Infrared detector and infrared detector preparation method
By adding ground leads to the readout circuit of the infrared detector and changing the interconnection method of the cell structure, the detector is completely isolated, the stress mismatch problem is solved, and performance and reliability are improved.
Patent Information
- Application Number
- CN202411616327.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-13
- Publication Date
- 2025-02-18
AI Technical Summary
Existing infrared detectors are difficult to completely solve the problem of stress mismatch, especially in large-scale array and long-wave band applications, resulting in performance degradation and cracking.
By adding ground leads to the readout circuit, the electrodes around the detector are directed to a single cell structure, and by changing the interconnection of the single cell structure and the readout circuit, the single cell structure forms a separate closed-loop lead structure. This achieves complete isolation.
Fully eliminate stress mismatch caused by the difference in thermal expansion coefficient between infrared material and readout circuit, improving detector performance, especially when the long wave band is sensitive to stress changes, avoiding crosstalk and slotting between cells Segmentation introduced etch damage.
Smart Images
Figure CN119486358A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of infrared detectors, and in particular to an infrared detector and a method for preparing the infrared detector. Background Art
[0002] The traditional infrared detector consists of two parts: the detector and the readout circuit. Figure 1 and Figure 2 As shown, the structural diagram of the readout circuit 2 is as follows Figure 3 As shown, Figure 1 The pixel structure array on the surface of the substrate 11 shown in the figure has only a single type (N type or P type), and the pixel structure array is electrically connected to the lead pad 21 on the surface of the readout circuit 2; a pixel structure of another polarity (P type or N type) is formed on the periphery of the pixel structure array, and the pixel structure is electrically connected to the ground lead 22 on the periphery of the readout circuit 2. The pixel structures of the two polarities form a conductive path through the common absorption layer 12, and the formation of the conductive path requires crossing the bulk resistance of the absorption layer 12.
[0003] With the development of infrared detector technology, the scale of device arrays continues to increase, and as a result, stress mismatch becomes more and more serious. In some aerospace applications, longer wavelengths and larger pixel areas are involved, resulting in stress mismatch performance being more easily degraded when manufacturing such products. In severe cases, the infrared detector array may crack and become scrapped.
[0004] At present, the methods of controlling stress in the industry are generally divided into several types: Figure 4 and Figure 5 As shown, glue 3 is filled between the detector and the readout circuit 2, and the amount of the bottom filling glue 3 is controlled; or as shown in FIG. Figure 6 As shown, a substrate 4 with a thermal expansion coefficient that is more matched to the infrared material (for example, HgCdTe) of the absorption layer 12 is added; or both methods are used at the same time. In the prior art, whether it is controlling the amount of the filling glue 3 or adding a substrate 4 with a matching expansion coefficient, it can only reduce the stress mismatch between the infrared material and the silicon readout circuit 2 as much as possible but cannot completely eliminate it, resulting in the performance of the infrared detector not being optimal.
[0005] In addition, for ultra-large detector arrays, the industry currently generally reduces stress by slotting and splitting the detectors. For example, 2Kx2K may need to be spliced together by 4 1Kx1Ks, but this will introduce etching damage and incompleteness in the array scale. Summary of the invention
[0006] The purpose of this application is to provide an infrared detector and a method for preparing the infrared detector, thereby reducing the structural stress of the infrared detector.
[0007] To achieve the above-mentioned object, the present application provides an infrared detector, comprising: a detector and a readout circuit;
[0008] The detector comprises a plurality of pixel structures arranged in an array; the pixel structure comprises an absorption layer, a first electrode and a second electrode; a first doping region and a second doping region are arranged on the surface of the absorption layer; the first electrode is arranged on the surface of the first doping region; and the second electrode is arranged on the surface of the second doping region;
[0009] A lead pad and a ground lead are provided on the surface of the readout circuit; the first electrode is electrically connected to the lead pad; and the second electrode is electrically connected to the ground lead.
[0010] Optionally, the lead pads and the ground leads are alternately arranged along a first direction, and the ground leads extend along a second direction.
[0011] Optionally, a first conductive structure is disposed on a surface of the first electrode facing away from the absorption layer; the first conductive structure is electrically connected to the lead pad;
[0012] A second conductive structure is disposed on a surface of the second electrode facing away from the absorption layer; and the second conductive structure is electrically connected to the ground lead.
