Photodetector for dual band detection and method of manufacturing the same

Abstract

Embodiments of the present application provide a kind of photoelectric detector for dual-band detection and its manufacturing method, belong to the technical field of photoelectric detection equipment.The photoelectric detector includes: first light absorption layer, for absorbing 400-1000nm wave band incident light;Second light absorption layer, set in the upper of first light absorption layer for absorbing 900-1500nm wave band incident light;Passivation layer, set in the upper of first light absorption layer and wrap second light absorption layer;First light absorption layer and second light absorption layer are formed PIN junction by ion doping and electrode conduction;Incident light is shot into photoelectric detector from the lower of first light absorption layer in back illumination mode, wherein 400-1000nm wave band light is absorbed by first light absorption layer, 900-1500nm wave band light penetrates first light absorption layer and is absorbed by second light absorption layer to simultaneously detect dual-band incident light and carry out photoelectric conversion.The photoelectric detector of the present application can simultaneously detect dual-band incident light, improve photoelectric conversion efficiency and detection sensitivity.

Description

Technical Field

[0001] This invention relates to the technical field of photoelectric detection equipment, and in particular to a photoelectric detector for dual-band detection and its manufacturing method. Background Technology

[0002] A photodetector is a device that converts weak light signals of different wavelengths into electrical signals. The absorption layer of a photodetector used to absorb externally incident light is usually a semiconductor structure layer with a specific bandgap width. Semiconductor structure layers of different materials are used to absorb the spectrum of a specific wavelength range.

[0003] Typical spectral bands include the 400-1000 nm band and the 900-1500 nm band. Photodetectors detecting the 400-1000 nm band can be used in imaging, visible light sensing, short-range optical communication, and laser ranging. Detecting the 900-1500 nm band can be used in fiber optic communication, long-range lidar, gas sensing, and precise optical computed tomography (OCT). Therefore, photodetectors can be widely used in fields such as fiber optic link maintenance, high-speed fiber optic communication, high-precision sensors, long-range radar, and health monitoring.

[0004] Currently, the detection of spectra by photodetectors is mostly limited to the fact that a single photodetector can only detect a certain band of spectrum. To detect spectra in different bands at the same time, multiple photodetectors are needed.

[0005] Newer technological iterations primarily focus on using Ge / Si APD photodetectors, which consist of two back-to-back SACM-APD (absorption multiplier splitter diode) structures to detect two different spectral bands. This approach not only involves complex fabrication processes but also risks breakdown within the germanium absorption layer, leading to increased dark current and decreased photodetector sensitivity.

[0006] In view of this, a novel photodetector for dual-band detection and its manufacturing method are proposed to solve all or part of the above problems. Summary of the Invention

[0007] To address at least one of the aforementioned problems and deficiencies in the prior art, embodiments of the present invention provide a photodetector for dual-band detection and its manufacturing method. By constructing a first and second light-absorbing layer of heterogeneous materials and employing a back-illuminated functional layer layout, simultaneous detection and photoelectric signal conversion are achieved in the 400-1000nm and 900-1500nm wavelength bands, thereby improving the detection efficiency and sensitivity of the photodetector and enhancing its photoelectric conversion efficiency. The technical solution is as follows:

[0008] According to one aspect of the present invention, a photodetector for dual-band detection is provided. The photodetector includes:

[0009] The first light absorption layer is used to absorb incident light in the 400-1000nm wavelength band;

[0010] The second light absorption layer is disposed above the first light absorption layer and is used to absorb incident light in the 900-1500nm wavelength band.

[0011] A passivation layer is disposed above the first light-absorbing layer and surrounds the second light-absorbing layer;

[0012] The first and second light absorption layers form a PIN junction through ion doping and electrode conduction;

[0013] Incident light enters the photodetector from below the first light-absorbing layer in a back-illuminated manner. Light in the 400-1000nm band is absorbed by the first light-absorbing layer, while light in the 900-1500nm band penetrates the first light-absorbing layer and is absorbed by the second light-absorbing layer, so as to simultaneously detect the incident light in both bands and perform photoelectric conversion.

