Uncooled infrared sensor structure and manufacturing method thereof
By using tin alloyed germanium material as the thermal layer in the CMOS process, the problem of VOx infrared sensor incompatible with CMOS process is solved, and a high sensitivity and high precision non-cooled infrared sensor is realized, which improves signal-to-noise ratio and imaging quality.
Patent Information
- Application Number
- CN202411677010.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-21
- Publication Date
- 2025-02-18
AI Technical Summary
The existing VOx infrared sensor technology is incompatible with standard CMOS process production lines, resulting in high manufacturing costs and difficulty in achieving large-scale production.
The tin alloyed germanium material is used as the thermal sensitive layer, and the resistivity is reduced through doping technology, the temperature sensitivity and temperature measurement accuracy are improved, and the manufacturing is achieved in the CMOS process.
Based on the CMOS process compatibility, non-cooled infrared thermal-sensitive materials with high sensitivity and high temperature measurement accuracy have been developed, which reduces the noise level and improves the signal-to-noise ratio and imaging quality.
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Figure CN119469424A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of semiconductors, and in particular to a non-refrigerated infrared sensor structure and a manufacturing method thereof. Background Art
[0002] Uncooled infrared sensor is a device that can detect infrared signals. It uses the thermal effect of infrared radiation. The infrared absorbing material converts infrared radiation into thermal energy, causing the temperature of the thermistor to rise. A physical parameter of the thermistor changes accordingly, and then it is converted into an electrical signal or visible light signal through a certain conversion mechanism involved to achieve detection of objects.
[0003] Commonly used materials for uncooled infrared sensors include amorphous silicon (a-Si) and vanadium oxide (VOx). They absorb infrared thermal radiation through photosensitive elements (i.e., infrared absorbing materials, such as vanadium oxide or amorphous silicon). The resistance of the thermistor changes with temperature. The readout circuit measures the current change caused by the change in resistance of the thermistor, and the electrical signal is collected, analyzed and read out by reading the current.
[0004] VOx infrared sensors occupy the majority of the market share of uncooled infrared sensors with their excellent sensitivity and temperature measurement accuracy (better than a-Si infrared sensors), and have gradually become the mainstream technology trend in this field. However, it is worth noting that the VOx technology route is not compatible with standard CMOS process production lines, which means that an independent CMOS compatible production line needs to be built, resulting in a significant increase in manufacturing costs and difficulty in large-scale production. In view of this, there is an urgent need to develop an uncooled infrared thermistor material that is compatible with CMOS manufacturing processes and has high sensitivity and high temperature measurement accuracy. Summary of the invention
[0005] In view of this, the purpose of the present application is to provide a non-cooled infrared sensor structure and a manufacturing method thereof, so as to obtain a non-cooled infrared thermosensitive material with high sensitivity and high temperature measurement accuracy on the basis of compatibility with standard CMOS process.
[0006] The present application embodiment provides a method for manufacturing an uncooled infrared sensor structure, comprising:
[0007] providing a substrate, wherein the substrate is provided with a readout circuit;
[0008] forming a protective layer on the substrate;
[0009] forming a first connection structure and a second connection structure penetrating the protective layer;
[0010] forming an electrode layer on the protective layer, wherein the electrode layer is divided into a first partial electrode and a second partial electrode by an isolation groove, wherein the first partial electrode is connected to the first connection structure, and the second partial electrode is connected to the second connection structure;
[0011] A thermosensitive layer is formed to cover the electrode layer and the isolation groove. The material of the thermosensitive layer includes a tin-alloyed germanium material. The thermosensitive layer is doped and is used to generate heat after absorbing infrared light, and its resistance changes with temperature.
[0012] Optionally, before forming the protective layer on the substrate, the method further includes:
[0013] A boss structure is formed on the substrate; the protective layer includes a bridge structure covering the upper surface of the boss structure, a support structure covering the side wall of the boss structure, and an extension structure of the substrate covering both sides of the boss structure; the first connecting structure penetrates the extension structure on one side of the boss structure, and the second connecting structure penetrates the extension structure on the other side of the boss structure; the isolation groove is located on the bridge structure;
[0014] After forming the thermosensitive layer covering the electrode layer and the isolation trench, the method further includes: removing the boss structure to form a cavity between the bridge structure and the substrate.
[0015] Optionally, the forming of a thermosensitive layer covering the electrode layer and the isolation trench includes:
[0016] Forming a germanium material layer that has been doped for the first time and covers the electrode layer and the tin alloy in the isolation groove by in-situ doping;
[0017] The germanium material layer is doped for the second time to obtain a thermosensitive layer.
