A resonant cavity enhanced germanium image sensor and a method for manufacturing the same

Abstract

The present application belongs to the field of semiconductor process technology, and discloses a resonant cavity enhanced germanium image sensor and a manufacturing method thereof, comprising a semi-insulating gallium arsenide substrate, a distributed Bragg reflector layer, a first electrode layer, an intrinsic germanium absorption layer, a second electrode layer and a passivation layer stacked in sequence; the distributed Bragg reflector layer adopts gallium arsenide material and aluminum arsenide material; a plurality of rectangular grooves of the same shape and distributed at preset intervals penetrate the second electrode layer and the intrinsic germanium absorption layer; the passivation layer uniformly covers the second electrode layer and the inner wall of each rectangular groove; the first electrode is arranged in the rectangular groove, penetrates the passivation layer and is connected to the first electrode layer; the second electrode penetrates the passivation layer and is connected to the second electrode layer. The present application can reduce the dark current of the sensor, and at the same time improve the responsiveness and response speed of the sensor.

Description

Technical Field

[0001] The present application relates to the field of semiconductor process technology, and in particular to a resonant cavity enhanced germanium image sensor and a method for manufacturing the same. Background Art

[0002] Short-wave infrared photodetectors have demonstrated important practical value in many fields due to their unique imaging capabilities and excellent performance advantages. Although III-V materials perform well in the short-wave infrared band, germanium materials are considered to be the key technical approach to achieve large-scale production of short-wave infrared image sensors due to their silicon-based epitaxy, high compatibility with CMOS manufacturing processes, and excellent photoelectric response in the short-wave infrared band. Therefore, a large number of photodetectors currently use silicon-based germanium structures.

[0003] However, for silicon-based germanium detectors with a vertically stacked structure, there is a mutually restrictive relationship between their responsivity and response speed: if the thickness of the absorption layer is increased to improve the responsivity, the response speed may be reduced accordingly, making it difficult to optimize them at the same time. Summary of the invention

[0004] The present application provides a resonant cavity enhanced germanium image sensor and a method for manufacturing the same, which can reduce the dark current of the sensor while improving the responsiveness and response speed of the sensor.

[0005] In a first aspect, an embodiment of the present application provides a resonant cavity enhanced germanium image sensor, comprising a semi-insulating gallium arsenide substrate, a distributed Bragg reflector layer, a first electrode layer, an intrinsic germanium absorption layer, a second electrode layer and a passivation layer stacked in sequence;

[0006] The distributed Bragg reflector layer is made of gallium arsenide material and aluminum arsenide material;

[0007] A plurality of rectangular grooves of the same shape and distributed at preset intervals penetrate the second electrode layer and the intrinsic germanium absorption layer;

[0008] The passivation layer uniformly covers the second electrode layer and the inner walls of each rectangular groove;

[0009] The first electrode is arranged in the rectangular groove, penetrates the passivation layer and is connected to the first electrode layer;

[0010] The second electrode penetrates the passivation layer and is connected to the second electrode layer.

[0011] Further, the total thickness of the DBR layer ranges from 1 micrometer to 16 micrometers.

[0012] Furthermore, the distributed Bragg reflector layer is a periodic structure, a single period includes a gallium arsenide layer and an aluminum arsenide layer, and the number of periods ranges from 5 to 40.

[0013] Furthermore, the thickness of the gallium arsenide layer and the aluminum arsenide layer are both in the range of 100 nanometers to 200 nanometers.

[0014] Furthermore, the thickness of the gallium arsenide layer in each period is 110.7 nanometers, and the thickness of the aluminum arsenide layer is 113.6 nanometers.

[0015] Furthermore, the first electrode layer is a P-type germanium electrode layer, and the second electrode layer is an N-type germanium electrode layer.

[0016] Furthermore, the first electrode layer is an N-type germanium electrode layer, and the second electrode layer is a P-type germanium electrode layer.

[0017] Furthermore, the intrinsic germanium absorption layer is a germanium multiple quantum well structure, a germanium-silicon multiple quantum well structure, a germanium-tin multiple quantum well structure or a silicon-germanium-tin multiple quantum well structure.