[0014] In some embodiments, specifically, the first light-absorbing layer and the second light-absorbing layer are intrinsic absorption layer structures made of semiconductor materials. The bandgap of the first light-absorbing layer is larger than the bandgap of the second light-absorbing layer. Preferably, the first light-absorbing layer is a silicon structure absorption layer, which is a silicon wafer or a high-resistivity silicon wafer; the second light-absorbing layer is a germanium absorption layer or a III-V group semiconductor compound absorption layer.

[0015] In some embodiments, specifically, the first light-absorbing layer includes a first ion-doped layer disposed below the first light-absorbing layer. The first light-absorbing layer also includes a first electrode, one end of which is in ohmic contact with the first ion-doped layer, and the other end which sequentially penetrates the first light-absorbing layer and the passivation layer and extends from above the passivation layer.

[0016] In some embodiments, specifically, the second light-absorbing layer includes a second ion-doped layer disposed above the second light-absorbing layer; the second light-absorbing layer also includes a second electrode, one end of which is in ohmic contact with the second ion-doped layer, and the other end which penetrates the passivation layer and extends from above the passivation layer.

[0017] In some embodiments, specifically, the ends of the first electrode and the second electrode extending out of the passivation layer are respectively provided with metal bump structures, and all the metal bump structures are located on the same plane for subsequent packaging integration and welding to the external substrate.

[0018] In some embodiments, preferably, the photodetector further includes a reflective metal plate disposed above the passivation layer and the reflective metal plate at least completely covers the second light-absorbing layer. When light that has not been absorbed by the first light-absorbing layer and / or the second light-absorbing layer penetrates the second light-absorbing layer and illuminates the surface of the reflective metal plate, the reflective metal plate reflects the light back into the first light-absorbing layer and / or the second light-absorbing layer for absorption.

[0019] In some embodiments, the second light-absorbing layer may alternatively include a dielectric layer that wraps around the outer surface of the second light-absorbing layer, the dielectric layer being made of materials including SiN and SiO2.

[0020] According to another aspect of the present invention, a method for manufacturing a photodetector for dual-band detection is provided, for manufacturing the photodetector described in the above aspect. The manufacturing method includes:

[0021] A silicon wafer is provided to form the first light-absorbing layer;

[0022] A second light-absorbing layer is formed by epitaxially growing a germanium absorption layer or a group III-V semiconductor compound absorption layer on the upper surface of a silicon wafer.

[0023] A passivation layer is formed on the upper surface of a silicon wafer and encapsulates a second light-absorbing layer.

[0024] In the passivation layer, through-silicon vias are formed to create electrode channels for extending the first electrode and fabricating the second electrode. Metal is then filled into the electrode channels to form the extension electrode of the first electrode and the second electrode, which are then extended above the passivation layer and brought out for soldering to the substrate during integrated packaging.

[0025] After being flipped and inverted, an electrode channel for leading out the first electrode is formed in the silicon wafer by manufacturing through-silicon vias. The electrode channel is then filled with metal to connect and conduct the first electrode to its extension electrode in the passivation layer, and then forms a PIN junction with the second electrode.

[0026] In some embodiments, preferably, the thickness of the second light-absorbing layer is in the range of 200 nm to 3 μm, the top surface area of ​​the second light-absorbing layer is smaller than its bottom surface area, and the cross-sectional shape of the second light-absorbing layer projected in the vertical direction is any one of a circle, an ellipse, a square, a rhombus, and a polygon.

[0027] In some embodiments, specifically, the step of forming electrode channels by fabricating through-silicon vias in the passivation layer and the silicon wafer specifically includes:

[0028] In the passivation layer, a first electrode channel for extending the first electrode and a second electrode channel for conducting the second electrode are formed by fabricating through-silicon vias, and metal is filled in the first electrode channel and the second electrode channel;

[0029] After being flipped and inverted, the silicon wafer is thinned and a third electrode channel for conducting the first electrode is formed by creating through-silicon vias.

[0030] A first electrode is formed on the thinned surface of a silicon wafer, and metal is filled in the third electrode channel to extend the first electrode above the passivation layer.