[0018] Optionally, the doping concentration of the germanium material layer is ≥ 1e 20 cm -3 , the doping concentration of the thermosensitive layer is ≥ 2e 20 cm -3 .
[0019] Optionally, the growth temperature of the in-situ doping method is ≤400°C.
[0020] Optionally, the in-situ doping method includes molecular beam epitaxy, chemical vapor deposition or magnetron sputtering, and the second doping method includes ion implantation.
[0021] Optionally, the content of tin in the heat-sensitive layer ranges from 1% to 30%.
[0022] Optionally, the material of the thermosensitive layer includes germanium tin, silicon germanium tin, carbon silicon germanium tin or silicon germanium tin lead.
[0023] Optionally, before forming a sacrificial layer of a mesa structure on the substrate, the method further includes:
[0024] A distributed Bragg reflection layer is formed on the substrate, and the distributed Bragg reflection layer covers the surface of the substrate.
[0025] Optionally, before removing the sacrificial layer, the method further includes:
[0026] A passivation layer is formed covering the heat sensitive layer.
[0027] Optionally, an angle between the support structure and the surface of the substrate is less than 90°.
[0028] Optionally, the method further includes:
[0029] The thermosensitive layer and the electrode layer are etched to obtain isolation grooves to isolate multiple device structures.
[0030] The present application provides an uncooled infrared sensor, comprising:
[0031] a substrate, wherein the substrate is provided with a readout circuit;
[0032] A protective layer on the substrate, and a first connecting structure and a second connecting structure penetrating the protective layer;
[0033] The electrode layer on the protective layer is divided into a first partial electrode and a second partial electrode by an isolation groove, one end of the first partial electrode is connected to the first connection structure, and one end of the second partial electrode is connected to the second connection structure;
[0034] A thermosensitive layer covers the electrode layer and the isolation groove, wherein the material of the thermosensitive layer includes a tin-alloyed germanium material, the thermosensitive layer is doped, and is used to generate heat after absorbing infrared light, and the resistance of the thermosensitive layer changes with temperature.
[0035] Optionally, the protective layer forms a bridge-like structure so that there is a cavity between the protective layer and the substrate, and the protective layer includes a bridge deck structure serving as the top of the cavity, a support structure serving as the side wall of the cavity, and an extension structure of the substrate covering both sides of the cavity; the first connecting structure passes through the extension structure on one side of the cavity, and the second connecting structure passes through the extension structure on the other side of the cavity; the isolation groove is located on the bridge deck structure.
[0036] Optionally, the doping concentration of the thermosensitive layer is ≥ 2e 20 cm -3 .
[0037] Optionally, the content of tin in the heat-sensitive layer ranges from 1% to 30%.
[0038] Optionally, the material of the thermosensitive layer includes germanium tin, silicon germanium tin, carbon silicon germanium tin or silicon germanium tin lead.
[0039] Optionally, the uncooled infrared sensor structure further includes: a distributed Bragg reflection layer between the substrate and the protective layer, wherein the distributed Bragg reflection layer covers the surface of the substrate.
[0040] Optionally, the uncooled infrared sensor structure further includes: a passivation layer covering the thermosensitive layer.
[0041] Optionally, an angle between the support structure and the surface of the substrate is less than 90°.
[0042] Optionally, the uncooled infrared sensor structure further includes:
[0043] The thermosensitive layer and the electrode layer are etched to obtain isolation grooves to isolate multiple device structures.
[0044] The present application provides a non-cooled infrared sensor structure and a manufacturing method thereof, providing a substrate, the substrate being provided with a readout circuit, forming a protective layer on the substrate, forming a first connection structure and a second connection structure penetrating the protective layer, forming an electrode layer on the protective layer, the electrode layer being separated into a first partial electrode and a second partial electrode by an isolation groove, the first partial electrode being connected to the first connection structure, the second partial electrode being connected to the second connection structure, forming a thermal layer covering the electrode layer and the isolation groove, the material of the thermal layer comprising a tin-alloyed germanium material, the thermal layer being doped, the thermal layer being used to generate heat after absorbing infrared light, and the resistance of which changes with temperature. That is to say, the first connection structure, the first part of the electrode, the thermistor layer, the second part of the electrode and the second connection structure can form a current path. The thermistor layer can absorb infrared light as a photosensitive material, and its resistance changes with temperature, that is, it acts as a thermistor material. The resistance change of the thermistor layer in the isolation groove can be determined by monitoring the current in the current path, thereby reflecting the change of infrared light. By tin-alloying the germanium material, the resistivity of the thermistor layer can be reduced, the temperature sensitivity and temperature measurement accuracy of the thermistor layer can be improved, and the noise level of the non-cooled infrared sensor can be reduced, thereby improving its signal-to-noise ratio. The reduction in the resistivity of the thermistor layer also solves the resistance matching problem when the readout circuit is interconnected with the infrared imaging chip, avoiding serious problems such as signal reflection, signal attenuation, signal distortion, system performance degradation and shortened chip service life that may occur during signal transmission, improving the integrity and stability of the signal, and improving key performance indicators such as imaging quality, response speed, sensitivity and signal-to-noise ratio of the infrared sensor. BRIEF DESCRIPTION OF THE DRAWINGS
[0045] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0046] Figure 1 A schematic flow chart of a method for manufacturing a non-cooled infrared sensor structure provided in an embodiment of the present application is shown;
[0047] Figure 2-12 A schematic diagram of the structure of an uncooled infrared sensor structure during the manufacturing process provided in an embodiment of the present application. DETAILED DESCRIPTION
[0048] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution 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, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.