[0018] In a second aspect, an embodiment of the present application provides a method for manufacturing a resonant cavity enhanced germanium image sensor, comprising:

[0019] Generate a semi-insulating gallium arsenide substrate based on a silicon substrate, ppb-level gallium materials and arsenic materials;

[0020] A distributed Bragg reflector layer is generated on a semi-insulating gallium arsenide substrate by using a molecular beam epitaxy method; wherein the distributed Bragg reflector layer is made of gallium arsenide material and aluminum arsenide material;

[0021] A first electrode layer, an intrinsic germanium absorption layer, and a second electrode layer are sequentially generated on the distributed Bragg reflector layer by using a molecular beam epitaxy method to obtain an image sensor wafer;

[0022] A plurality of rectangular grooves having the same shape and distributed at preset intervals are arranged on the image sensor wafer; the rectangular grooves penetrate the second electrode layer and the intrinsic germanium absorption layer;

[0023] forming a passivation layer on the second electrode layer and the inner wall of each rectangular groove;

[0024] A first electrode connected to the first electrode layer is arranged at the bottom of the rectangular groove;

[0025] A second electrode connected to the second electrode layer is disposed on the second electrode layer.

[0026] Furthermore, the above-mentioned method of generating a semi-insulating gallium arsenide substrate based on a silicon substrate, a gallium material of ppb level and an arsenic material includes:

[0027] Chemical detergents are used to remove oxides and organic matter from the surface of the silicon substrate;

[0028] Adding a preset ratio of deep energy level compensator to ppb-level gallium material and arsenic material to obtain a target material;

[0029] The target material is controlled to undergo crystal growth on a silicon substrate to obtain a semi-insulating gallium arsenide substrate.

[0030] Furthermore, the above-mentioned providing a plurality of rectangular grooves of the same shape and distributed at preset intervals on the image sensor wafer includes: providing each rectangular groove on the image sensor wafer by adopting a wet etching method.

[0031] Furthermore, the above-mentioned providing a plurality of rectangular grooves of the same shape and distributed at preset intervals on the image sensor wafer includes: providing each rectangular groove on the image sensor wafer by adopting a dry etching method.

[0032] Furthermore, the method also includes:

[0033] A distributed Bragg reflector layer is formed on a semi-insulating gallium arsenide substrate by using a metal organic chemical vapor deposition method.

[0034] Furthermore, the method also includes:

[0035] A first electrode layer, an intrinsic germanium absorption layer and a second electrode layer are sequentially formed by a chemical vapor deposition method.

[0036] Furthermore, the method also includes:

[0037] The first electrode and the second electrode are connected to the readout circuit by using the flip chip technology.

[0038] In summary, compared with the prior art, the technical solution provided in the embodiment of the present application has at least the following beneficial effects:

[0039] A resonant cavity enhanced germanium image sensor provided in an embodiment of the present application, firstly, the present application introduces a distributed Bragg reflector composed of gallium arsenide and aluminum arsenide under the intrinsic germanium absorption layer. Gallium arsenide is a high reflectivity material, and aluminum arsenide is a low reflectivity material. This material structure enables the reflector to make the incident photons reflect multiple times in the intrinsic germanium absorption layer, thereby enhancing the residence time of the photons in the absorption layer and increasing the absorption efficiency, so as to improve the responsiveness of the device without increasing the thickness of the material or slowing down the response speed. Secondly, the present application adopts semi-insulating gallium arsenide as the substrate. The semi-insulating gallium arsenide and the germanium absorption layer are highly matched in lattice constant and thermal expansion coefficient, ensuring excellent heterogeneous interface quality and solving the lattice and thermal mismatch problems in traditional silicon-based structures, thereby reducing the dark current of the device; moreover, the semi-insulating gallium arsenide substrate of the present application is generated based on ppb-level gallium materials and arsenic materials, which can greatly reduce impurities in gallium arsenide crystals, especially shallow energy level impurities, so that the semi-insulating gallium arsenide substrate achieves extremely high resistivity (greater than 1e10^7Ω·cm), further reducing the dark current of the germanium image sensor, and ultimately improving the responsiveness and response speed of the device by reducing the dark current. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A structural diagram of a cavity-enhanced germanium image sensor provided in accordance with an embodiment of the present application.

[0041] Figure 2 A flow chart of a method for manufacturing a cavity-enhanced germanium image sensor provided in one embodiment of the present application.

[0042] Figure 3 A structural diagram of an image sensor wafer provided in accordance with one embodiment of the present application.

[0043] Figure 4 A structural diagram of an image sensor wafer after etching rectangular grooves provided in one embodiment of the present application.

[0044] Figure 5 A structural diagram of an image sensor wafer after a passivation layer is formed according to an embodiment of the present application.

[0045] Figure 6 A structural diagram of an image sensor wafer after electrodes are provided according to an embodiment of the present application.