[0031] The photodetector for dual-band detection and its manufacturing method provided by the embodiments of the present invention have at least one or a portion of the following advantages:

[0032] (1) By constructing a first light absorption layer and a second light absorption layer of heterogeneous material structure and adopting a back-illuminated functional layer layout, the photodetector can simultaneously detect and perform photoelectric signal conversion in the 400-1000nm and 900-1500nm bands, thereby improving the detection efficiency and sensitivity of the photodetector and increasing the photoelectric conversion efficiency.

[0033] (2) By using silicon wafers as the first light absorption layer, the wafer substrate and the first light absorption layer can be integrated into one, effectively reducing processing steps and procedures, and effectively simplifying the manufacturing process of photodetectors.

[0034] (3) By using silicon wafer as the first light absorption layer, it can fully absorb incident light in the 400-1000nm band while also having high light transmittance in the 900-1500nm band, effectively reducing the loss of incident light in the 900-1500nm band, which in turn helps to improve the detection sensitivity of the second light absorption layer, thereby improving the overall detection sensitivity of the photodetector.

[0035] (4) By covering the passivation layer with a reflective metal plate, the light that is not completely absorbed by the first light absorption layer and the second light absorption layer can be reflected and re-enter the first light absorption layer and / or the second light absorption layer to be absorbed, effectively reducing the loss of detection light and further improving the light detection efficiency.

[0036] (5) By constructing a PIN junction of the first light absorption layer and the second light absorption layer, incident light in two bands can be detected simultaneously. The device structure is simple, the manufacturing process is simplified, and the production cost is reduced.

[0037] (6) By creating through-silicon vias (TSVs) in the silicon wafer layer and passivation layer to form electrode channels, the electrodes of the first and second light absorption layers are effectively extended to the plane above the passivation layer, which helps to quickly weld to the external substrate in batches during packaging integration.

[0038] (7) By setting the photodetector as a back-illuminated light incident structure, it is possible to detect dual-band spectra simultaneously without changing the power supply voltage of the photodetector or other external controls and without flipping the photodetector. The operation is simple and the efficiency is high. Attached Figure Description

[0039] These and / or other aspects and advantages of the present invention will become apparent and readily understood from the following description of preferred embodiments taken in conjunction with the accompanying drawings, in which:

[0040] Figure 1 This is a schematic diagram of the cross-sectional structure of a photodetector according to an embodiment of the present invention;

[0041] Figure 2 A flowchart illustrating the steps of a method for manufacturing a photodetector according to an embodiment of the present invention;

[0042] Figure 3 In accordance with Figure 2 The manufacturing method shown involves the following steps: Figure 1 The diagram shows the manufacturing process of the photodetector.

[0043] Figure 4a This is a schematic diagram of the structure of a second light-absorbing layer of a photodetector according to an embodiment of the present invention;

[0044] Figure 4b This is a schematic diagram of the structure of another second light-absorbing layer of a photodetector according to an embodiment of the present invention;

[0045] Figure 4c This is a schematic diagram of the structure of another second light-absorbing layer of a photodetector according to an embodiment of the present invention. Detailed Implementation

[0046] The technical solution of the present invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings. In this specification, the same or similar reference numerals indicate the same or similar components. The following description of the embodiments of the present invention with reference to the accompanying drawings is intended to explain the overall inventive concept of the present invention and should not be construed as a limitation thereof.

[0047] It should also be understood that although the terms "first," "second," "third," etc., may be used in the following embodiments of the present invention to describe a component comprising two or more of the same component, these components should not be limited to these terms, which are only used to distinguish each component from one another. Furthermore, descriptions indicating orientation such as "upper," "lower," "left," and "right" are merely illustrative of the relative positions of components and should not be construed as a limitation of the present invention.

[0048] Embodiments of the present invention provide a novel photodetector for dual-band detection and its manufacturing method. This photodetector is a back-illuminated photodetector capable of simultaneously detecting in the 400-1000nm and 900-1500nm wavelength bands. By constructing a first and second light-absorbing layer of heterogeneous material structures (e.g., silicon and germanium) and employing a back-illuminated functional layer layout, simultaneous detection and photoelectric signal conversion in the 400-1000nm and 900-1500nm wavelength bands are achieved, improving the detection efficiency and sensitivity of the photodetector, as well as its photoelectric conversion efficiency.