[0049] In the following description, many specific details are set forth to facilitate a full understanding of the present application, but the present application may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.
[0050] This application is described in detail with reference to schematic diagrams. When describing the embodiments of this application in detail, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of this application. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.
[0051] At present, VOx infrared sensors occupy the majority of the market share of uncooled infrared sensors with their excellent sensitivity and temperature measurement accuracy (better than a-Si infrared sensors), and have gradually become the mainstream technology trend in this field. However, it is worth noting that the VOx technology route is not compatible with standard CMOS process production lines, which means that an independent CMOS compatible production line needs to be built, resulting in a significant increase in manufacturing costs and difficulty in large-scale production. In view of this, there is an urgent need to develop an uncooled infrared thermistor material that is compatible with CMOS manufacturing processes and has high sensitivity and high temperature measurement accuracy.
[0052] As one of the Group IV semiconductor materials, amorphous germanium (a-Ge) exhibits outstanding advantages such as remarkable physical and chemical stability (strong resistance to environmental factors), mature growth technology, high compatibility with standard CMOS manufacturing processes, and low manufacturing costs. Therefore, it is regarded as an important material in the field of uncooled infrared detection. However, a-Ge materials perform mediocrely in terms of temperature sensitivity, temperature measurement accuracy, and noise characteristics, which is mainly attributed to its relatively high resistivity. In particular, when the uncooled infrared imaging chip is interconnected with the readout circuit, the problem of resistance mismatch is particularly prominent, which greatly damages the signal transmission quality, reduces the stability and reliability of the system, and leads to a decrease in signal-to-noise ratio, impaired temperature measurement accuracy, and aggravated noise interference and power loss. In view of this, reducing the resistivity of a-Ge materials has become one of the key research directions for the development of high-sensitivity, high-precision uncooled infrared thermosensitive materials.
[0053] Based on the above technical problems, an embodiment of the present application provides a non-cooled infrared sensor structure and a manufacturing method thereof, providing a substrate, the substrate being provided with a readout circuit, forming a protective layer on the substrate, forming a first connection structure and a second connection structure penetrating the protective layer, forming an electrode layer on the protective layer, the electrode layer being separated into a first partial electrode and a second partial electrode by an isolation groove, the first partial electrode being connected to the first connection structure, the second partial electrode being connected to the second connection structure, forming a thermistor layer covering the electrode layer and the isolation groove, the material of the thermistor layer comprising a tin-alloyed germanium material, the thermistor layer being doped, the thermistor layer being used to generate heat after absorbing infrared light, and the resistance changes with temperature. That is to say, the first connection structure, the first part of the electrode, the thermistor layer, the second part of the electrode and the second connection structure can form a current path. The thermistor layer can absorb infrared light as a photosensitive material, and its resistance changes with temperature, that is, it acts as a thermistor material. The resistance change of the thermistor layer in the isolation groove can be determined by monitoring the current in the current path, thereby reflecting the change of infrared light. By tin-alloying the germanium material, the resistivity of the thermistor layer can be reduced, the temperature sensitivity and temperature measurement accuracy of the thermistor layer can be improved, and the noise level of the non-cooled infrared sensor can be reduced, thereby improving its signal-to-noise ratio. The reduction in the resistivity of the thermistor layer also solves the resistance matching problem when the readout circuit is interconnected with the infrared imaging chip, avoiding serious problems such as signal reflection, signal attenuation, signal distortion, system performance degradation and shortened chip service life that may occur during signal transmission, improving the integrity and stability of the signal, and improving key performance indicators such as imaging quality, response speed, sensitivity and signal-to-noise ratio of the infrared sensor.