[0046] Description of reference numerals:

[0047] 101. semi-insulating gallium arsenide substrate; 102. distributed Bragg reflector layer; 103. first electrode layer; 104. intrinsic germanium absorption layer; 105. second electrode layer; 201. first electrode; 202. second electrode. DETAILED DESCRIPTION

[0048] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments.

[0049] Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of this application.

[0050] See also Figure 1 The embodiment of the present application provides a resonant cavity enhanced germanium image sensor, comprising a semi-insulating gallium arsenide substrate 101, a distributed Bragg reflector layer 102, a first electrode layer 103, an intrinsic germanium absorption layer 104, a second electrode layer 105 and a passivation layer stacked in sequence. The intrinsic germanium absorption layer 104 can be a germanium multi-quantum well structure, a germanium-silicon multi-quantum well structure, a germanium-tin multi-quantum well structure, a silicon-germanium-tin multi-quantum well structure or a multiple combination of the above structures.

[0051] The DBR layer 102 is made of gallium arsenide material and aluminum arsenide material.

[0052] The total thickness of the DBR layer 102 is in a range of 1 micrometer to 16 micrometers.

[0053] The distributed Bragg reflector layer 102 is a periodic structure. A single period includes a gallium arsenide layer and an aluminum arsenide layer. The thickness of a single period ranges from 200 nanometers to 400 nanometers. The number of periods ranges from 5 to 40.

[0054] The thickness of the gallium arsenide layer and the aluminum arsenide layer are both in the range of 100 nanometers to 200 nanometers.

[0055] The present application uses the distributed Bragg reflector layer 102 to generate a resonant cavity enhancement effect, and alleviates the restrictive relationship between the responsivity and the response speed of the germanium photodetector through the resonant cavity enhancement effect.

[0056] A plurality of rectangular grooves of the same shape and distributed at preset intervals penetrate the second electrode layer 105 and the intrinsic germanium absorption layer 104 .

[0057] Specifically, Figure 1 As shown, after the rectangular groove penetrates the intrinsic germanium absorption layer 104 , a portion of the first electrode layer 103 is also etched to ensure that the first electrode 201 at the bottom of the rectangular groove can be connected to the first electrode layer 103 .

[0058] The passivation layer uniformly covers the second electrode layer 105 and the inner walls of each rectangular groove.

[0059] The first electrode 201 is disposed in the rectangular groove, penetrates the passivation layer and is connected to the first electrode layer 103 .

[0060] The second electrode 202 penetrates the passivation layer and is connected to the second electrode layer 105 .

[0061] Specifically, the first electrode 201 may be a P-type electrode, the second electrode 202 may be an N-type electrode, the first electrode layer 103 may be a P-type germanium electrode layer, and the second electrode layer 105 may be an N-type germanium electrode layer.

[0062] Alternatively, the first electrode 201 may be an N-type electrode, the second electrode 202 may be a P-type electrode, the first electrode layer 103 may be an N-type germanium electrode layer, and the second electrode layer 105 may be a P-type germanium electrode layer.

[0063] The above embodiment provides a resonant cavity enhanced germanium image sensor, which first introduces a distributed Bragg reflector composed of gallium arsenide and aluminum arsenide under the intrinsic germanium absorption layer 104. Gallium arsenide is a high reflectivity material, and aluminum arsenide is a low reflectivity material. This material structure enables the reflector to make the incident photons reflect multiple times in the intrinsic germanium absorption layer 104, generating a resonant cavity enhancement effect, thereby enhancing the residence time of the photons in the absorption layer and increasing the absorption efficiency, thereby achieving the ability to improve the responsiveness of the device without increasing the thickness of the material or slowing down the response speed.

[0064] Secondly, the present application uses semi-insulating gallium arsenide as the substrate, and the semi-insulating gallium arsenide and germanium absorption layer have a lattice constant (approximately ) and thermal expansion coefficient (both are about 6.0x10^-6 / K), ensuring excellent heterogeneous interface quality, solving the lattice and thermal mismatch problems in traditional silicon-based structures, and reducing the dark current of the device; moreover, the semi-insulating gallium arsenide substrate 101 of the present application is generated based on ppb-level gallium materials and arsenic materials, which can greatly reduce impurities in gallium arsenide crystals, especially shallow energy level impurities, so that the semi-insulating gallium arsenide substrate 101 achieves extremely high resistivity (greater than 1e10^7Ω·cm), further reducing the dark current of the germanium image sensor, and ultimately improving the responsiveness and response speed of the device by reducing the dark current.

