Avalanche photo diode (APD) type laminated laser detector capable of resisting strong sunlight and manufacturing method of APD type laminated laser detector

Abstract

The invention relates to a strong sunlight resistant APD type laminated laser detector and a manufacturing method thereof, and belongs to the field of photoelectric detector chips. The detector comprises two stacked sub-detectors, the sub-detector I is arranged at the upper part, and the sub-detector II is arranged at the lower part; a filter film I is arranged on the sub-detector II; a bonding layer is arranged on the filter film I and is connected with the sub-detector I and the sub-detector II; the electrode II and the electrode III are provided with through holes so as to be interconnected with a peripheral circuit. The detector is packaged in a tube shell, a light window is arranged above the tube shell, a light filtering film II is arranged above the light window, and a light filtering film III is arranged below the light window. During packaging, the electrode II of the sub-detector I and the electrode III of the sub-detector II are in short circuit. Through optical and electrical design, sunlight currents generated by the two sub-detectors are mutually offset, and only laser signal currents are reserved.

Description

Technical Field

[0001] This invention belongs to the field of photoelectric detector chips and relates to an APD-type stacked laser detector resistant to strong sunlight and its manufacturing method. Background Technology

[0002] Laser detectors measure targets by detecting the echo signal from a laser beam illuminating the target object. The detector is typically connected in series with a sampling resistor and extracts the AC signal through a DC blocking capacitor. When the detector receives light, it generates a photocurrent, which flows through the sampling resistor and is converted into a voltage signal. The DC component of the voltage signal is filtered out by the DC blocking capacitor, allowing only the AC component to enter the downstream circuitry. However, when the laser detector is exposed to strong sunlight, the intense sunlight causes it to output a very large photocurrent. This large current causes the voltage drop across the sampling resistor to rise rapidly, resulting in a significant decrease in the voltage difference across the detector. This causes the detector to deviate considerably from its optimal operating voltage and malfunction. An avalanche photodiode (APD) detector is a special type of laser detector that internally amplifies the current through avalanche multiplication. Under the same incident light intensity, an APD detector generates a larger current than a conventional detector, causing a greater voltage rise in the sampling resistor. Therefore, it is more susceptible to the effects of strong sunlight than a conventional detector.

[0003] Patent application CN119653881A discloses a laser detector suitable for strong sunlight environments and its fabrication method. It involves arranging two identical sub-detectors in parallel and setting different filters at their front ends to ensure that the sunlight entering the two sub-detectors is the same, followed by differential cancellation of sunlight current. However, when the system containing the detector has an optical lens, sunlight is focused onto the detector as a bright spot, making it difficult to distribute evenly on the photosensitive surfaces of the two sub-detectors, thus failing to eliminate sunlight current. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide an APD-type stacked laser detector resistant to strong sunlight, overcoming the problems of existing laser detectors easily failing in strong sunlight environments and existing strong light resistance technologies failing when used with optical lenses, thereby achieving automatic cancellation of sunlight current. This invention provides a stacked detector structure that, through optical and electrical design, allows the sunlight currents generated by the two sub-detectors to cancel each other out, retaining only the laser signal current.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] Option 1: An APD-type stacked laser detector resistant to strong sunlight, comprising two stacked sub-detectors; wherein, one sub-detector I is placed on top, including N + Contact area I, located at N +Avalanche zone I above contact zone I, protective ring I outside avalanche zone I, stop ring I outside protective ring I, i-absorption zone I above avalanche zone I, and P above i-absorption zone I. + Contact area I, located at P + An antireflection membrane above contact area I, electrode I disposed above the antireflection membrane, and electrode I disposed on N. + A dielectric layer I beneath contact region I, and an electrode II disposed beneath dielectric layer I; the N + Contact area I and electrode II are in contact through contact holes on dielectric layer I; the P + Contact area I is in contact with electrode I through contact holes on the antireflection membrane.

[0007] Another sub-detector II is placed below, containing N + Contact area II, located at N + Avalanche zone II above contact zone II, protective ring II outside avalanche zone II, stop ring II outside protective ring II, i-absorption zone II above avalanche zone II, and P above i-absorption zone II. + Contact area II, located at P + Dielectric layer II above contact area II, electrode III disposed above dielectric layer II, and electrode III disposed on N. + The dielectric layer III beneath contact region II, and the electrode IV disposed beneath dielectric layer III; the N + Contact area II and electrode IV are in contact through contact holes on dielectric layer III; the P + Contact area II and electrode III are in contact through contact holes on dielectric layer II.