[0054] In order to better understand the technical solution and technical effects of the present application, specific embodiments will be described in detail below with reference to the accompanying drawings.
[0055] refer to Figure 1FIG. 1 is a flow chart of a method for manufacturing a non-cooled infrared sensor structure provided in an embodiment of the present application, with reference to FIG. Figure 2-12 FIG. 1 is a schematic diagram of a structure of a non-cooled infrared sensor structure provided in an embodiment of the present application during a manufacturing process. The manufacturing method includes:
[0056] S101, providing a substrate 110, wherein the substrate 110 is provided with a readout circuit, Figure 2 shown.
[0057] In the embodiment of the present application, the substrate 110 can provide support for the film layer thereon, and a read-out circuit (ROIC) can be provided in the substrate 110, that is, the substrate 110 can be used as a read-out circuit wafer. The present solution forms a film layer on the substrate 110, which can reduce the bonding steps between the read-out circuit wafer and the device wafer, simplify the process flow, and reduce production costs.
[0058] S102, forming a protective layer 130 on the substrate 110, referring to Figure 3-Figure 6 shown.
[0059] A protective layer 130 may be formed on the substrate 110. The protective layer 130 is used to isolate the readout circuit on the substrate 110 from other structures on the protective layer 130. The material of the protective layer 130 is an insulating material, such as silicon nitride or silicon oxide, etc. The thickness of the protective layer 130 ranges from 10 to 100 nm.
[0060] In the embodiment of the present application, a distributed Bragg reflection layer 120 may be provided between the substrate 110 and the protective layer 130. That is, before forming the protective layer 130, the distributed Bragg reflection layer 120 may be formed on the substrate 110. Figure 3 As shown, the distributed Bragg reflector 120 covers the surface of the substrate 110, that is, covers the readout circuit, and is used to reflect light to improve the absorption efficiency of infrared light, thereby improving the detection sensitivity of infrared light. The distributed Bragg reflector 120 can be periodically stacked to form a distributed Bragg reflector. The setting of the distributed Bragg reflector 120 is beneficial to optimize the behavior of thermal radiation within a specific wavelength range, ensuring that the thermal radiation is effectively enhanced and amplified in the resonant cavity, thereby realizing a non-cooled infrared sensor with high temperature sensitivity and high temperature measurement accuracy.
[0061] In the embodiment of the present application, the device may have a cavity, so before forming the protective layer 130 on the substrate 110, a boss structure 170 may be formed on the substrate 110. The boss structure 170 serves as a sacrificial structure to support the protective layer 130 on the boss structure 170. After the boss structure 170 is removed, a cavity is formed at the location of the boss structure 170. The cavity is formed between the protective layer 130 and the substrate 110, and can store heat to improve the detection sensitivity of infrared light. In addition, the cavity can also enhance the reflection of the incident infrared light to improve the absorption efficiency of the infrared light, thereby improving the detection sensitivity of the infrared light.
[0062] The material of the boss structure 170 can be an insulating material or a conductive material. If the boss structure 170 is a conductive material, the surface of the readout circuit is covered by an insulating layer (such as a distributed Bragg reflector 120, etc.) and will not be connected to the conductive material. Specifically, before forming the protective layer 130, a protective material layer 171 can be formed on the substrate 110, referring to Figure 4 Then the protective material layer 171 is etched to obtain the boss structure 170, refer to Figure 5 When a distributed Bragg reflector 120 is formed on the substrate 110, a protective material layer 171 is disposed on the distributed Bragg reflector 120, so that the boss structure 170 is disposed on the Bragg reflector 120. The thickness of the protective material layer 171 is in the range of 100-1000 nm, and the height of the boss structure 170 and the height of the subsequently formed cavity are equal to the thickness of the protective material layer 171.
[0063] When the protrusion structure 170 is formed, the protection layer 130 covers the protrusion structure 170 and the surface of the substrate 110 not covered by the protrusion structure 170. Figure 6 As shown, the protective layer 130 may include a bridge structure, a support structure and an extension structure, wherein the bridge structure covers the upper surface of the boss structure 170, the support structure covers the side wall of the boss structure 170, and the extension structure covers the substrate 110 on both sides of the boss structure 170. The angle between the support structure and the surface of the substrate 110 is less than 90°, so that the boss structure 170 forms a trapezoidal structure, which is beneficial to the stability of the cavity.
[0064] S103, forming a first connection structure 131 and a second connection structure 132 penetrating the protective layer 130, referring to Figure 7 shown.