[0013] Optionally, the pixel structure further includes a passivation layer; the passivation layer is arranged on the surface of the absorption layer;
[0014] The passivation layer is provided with a first contact hole and a second contact hole; the first contact hole corresponds to the first doped region and at least penetrates the passivation layer along the thickness direction of the passivation layer; the second contact hole corresponds to the second doped region and at least penetrates the passivation layer along the thickness direction of the passivation layer.
[0015] Optionally, a first step and a second step are provided on the surface of the absorption layer; the first step surface is provided with the first doped region; and the second step surface is provided with the second doped region.
[0016] To achieve the above object, the present application also provides a method for preparing an infrared detector, comprising:
[0017] A lead pad and a ground lead are arranged on the surface of the readout circuit;
[0018] Etching the absorption layer to form a plurality of absorption layers arranged in an array;
[0019] Disposing a first doping region and a second doping region on the surface of the absorption layer;
[0020] The first electrode is arranged on the surface of the first doping region, and the second electrode is arranged on the surface of the second doping region to form the pixel structure and obtain a detector;
[0021] The readout circuit and the detector are interconnected, the first electrode and the lead pad are electrically connected, and the second electrode and the ground lead are electrically connected to obtain an infrared detector.
[0022] Optionally, providing a lead pad and a ground lead on the surface of the readout circuit includes:
[0023] Coating a first mask layer on the surface of the readout circuit, and photolithographically forming a patterned first mask layer;
[0024] After forming the patterned first mask layer, depositing a first conductive layer on the surface of the readout circuit;
[0025] After forming the first conductive layer, the first mask layer is removed, and the lead pads and the ground leads are formed on the surface of the readout circuit; the lead pads and the ground leads are alternately arranged along a first direction, and the ground leads extend along a second direction.
[0026] Optionally, interconnecting the readout circuit and the detector, electrically connecting the first electrode to the lead pad, and electrically connecting the second electrode to the ground lead, to obtain an infrared detector, comprises:
[0027] A first conductive structure is disposed on a surface of the first electrode facing away from the absorption layer, and a second conductive structure is disposed on a surface of the second electrode facing away from the absorption layer;
[0028] The readout circuit and the detector are flip-chip interconnected, the first conductive structure and the lead pad are electrically connected, and the second conductive structure and the ground lead are electrically connected, so as to obtain the infrared detector.
[0029] Optionally, after the first doping region and the second doping region are provided on the surface of the absorption layer, the method further comprises:
[0030] Depositing a passivation layer on the surface of the absorption layer where the first doping region and the second doping region are formed;
[0031] The passivation layer is etched to form a first contact hole and a second contact hole; the first contact hole corresponds to the first doped region and at least penetrates the passivation layer along the thickness direction of the passivation layer; the second contact hole corresponds to the second doped region and at least penetrates the passivation layer along the thickness direction of the passivation layer.
[0032] Optionally, etching the absorption layer to form a plurality of absorption layers arranged in an array includes:
[0033] epitaxially growing the absorption layer on a substrate;
[0034] Etching the absorption layer to form a plurality of absorption layers arranged in an array;
[0035] Correspondingly, after the readout circuit and the detector are interconnected, the first electrode and the lead pad are electrically connected, and the second electrode and the ground lead are electrically connected, the method further includes:
[0036] The substrate is removed.
[0037] Optionally, providing a first doping region and a second doping region on the surface of the absorption layer includes:
[0038] Etching the absorption layer to form a first step and a second step on the surface of the absorption layer;
[0039] Disposing the first doping region on the surface of the first step;
[0040] The second doping region is disposed on the surface of the second step.
[0041] Obviously, the infrared detector provided by the present application leads the electrodes on the periphery of the detector to a single pixel structure by adding an additional ground lead to the readout circuit, and by changing the interconnection between the single pixel structure and the readout circuit, so that the single pixel structure forms a separate closed-loop lead-out structure, thereby achieving complete isolation of the single pixel structure, and has the following beneficial effects:
[0042] (1) The stress mismatch caused by the difference in thermal expansion coefficient between the infrared material and the readout circuit is fully eliminated, thereby improving the performance of the detector, especially in the long-wave band, which is more sensitive to stress changes. It is foreseeable that the larger the array size, the greater the performance advantage it brings.