[0008] A filter film I is disposed on top of sub-detector II; a bonding layer is disposed on filter film I to connect sub-detector I and sub-detector II; through holes are disposed on electrodes II and III for interconnection with peripheral circuits. The detector is encapsulated in a housing, with an optical window above the housing, filter film II disposed above the optical window, and filter film III disposed below the optical window; electrodes II and III are short-circuited during encapsulation.

[0009] Preferably, the thickness of sub-detector I is less than the thickness of sub-detector II.

[0010] Preferably, the size of electrode II should not exceed that of cutoff ring I; the size of electrode IV should not exceed that of cutoff ring II.

[0011] Preferably, the bonding layer is characterized by being able to transmit incident light.

[0012] Preferably, the antireflective membrane is a broadband antireflective membrane.

[0013] Preferably, filter film I is characterized by having a high reflectivity in the wavelength band corresponding to the laser signal and a very low reflectivity outside the wavelength band corresponding to the laser signal.

[0014] Preferably, filter II is a bandpass filter, characterized in that the starting wavelength of the passband width is determined by the signal light wavelength, and the cutoff wavelength is determined by the detector design; filter III is a bandstop filter, characterized in that the starting wavelength of the stopband width is determined by the signal light wavelength, and the cutoff wavelength is determined by the detector design; filter II and filter III together form two narrow wavelength ranges of light transmission bands, one corresponding to the laser signal band, and the other used to cancel the output current generated by strong sunlight.

[0015] Preferably, taking advantage of the characteristic that longer incident light wavelengths penetrate deeper into the detector, most of the long-wavelength light in sunlight penetrates sub-detector I and enters sub-detector II. When the photocurrents generated by sunlight in sub-detector I and sub-detector II are equal, the sunlight current can be eliminated; at the same time, filter film I is used to prevent signal light from entering sub-detector II, thus avoiding affecting the signal photocurrent when eliminating the sunlight current.

[0016] Preferably, filter I needs to have high reflectivity in the λ0-λ1 to λ0+λ1 wavelength range and low reflectivity in the wavelength range after λ0+λ1; λ0±λ1 is the signal light wavelength range; filter II needs to have high reflectivity in the λ0-λ1 to λ0+λ1 wavelength range. n2 Low reflectivity in one wavelength band and high reflectivity in other wavelength bands; the filter film III needs to satisfy the condition from λ0+λ1 to λ n1 High reflectivity in one band, low reflectivity in other bands; where λ n1 and λ n2 The values ​​of λ0-λ1 to λ0+λ1 band and λ n1 To λ n2 The current generated by sunlight in the wavelength band in sub-detector I and λ n1 To λ n2 The current generated by sunlight in the band is equivalent to that in sub-detector II.

[0017] Option 2: A method for manufacturing an APD-type stacked laser detector resistant to strong sunlight, the process of which is as follows: (1) Prepare a clean P-type epitaxial silicon wafer; (2) The cutoff ring I pattern of the sub-detector I is formed by photolithography, and the cutoff ring I is formed by injecting a large dose of boron. (3) The pattern of the protective ring I of the sub-detector I is formed by photolithography, and the protective ring I is formed by injecting an appropriate amount of phosphorus. (4) The avalanche zone I pattern of the sub-detector I is formed by photolithography, and the avalanche zone I is formed by high-energy injection of an appropriate amount of boron. (5) The N-type sub-detector I is formed by photolithography. + Contact area I pattern, and N is formed by injecting a large dose of phosphorus. + Contact area I; (6) Deposition medium layer I; (7) Etch contact holes in dielectric layer I; (8) Electrode II is formed by depositing metallic aluminum on the front side and then photolithography and etching. (9) Flip the epitaxial silicon wafer so that the front side is down and the back side is up, in preparation for bonding; (10) Prepare a clean P-type monocrystalline silicon wafer; (11) The cutoff ring II pattern of the sub-detector II is formed by photolithography, and the cutoff ring II is formed by injecting a large dose of boron. (12) The pattern of the protective ring II of the sub-detector II is formed by photolithography, and the protective ring II is formed by injecting an appropriate amount of phosphorus element; (13) The avalanche region II pattern of the sub-detector II is formed by photolithography, and the avalanche region II is formed by high-energy injection of an appropriate amount of boron. (14) The N of the sub-detector II is formed by photolithography. + Contact area II pattern, and N formed by injecting a large dose of phosphorus. + Contact area II; (15) Deposition medium layer III; (16) Etch contact holes in dielectric layer III; (17) Metallic aluminum is deposited on the front side, and electrode IV is formed by photolithography and etching; (18) The single-crystal silicon wafer is thinned from the back side by first mechanical grinding and then polishing; (19) Flip the monocrystalline silicon wafer so that the front side is down and the back side is up; (20) The P of the sub-detector II was formed by injecting a large dose of boron. + Contact area II; (21) Deposition medium layer II; (22) Etch contact holes in dielectric layer II; (23) Deposit metallic aluminum and form electrode III by photolithography and etching; (24) Deposition of filter film I; (25) The front side of the epitaxial silicon wafer containing sub-detector I is bonded to the back side of the single-crystal silicon wafer containing sub-detector II through a bonding layer; (26) The low resistivity substrate of the epitaxial silicon wafer is removed by mechanical polishing and self-stopping etching in sequence; (27) P of sub-detector I is formed by photolithography + Contact area I pattern, and P formed by high-dose boron injection. + Contact area I; (28) Deposition of antireflective coating; (29) Etch contact holes in the antireflection film; (30) Deposit metallic aluminum and form electrode I through photolithography and etching; (31) Through holes corresponding to electrode II and electrode III are formed sequentially by photolithography and deep silicon etching.