[0065] After forming the protective layer 130, a first connection structure 131 and a second connection structure 132 penetrating the protective layer 130 may be formed. The materials of the first connection structure 131 and the second connection structure 132 are conductive materials, such as metal materials. The first connection structure 131 and the second connection structure 132 are respectively connected to the readout circuit to conduct the generated current signal to the readout circuit. A plurality of device structures may be formed on a substrate 110, each device structure being a pixel, which may include a first connection structure 131 and a second connection structure 132, which appear in pairs.
[0066] When the boss structure 170 is formed, the first connecting structure 131 and the second connecting structure 132 are respectively located on both sides of the boss structure 170, so that after the boss structure 170 is removed to obtain a cavity, the first connecting structure 131 and the second connecting structure 132 are respectively located on both sides of the cavity. Specifically, the first connecting structure 131 passes through the extension structure on one side of the boss structure 170, and the second connecting structure 132 passes through the extension structure on the other side of the boss structure 170.
[0067] S104, forming an electrode layer on the protective layer 130, wherein the electrode layer is separated into a first partial electrode 141 and a second partial electrode 142 by an isolation groove 143, wherein the first partial electrode 141 is connected to the first connection structure 131, and the second partial electrode 142 is connected to the second connection structure 132, Figure 8 shown.
[0068] An electrode layer may be formed on the protective layer 130. The electrode layer is separated into a first partial electrode 141 and a second partial electrode 142 by an isolation groove 143. The first partial electrode 141 is connected to the first connection structure 131 and further connected to the readout circuit. The second partial electrode 142 is connected to the second connection structure 132 and further connected to the readout circuit. The material of the electrode layer is a conductive material, such as a metal material. The thickness of the click layer is in the range of 50-150 nm.
[0069] When the boss structure 170 is formed, the isolation groove 143 is located on the bridge deck structure, so that the first partial electrode 141 extends from one side of the bridge deck structure to the support structure and the extension structure and is connected to the first connection structure 131, and the second partial electrode 142 extends from one side of the bridge deck structure to the support structure and the extension structure and is connected to the second connection structure 132.
[0070] S105, forming a thermosensitive layer 150 covering the electrode layer and the isolation trench 143, wherein the material of the thermosensitive layer 150 includes a tin-alloyed germanium material, and the thermosensitive layer 150 is doped, Figure 9-12 shown.
[0071] After forming the electrode layer, a thermosensitive layer 150 covering the electrode layer and the isolation trench 143 may be formed. Fig. 9 As shown, the material of the thermosensitive layer 150 includes a tin-alloyed germanium material. The thermosensitive layer 150 is doped to generate heat after absorbing infrared light and its resistance changes with temperature. That is to say, the first connecting structure 131, the first partial electrode 141, the thermosensitive layer 150, the second partial electrode 142 and the second connecting structure 132 can form a current path. The thermosensitive layer 150 can absorb infrared light as a photosensitive material, and its resistance changes with temperature, that is, it acts as a thermosensitive material. By monitoring the current in the current path, the resistance change of the thermosensitive layer 150 in the isolation groove 143 can be determined, thereby reflecting the change of infrared light.
[0072] The tin (Sn) alloyed germanium material may specifically be a-GeSn (germanium tin), a-SiGeSn (silicon germanium tin), a-CSiGeSn (carbon silicon germanium tin) and SiGeSnPb (silicon germanium tin lead), etc. The tin content of the thermal layer 150 ranges from 1% to 30%, and the thickness ranges from 100 to 300 nm.
[0073] Compared with the amorphous silicon technology route, the amorphous germanium technology route has the following advantages: 1) Amorphous germanium has a higher temperature coefficient of resistance, which means that the resistance change of amorphous germanium material will be larger under the same temperature change, and the sensitivity and resolution of the microbolometer will be higher; 2) Compared with the amorphous silicon technology route, amorphous germanium has lower thermal conductivity, which makes it easy for heat to accumulate inside the amorphous germanium material after absorbing infrared radiation, causing greater temperature and resistance changes, which is beneficial to improving the response speed and sensitivity of the microbolometer.
[0074] As a metal element, the incorporation of Sn will change the short-range order of atomic arrangement in a-Ge materials, increase the carrier concentration in a-Ge, improve the conductivity of a-Ge materials, reduce the resistivity of a-Ge materials, and reduce the high doping concentration required for in-situ doping. In addition, the introduction of Sn elements transforms a-Ge materials into a-GeSn materials, and its band gap structure becomes narrower, which significantly enhances the sensitivity of a-Ge thermosensitive materials to infrared thermal radiation.