[0049] According to one aspect of the present invention, a photodetector for dual-band detection is provided.

[0050] See Figure 1 The diagram illustrates a cross-sectional structure of a photodetector 100 according to one embodiment. This photodetector 100 is a back-illuminated photodetector, with incident light gradually entering its interior from the bottom. From bottom to top, the photodetector 100 comprises three main functional layers: a first light-absorbing layer 10 for absorbing incident light in the 400-1000 nm wavelength range, a second light-absorbing layer 20 for absorbing incident light in the 900-1500 nm wavelength range, and a passivation layer 30 encapsulating the second light-absorbing layer 20. Simultaneously, a first electrode 13 is arranged within the first light-absorbing layer 10, and a second electrode 23 is arranged within the second light-absorbing layer 20, thereby forming a PIN junction inside the photodetector 100 through ion doping and electrode conduction.

[0051] In use, incident light enters the photodetector 100 from below the first light absorption layer 10 in a back-illuminated manner. Light in the 400-1000nm band is absorbed by the first light absorption layer 10, while light in the 900-1500nm band penetrates the first light absorption layer 10 and is absorbed by the second light absorption layer 20 to simultaneously detect dual-band incident light and perform photoelectric conversion.

[0052] In one example, specifically, the first light-absorbing layer 10 and the second light-absorbing layer 20 are intrinsic absorption layer structures made of semiconductor materials. Depending on the wavelength range of the incident light to be absorbed, semiconductor materials with different bandgap widths are required to form the intrinsic absorption layer structures.

[0053] Specifically, in this embodiment of the invention, the first light absorption layer 10 is used to absorb incident light in the 400-1000nm wavelength band, and the second light absorption layer 20 is used to absorb incident light in the 900-1500nm wavelength band. Therefore, the bandgap of the first light absorption layer 10 needs to be greater than the bandgap of the second light absorption layer 20.

[0054] Preferably, the first light-absorbing layer 10 is a silicon structure absorption layer 11. Alternatively, the silicon structure absorption layer 11 can be a silicon wafer or a high-resistivity silicon wafer. In this case, the silicon wafer or high-resistivity silicon wafer can also serve as the wafer substrate of the photodetector 100, that is, the wafer substrate and the first light-absorbing layer 10 are combined into one, which can reduce one step in the fabrication of the absorption layer and simplify the manufacturing process.

[0055] Preferably, the second light-absorbing layer 20 is a germanium absorption layer 21 or a III-V semiconductor compound absorption layer 21. Alternatively, the material of the III-V semiconductor compound absorption layer 21 can be GaSb, InAs, InGaAs, etc.

[0056] The materials chosen for the first light-absorbing layer 10 and the second light-absorbing layer 20 depend primarily on their absorption capacity for light in the corresponding wavelength bands. The above are merely illustrative examples and should not be construed as limiting the invention by those skilled in the art.

[0057] In one example, specifically, the first light-absorbing layer 10 includes a first ion-doped layer 12 disposed below the first light-absorbing layer 10. The first light-absorbing layer 10 also includes a first electrode 13, one end of which is in ohmic contact with the first ion-doped layer 12, and the other end which passes through the first light-absorbing layer 10 and the passivation layer 30 in sequence and extends from above the passivation layer 30.

[0058] In one example, specifically, similar to the first light-absorbing layer 10, the second light-absorbing layer 20 includes a second ion-doped layer 22 disposed above the second light-absorbing layer 20; the second light-absorbing layer 20 also includes a second electrode 23, one end of which is in ohmic contact with the second ion-doped layer 22, and the other end which penetrates the passivation layer 30 and extends from above the passivation layer 30.

[0059] In one example, specifically, in the first light-absorbing layer 10, a first ion-doped layer 12 of a certain thickness is formed by ion implantation on the plane below the silicon structure absorption layer 11 (e.g., a silicon wafer). Similarly, in the second light-absorbing layer 20, a second ion-doped layer 22 of a certain thickness is formed by ion implantation on the plane above, for example, a germanium absorption layer 21.

