature thin layer oxidation is performed;

[0015] The back contact layer is injected at the lower surface of the intrinsic silicon substrate;

[0016] Third low-temperature thin layer oxidation is performed;

[0017] The protection ring is etched and phosphorus is injected;

[0018] Fourth low-temperature thin layer oxidation is performed;

[0019] Carry out cut-off ring, protection ring, multiplication layer, back contact layer diffusion;

[0020] Surface photolithography photosensitive surface area on intrinsic silicon substrate;

[0021] Carry out the fifth low temperature thin layer oxidation, and carry out phosphorus injection;

[0022] Annealing activation photosensitive surface area;

[0023] Utilize physical vapor deposition method to prepare Si3N4 layer on photosensitive surface;

[0024] Photolithography, etching surface Si3N4 layer, forming full dielectric antireflection film super surface;

[0025] Back contact layer photolithography, etching back microstructure unit, forming full dielectric contact layer super surface;

[0026] Photolithography, etching metal contact hole;

[0027] Depositing front Al metal;

[0028] Photolithography etching front metal electrode;

[0029] Depositing front Al metal and photolithography;

[0030] Depositing back Al metal;

[0031] Carrying out rapid annealing to complete preparation.

[0032] Further, the intrinsic silicon substrate is <100> double-polished intrinsic silicon substrate with resistance >1000Ω and thickness ≥400μm.

[0033] Further, the dry oxygen oxidation temperature is 800-1100℃, and the thickness is

[0034] Further, the boron injection dose when carrying out boron injection at cut-off ring is 2×1018cm-2, injection energy is 50-100KeV, and etching depth is 15 -2

[0035] The boron doping concentration when carrying out boron injection after photolithography and etching multiplication layer area is 2.5×1018cm-2, and etching depth is 17 -3

[0036] Further, the first low temperature thin layer oxidation temperature is 900℃, and the doping concentration is 2.5×1018cm-2. 19 -3 ​​​​​The temperature of the second low-temperature thin-layer oxidation, the third low-temperature thin-layer oxidation and the fourth low-temperature thin-layer oxidation is 800-1100 DEG C, and the thickness is

[0037] Further, the phosphorus injection dose when injecting the back contact layer on the lower surface of the intrinsic silicon substrate is 2*10 15 cm -2 , the injection energy is 50-100KeV;

[0038] The etching depth when etching the protection ring and performing the phosphorus injection is

[0039] When performing the fifth low-temperature thin-layer oxidation and the phosphorus injection, the temperature of the low-temperature thin-layer oxidation is 800-1100 DEG C, the doping concentration when performing the phosphorus injection is 2.5*10 19 cm -3 , the phosphorus injection dose is 2*10 15 cm -2 , and the injection energy is 50-100KeV;

[0040] Further, when diffusing the stop ring, the protection ring, the multiplication layer and the bottom contact layer, the diffusion temperature is 1050 DEG C, and the diffusion length is 2-3 mu m;

[0041] When etching the light-sensitive surface area, the etching depth is

[0042] When etching the metal contact hole, the etching depth is

[0043] Further, the annealing temperature of the rapid annealing is 200 DEG C-500 DEG C, and the time is 30s-300s.

[0044] Compared with the prior art, the present application has the following advantages:

[0045] (1) The all-dielectric super surface enhanced wide-band photovoltaic response avalanche photodetector proposed by the present application improves the photoelectric response characteristics of the avalanche photodetector by relying on the structural design of the material, and the whole process is compatible with the process of the detector itself, and has strong structural controllability and device consistency advantages.

[0046] (2) The present application promotes the wide-band photovoltaic response characteristics of the avalanche photodetector through the synergistic design of the all-dielectric antireflection film super surface and the all-dielectric contact layer super surface. The preparation process of the all-dielectric super surface proposed by the present application is completed by the photolithography process, and only relies on the specific all-dielectric super surface structure to strengthen the photoelectric response characteristics of the detector, without introducing the dopant incompatible with the process, therefore, the process of the avalanche photodetector proposed by the present application is completely compatible with the semiconductor process. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the structure of the all-dielectric metasurface enhanced broadband photoelectric response avalanche photodetector of the present invention.