[0043] (2) The photoelectric NP junction realizes a closed loop of a single pixel structure. The pixel structure of the other polarity is supplied through the ground lead on the readout circuit, and the parasitic impedance is low, which avoids the response inconsistency caused by the inconsistent series resistance of the central pixel structure and the edge pixel structure when the two polarity pixel structures share the same absorption layer in an ultra-large-scale array;
[0044] (3) Completely independent pixel structure, eliminating the crosstalk between pixels caused by the shared absorption layer of two polar pixel structures in an ultra-large array;
[0045] (4) It avoids the etching damage and array scale incompleteness introduced by the method of slotting and dividing the detector.
[0046] The present application also provides a method for preparing an infrared detector, by which the above-mentioned infrared detector can be prepared, so it also has the above-mentioned beneficial effects. BRIEF DESCRIPTION OF THE DRAWINGS
[0047] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.
[0048] Figure 1 is a cross-sectional view of the detector end in a conventional infrared detector;
[0049] Figure 2 It is a top view of the detector end in a traditional infrared detector;
[0050] Figure 3 This is a wiring diagram of the readout circuit end in a traditional infrared detector;
[0051] Figure 4 This is a schematic diagram of the structure of a conventional infrared detector with the first bottom-filled glue;
[0052] Figure 5 A schematic diagram of the structure of a conventional infrared detector with a second bottom-filled glue;
[0053] Figure 6 A schematic diagram of the structure of a traditional infrared detector with an added substrate;
[0054] Figure 7 A schematic diagram of the structure of an infrared detector provided in an embodiment of the present application
[0055] Figure 8 A schematic diagram of wiring of a readout circuit terminal provided in an embodiment of the present application;
[0056] Fig. 9 A flowchart of a method for preparing an infrared detector provided in an embodiment of the present application;
[0057] Figures 10 to 15 A schematic diagram of a detector end processing flow provided in an embodiment of the present application;
[0058] Fig.16 A top view of a detector end provided in an embodiment of the present application;
[0059] Fig.17 A schematic diagram of the interconnection between a readout circuit terminal and a detector terminal provided in an embodiment of the present application.
[0060] The following are the descriptions of the reference numerals:
[0061] 11-substrate; 12-absorption layer; 131-first electrode; 132-second electrode; 141-first conductive structure; 142-second conductive structure; 2-readout circuit; 21-lead pad; 22-ground lead; 3-glue; 4-base. DETAILED DESCRIPTION
[0062] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme 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 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.
[0063] Please refer to Figure 7 and Figure 8 , Figure 7 A schematic diagram of the structure of an infrared detector provided in an embodiment of the present application; Figure 8 A schematic diagram of the surface wiring of a readout circuit provided in an embodiment of the present application. An infrared detector provided in an embodiment of the present application may include: a detector and a readout circuit 2;
[0064] The detector includes a plurality of pixel structures arranged in an array; the pixel structure includes an absorption layer 12, a first electrode 131 and a second electrode 132; a first doping region and a second doping region are arranged on the surface of the absorption layer 12; the first electrode 131 is arranged on the surface of the first doping region; the second electrode 132 is arranged on the surface of the second doping region;
[0065] A lead pad 21 and a ground lead 22 are provided on the surface of the readout circuit 2 ; the first electrode 131 is electrically connected to the lead pad 21 ; and the second electrode 132 is electrically connected to the ground lead 22 .
[0066] The embodiment does not limit the specific type of the absorption layer 12 , and the absorption layer 12 may be any infrared material. For example, the absorption layer 12 may be a mercury cadmium telluride layer.
[0067] This embodiment does not limit the specific type of the first doping region, and the specific type of the first doping region can be determined according to the specific type of the doped impurities. For example, when the doped impurities are P-type impurities, the first doping region can be a P-type region; when the doped impurities are N-type impurities, the first doping region can be an N-type region. This embodiment does not limit the specific type of the second doping region, and the specific type of the second doping region can be determined according to the specific type of the doped impurities. For example, when the doped impurities are P-type impurities, the second doping region can be a P-type region; when the doped impurities are N-type impurities, the second doping region can be an N-type region. It should be noted that this embodiment ensures that the first doping region and the second doping region are of different types, that is, when the first doping region is an N-type region, the second doping region is a P-type region; when the first doping region is a P-type region, the second doping region is an N-type region.
[0068] The present embodiment does not limit the specific type of the first electrode 131, as long as the first electrode 131 is conductive, for example, the first electrode 131 may be a metal electrode. The present embodiment does not limit the specific type of the second electrode 132, as long as the second electrode 132 is conductive, for example, the second electrode 132 may be a metal electrode.