[0018] Furthermore, during the initial fabrication of this detector, calibration is required using filter film II and filter film III on the optical window of the tube shell. The procedure is as follows: (1) The detector is encapsulated in a tube shell, but the light window is not sealed; (2) Using a simulated solar light source, the output current of the two sub-detectors at different wavelengths was tested respectively; (3) Measure and record the output current value of sub-detector I every 10 nm from wavelength λ0-λ1 to λ0+λ1; (4) Starting from wavelength λ0-λ1, measure and record the output current value of sub-detector II every 10nm; (5) The output current values ​​of sub-detector I from wavelength λ0-λ1 to λ0+λ1 are accumulated and denoted as I1; (6) The output current values ​​of sub-detector II from wavelength λ0-λ1 to λ0+λ1 are accumulated and denoted as I2; (7) Select an appropriate wavelength λ n1 and λ n2 The sub-detector II will be moved from wavelength λ n1 Start to λ n2 The output current values ​​are accumulated and denoted as I3. Since the photocurrent of sub-detector II is larger relative to that of sub-detector I as the wavelength increases, there must exist a wavelength λ... n1 and λ n2 This makes I3 = I1 - I2; (8) Filter film II and filter film III are deposited on the optical window. Filter film II is characterized by being able to transmit only wavelengths from λ0 to λ1. n2 The characteristic of filter film III is that it cannot transmit light with wavelengths from λ0+λ1 to λ n1 The light; (9) Seal the light window with filter film II and filter film III onto the tube shell.

[0019] The beneficial effects of this invention are as follows: (1) Adapting to optical lens systems and eliminating the influence of light spots. This scheme adopts a stacked sub-detector structure (sub-detector I is placed on top, and sub-detector II is placed on the bottom). Taking advantage of the deep penetration of long-wavelength light, sunlight penetrates the upper layer and enters the lower layer. This vertical structure ensures that no matter what shape the bright spot is formed by the sunlight after being focused by the lens, the path of the beam passing through the upper photosensitive surface will always correspond to the lower photosensitive surface, avoiding the problem of uneven illumination causing the inability to differentiate in parallel arrangement structures, thus enabling effective application to whole systems with optical lenses.

[0020] (2) Effectively cancels background sunlight current, ensuring detection sensitivity. This scheme uses an electrical connection (short-circuiting electrode II of sub-detector I with electrode III of sub-detector II) and Kirchhoff's current law to subtract the sunlight current generated by the two sub-detectors at the output node. By adjusting the light transmission band (λ) of the filter film... n1 To λ n2 This allows for precise control of the light flux entering sub-detector II, ensuring that the sunlight current generated by the two sub-detectors is essentially the same, thereby eliminating the DC component generated by sunlight at the output and preventing circuit saturation.

[0021] (3) Lossless preservation of laser signal. In this scheme, a filter film I is set between the two sub-detectors. This filter film has high reflectivity in the laser signal band. This prevents the signal light from entering the lower sub-detector II, ensuring that the current generated by the laser signal exists only in sub-detector I and will not be canceled out during the current subtraction process, thereby ensuring effective detection of the laser signal.