[0065] It is understandable that when the dark current is high, the detected signal will be overwhelmed by the noise, resulting in a decrease in the actual effective response; therefore, reducing the dark current means reducing the background noise, allowing the detector to more effectively distinguish weak light signals, which can improve the effective response without changing the detector's light absorption capacity.

[0066] Secondly, the response speed of the photodetector is related to its capacitance, resistance and other factors; higher dark current will increase the carrier recombination time, which in turn affects the speed of the detector. The increase in dark current is accompanied by more carriers being thermally excited. These additional carriers will introduce additional charge accumulation, affecting the dynamic response characteristics of the detector. High dark current will also increase the capacitance effect, resulting in a decrease in the response speed of the detector; therefore, by reducing the dark current, the accumulation of invalid carriers can be reduced, thereby reducing the impact of the capacitance effect on the device response time, which allows the detector to maintain a faster response speed at higher frequencies.

[0067] Under high dark current, in order to improve the signal-to-noise ratio, photodetectors usually increase the thickness of the detector to improve the light absorption efficiency (responsivity), but this will lead to a decrease in response speed. Therefore, reducing the dark current can simultaneously improve the signal-to-noise ratio and allow the detector to have a higher sensitivity while maintaining a high-speed response.

[0068] In addition to being able to reduce dark current, the band gap of the semi-insulating gallium arsenide substrate 101 of the present application is approximately 1.42 eV, which gives it good transmittance in the infrared light region, avoids the light being affected by the circuit and transistor between the microlens and the photodiode in the traditional sensor structure, and improves the light collection efficiency and sensitivity.

[0069] At the same time, the good thermal conductivity of the semi-insulating gallium arsenide substrate 101 ensures that the germanium image sensor can still operate stably under high power and high temperature conditions, thereby enhancing its reliability and radiation resistance.

[0070] The current silicon-based germanium detector has limited responsivity in the 1550nm band, which is mainly attributed to the intrinsic absorption characteristics of germanium. The distributed Bragg reflector layer 102 of the present application can achieve efficient reflection of 1550nm wavelength light by controlling the thickness of each layer. Specifically, the refractive indices of GaAs and AlAs are 3.5 and 2.9, respectively. According to the Bragg condition, the optical thickness of each layer should be 1 / 4 of the working wavelength. For the design with a central wavelength of 1550nm, the thickness of the GaAs layer is 110.7nm and the thickness of the AlAs layer is 133.6nm. In other words, when the thickness of the gallium arsenide layer of each period is 110.7 nanometers and the thickness of the aluminum arsenide layer is 113.6 nanometers, an AlAs / GaAs distributed Bragg reflector structure with a central wavelength of 1550nm can be obtained. If the thickness is not satisfied, there is also a reflection effect, but the reflectivity is reduced.

[0071] Secondly, the more the number of periods of the distributed Bragg reflector layer 102 is, the higher its reflectivity is. However, the more layers there are, the more difficult the manufacturing process is. Therefore, the application provides a range of the number of periods of the distributed Bragg reflector layer 102. When the number of periods is less than the range of the number of periods specified in the application, there will be a certain reflection effect, but the effect will be poor.

[0072] In summary, the resonant cavity enhanced germanium image sensor proposed in this application not only reduces the dark current of the germanium image sensor and alleviates the restrictive relationship between responsivity and response speed, but also significantly improves the responsivity of the germanium image sensor in the 1550nm band, reduces the manufacturing cost of the germanium short-wave infrared image sensor, and improves its mass production efficiency.

[0073] See also Figure 2 Another embodiment of the present application provides a method for manufacturing a resonant cavity enhanced germanium image sensor, comprising:

[0074] Step S1 : generating a semi-insulating gallium arsenide substrate 101 based on a silicon substrate, a gallium material of ppb level, and an arsenic material.

[0075] Among them, ppb is the abbreviation of "parts per billion", which means "one billionth". It is a unit of concentration or ratio, used to describe very small quantities. In semiconductor materials (such as silicon, germanium, etc.), the ppb level refers to the ratio of the number of impurity atoms to the total number of atoms in the material. Such impurity content control requires the ability to reduce the introduction of impurities when growing crystals.

[0076] Step S2, using a molecular beam epitaxy method to form a distributed Bragg reflector layer 102 on a semi-insulating gallium arsenide substrate 101; wherein the distributed Bragg reflector layer 102 is made of gallium arsenide material and aluminum arsenide material.