[0060] For example, P-type ions can be implanted into the silicon absorption layer 11, while N-type ions are implanted into the germanium absorption layer 21, thereby ensuring the formation of a complete PIN junction after the electrode is turned on. Conversely, N-type ions can be implanted into the silicon absorption layer 11, while P-type ions are implanted into the germanium absorption layer 21. This example is merely illustrative and should not be construed as a limitation of the invention by those skilled in the art.

[0061] In one example, specifically, the ends of the first electrode 13 and the second electrode 23 that extend out of the passivation layer 30 are respectively provided with metal bump structures, and all the metal bump structures are located on the same plane for subsequent packaging integration and welding to the external substrate.

[0062] In one example, such as Figure 1 As shown, the first electrode 13 extends to the upper surface of the passivation layer 30 after being filled with metal through the vias of the silicon structure absorption layer 11 and the passivation layer 30, and then the first metal bump structure 14 is formed.

[0063] In one example, the second electrode 23 extends to the upper surface of the passivation layer 30 after being filled with metal through a via in the passivation layer 30, and then a second metal bump structure 24 is provided.

[0064] In one example, after the passivation layer 30 is formed, its upper surface is smoothed by mechanical polishing. After the first electrode 13 and the second electrode 23 extend from the upper surface of the passivation layer 30, metal processing is performed to ensure that all the first metal bump structures 14 and the second metal bump structures 24 are on the same plane. Thus, during integrated packaging, the outer substrate plane can be batch-welded with all the metal bump structures on the same plane.

[0065] In one example, preferably, the photodetector 100 further includes a reflective metal plate 40 disposed above the passivation layer 30, and the reflective metal plate 40 at least completely covers the second light-absorbing layer 20. When light that has not been absorbed by the first light-absorbing layer 10 and / or the second light-absorbing layer 20 penetrates the second light-absorbing layer 20 and illuminates the surface of the reflective metal plate 40, the reflective metal plate 40 reflects the light back into the first light-absorbing layer 10 and / or the second light-absorbing layer 20 for absorption. Similarly, the first light-absorbing layer 10 is still responsible for absorbing reflected light in the 400-1000nm wavelength band, and the second light-absorbing layer 20 is still responsible for absorbing reflected light in the 900-1500nm wavelength band.

[0066] In one example, preferably, the planar area of ​​the reflective metal plate 40 is equal to the planar area of ​​the passivation layer 30 and the first light-absorbing layer 10 below it. That is, the reflective metal plate 40 completely covers the entire passivation layer 30 and the first light-absorbing layer 10. In this way, it can be ensured that the light that is not absorbed in the first step can be completely reflected and absorbed a second time, effectively reducing light loss, improving light absorption efficiency, and thus improving detection sensitivity.

[0067] In one example, alternatively, the second light-absorbing layer 20 may also include a dielectric layer 25, which wraps around the outer surface of the second light-absorbing layer 20 (e.g., germanium absorber layer 21). The dielectric layer 25 may be made of materials including SiN and SiO2. The main function of the dielectric layer 25 is to prevent oxidation and also to increase mechanical strength.

[0068] According to another aspect of the present invention, a method for manufacturing a photodetector for dual-band detection is provided, for manufacturing the photodetector 100 described in the above embodiments.

[0069] See Figure 2 The main process flow of this manufacturing method is shown. See also Figure 3 This shows the state of the cross-sectional structure of the functional layer corresponding to each process step.

[0070] Combination Figure 2 and Figure 3 As shown, to manufacture as Figure 1 Taking the photodetector 100 shown as an example, the manufacturing method includes:

[0071] Step S201: Provide a silicon structure absorption layer 11 for forming the first light absorption layer 10 on a silicon wafer;

[0072] Step S202: Epitaxially grow a germanium absorption layer 21 or a III-V semiconductor compound absorption layer 21 on the upper surface of a silicon wafer to form a second light absorption layer 20;

[0073] Step S203: Fabricate a passivation layer 30, which is formed on the upper surface of a silicon wafer (silicon structure absorption layer 11) and encapsulates a second light absorption layer 20.

[0074] Step S204: Electrode channels (first electrode channel 311 and second electrode channel 312) are formed in the passivation layer 30 by fabricating through-silicon vias. Metal is filled in the electrode channels to form an extension electrode of the first electrode 13 and a second electrode 23, which extend above the passivation layer 30 and are brought out for bonding to the substrate during integrated packaging.