[0022] (4) Highly adjustable, with a closed-loop process. This invention provides a calibration method, which calculates the required additional wavelengths by measuring the current response of the two sub-detectors under different wavelengths during the initial fabrication, and then customizes external filters (filter II and filter III) to balance the current. This ensures the consistency of the finished product and an extremely high sunlight current suppression ratio.

[0023] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0024] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein: Figure 1 This is a schematic diagram of the APD-type stacked laser detector structure that is resistant to strong sunlight provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the optical principle of the detector in an embodiment of the present invention; Figure 3 This is a schematic diagram of the reflectance of filter film I of the detector in an embodiment of the present invention; Figure 4 This is a schematic diagram of the reflectance of filter film II of the detector in an embodiment of the present invention; Figure 5 This is a schematic diagram of the reflectance of filter film III of the detector in an embodiment of the present invention; Figure 6This is a schematic diagram of the electrical principle of the detector in an embodiment of the present invention; Figure 7 This is a process flow diagram of the detector according to an embodiment of the present invention; Figure 8 This is an IV curve diagram of the detector in an embodiment of the present invention. Detailed Implementation

[0025] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0026] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0027] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0028] Example 1: Please see Figures 1-6 This invention provides an APD-type stacked laser detector resistant to strong sunlight, such as... Figure 1 As shown. Its structure includes two stacked sub-detectors. Among them, A sub-detector I is placed above, containing N + Contact area I, located at N + Avalanche zone I above contact zone I, protective ring I outside avalanche zone I, stop ring I outside protective ring I, i-absorption zone I above avalanche zone I, and P above i-absorption zone I.+ Contact area I, located at P + An antireflection coating above contact area I, electrode I disposed above the antireflection coating, P + Contact area I is in contact with electrode I through a contact hole, located at N. + Dielectric layer I beneath contact region I, electrode II disposed beneath dielectric layer I, N + Contact area I and electrode II are in contact through a contact hole.

[0029] Another sub-detector II is placed below, containing N + Contact area II, located at N + Avalanche zone II above contact zone II, protective ring II outside avalanche zone II, stop ring II outside protective ring II, i-absorption zone II above avalanche zone II, and P above i-absorption zone II. + Contact area II, located at P + Dielectric layer II above contact region II, electrode III disposed above dielectric layer II, P + Contact area II and electrode III are in contact through a contact hole, located at N. + Dielectric layer III beneath contact region II, electrode IV disposed beneath dielectric layer III, N + Contact area II is in contact with electrode IV through a contact hole.

[0030] A filter film I is placed on top of sub-detector II. A bonding layer is placed on filter film I to connect sub-detector I and sub-detector II. Through holes are provided on electrodes II and III for interconnection with external circuitry. The detector is encapsulated in a housing. Above the housing is an optical window, above the optical window is filter film II, and below the optical window is filter film III. Electrodes II and III are shorted during encapsulation.

[0031] The thickness of sub-detector I is less than the thickness of sub-detector II. The size of electrode II should not exceed that of cutoff ring I; the size of electrode IV should not exceed that of cutoff ring II.

[0032] The antireflective coating is a broadband antireflective coating. The bonding layer allows incident light to pass through.

[0033] The optical principle of the detector is as follows: Figure 2 As shown. Utilizing the property that longer incident light wavelengths penetrate deeper into the detector, longer wavelengths of sunlight are allowed to penetrate sub-detector I and enter sub-detector II. When the photocurrents generated by sunlight in sub-detector I and sub-detector II are equivalent, the sunlight current can be eliminated. Simultaneously, filter I prevents signal light from entering sub-detector II, avoiding interference with the signal photocurrent during sunlight current elimination. Therefore, if the signal light wavelength range is λ0±λ1, filter I must satisfy the requirement of high reflectivity in the λ0-λ1 to λ0+λ1 band and low reflectivity in the band after λ0+λ1; filter II must satisfy the requirement of high reflectivity in the λ0-λ1 to λ0+λ1 band and low reflectivity in the band after λ0+λ1. n2The reflectivity is low in the [wavelength band], and high in the other [wavelength bands]. Wherein, λ n2 The value of is determined by the detector design. Filter III must satisfy the condition from λ0+λ1 to λ n1 The reflectivity is high in the [wavelength band], and low in the other [wavelength bands]. Wherein, λ n1 The value of is determined by the detector design. Filter II and filter III together form two narrow wavelength ranges of light transmission bands, namely the λ0-λ1 to λ0+λ1 band and the λ... n1 To λ n2 Bands. Among them, the λ0-λ1 to λ0+λ1 bands transmit signal laser light and sunlight of corresponding wavelengths, λ n1 To λ n2 The band will allow sunlight of the corresponding wavelength to pass through.