[0069] The present embodiment does not limit the specific type of the lead pad, as long as the lead pad is conductive, for example, the lead pad 21 may be a composite metal layer. It should be noted that the composite metal layer can achieve good ohmic contact and film adhesion. The present embodiment does not limit the specific type of the ground lead 22, as long as the ground lead 22 is conductive, for example, the ground lead 22 may be a composite metal layer. The present embodiment does not limit the specific type of the composite metal, for example, the composite metal layer may include a Cr layer, a Pt layer and an Au layer sequentially arranged along the thickness direction of the readout circuit 2, or a Ti layer, a Pb layer and an Au layer sequentially arranged along the thickness direction of the readout circuit 2.
[0070] This embodiment does not limit the specific arrangement of the lead pads 21 and the ground lead 22, as long as the specific arrangement of the lead pads 21 and the ground lead 22 can correspond to the specific arrangement of the first doping region and the second doping region, for example: Figure 8 As shown, the lead pads 21 and the ground lead 22 can be arranged alternately along the first direction, and the ground lead 22 extends along the second direction. This embodiment does not limit the specific structure of the lead pads 21, and the lead pads 21 can be, but are not limited to, a truncated cone surrounding a square opening. It should be noted that the first direction and the second direction are both parallel to the surface of the readout circuit 2, and the second direction is perpendicular to the first direction.
[0071] Further, in order to facilitate the interconnection between the readout circuit 2 and the detector, in this embodiment, the surface of the first electrode 131 facing away from the absorption layer 12 may be provided with a first conductive structure 141; the first conductive structure 141 may be electrically connected to the lead pad 21; the surface of the second electrode 132 facing away from the absorption layer 12 may be provided with a second conductive structure 142; the second conductive structure 142 may be electrically connected to the ground lead 22. This embodiment does not limit the specific type of the first conductive structure 141, as long as the first conductive structure 141 can be conductive, for example, the first conductive structure 141 may be an indium column. This embodiment does not limit the specific type of the second conductive structure 142, as long as the second conductive structure 142 can be conductive, for example, the second conductive structure 142 may be an indium column.
[0072] Furthermore, in order to improve the performance of the infrared detector, the pixel structure in this embodiment may also include a passivation layer; the passivation layer may be arranged on the surface of the absorption layer 12; the passivation layer may be provided with a first contact hole and a second contact hole; the first contact hole may correspond to the first doped region and at least penetrate the passivation layer along the thickness direction of the passivation layer; the second contact hole may correspond to the second doped region and at least penetrate the passivation layer along the thickness direction of the passivation layer. This embodiment does not limit the specific type of the passivation layer, as long as the passivation layer can be insulated, for example, the passivation layer may include a CdTe layer and a ZnS layer arranged in sequence along the thickness direction of the passivation layer.
[0073] Furthermore, in order to improve the reliability of the interconnection between the readout circuit 2 and the detector, epoxy resin glue may be filled between the readout circuit 2 and the detector in this embodiment.
[0074] Furthermore, in order to effectively isolate the first doped region from the second doped region, in this embodiment, the surface of the absorption layer 12 may be provided with a first step and a second step; the surface of the first step may be provided with a first doped region; the surface of the second step may be provided with a second doped region.
[0075] Based on the above embodiments, the present application leads the electrodes on the periphery of the detector to a single pixel structure by adding an additional ground lead to the readout circuit, and by changing the interconnection between the single pixel structure and the readout circuit, the single pixel structure forms a separate closed-loop lead-out structure, thereby achieving complete isolation of the single pixel structure, and specifically achieving the following beneficial effects:
[0076] (1) The stress mismatch caused by the difference in thermal expansion coefficient between the infrared material and the readout circuit is fully eliminated, thereby improving the performance of the detector, especially in the long-wave band, which is more sensitive to stress changes. It is foreseeable that the larger the array size, the greater the performance advantage it brings.
[0077] (2) The photoelectric NP junction realizes a closed loop of a single pixel structure. The pixel structure of the other polarity is supplied through the ground lead on the readout circuit, and the parasitic impedance is low, which avoids the response inconsistency caused by the inconsistent series resistance of the central pixel structure and the edge pixel structure when the two polarity pixel structures share the same absorption layer in an ultra-large-scale array;
[0078] (3) Completely independent pixel structure, eliminating the crosstalk between pixels caused by the shared absorption layer of two polar pixel structures in an ultra-large array;
[0079] (4) It avoids the etching damage and array scale incompleteness introduced by the method of slotting and dividing the detector.