[0075] Tin alloying and doping the germanium material can reduce the resistivity of the thermistor layer 150, improve the temperature sensitivity and temperature measurement accuracy of the thermistor layer 150, reduce the noise level of the non-cooled infrared sensor, and thus improve its signal-to-noise ratio. The reduction in the resistivity of the thermistor layer 150 also solves the resistance matching problem when the readout circuit is interconnected with the infrared imaging chip, avoids serious problems such as signal reflection, signal attenuation, signal distortion, system performance degradation, and shortened chip service life that may occur during signal transmission, improves signal integrity and stability, and improves key performance indicators such as imaging quality, response speed, sensitivity, and signal-to-noise ratio of the infrared sensor.
[0076] The process of forming the thermosensitive layer 150 may specifically be to form a doped tin-alloyed germanium material layer covering the electrode layer and the isolation groove 143 as the thermosensitive layer 150 by an in-situ doping method; or, to form a tin-alloyed germanium material layer covering the electrode layer and the isolation groove 143 by an in-situ doping method after a first doping, and then to perform a second doping on the germanium material layer to further increase the doping concentration to obtain the thermosensitive layer 150, that is, the thermosensitive layer 150 may be doped by a mixed doping process of the first doping and the second doping to achieve a higher doping concentration of the thermosensitive layer 150. That is, the formation method of the thermosensitive layer 150 is compatible with the CMOS process.
[0077] The growth temperature of the in-situ doping method is ≤400°C, which may include molecular beam epitaxy (MBE), chemical vapor deposition (CVD) or magnetron sputtering, etc. The second doping method includes ion implantation, etc. The doping concentration of the germanium material layer is ≥1e 20 cm -3 , the doping concentration of the thermosensitive layer 150 is ≥ 2e 20 cm -3 The doping type may be P-type doping or N-type doping.
[0078] The in-situ doping method introduces N-type or P-type doping elements, which improves the doping uniformity and controllability of the a-Ge material. It does not require an additional annealing step, simplifies the process flow, reduces production costs, enhances the conductivity of the a-Ge material, and is beneficial to reducing the resistivity of the a-Ge material, meeting the requirements of resistance matching between the a-Ge infrared imaging chip and the readout circuit.
[0079] Since the thermosensitive layer 150 is formed by a low temperature process, the readout circuit wafer can be directly used as the substrate 110, avoiding the influence of the growth temperature of the a-Ge infrared thermosensitive material on the performance of the readout circuit wafer, and realizing a monolithic non-cooled a-Ge infrared sensor, which means that the a-Ge infrared thermosensitive material has low energy consumption and low growth cost during the growth process. In addition, the a-Ge infrared thermosensitive material formed at a low temperature has the advantages of good uniformity and good photoelectric properties.
[0080] After forming the thermosensitive layer 150, a passivation layer 160 covering the thermosensitive layer 150 may be formed. Fig.10 As shown, the passivation layer 160 is used to protect the thermal sensitive layer 150. The material of the passivation layer 160 can be silicon oxide or silicon nitride, etc., and the thickness of the passivation layer 160 ranges from 10 to 100 nm.
[0081] After forming the thermosensitive layer 150, the thermosensitive layer 150 and the electrode layer may be etched to obtain an isolation groove 190 to isolate multiple device structures. Fig.11 As shown, each device structure includes a first connection structure 131 and a second connection structure 132 , a boss structure 170 , a first partial electrode 141 and a second partial electrode 142 , and a passivation layer 160 of the thermosensitive layer 150 on the boss structure 170 .
[0082] After forming the thermal sensitive layer 150, the boss structure 170 can be removed to form a cavity 180 between the bridge deck structure and the substrate 110. Fig.12 As shown, the bridge structure serves as the top of the cavity 180, the support structure serves as the sidewall of the cavity 180, and the extension structure covers the substrate 110 on both sides of the cavity. A single device structure can be used as a pixel. Fig.12 The first pixel 100 and the second pixel 200 are included.