[0077] Specifically, in addition to the molecular beam epitaxy method, a metal organic chemical vapor deposition method can also be used to form the distributed Bragg reflector layer 102 on the semi-insulating gallium arsenide substrate 101 .

[0078] Step S3, using a molecular beam epitaxy method to sequentially generate a first electrode layer 103, an intrinsic germanium absorption layer 104 and a second electrode layer 105 on the distributed Bragg reflector layer 102 to obtain an image sensor wafer.

[0079] See also Figure 3 Specifically, in addition to the molecular beam epitaxy method, the chemical vapor deposition method can also be used to sequentially generate the first electrode layer 103, the intrinsic germanium absorption layer 104 and the second electrode layer 105.

[0080] Step S4 , providing a plurality of rectangular grooves of the same shape and distributed at preset intervals on the image sensor wafer; the rectangular grooves penetrate the second electrode layer 105 and the intrinsic germanium absorption layer 104 .

[0081] See also Figure 4 Specifically, each rectangular groove can be set on the image sensor wafer by wet etching or dry etching; after the rectangular groove penetrates the intrinsic germanium absorption layer 104, a portion of the first electrode layer 103 is also etched.

[0082] Step S5: forming a passivation layer on the second electrode layer 105 and the inner walls of each rectangular groove.

[0083] See also Figure 5 The passivation layer covers the bottom and sidewalls of the rectangular groove, and the terrace of the second electrode layer 105 .

[0084] Step S6 , disposing a first electrode 201 connected to the first electrode layer 103 at the bottom of the rectangular groove; and disposing a second electrode 202 connected to the second electrode layer 105 on the second electrode layer 105 .

[0085] See also Figure 6, wherein the first electrode 201 may be a P-type electrode, the second electrode 202 may be an N-type electrode, the first electrode layer 103 may be a P-type germanium electrode layer, and the second electrode layer 105 may be an N-type germanium electrode layer; or the first electrode 201 may be an N-type electrode, the second electrode 202 may be a P-type electrode, the first electrode layer 103 may be an N-type germanium electrode layer, and the second electrode layer 105 may be a P-type germanium electrode layer. After the first electrode 201 and the second electrode 202 are provided, the first electrode 201 and the second electrode 202 may be connected to the readout circuit by using a flip-chip bonding technique.

[0086] In some embodiments, the above-mentioned generation of the semi-insulating gallium arsenide substrate 101 based on the silicon substrate, the gallium material and the arsenic material in the ppb level may specifically include the following steps:

[0087] Step S11, using a chemical detergent to remove oxides and organic matter on the surface of the silicon substrate.

[0088] The chemical detergent may be acetone or deionized water.

[0089] Step S12, adding a preset ratio of deep energy level compensator to ppb level gallium material and arsenic material to obtain a target material.

[0090] Among them, common deep level compensators are chromium (Cr) or oxygen (O).

[0091] Shallow energy level impurities (such as silicon and carbon) will form conductive free carriers in GaAs, reducing the resistivity of the material, while deep energy level compensators will form deep energy level defects (such as the deep acceptor energy level of Cr) in GaAs crystals. These deep energy level defects can capture free carriers and compensate for the conductive effect of shallow energy level impurities, thereby significantly increasing the resistivity of the material; deep energy level defects reduce the conductivity of the material by capturing thermally excited free electrons or holes, making the GaAs material exhibit semi-insulating properties.

[0092] Step S13 , controlling the target material to perform crystal growth on the silicon substrate to obtain a semi-insulating gallium arsenide substrate 101 .

[0093] Specifically, during the crystal growth process, the growth temperature must be strictly and accurately controlled to ensure that the diffusion of shallow energy level impurities (such as silicon or carbon) is limited during the crystal formation process, thereby reducing the distribution of impurities in the crystal. It is understandable that the above-mentioned substrate generation process is a conventional crystal growth process, and this application only updates the raw materials and does not involve improvements to the process flow.

[0094] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0095] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A cavity-enhanced germanium image sensor, characterized in that: It includes a semi-insulating gallium arsenide substrate, a distributed Bragg reflector layer, a first electrode layer, an intrinsic germanium absorption layer, a second electrode layer and a passivation layer which are stacked in sequence; The distributed Bragg reflector layer is made of gallium arsenide material and aluminum arsenide material; A plurality of rectangular grooves of the same shape and distributed at preset intervals penetrate the second electrode layer and the intrinsic germanium absorption layer; The passivation layer uniformly covers the second electrode layer and the inner wall of each of the rectangular grooves; The first electrode is disposed in the rectangular groove, penetrates the passivation layer and is connected to the first electrode layer; The second electrode penetrates the passivation layer and is connected to the second electrode layer.