[0080] Please refer to Fig. 9 , Fig. 9 A flowchart of a method for preparing an infrared detector provided in an embodiment of the present application, the method may include:
[0081] S101: Arrange lead pads and ground leads on the surface of the readout circuit.
[0082] This embodiment does not limit the specific method of setting the lead pad and the ground lead, as long as the lead pad and the ground lead can be formed on the surface of the readout circuit, for example, the following method can be used:
[0083] Coating a first mask layer on the surface of the readout circuit, and photolithographically forming a patterned first mask layer;
[0084] After forming a patterned first mask layer, depositing a first conductive layer on the surface of the readout circuit;
[0085] After forming the first conductive layer, the first mask layer is removed, and lead pads and ground leads are formed on the surface of the readout circuit; the lead pads and ground leads are alternately arranged along the first direction, and the ground leads extend along the second direction.
[0086] It should be noted that, in this embodiment, the lead pads and the ground leads correspond to the pattern of the first mask layer, and photolithography can be performed according to the arrangement of the lead pads and the ground leads to form a patterned first mask layer.
[0087] The present embodiment does not limit the specific type of the first conductive layer, as long as the first conductive layer can conduct electricity. For example, the first conductive layer can be a composite metal layer. The present embodiment does not limit the specific type of the composite metal. For example, the composite metal layer can include a Cr layer, a Pt layer and an Au layer arranged in sequence along the thickness direction of the readout circuit, or a Ti layer, a Pb layer and an Au layer arranged in sequence along the thickness direction of the readout circuit. The present embodiment does not limit the specific deposition equipment used to deposit the first conductive layer. The specific deposition equipment used can be determined according to the specific type of the first conductive layer. For example, when the first conductive layer is a composite metal layer, an ion beam deposition device can be used to deposit the composite metal layer on the surface of the readout circuit. This embodiment does not limit the specific method of depositing the first conductive layer. The specific method of depositing the first conductive layer may be determined according to the specific type of the first conductive layer. For example, when the first conductive layer includes a Cr layer, a Pt layer and an Au layer sequentially arranged along the thickness direction of the readout circuit, the Cr layer, the Pt layer and the Au layer may be sequentially deposited on the surface of the readout circuit along the thickness direction of the readout circuit; when the first conductive layer includes a Ti layer, a Pb layer and an Au layer sequentially arranged along the thickness direction of the readout circuit, the Ti layer, the Pb layer and the Au layer may be sequentially deposited on the surface of the readout circuit along the thickness direction of the readout circuit.
[0088] This embodiment does not limit the specific type of the first mask layer, and can be any first mask layer suitable for photolithography process, for example, the first mask layer can be photoresist. This embodiment does not limit the specific method of removing the first mask layer, and the specific method of removing the first mask layer can be determined according to the specific type of the first mask layer. For example, when the first mask layer is photoresist, the photoresist can be removed by a stripping method.
[0089] S102: etching the absorption layer to form a plurality of absorption layers arranged in an array.
[0090] This embodiment does not limit the specific method of forming the plurality of absorption layers arranged in an array, and may be, but is not limited to, the following methods:
[0091] epitaxially growing an absorption layer on a substrate;
[0092] Etching the absorption layer to form a plurality of absorption layers arranged in an array;
[0093] Accordingly, after the readout circuit and the detector are interconnected, the first electrode and the lead pad are electrically connected, and the second electrode and the ground lead are electrically connected, the method may further include:
[0094] Remove the substrate.
[0095] It should be noted that, in this embodiment, when etching the absorption layer, the absorption layer will be completely penetrated along the thickness direction of the absorption layer to ensure that the formed absorption layers are independent of each other. Among them, the shape of each absorption layer after etching is a table structure.
[0096] This embodiment does not limit the specific method of epitaxially growing the absorption layer, as long as it is possible to form the absorption layer on the substrate surface. For example, the absorption layer can be epitaxially grown on the substrate by liquid phase epitaxy or molecular beam epitaxy.
[0097] This embodiment does not limit the specific method of removing the substrate, as long as the substrate can be completely removed, for example, the following method can be used:
[0098] Protect the lead pads of the readout circuit with photoresist;
[0099] Remove the substrate of preset thickness by single-point lathe equipment or mechanical polishing equipment;
[0100] The remaining substrate is etched clean by wet etching.