[0083] The present application provides a method for manufacturing a non-cooled infrared sensor structure, providing a substrate, the substrate being provided with a readout circuit, forming a protective layer on the substrate, forming a first connection structure and a second connection structure penetrating the protective layer, forming an electrode layer on the protective layer, the electrode layer being separated into a first partial electrode and a second partial electrode by an isolation groove, the first partial electrode being connected to the first connection structure, the second partial electrode being connected to the second connection structure, forming a thermal layer covering the electrode layer and the isolation groove, the material of the thermal layer comprising a tin-alloyed germanium material, the thermal layer being doped, the thermal layer being used to generate heat after absorbing infrared light, and the resistance of which changes with temperature. That is to say, the first connection structure, the first part of the electrode, the thermistor layer, the second part of the electrode and the second connection structure can form a current path. The thermistor layer can absorb infrared light as a photosensitive material, and its resistance changes with temperature, that is, it acts as a thermistor material. The resistance change of the thermistor layer in the isolation groove can be determined by monitoring the current in the current path, thereby reflecting the change of infrared light. By tin-alloying the germanium material, the resistivity of the thermistor layer can be reduced, the temperature sensitivity and temperature measurement accuracy of the thermistor layer can be improved, and the noise level of the non-cooled infrared sensor can be reduced, thereby improving its signal-to-noise ratio. The reduction in the resistivity of the thermistor layer also solves the resistance matching problem when the readout circuit is interconnected with the infrared imaging chip, avoiding serious problems such as signal reflection, signal attenuation, signal distortion, system performance degradation and shortened chip service life that may occur during signal transmission, improving the integrity and stability of the signal, and improving key performance indicators such as imaging quality, response speed, sensitivity and signal-to-noise ratio of the infrared sensor.
[0084] Based on the manufacturing method of a non-cooled infrared sensor structure provided in the above embodiment, the present application embodiment also provides a non-cooled infrared sensor, see Fig.12 , uncooled infrared sensors can include:
[0085] a substrate, wherein the substrate is provided with a readout circuit;
[0086] A protective layer on the substrate, and a first connecting structure and a second connecting structure penetrating the protective layer;
[0087] The electrode layer on the protective layer is divided into a first partial electrode and a second partial electrode by an isolation groove, one end of the first partial electrode is connected to the first connection structure, and one end of the second partial electrode is connected to the second connection structure;
[0088] A thermosensitive layer covers the electrode layer and the isolation groove, wherein the material of the thermosensitive layer includes a tin-alloyed germanium material, the thermosensitive layer is doped, and is used to generate heat after absorbing infrared light, and the resistance of the thermosensitive layer changes with temperature.
[0089] Optionally, the protective layer forms a bridge-like structure so that there is a cavity between the protective layer and the substrate, and the protective layer includes a bridge deck structure serving as the top of the cavity, a support structure serving as the side wall of the cavity, and an extension structure of the substrate covering both sides of the cavity; the first connecting structure passes through the extension structure on one side of the cavity, and the second connecting structure passes through the extension structure on the other side of the cavity; the isolation groove is located on the bridge deck structure.
[0090] Optionally, the doping concentration of the thermosensitive layer is ≥ 2e 20 cm -3 .
[0091] Optionally, the content of tin in the heat-sensitive layer ranges from 1% to 30%.
[0092] Optionally, the material of the thermosensitive layer includes germanium tin, silicon germanium tin, carbon silicon germanium tin or silicon germanium tin lead.
[0093] Optionally, the uncooled infrared sensor structure further includes: a distributed Bragg reflection layer between the substrate and the protective layer, wherein the distributed Bragg reflection layer covers the surface of the substrate.
[0094] Optionally, the uncooled infrared sensor structure further includes: a passivation layer covering the thermosensitive layer.
[0095] Optionally, an angle between the support structure and the surface of the substrate is less than 90°.
[0096] Optionally, the uncooled infrared sensor structure further includes:
[0097] The thermosensitive layer and the electrode layer are etched to obtain isolation grooves to isolate multiple device structures.
[0098] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the structural embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment. Ordinary technicians in this field can understand and implement it without paying creative work.
[0099] The above is only a preferred implementation of the present application. Although the present application has been disclosed as a preferred embodiment, it is not intended to limit the present application. Any technician familiar with the art can use the above disclosed methods and technical contents to make many possible changes and modifications to the technical solution of the present application without departing from the scope of the technical solution of the present application, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present application without departing from the content of the technical solution of the present application still falls within the scope of protection of the technical solution of the present application.
Claims
1. A method for manufacturing an uncooled infrared sensor structure, characterized in that: include: providing a substrate, wherein the substrate is provided with a readout circuit; forming a protective layer on the substrate; forming a first connection structure and a second connection structure penetrating the protective layer; forming an electrode layer on the protective layer, wherein the electrode layer is divided into a first partial electrode and a second partial electrode by an isolation groove, wherein the first partial electrode is connected to the first connection structure, and the second partial electrode is connected to the second connection structure; A thermosensitive layer is formed to cover the electrode layer and the isolation groove. The material of the thermosensitive layer includes a tin-alloyed germanium material. The thermosensitive layer is doped and is used to generate heat after absorbing infrared light, and its resistance changes with temperature.