[0075] Step S205: After flipping and inverting, an electrode channel (third electrode channel 111) is formed in the silicon structure absorption layer 11 by manufacturing silicon vias. The electrode channel is filled with metal to connect the first electrode 13 and its extension electrode in the passivation layer 30 and form a PIN junction with the second electrode 23.

[0076] In one example, preferably, the process flow for step S202, which involves epitaxially growing, for example, a germanium absorber layer 21 on the upper surface of a silicon wafer to form a second light-absorbing layer 20, is as follows: First, an oxide layer (e.g., silicon oxide) is deposited on a silicon wafer substrate. Photoresist is then coated onto the oxide layer and exposed and developed. Afterward, the oxide layer not protected by the photoresist is etched using an etching method to form the area ready for germanium growth.

[0077] In one example, preferably, the thickness of the second light-absorbing layer 20 is in the range of 200 nm to 3 μm. The specific thickness needs to be set according to the light detection responsivity index that the photodetector 100 needs to achieve.

[0078] In one example, alternatively, the top surface area of ​​the second light-absorbing layer 20 is smaller than its bottom surface area, that is, with Figure 1 For example, the cross-sectional shape of the second light-absorbing layer 20 is approximately trapezoidal, and the area of ​​the upper plane is smaller than the area of ​​the lower plane. The planar shape of the second light-absorbing layer 20 projected in the vertical direction can be any one of a circle, ellipse, square, rhombus, and polygon.

[0079] See Figures 4a-4c The illustration exemplarily shows three structures for the second light-absorbing layer 20: a polygonal plane, a conical prism, and a tetrahedron, all of which have an upper surface area smaller than their lower surface area. This example is merely illustrative and should not be construed as a limitation of the invention by those skilled in the art.

[0080] In one example, before fabricating the passivation layer 30 in step S203, a second ion-doped layer 22 is formed on the upper surface of the second light-absorbing layer 20. Correspondingly, step S205 further includes forming a second ion-doped layer 12 on the upper surface of the first light-absorbing layer 10.

[0081] Taking N-type ion implantation on the second light-absorbing layer 20 as an example (correspondingly, P-type ion implantation on the first light-absorbing layer 10), the atoms used include, but are not limited to, As or P atoms. The ion implantation depth does not exceed the thickness of the functional layer, and the ion implantation range should cover the surface of the functional layer. The process of implanting N-type ions into the first light-absorbing layer 10 and simultaneously implanting P-type ions into the second light-absorbing layer 20 is similar and will not be described in detail here.

[0082] In one example, alternatively, a dielectric layer 25 may be fabricated on the outer surface of, for example, the germanium absorption layer 21 of the second light absorption layer 20. For example, silicon nitride and silicon oxide may be deposited as dielectric layer 25 using CVD (chemical vapor deposition) or PVD (physical vapor deposition), respectively, and the dielectric layer 25 may protect the second light absorption layer 20 from moisture and air erosion.

[0083] In one example, a metal layer A can be deposited on the contact surface where the first light-absorbing layer 10 formed on the silicon wafer meets the passivation layer 30 for subsequent electrode conduction, especially when the first electrode 13 extends upward through the passivation layer 30.

[0084] In one example, after the fabrication of each functional layer is completed, and before forming electrode channels by fabricating through-silicon vias, the upper surface of the passivation layer 30 needs to be ground flat. Exemplarily, a chemical mechanical polishing process can be used to grind the upper surface of the passivation layer 30 flat. The purpose of grinding is to ensure that the electrodes and the metal bump structures connecting the electrode protrusions are on the same plane during subsequent fabrication, which is beneficial for the subsequent packaging and integration of the photodetector 100.

[0085] In one example, specifically, the step of forming an electrode channel by fabricating a through-silicon via in the silicon wafer of the passivation layer 30 and the first light-absorbing layer 10 specifically includes:

[0086] In the passivation layer 30, a first electrode channel 311 for extending the first electrode 13 and a second electrode channel 312 for conducting the second electrode 23 are formed by fabricating silicon vias, and metal is filled in the first electrode channel 311 and the second electrode channel 312.