[0101] It should be noted that at this time, the pixel structure will become an independent individual, completely avoiding stress and crosstalk between pixels.
[0102] Furthermore, in order to improve the reliability of the interconnection between the readout circuit and the detector, before removing the substrate, the present embodiment may further include:
[0103] Fill the space between the readout circuit and the detector with epoxy glue.
[0104] S103: Disposing a first doping region and a second doping region on the surface of the absorption layer.
[0105] Further, in order to effectively isolate the first doping region from the second doping region, step S103 in this embodiment may include:
[0106] Etching the absorption layer to form a first step and a second step on the surface of the absorption layer;
[0107] Disposing a first doped region on the surface of the first step;
[0108] A second doping region is disposed on the surface of the second step.
[0109] This embodiment does not limit the specific method of setting the first doping region, as long as it is ensured that the first doping region can be formed on the surface of the first step, for example, impurities can be doped into the first step by ion implantation or molecular beam epitaxy (MBE) to form the first doping region on the surface of the first step. This embodiment does not limit the specific method of setting the second doping region, as long as it is ensured that the second doping region can be formed on the surface of the second step, for example, impurities can be doped into the second step by liquid phase epitaxy or molecular beam epitaxy to form the second doping region on the surface of the second step.
[0110] Furthermore, in order to improve the performance of the infrared detector, this embodiment may further include, after step S103:
[0111] Depositing a passivation layer on the surface of the absorption layer having the first doping region and the second doping region;
[0112] The passivation layer is etched to form a first contact hole and a second contact hole; the first contact hole corresponds to the first doped region and at least penetrates the passivation layer along the thickness direction of the passivation layer; the second contact hole corresponds to the second doped region and at least penetrates the passivation layer along the thickness direction of the passivation layer.
[0113] S104: Disposing a first electrode on the surface of the first doping region, and disposing a second electrode on the surface of the second doping region to form a pixel structure, thereby obtaining a detector.
[0114] This embodiment does not limit the specific method of setting the first electrode and the second electrode, as long as it is ensured that the first electrode can be formed on the surface of the first doping region and the second electrode can be formed on the surface of the second doping region, for example, the following method can be used:
[0115] Depositing a second conductive layer on the surface of the absorption layer having the first doping region and the second doping region formed therein;
[0116] The second conductive layer is etched to form a first electrode on the surface of the first doping region, and a second electrode on the surface of the second doping region.
[0117] This embodiment does not limit the specific type of the second conductive layer, as long as the second conductive layer can conduct electricity, for example, the second conductive layer can be a metal layer. Accordingly, the formed first electrode can be a metal electrode, and the second electrode can be a metal electrode.
[0118] S105: interconnecting the readout circuit and the detector, electrically connecting the first electrode to the lead pad, and electrically connecting the second electrode to the ground lead, to obtain an infrared detector.
[0119] Further, in order to facilitate the interconnection between the readout circuit and the detector, step S105 in this embodiment may include:
[0120] A first conductive structure is disposed on a surface of the first electrode facing away from the absorption layer, and a second conductive structure is disposed on a surface of the second electrode facing away from the absorption layer;
[0121] The readout circuit and the detector are flip-chip interconnected, the first conductive structure and the lead pad are electrically connected, and the second conductive structure and the ground lead are electrically connected to obtain an infrared detector.
[0122] This embodiment does not limit the specific manner of setting the first conductive structure and the second conductive structure, as long as the first conductive structure can be formed on the surface of the first electrode away from the absorption layer, and the second conductive structure can be formed on the surface of the second electrode away from the absorption layer, for example, the following manner can be adopted:
[0123] Coating a second mask layer on the surface of the absorption layer having the first electrode and the second electrode, and photolithographically forming a patterned second mask layer;
[0124] After forming a patterned second mask layer, a third conductive layer is deposited on the surface of the absorption layer;
[0125] After forming the third conductive layer, the second mask layer is removed, a first conductive structure is formed on a surface of the first electrode away from the absorption layer, and a second conductive structure is formed on a surface of the second electrode away from the absorption layer.
[0126] It should be noted that, in this embodiment, the first conductive structure and the second conductive structure correspond to the pattern of the second mask layer, and photolithography can be performed according to the arrangement of the first conductive structure and the second conductive structure (i.e., the arrangement of the first electrode and the second electrode) to form a patterned second mask layer.