[0034] Since the photocurrent of sub-detector II is larger relative to that of sub-detector I as the wavelength increases, there must exist a wavelength λ. n1 and λ n2 This ensures that the photocurrents of sub-detector I and sub-detector II are essentially the same.

[0035] The electrical principle of the detector is as follows: Figure 6 As shown. Electrode II of sub-detector I is short-circuited to electrode III of sub-detector II and grounded through a sampling resistor. According to Kirchhoff's current law, the algebraic sum of the currents flowing into any node of the circuit is zero. For node V0, the inflow current is the sunlight current I generated by sub-detector I and the laser current, and the outflow current is the sunlight current II generated by sub-detector II and the sampling current flowing through the sampling resistor. That is: Sunlight current I + Laser current = Sunlight current II + Sampling current. Wherein, sunlight current I comes from the λ0-λ1 to λ0+λ1 band and λ... n1 To λ n2 The sunlight in the wavelength band generates a current in sub-detector I; the sunlight current II originates from λ. n1 To λ n2 The current generated by sunlight in the wavelength band in sub-detector II. When the wavelength λ is set appropriately... n1 and λ n2 When the sunlight current I and sunlight current II are equal, the sampling current equals the laser current. At this point, the photocurrent generated by sunlight is eliminated and no longer affects the detection of the laser signal by the stacked detector.

[0036] Example 2: This embodiment provides a method for manufacturing an APD-type stacked laser detector resistant to strong sunlight, such as... Figure 7 As shown, the main manufacturing process is as follows: (1) Prepare a clean P-type epitaxial silicon wafer with an epitaxial layer resistivity ≥100Ωcm; an epitaxial layer thickness of 20μm (the epitaxial layer thickness depends on the wavelength of the laser signal); and a substrate resistivity of 0.01~0.05Ωcm. (2) The cutoff ring I pattern of the sub-detector I is formed by photolithography, and the cutoff ring I is formed by implanting a large dose of boron. The preferred cutoff ring body concentration range is 1E18cm⁻¹. -Ⅲ ~1E20cm -Ⅲ ; (3) The pattern of the guard ring I of the sub-detector I is formed by photolithography, and the guard ring I is formed by injecting an appropriate amount of phosphorus. The preferred concentration range of the guard ring is 5E15 cm⁻¹. -Ⅲ ~5E17cm -Ⅲ ; (4) The avalanche region I pattern of the sub-detector I is formed by photolithography, and the avalanche region I is formed by high-energy injection of an appropriate amount of boron. The preferred avalanche region injection energy is 600keV~1000keV, and the volume concentration range is 2E16 cm⁻¹. -Ⅲ ~2E17cm -Ⅲ ; (5) The N-type sub-detector I is formed by photolithography. + Contact area I pattern, and N is formed by injecting a large dose of phosphorus. + Contact area I, preferably N + The concentration range of contact zone I is 1E18cm. -Ⅲ ~1E20cm -Ⅲ ; (6) Deposit dielectric layer I, preferably silicon oxide, to passivate the surface; (7) Etch contact holes in dielectric layer I; (8) Electrode II is formed by depositing metallic aluminum on the front side and then photolithography and etching. (9) Flip the epitaxial silicon wafer so that the front side is down and the back side is up, in preparation for bonding; (10) Prepare a clean P-type single crystal silicon wafer with a resistivity ≥1000Ωcm; (11) The cutoff ring II pattern of the sub-detector II is formed by photolithography, and the cutoff ring II is formed by implanting a large dose of boron. The preferred cutoff ring body concentration range is 1E18cm⁻¹. -Ⅲ ~1E20cm -Ⅲ ; (12) The pattern of the guard ring II of the sub-detector II is formed by photolithography, and the guard ring II is formed by implanting an appropriate amount of phosphorus. The preferred concentration range of the guard ring is 5E15 cm⁻¹. -Ⅲ ~5E17cm -Ⅲ ; (13) The avalanche region II pattern of the sub-detector II is formed by photolithography, and the avalanche region II is formed by high-energy injection of an appropriate amount of boron. The preferred avalanche region injection energy is 1000keV~1400keV, and the volume concentration range is 1E16 cm⁻¹. -Ⅲ ~1E17cm-Ⅲ ; (14) The N of the sub-detector II is formed by photolithography. + Contact area II pattern, and N formed by injecting a large dose of phosphorus. + Contact area II, preferably N + The concentration range of contact zone II is 1E18cm. -Ⅲ ~1E20cm -Ⅲ ; (15) Deposit dielectric layer III, preferably silicon oxide, which serves as a surface passivation material; (16) Etch contact holes in dielectric layer III; (17) Metallic aluminum is deposited on the front side, and electrode IV is formed by photolithography and etching; (18) The single-crystal silicon wafer was thinned to 150μm from the back side by mechanical grinding followed by polishing; (19) Flip the monocrystalline silicon wafer so that the front side is down and the back side is up; (20) The P of the sub-detector II was formed by injecting a large dose of boron. + Contact area II, preferably P + The concentration range of contact zone II is 1E18cm. -Ⅲ ~1E20cm -Ⅲ ; (21) Deposit dielectric layer II, preferably silicon oxide, which serves as a surface passivation material; (22) Etch contact holes in dielectric layer II; (23) Deposit metallic aluminum and form electrode III by photolithography and etching; (24) Deposit filter film I, which has a high reflectivity in the wavelength band corresponding to the laser signal and a low reflectivity outside the wavelength band corresponding to the laser signal; (25) The front side of the epitaxial silicon wafer containing sub-detector I is bonded to the back side of the single-crystal silicon wafer containing sub-detector II through a bonding layer. The bonding layer is transparent to incident light. The bonding layer material can be a polymer adhesive or silicon oxide; (26) The low resistivity substrate of the epitaxial silicon wafer is removed by mechanical polishing and self-stopping etching. Preferably, the remaining substrate thickness after mechanical polishing is 50μm~80μm; the preferred self-stopping etching solution consists of nitric acid, hydrofluoric acid and glacial acetic acid, and automatically stops after etching by utilizing the difference in etching rate of silicon materials with different doping concentrations.