[0087] After being flipped and inverted, the silicon wafer is thinned, typically to less than 100 μm, and a third electrode channel 111 for conducting the first electrode 13 is formed by creating through-silicon vias in the silicon wafer.

[0088] On the thinned surface of the silicon wafer ( Figure 1 The bottom surface of the completed photodetector 100 is used to form a first electrode 13 and fill the third electrode channel 111 with metal to extend the first electrode 13 above the passivation layer 30.

[0089] In one example, preferably, in order to reduce light absorption loss and improve light absorption efficiency, a reflective metal plate 40 can be covered on top of the passivation layer 30 to reflect the light that is not fully absorbed and reabsorbed by the first light absorption layer 10 and / or the second light absorption layer 20.

[0090] The photodetector for dual-band detection and its manufacturing method provided by the embodiments of the present invention have at least one or a portion of the following advantages:

[0091] (1) By constructing a first light absorption layer and a second light absorption layer of heterogeneous material structure and adopting a back-illuminated functional layer layout, the photodetector can simultaneously detect and perform photoelectric signal conversion in the 400-1000nm and 900-1500nm bands, thereby improving the detection efficiency and sensitivity of the photodetector and increasing the photoelectric conversion efficiency.

[0092] (2) By using silicon wafers as the first light absorption layer, the wafer substrate and the first light absorption layer can be integrated into one, effectively reducing processing steps and procedures, and effectively simplifying the manufacturing process of photodetectors.

[0093] (3) By using silicon wafer as the first light absorption layer, it can fully absorb incident light in the 400-1000nm band while also having high light transmittance in the 900-1500nm band, effectively reducing the loss of incident light in the 900-1500nm band, which in turn helps to improve the detection sensitivity of the second light absorption layer, thereby improving the overall detection sensitivity of the photodetector.

[0094] (4) By covering the passivation layer with a reflective metal plate, the light that is not completely absorbed by the first light absorption layer and the second light absorption layer can be reflected and re-enter the first light absorption layer and / or the second light absorption layer to be absorbed, effectively reducing the loss of detection light and further improving the light detection efficiency.

[0095] (5) By constructing a PIN junction of the first light absorption layer and the second light absorption layer, incident light in two bands can be detected simultaneously. The device structure is simple, the manufacturing process is simplified, and the production cost is reduced.

[0096] (6) By creating through-silicon vias (TSVs) in the silicon wafer layer and passivation layer to form electrode channels, the electrodes of the first and second light absorption layers are effectively extended to the plane above the passivation layer, which helps to quickly weld to the external substrate in batches during packaging integration.

[0097] (7) By setting the photodetector as a back-illuminated light incident structure, it is possible to detect dual-band spectra simultaneously without changing the power supply voltage of the photodetector or other external controls and without flipping the photodetector. The operation is simple and the efficiency is high.

[0098] While some embodiments of the present general inventive concept have been shown and described, those skilled in the art will understand that changes may be made to these embodiments without departing from the principles and spirit of the present general inventive concept, the scope of which is defined by the claims and their equivalents.

Claims

1. A photodetector for dual-band detection, characterized in that, The photodetector includes: The first light absorption layer is used to absorb incident light in the 400-1000nm wavelength band. The second light absorption layer is disposed directly above the first light absorption layer and is used to absorb incident light in the 900-1500nm wavelength band. A passivation layer is disposed above the first light-absorbing layer and surrounds the second light-absorbing layer; The first light-absorbing layer and the second light-absorbing layer form a PIN junction through ion doping and electrode conduction, wherein, The first light-absorbing layer includes a first ion-doped layer, which is disposed below the first light-absorbing layer. The second light-absorbing layer includes a second ion-doped layer, which is disposed above the second light-absorbing layer. P-type ions are implanted on the first ion-doped layer, and N-type ions are implanted on the second ion-doped layer, or N-type ions are implanted on the first ion-doped layer and P-type ions are implanted on the second ion-doped layer, forming a complete PIN junction with the first light-absorbing layer and the second light-absorbing layer after the conduction electrode is turned on. Incident light enters the photodetector from below the first light-absorbing layer in a back-illuminated manner, wherein light in the 400-1000nm band is absorbed by the first light-absorbing layer, and light in the 900-1500nm band penetrates the first light-absorbing layer and is absorbed by the second light-absorbing layer to simultaneously detect dual-band incident light and perform photoelectric conversion.