[0127] This embodiment does not limit the specific type of the third conductive layer, as long as the third conductive layer can conduct electricity, for example, the third conductive layer can be an indium layer. Accordingly, the first conductive structure formed can be an indium column, and the second conductive structure can be an indium column.
[0128] This embodiment does not limit the specific type of the second mask layer, and can be any second mask layer suitable for photolithography process, for example, the second mask layer can be photoresist. This embodiment does not limit the specific method of removing the second mask layer, and the specific method of removing the second mask layer can be determined according to the specific type of the second mask layer. For example, when the second mask layer is photoresist, the photoresist can be removed by a stripping method.
[0129] Based on the above embodiments, the present application can prepare the above infrared detector through this method, so it also has the above beneficial effects.
[0130] The following is a specific example to illustrate the infrared detector preparation process. Please refer to Figures 8 to 17 Different from the conventional manufacturing process in the industry, this embodiment cancels the process of manufacturing indium pillars at the readout circuit end, and instead performs surface wiring at the readout circuit 2 end, prepares indium pillars for interconnection at the detector end, and thins after interconnection. The specific process is as follows:
[0131] 1. Processing interconnection base metal on the readout circuit 2 and preparing ground lead 22 between lead pads 21; the specific method is: coating photoresist on the surface of the readout circuit 2 and photolithography such as Figure 8The figure shown in the figure is formed by depositing a composite metal layer by ion beam deposition or other equipment; the photoresist is removed by a stripping method, and a contact metal truncated cone is prepared on the readout circuit 2 as a lead pad 21, and a metal wire is used as a ground lead 22;
[0132] 2. Detector end processing: Figure 1 The conventional structure shown is different, such as Fig.13 and Fig.16 As shown, in this embodiment, each pixel structure at the detector end has an independent grounding structure; the processing flow of the detector end is as follows:
[0133] (1) If Fig.10 As shown, a (CdMercuryCdTe) absorption layer 12 is epitaxially grown on a (CdZnTe) substrate 11, and the growth method is not limited to liquid phase epitaxy or molecular beam epitaxy;
[0134] (2) If Fig.11 As shown, the absorption layer 12 is etched for the first time to form a plurality of absorption layers 12 arranged in an array; wherein the absorption layer 12 is in a mesa structure;
[0135] (3) If Fig.12 As shown, the absorption layer 12 is etched for the second time, and after the first step and the second step are formed on the surface of the absorption layer 12, a first doping region (an N-type region in this embodiment) is arranged on the surface of the first step, and a second doping region (a P-type region in this embodiment) is arranged on the surface of the second step, and a passivation process is performed on the surface of the absorption layer 12;
[0136] (4) If Fig.13 As shown, the passivation layer is etched to form a first contact hole and a second contact hole;
[0137] (5) Fig.14 As shown, metal is deposited on the surface of the passivation layer, and a metal etching process is performed to form a first electrode 131 and a second electrode 132;
[0138] (6) If Fig.15 As shown, a first conductive structure 141 and a second conductive structure 142 for flip-chip interconnection at the detector end are formed by photolithography, indium deposition, and lift-off processes.
[0139] 3. If Fig.17 As shown, the readout circuit 2 end and the detector end are flip-chip interconnected; the first doped region is connected to the lead pad 21 of the readout circuit 2, and the second doped region is connected to the ground lead 22 on the circuit;
[0140] 4. Thinning process: You can choose to fill the bottom with epoxy resin glue, or you can choose not to fill the bottom. After interconnection, the detector chip substrate 11 is thinned, and the substrate 11 is removed by single-point lathe, mechanical polishing and other equipment. After removing to a certain thickness, the remaining substrate 11 is etched clean by wet etching, and finally the following is obtained: Figure 7 Infrared detector shown.
[0141] Specific examples are used herein to illustrate the principles and implementation methods of the present application, and the embodiments are in a progressive relationship, each embodiment focuses on the differences from other embodiments, and the same and similar parts between the embodiments can be referred to each other. The description of the above embodiments is only used to help understand the method and core ideas of the present application. For ordinary technicians in this technical field, without departing from the principles of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the scope of protection of the claims of the present application.
[0142] It should also be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or equipment including the elements.
Claims
1. An infrared detector, characterized in that: include: detector and readout circuitry; The detector comprises a plurality of pixel structures arranged in an array; the pixel structure comprises an absorption layer, a first electrode and a second electrode; a first doping region and a second doping region are arranged on the surface of the absorption layer; the first electrode is arranged on the surface of the first doping region; and the second electrode is arranged on the surface of the second doping region; A lead pad and a ground lead are provided on the surface of the readout circuit; the first electrode is electrically connected to the lead pad; and the second electrode is electrically connected to the ground lead.