[0037] (27) P of sub-detector I is formed by photolithography + Contact area I pattern, and P formed by high-dose boron injection. + Contact area I, preferably P + The concentration range of contact zone I is 1E18cm.-3 ~1E20cm -3 .

[0038] (28) Deposition of antireflective coating; (29) Etch contact holes in the antireflection film; (30) Deposit metallic aluminum and form electrode I through photolithography and etching; (31) Through holes corresponding to electrode II and electrode III are formed by photolithography and deep silicon etching.

[0039] When fabricating an APD-type stacked laser detector resistant to strong sunlight for the first time, calibration is required using filter film 2 and filter film III on the optical window of the tube shell. The procedure is as follows: (1) The detector is encapsulated in a tube shell, but the light window is not sealed; (2) Using a simulated solar light source, the output current of the two sub-detectors at different wavelengths was tested respectively; (3) Measure and record the output current value of sub-detector I every 10 nm from wavelength λ0-λ1 to λ0+λ1; (4) Starting from wavelength λ0-λ1, measure and record the output current value of sub-detector II every 10nm; (5) The output current values ​​of sub-detector I from wavelength λ0-λ1 to λ0+λ1 are accumulated and denoted as I1; (6) The output current values ​​of sub-detector II from wavelength λ0-λ1 to λ0+λ1 are accumulated and denoted as I2; (7) Select an appropriate λ n1 and λ n2 The sub-detector II will be moved from wavelength λ n1 Start to λ n2 The output current values ​​are accumulated and denoted as I3. Since the photocurrent of sub-detector II is larger relative to that of sub-detector I as the wavelength increases, there must exist a wavelength λ... n1 and λ n2 This makes I3 = I1 - I2; (8) Filter film II and filter film III are deposited on the optical window. Filter film II is characterized by being able to transmit only wavelengths from λ0 to λ1. n2 The characteristic of filter film III is that it cannot transmit light with wavelengths from λ0+λ1 to λ n1 The light; (9) Seal the light window with filter film II and filter film III onto the tube shell.