2. The method according to claim 1, characterized in that Before forming the protective layer on the substrate, the method further includes: A boss structure is formed on the substrate; the protective layer includes a bridge structure covering the upper surface of the boss structure, a support structure covering the side wall of the boss structure, and an extension structure of the substrate covering both sides of the boss structure; the first connecting structure penetrates the extension structure on one side of the boss structure, and the second connecting structure penetrates the extension structure on the other side of the boss structure; the isolation groove is located on the bridge structure; After forming the thermosensitive layer covering the electrode layer and the isolation trench, the method further includes: removing the boss structure to form a cavity between the bridge structure and the substrate.
3. The method according to claim 1, characterized in that The forming of a thermal sensitive layer covering the electrode layer and the isolation trench comprises: Forming a germanium material layer that has been doped for the first time and covers the electrode layer and the tin alloy in the isolation groove by in-situ doping; The germanium material layer is doped for the second time to obtain a thermosensitive layer.
4. The method according to claim 3, characterized in that The doping concentration of the germanium material layer is ≥ 1e 20 cm -3 , the doping concentration of the thermosensitive layer is ≥ 2e 20 cm -3 .
5. The method according to claim 3, characterized in that: The growth temperature of the in-situ doping method is ≤400°C.
6. The method according to claim 3, characterized in that The in-situ doping method includes molecular beam epitaxy, chemical vapor deposition or magnetron sputtering, and the second doping method includes ion implantation.
7. The method according to any one of claims 1 to 6, characterized in that: The content of tin in the heat-sensitive layer ranges from 1% to 30%.
8. The method according to any one of claims 1 to 6, characterized in that: The material of the heat sensitive layer includes germanium tin, silicon germanium tin, carbon silicon germanium tin or silicon germanium tin lead.
9. The method according to any one of claims 1 to 6, characterized in that: Before forming a sacrificial layer of a mesa structure on the substrate, the method further comprises: A distributed Bragg reflection layer is formed on the substrate, and the distributed Bragg reflection layer covers the surface of the substrate.
10. The method according to any one of claims 1 to 6, characterized in that: Before removing the sacrificial layer, the method further comprises: A passivation layer is formed covering the heat sensitive layer.
11. The method according to any one of claims 1 to 6, characterized in that: The angle between the support structure and the surface of the substrate is less than 90°.
12. The method according to any one of claims 1 to 6, characterized in that: The method further comprises: The thermosensitive layer and the electrode layer are etched to obtain isolation grooves to isolate multiple device structures.
13. An uncooled infrared sensor structure, characterized in that: include: a substrate, wherein the substrate is provided with a readout circuit; A protective layer on the substrate, and a first connecting structure and a second connecting structure penetrating the protective layer; The electrode layer on the protective layer is divided into a first partial electrode and a second partial electrode by an isolation groove, one end of the first partial electrode is connected to the first connection structure, and one end of the second partial electrode is connected to the second connection structure; A thermosensitive layer covers the electrode layer and the isolation groove, wherein the material of the thermosensitive layer includes a tin-alloyed germanium material, the thermosensitive layer is doped, and is used to generate heat after absorbing infrared light, and the resistance of the thermosensitive layer changes with temperature.
14. The uncooled infrared sensor structure according to claim 13, characterized in that: The protective layer forms a bridge-like structure, so that there is a cavity between the protective layer and the substrate. The protective layer includes a bridge deck structure as the top of the cavity, a support structure as the side wall of the cavity, and an extension structure of the substrate covering both sides of the cavity; the first connecting structure runs through the extension structure on one side of the cavity, and the second connecting structure runs through the extension structure on the other side of the cavity; the isolation groove is located on the bridge deck structure.
15. The uncooled infrared sensor structure according to claim 13, characterized in that: The doping concentration of the thermosensitive layer is ≥2e 20 cm -3 .
16. The uncooled infrared sensor structure according to any one of claims 13 to 15, characterized in that: The content of tin in the heat-sensitive layer ranges from 1% to 30%.
17. The uncooled infrared sensor structure according to any one of claims 13 to 15, characterized in that: The material of the heat sensitive layer includes germanium tin, silicon germanium tin, carbon silicon germanium tin or silicon germanium tin lead.
18. The uncooled infrared sensor structure according to any one of claims 13 to 15, characterized in that: Also includes: A distributed Bragg reflector layer is provided between the substrate and the protective layer, and covers a surface of the substrate.
19. The uncooled infrared sensor structure according to any one of claims 13 to 15, characterized in that: Also includes: A passivation layer covers the heat-sensitive layer.