2. The infrared detector method according to claim 1, characterized in that: The lead pads and the ground leads are alternately arranged along a first direction, and the ground leads extend along a second direction.
3. The infrared detector method according to claim 1, characterized in that: A first conductive structure is disposed on a surface of the first electrode facing away from the absorption layer; the first conductive structure is electrically connected to the lead pad; A second conductive structure is disposed on a surface of the second electrode facing away from the absorption layer; The second conductive structure is electrically connected to the ground lead.
4. The infrared detector method according to claim 1, characterized in that: The pixel structure further includes a passivation layer; the passivation layer is arranged on the surface of the absorption layer; The passivation layer is provided with a first contact hole and a second contact hole; the first contact hole corresponds to the first doped region and at least penetrates the passivation layer along the thickness direction of the passivation layer; The second contact hole corresponds to the second doping region and at least penetrates the passivation layer along a thickness direction of the passivation layer.
5. The infrared detector method according to any one of claims 1 to 4, characterized in that: The surface of the absorption layer is provided with a first step and a second step; the surface of the first step is provided with the first doping region; the surface of the second step is provided with the second doping region.
6. A method for preparing an infrared detector, characterized in that: include: A lead pad and a ground lead are arranged on the surface of the readout circuit; Etching the absorption layer to form a plurality of absorption layers arranged in an array; Disposing a first doping region and a second doping region on the surface of the absorption layer; The first electrode is arranged on the surface of the first doping region, and the second electrode is arranged on the surface of the second doping region to form the pixel structure and obtain a detector; The readout circuit and the detector are interconnected, the first electrode and the lead pad are electrically connected, and the second electrode and the ground lead are electrically connected to obtain an infrared detector.
7. The method for preparing an infrared detector according to claim 6, characterized in that: The method of providing a lead pad and a ground lead on the surface of the readout circuit comprises: Coating a first mask layer on the surface of the readout circuit, and photolithographically forming a patterned first mask layer; After forming the patterned first mask layer, depositing a first conductive layer on the surface of the readout circuit; After forming the first conductive layer, the first mask layer is removed, and the lead pads and the ground leads are formed on the surface of the readout circuit; the lead pads and the ground leads are alternately arranged along a first direction, and the ground leads extend along a second direction.
8. The method for preparing an infrared detector according to claim 6, characterized in that: The readout circuit and the detector are interconnected, the first electrode and the lead pad are electrically connected, and the second electrode and the ground lead are electrically connected to obtain an infrared detector, comprising: A first conductive structure is disposed on a surface of the first electrode facing away from the absorption layer, and a second conductive structure is disposed on a surface of the second electrode facing away from the absorption layer; The readout circuit and the detector are flip-chip interconnected, the first conductive structure and the lead pad are electrically connected, and the second conductive structure and the ground lead are electrically connected, so as to obtain the infrared detector.
9. The method for preparing an infrared detector according to claim 6, characterized in that: After the first doping region and the second doping region are arranged on the surface of the absorption layer, the method further includes: Depositing a passivation layer on the surface of the absorption layer where the first doping region and the second doping region are formed; The passivation layer is etched to form a first contact hole and a second contact hole; the first contact hole corresponds to the first doped region and at least penetrates the passivation layer along the thickness direction of the passivation layer; the second contact hole corresponds to the second doped region and at least penetrates the passivation layer along the thickness direction of the passivation layer.
10. The method for preparing an infrared detector according to claim 6, characterized in that: The step of etching the absorption layer to form a plurality of absorption layers arranged in an array comprises: epitaxially growing the absorption layer on a substrate; Etching the absorption layer to form a plurality of absorption layers arranged in an array; Correspondingly, after the readout circuit and the detector are interconnected, the first electrode and the lead pad are electrically connected, and the second electrode and the ground lead are electrically connected, the method further includes: The substrate is removed.
11. The method for preparing an infrared detector according to any one of claims 6 to 10, characterized in that: The step of providing a first doping region and a second doping region on the surface of the absorption layer comprises: Etching the absorption layer to form a first step and a second step on the surface of the absorption layer; Disposing the first doping region on the surface of the first step; The second doping region is disposed on the surface of the second step.