[0040] Figure 8The diagram shows the IV curve of the detector in this embodiment under simulated sunlight. A voltage of -100V is applied to electrode I of sub-detector I, and then the voltage of electrode IV of sub-detector II is gradually increased. At this time, due to the increased avalanche multiplication of sub-detector II, the output photocurrent increases, and the difference between the output photocurrents of sub-detector I and sub-detector II decreases. Therefore, the current output from electrode II / electrode III gradually decreases, reaching a minimum of approximately 50nA when the voltage reaches 225V. When the voltage is further increased, the output current of sub-detector II surpasses that of sub-detector I, and the current output from electrode II / electrode III gradually increases.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. An APD-type stacked laser detector resistant to strong sunlight, characterized in that, It includes two stacked sub-detectors; wherein, sub-detector I is placed on top, including N + Contact area I, located at N + Avalanche zone I above contact zone I, protective ring I outside avalanche zone I, stop ring I outside protective ring I, i-absorption zone I above avalanche zone I, and P above i-absorption zone I. + Contact area I, located at P + An antireflection membrane above contact area I, electrode I disposed above the antireflection membrane, and electrode I disposed on N. + A dielectric layer I beneath contact region I, and an electrode II disposed beneath dielectric layer I; the N + Contact area I and electrode II are in contact through contact holes on dielectric layer I; the P + Contact area I is in contact with electrode I through contact holes on the antireflection membrane; Another sub-detector II is placed below, containing N + Contact area II, located at N + Avalanche zone II above contact zone II, protective ring II outside avalanche zone II, stop ring II outside protective ring II, i-absorption zone II above avalanche zone II, and P above i-absorption zone II. + Contact area II, located at P + Dielectric layer II above contact area II, electrode III disposed above dielectric layer II, and electrode III disposed on N. + The dielectric layer III beneath contact region II, and the electrode IV disposed beneath dielectric layer III; the N + Contact area II and electrode IV are in contact through contact holes on dielectric layer III; the P + Contact area II and electrode III are in contact through contact holes on dielectric layer II; A filter film I is disposed on the sub-detector II; a bonding layer is disposed on the filter film I to connect the sub-detector I and the sub-detector II; through holes are disposed on the electrodes II and III to interconnect with the peripheral circuit.

2. The APD-type stacked laser detector resistant to strong sunlight according to claim 1, characterized in that, The detector is encapsulated in a tube, with an optical window above the tube, a filter film II above the optical window, and a filter film III below the optical window; during encapsulation, electrodes II and III are short-circuited.

3. The APD-type stacked laser detector resistant to strong sunlight according to claim 1, characterized in that, The thickness of sub-detector I is less than the thickness of sub-detector II.

4. The APD-type stacked laser detector resistant to strong sunlight according to claim 1, characterized in that, The size of electrode II should not exceed that of cutoff ring I; the size of electrode IV should not exceed that of cutoff ring II.

5. The APD-type stacked laser detector resistant to strong sunlight according to claim 1, characterized in that, The filter film II is a bandpass filter film, the starting wavelength of its passband width is determined by the signal light wavelength, and the cutoff wavelength is determined by the detector design; the filter film III is a bandstop filter film, the starting wavelength of its stopband width is determined by the signal light wavelength, and the cutoff wavelength is determined by the detector design; the filter film II and the filter film III together form two narrow wavelength ranges of light transmission bands, one corresponding to the laser signal band, and the other used to cancel the output current generated by strong sunlight.

6. The APD-type stacked laser detector resistant to strong sunlight according to claim 5, characterized in that, When the photocurrents generated by sunlight in sub-detector I and sub-detector II are equal, the sunlight current can be eliminated; at the same time, filter film I is used to prevent signal light from entering sub-detector II, so as to avoid affecting the signal photocurrent when eliminating the sunlight current.

7. The APD-type stacked laser detector resistant to strong sunlight according to claim 6, characterized in that, The filter film I must have high reflectivity in the λ0-λ1 to λ0+λ1 band and low reflectivity in the band after λ0+λ1; λ0±λ1 is the wavelength range of the signal light. The filter film II needs to meet the requirement of λ0-λ1 to λ n2 Low reflectivity in one wavelength band and high reflectivity in other wavelength bands; the filter film III needs to satisfy the condition from λ0+λ1 to λ n1 High reflectivity in one band, low reflectivity in other bands; where λ n1 and λ n2 The values ​​of λ0-λ1 to λ0+λ1 band and λ n1 To λ n2 The current generated by sunlight in the wavelength band in sub-detector I and λ n1 To λ n2 The current generated by sunlight in the band is equivalent to that in sub-detector II.

8. The APD-type stacked laser detector resistant to strong sunlight according to claim 1, characterized in that, The bonding layer is able to transmit incident light.