2. The photodetector according to claim 1, characterized in that, The first light-absorbing layer and the second light-absorbing layer are intrinsic absorption layer structures made of semiconductor materials; The band gap of the first light absorption layer is greater than the band gap of the second light absorption layer; The first light-absorbing layer is a silicon structure absorption layer, which is a silicon wafer or a high-resistivity silicon wafer; The second light-absorbing layer is a germanium absorption layer or a III-V group semiconductor compound absorption layer.

3. The photodetector according to claim 2, characterized in that, The first light-absorbing layer further includes a first electrode, one end of which is in ohmic contact with the first ion-doped layer, and the other end of which passes through the first light-absorbing layer and the passivation layer in sequence and extends from above the passivation layer.

4. The photodetector according to claim 3, characterized in that, The second light-absorbing layer further includes a second electrode, one end of which is in ohmic contact with the second ion-doped layer, and the other end of which penetrates the passivation layer and extends from above the passivation layer.

5. The photodetector according to claim 4, characterized in that, The first electrode and the second electrode are each provided with a metal bump structure at the end extending from the passivation layer. All of the metal bump structures are located on the same plane for subsequent packaging integration and soldering to an external substrate.

6. The photodetector according to any one of claims 1-5, characterized in that, The photodetector also includes a reflective metal plate. The reflective metal plate is disposed above the passivation layer and the reflective metal plate at least completely covers the second light-absorbing layer. When light that has not been absorbed by the first light absorption layer and / or the second light absorption layer penetrates the second light absorption layer and shines on the surface of the reflective metal plate, the reflective metal plate reflects the light so that it re-enters the first light absorption layer and / or the second light absorption layer and is absorbed.

7. The photodetector according to claim 6, characterized in that, The photodetector further includes a dielectric layer, which is disposed on the outer surface of the second light-absorbing layer. The dielectric layer is made of materials including SiN and SiO2.

8. A method for manufacturing a photodetector for dual-band detection, used to manufacture a photodetector according to any one of claims 1-7, characterized in that, The manufacturing method includes: Provides a silicon wafer to form the first light-absorbing layer; A second light-absorbing layer is formed by epitaxially growing a germanium absorption layer or a group III-V semiconductor compound absorption layer on the upper surface of the silicon wafer; A passivation layer is formed on the upper surface of the silicon wafer and encapsulates the second light-absorbing layer; In the passivation layer, through-silicon vias are formed to create electrode channels for extending the first electrode and fabricating the second electrode. Metal is then filled into the electrode channels to form the extended electrode of the first electrode and the second electrode, which are then extended above the passivation layer and brought out for soldering to the substrate during integrated packaging. After being flipped and inverted, an electrode channel for leading out the first electrode is formed in the silicon wafer by manufacturing through-silicon vias, and a metal connection is filled in the electrode channel to connect the first electrode and its extension electrode in the passivation layer, and then a PIN junction is formed with the second electrode.

9. The manufacturing method according to claim 8, characterized in that, The thickness of the second light-absorbing layer ranges from 200 nm to 3 μm. The top surface area of ​​the second light-absorbing layer is smaller than its bottom surface area. The cross-sectional shape of the second light-absorbing layer projected in the vertical direction is any one of a circle, ellipse, square, rhombus, and polygon.

10. The manufacturing method according to claim 8 or 9, characterized in that, The step of forming electrode channels by fabricating through-silicon vias in the passivation layer and the silicon wafer specifically includes: In the passivation layer, a first electrode channel for extending the first electrode and a second electrode channel for conducting the second electrode are formed by fabricating through-silicon vias, and metal is filled in the first electrode channel and the second electrode channel; After being flipped and inverted, the silicon wafer is thinned and a third electrode channel for conducting the first electrode is formed by manufacturing through-silicon vias. The first electrode is formed on the thinned surface of the silicon wafer, and metal is filled in the third electrode channel to extend the first electrode over the passivation layer.

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