[0048] Figure 2 This is a schematic diagram of the columnar array all-dielectric metasurface structure provided by the present invention.

[0049] Figure 3 This is a schematic diagram of the porous array all-dielectric metasurface structure provided by the present invention.

[0050] Figure 4 This is a schematic diagram of the slit annular array all-dielectric metasurface structure provided by the present invention. Detailed Implementation

[0051] The present invention will now be described in detail through exemplary embodiments.

[0052] A fully dielectric metasurface-enhanced broadband photoresponse avalanche photodetector, the structure of which is as follows: Figure 1 As shown, it has a vertical two-end device structure. The avalanche photodetector is fabricated from an intrinsic silicon substrate with a resistivity of 100Ω·cm to 10000Ω·cm through doping, ion implantation, photolithography, etching, oxidation, and deposition processes.

[0053] A wideband photoelectric response avalanche photodetector with all-dielectric metasurface enhancement includes an all-dielectric antireflection coating metasurface 1, an upper electrode 2, a lower motor 10, an oxide layer 3, a photosensitive surface 4, a protective ring 5, a cutoff ring 6, a multiplication layer 7, an intrinsic absorption layer 8, and an all-dielectric contact layer metasurface 9.

[0054] The upper surface of the intrinsic absorption layer 8 is photolithographically etched to form a stop ring 6 and a guard ring 5, with the guard ring 5 located within the stop ring 6. The upper and lower sides of the intrinsic absorption layer 8 are respectively an oxide layer 3 and a fully dielectric contact layer metasurface 9. The upper surface of the intrinsic absorption layer 8 is photolithographically etched to form a multiplication layer 7 and a photosensitive surface 4, with the multiplication layer 7 located below the photosensitive surface 4 and the fully dielectric antireflection film metasurface 1 above the photosensitive surface 4. The upper motor 2 is located above the guard ring 5, and the lower electrode 10 is located below the fully dielectric contact layer metasurface 9.

[0055] When the avalanche photodetector is in operation, a reverse bias voltage is applied to the upper electrode and connected to the lower electrode to form a circuit. Incident photons pass through the all-dielectric antireflection coating metasurface 1 and are incident on the photosensitive surface 4 of the detector. The incident photons collide and ionize with the material lattice, generating electron-hole pairs. The electron-hole pairs diffuse and drift to the multiplication layer 7. The electric field of the multiplication layer 7 further accelerates the movement of electrons and holes, further promoting collisional ionization and triggering the avalanche effect.

[0056] The full dielectric antireflection film super surface is grown on the photosensitive surface by low-temperature chemical vapor deposition method and patterned photolithography process, and the material is a laminated structure composed of SiO2 and Si3N4. 19 cm -3 The full dielectric contact layer super surface is made by ion implantation, high-temperature diffusion and patterned photolithography process, and the material is a high-doped detector body material with a doping concentration of about 1×10 Figure 2 The patterned scheme for the full dielectric antireflection film super surface and the full dielectric contact layer super surface is composed of a periodic array of microstructure units, which can be one or a combination of column type Figure 3 ), cone type, spherical type, polygonal type and slit ring type Figure 4 ). The gray area represents the unetched area 11. The blank area represents the etched area 12.

[0057] A full dielectric super surface enhanced wide band photovoltaic response silicon APD photodetector, the structure is as shown in Figure 1 The specific implementation method is as follows:

[0058] 1. Preparation: <100> double-polished intrinsic silicon substrate with resistance >1000Ω, thickness >400μm;

[0059] 2. Cleaning of intrinsic silicon substrate, dry oxygen oxidation, temperature: 800-1100℃, thickness:

[0060] 3. Photolithography and etching of stop ring 6 on the upper surface of the intrinsic silicon substrate, boron implantation of the stop ring 6, and the preferred boron implantation dose is 2×10 15 cm -2 , implantation energy is 50-100KeV, and etching depth is:

[0061] 4. Low-temperature thin layer oxidation, temperature: 900℃, doping concentration: 2.5×10 19 cm -3 ;

[0062] 5. Photolithography and etching of the multiplication layer 7 region, and boron implantation, boron doping concentration: 2.5×10 17 cm -3 , etching depth:

[0063] 6. Low-temperature thin layer oxidation, temperature: 800-1100℃, thickness:

[0064] 7. Back contact layer implantation, preferred phosphorus implantation dose is 2×10 15 cm -2The injected energy is 50–100 keV;

[0065] 8. Low-temperature thin-layer oxidation, temperature: 800~1100℃, thickness:

[0066] 9. Photolithography and etching of the protective ring 5, followed by phosphorus implantation. Etching depth:

[0067] 10. Low-temperature thin-layer oxidation, temperature: 800~1100℃, thickness:

[0068] 11. The diffusion consists of a stop ring 6, a protective ring 5, a multiplication layer 7, and a bottom contact layer. The preferred diffusion temperature is 1050℃, and the diffusion length is 2-3 μm.

[0069] 12. Photolithography of photosensitive surface region 4, etching depth:

[0070] 13. Low-temperature thin-layer oxidation, temperature: 800~1100℃, with phosphorus implantation, doping concentration: 2.5×10⁻⁶ 19 cm -3 The preferred phosphorus injection dose is 2×10 15 cm -2 The injected energy is 50–100 keV;

[0071] 14. Rapid annealing activates four areas of the photosensitive surface;

[0072] 15. Prepare Si3N4 with a thickness of approximately 100 nm to 200 nm on the surface of a photosensitive surface using physical vapor deposition;

[0073] 16. Photolithography and etching of Si3N4 surface to form all-dielectric antireflection film metasurface 1, preferably with an etching depth of 1μm;

[0074] 17. Photolithography and etching of the back microstructure to form a fully dielectric contact layer metasurface 9, with an etching depth of 1 μm;

[0075] 18. The etching depth of the metal contact holes in photolithography and etching is:

[0076] 19. Deposit Al metal on the front side, preferably with a thickness of 2 μm;

[0077] 20. Photolithographic etching of the front metal electrode;

[0078] 21. Deposit Al metal on the front side and perform photolithography, preferably with a thickness of 2 μm;

[0079] 22. Deposit Al metal on the back side, preferably with a thickness of 2 μm;

[0080] 23. Rapid annealing to reduce contact resistance, annealing temperature 200°C to 500°C, time 30s to 300s, to complete the fabrication.

[0081] Portions of the disclosure that are not specifically described herein are well understood by those skilled in the art.

Claims

1. An all-dielectric metasurface-enhanced broadband photovoltaic response avalanche photodetector, characterized in that, The intrinsic absorption layer (8) is etched by photolithography to form the cutoff ring (6) and the protection ring (5), and the protection ring (5) is located in the inner ring of the cutoff ring (6); the upper and lower sides of the intrinsic absorption layer (8) are respectively the oxidation layer (3) and the full dielectric contact layer super surface (9), and the multiplication layer (7) and the photosensitive surface (4) are etched by photolithography on the upper surface of the intrinsic absorption layer (8), the multiplication layer (7) is located below the photosensitive surface (4), and the full dielectric antireflection film super surface (1) is located above the photosensitive surface (4); the upper electrode (2) is located above the protection ring (5), and the lower electrode (10) is located below the full dielectric contact layer super surface (9). The pattern for the full dielectric antireflection film super surface (1) and the full dielectric contact layer super surface (9) is a periodic array of microstructure units, and the microstructure units are one or a combination of column type, hole type, cone type, ball type, polygon type and slit ring type.

2. The all-dielectric metasurface-enhanced wide-band photovoltaic avalanche photodetector according to claim 1, wherein, The method comprises the following steps:

3. A processing method of a full-dielectric metasurface enhanced broadband photovoltaic response avalanche photodetector, characterized in that, The intrinsic silicon substrate is cleaned and dry oxygen oxidation is performed; The cutoff ring (6) is etched by photolithography on the upper surface of the intrinsic silicon substrate, and boron implantation is performed at the cutoff ring (6); The first low-temperature thin layer oxidation is performed; The multiplication layer (7) region is etched by photolithography, and boron implantation is performed; The second low-temperature thin layer oxidation is performed; The back contact layer is implanted on the lower surface of the intrinsic silicon substrate; The third low-temperature thin layer oxidation is performed; The protection ring (5) is etched by photolithography, and phosphorus implantation is performed; The fourth low-temperature thin layer oxidation is performed; The cutoff ring (6), the protection ring (5), the multiplication layer (7) and the back contact layer are diffused; The photosensitive surface (4) region is etched by photolithography on the upper surface of the intrinsic silicon substrate; The fifth low-temperature thin layer oxidation is performed, and phosphorus implantation is performed; The photosensitive surface (4) region is activated by annealing; The Si3N4 layer is prepared on the surface of the photosensitive surface (4) by physical vapor deposition; The full dielectric antireflection film super surface (1) is formed by etching the surface Si3N4 layer by photolithography and etching; The full dielectric contact layer super surface (9) is formed by etching the back microstructure unit by photolithography and etching on the back contact layer; The metal contact hole is etched by photolithography and etching; The front Al metal is deposited; The front metal electrode is etched by photolithography and etching; The front Al metal is deposited and etched by photolithography; The back Al metal is deposited; The preparation is completed by rapid annealing. The intrinsic silicon substrate is a <100> double-polished intrinsic silicon substrate with a resistance of >1000Ω and a thickness of ≥400μm.

4. The processing method of a full-dielectric metasurface enhanced wide-band photovoltaic response avalanche photodetector according to claim 3, wherein, When the cutoff ring (6), the protection ring (5), the multiplication layer (7) and the bottom contact layer are diffused, the diffusion temperature is 1050℃, and the diffusion length is 2-3μm; 5. The processing method of a full-dielectric metasurface-enhanced wide-band photovoltaic response avalanche photodetector according to claim 4, wherein, The dry oxygen oxidation temperature is 800-1100℃, and the thickness is 6. The processing method of a full-dielectric metasurface-enhanced wide-band photovoltaic response avalanche photodetector according to claim 5, wherein, The boron implant dose was 2 x 1013cm"2 at an implant energy of 50-100 KeV with an etch depth of 0.5-1.0 μm at the cut-off ring (6). 15 cm -2 ​ The boron doping concentration is 2.5 x 1019cm-3 when the photoetching, etching the multiplication layer (7) region and boron injection are performed. 17 cm -3 The etching depth is 7. The processing method of a full-dielectric metasurface enhanced wide-band photovoltaic response avalanche photodetector according to claim 6, wherein, The first low-temperature thin-layer oxidation temperature is 900°C, and the doping concentration is 2.5 x 10 19 cm -3 -2.5 The temperature of the second low-temperature thin-layer oxidation, the third low-temperature thin-layer oxidation and the fourth low-temperature thin-layer oxidation is 800-1100°C, and the thickness is 0.1-1.0 μm.

8. The processing method of a full-dielectric metasurface-enhanced wide-band photovoltaic response avalanche photodetector according to claim 7, wherein, The phosphorus implantation dose is 2 x 1013cm-2, and the implantation energy is 50-100 KeV when implanting the back contact layer on the lower surface of the intrinsic silicon substrate. 15 cm -2 , and the implantation energy is 50-100 KeV. The etch depth when lithographically and etching the guard ring (5) and performing the phosphorous implantation is The fifth low temperature thin layer oxidation is performed, and the phosphorus implantation is performed, wherein the temperature of the low temperature thin layer oxidation is 800-1100 °C, the doping concentration of the phosphorus implantation is 2.5 x 1019 cm-3, the phosphorus implantation dose is 2 x 1015 cm-2, and the implantation energy is 50-100 KeV. 19 cm -3 , the phosphorus implantation dose is 2 x 1015 cm-2, and the implantation energy is 50-100 KeV. 15 cm -2 , the phosphorus implantation dose is 2 x 1015 cm-2, and the implantation energy is 50-100 KeV.

9. The processing method of a full-dielectric metasurface-enhanced wide-band photovoltaic response avalanche photodetector according to claim 8, wherein, The annealing temperature of the rapid annealing is 200-500℃, and the time is 30-300s. The etching depth is 0.5-2.0 μm when the photoresist surface (4) is exposed to light. The etching depth is: Si3N4 etching depth is SiO2 etching depth is Si etching depth is 10. The processing method of a full-dielectric metasurface-enhanced wide-band photovoltaic response avalanche photodetector according to claim 9, wherein, ​

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