9. The APD-type stacked laser detector resistant to strong sunlight according to any one of claims 1 to 8, characterized in that, The manufacturing process of this detector is as follows: (1) Prepare a clean P-type epitaxial silicon wafer; (2) The cutoff ring I pattern of the sub-detector I is formed by photolithography, and the cutoff ring I is formed by injecting a large dose of boron. (3) The pattern of the protective ring I of the sub-detector I is formed by photolithography, and the protective ring I is formed by injecting an appropriate amount of phosphorus. (4) The avalanche zone I pattern of the sub-detector I is formed by photolithography, and the avalanche zone I is formed by high-energy injection of an appropriate amount of boron. (5) The N-type detector I is formed by photolithography. + Contact area I pattern, and N is formed by injecting a large dose of phosphorus. + Contact area I; (6) Deposition medium layer I; (7) Etch contact holes in dielectric layer I; (8) Electrode II is formed by depositing metallic aluminum on the front side and then photolithography and etching. (9) Flip the epitaxial silicon wafer so that the front side is down and the back side is up, in preparation for bonding; (10) Prepare a clean P-type monocrystalline silicon wafer; (11) The cutoff ring II pattern of the sub-detector II is formed by photolithography, and the cutoff ring II is formed by injecting a large dose of boron. (12) The pattern of the protective ring II of the sub-detector II is formed by photolithography, and the protective ring II is formed by injecting an appropriate amount of phosphorus element; (13) The avalanche region II pattern of the sub-detector II is formed by photolithography, and the avalanche region II is formed by high-energy injection of an appropriate amount of boron. (14) The N of the sub-detector II is formed by photolithography. + Contact area II pattern, and N formed by injecting a large dose of phosphorus. + Contact area II; (15) Deposition medium layer III; (16) Etch contact holes in dielectric layer III; (17) Metallic aluminum is deposited on the front side, and electrode IV is formed by photolithography and etching; (18) The single-crystal silicon wafer is thinned from the back side by first mechanical grinding and then polishing; (19) Flip the monocrystalline silicon wafer so that the front side is down and the back side is up; (20) The P of the sub-detector II was formed by injecting a large dose of boron. + Contact area II; (21) Deposition medium layer II; (22) Etch contact holes in dielectric layer II; (23) Deposit metallic aluminum and form electrode III by photolithography and etching; (24) Deposition of filter film I; (25) The front side of the epitaxial silicon wafer containing sub-detector I is bonded to the back side of the single-crystal silicon wafer containing sub-detector II through a bonding layer; (26) The low resistivity substrate of the epitaxial silicon wafer is removed by mechanical polishing and self-stopping etching in sequence; (27) P of sub-detector I is formed by photolithography + Contact area I pattern, and P formed by high-dose boron injection. + Contact area I; (28) Deposition of antireflective coating; (29) Etch contact holes in the antireflection film; (30) Deposit metallic aluminum and form electrode I through photolithography and etching; (31) Through holes corresponding to electrode II and electrode III are formed sequentially by photolithography and deep silicon etching.

10. The APD-type stacked laser detector resistant to strong sunlight according to claim 9, characterized in that, When manufacturing this detector for the first time, calibration is required using filter film II and filter film III on the optical window of the tube shell. The procedure is as follows: (1) The detector is encapsulated in a tube shell, but the light window is not sealed; (2) Using a simulated solar light source, the output current of the two sub-detectors at different wavelengths was tested respectively; (3) Measure and record the output current value of sub-detector I every 10 nm from wavelength λ0-λ1 to λ0+λ1; (4) Starting from wavelength λ0-λ1, measure and record the output current value of sub-detector II every 10nm; (5) The output current values ​​of sub-detector I from wavelength λ0-λ1 to λ0+λ1 are accumulated and denoted as I1; (6) The output current values ​​of sub-detector II from wavelength λ0-λ1 to λ0+λ1 are accumulated and denoted as I2; (7) Select wavelength λ n1 and λ n2 The sub-detector II will be moved from wavelength λ n1 Start to λ n2 The output current values ​​are accumulated and denoted as I3. Since the photocurrent of sub-detector II is larger relative to that of sub-detector I as the wavelength increases, there must exist a wavelength λ... n1 and λ n2 This makes I3 = I1 - I2; (8) Filter film II and filter film III are deposited on the optical window. Filter film II is characterized by being able to transmit only wavelengths from λ0 to λ1. n2 The characteristic of filter film III is that it cannot transmit light with wavelengths from λ0+λ1 to λ n1 The light; (9) Seal the light window with filter film II and filter film III onto the tube shell.

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