2. The resonant cavity enhanced germanium image sensor according to claim 1, characterized in that: The total thickness of the DBR layer ranges from 1 micrometer to 16 micrometers.

3. The resonant cavity enhanced germanium image sensor according to claim 2, characterized in that: The distributed Bragg reflector layer is a periodic structure, a single period includes a gallium arsenide layer and an aluminum arsenide layer, and the number of periods ranges from 5 to 40.

4. The cavity-enhanced germanium image sensor according to claim 3, characterized in that: The thickness of the gallium arsenide layer and the aluminum arsenide layer are both in the range of 100 nanometers to 200 nanometers.

5. The resonant cavity enhanced germanium image sensor according to claim 4, characterized in that: The thickness of the gallium arsenide layer in each period is 110.7 nanometers, and the thickness of the aluminum arsenide layer is 113.6 nanometers.

6. The cavity-enhanced germanium image sensor according to claim 1, characterized in that: The first electrode layer is a P-type germanium electrode layer, and the second electrode layer is an N-type germanium electrode layer.

7. The resonant cavity enhanced germanium image sensor according to claim 1, characterized in that: The first electrode layer is an N-type germanium electrode layer, and the second electrode layer is a P-type germanium electrode layer.

8. The resonant cavity enhanced germanium image sensor according to claim 1, characterized in that: The intrinsic germanium absorption layer is a germanium multiple quantum well structure, a germanium-silicon multiple quantum well structure, a germanium-tin multiple quantum well structure or a silicon-germanium-tin multiple quantum well structure.

9. A method for manufacturing a cavity-enhanced germanium image sensor, characterized in that: include: Generate a semi-insulating gallium arsenide substrate based on a silicon substrate, ppb-level gallium materials and arsenic materials; A distributed Bragg reflector layer is generated on the semi-insulating gallium arsenide substrate by a molecular beam epitaxy method; wherein the distributed Bragg reflector layer is made of gallium arsenide material and aluminum arsenide material; A first electrode layer, an intrinsic germanium absorption layer, and a second electrode layer are sequentially generated on the distributed Bragg reflector layer by a molecular beam epitaxy method to obtain an image sensor wafer; A plurality of rectangular grooves having the same shape and distributed at preset intervals are arranged on the image sensor wafer; the rectangular grooves penetrate the second electrode layer and the intrinsic germanium absorption layer; forming a passivation layer on the second electrode layer and the inner wall of each of the rectangular grooves; A first electrode connected to the first electrode layer is arranged at the bottom of the rectangular groove; A second electrode connected to the second electrode layer is disposed on the second electrode layer.

10. The method for manufacturing a cavity-enhanced germanium image sensor according to claim 9, characterized in that: The method of generating a semi-insulating gallium arsenide substrate based on a silicon substrate, a gallium material of ppb level and an arsenic material comprises: Using chemical detergent to remove oxides and organic matter on the surface of the silicon substrate; Adding a preset ratio of deep energy level compensator to ppb-level gallium material and arsenic material to obtain a target material; The target material is controlled to undergo crystal growth on the silicon substrate to obtain the semi-insulating gallium arsenide substrate.

11. The method for manufacturing a cavity-enhanced germanium image sensor according to claim 9, characterized in that: The method of providing a plurality of rectangular grooves of the same shape and distributed at preset intervals on the image sensor wafer comprises: The rectangular grooves are formed on the image sensor wafer by wet etching.

12. The method for manufacturing a cavity-enhanced germanium image sensor according to claim 9, characterized in that: The method of providing a plurality of rectangular grooves of the same shape and distributed at preset intervals on the image sensor wafer comprises: The rectangular grooves are arranged on the image sensor wafer by dry etching.

13. The method for manufacturing a cavity-enhanced germanium image sensor according to claim 9, characterized in that: Also includes: A distributed Bragg reflector layer is formed on the semi-insulating gallium arsenide substrate by adopting a metal organic chemical vapor deposition method.

14. The method for manufacturing a resonant cavity enhanced germanium image sensor according to claim 9, characterized in that: Also includes: A first electrode layer, an intrinsic germanium absorption layer and a second electrode layer are sequentially formed by a chemical vapor deposition method.

15. The method for manufacturing a cavity-enhanced germanium image sensor according to claim 9, characterized in that: Also includes: The first electrode and the second electrode are connected to a readout circuit by using a flip-chip bonding technology.

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