Infrared detector and preparation method thereof

Abstract

The present disclosure provides an infrared detector and a preparation method thereof, the preparation method comprising: S1, providing a substrate, growing an epitaxial layer on the substrate; S2, etching the epitaxial layer by a dry etching process to form a detector table; S3, corroding the surface of the detector table according to the structure obtained in step S2; S4, sulfurizing the surface of the detector table after the corrosion treatment to form a first passivation layer on the surface of the detector table, and then depositing a dielectric film on the surface of the detector table after the sulfurization treatment to form a second passivation layer; S5, opening the first passivation layer and the second passivation layer to expose the surface of the detector table, and forming a first electrode and a second electrode on the surface of the detector table; S6, providing a readout circuit, connecting the first electrode and the second electrode to the readout circuit. The present disclosure can suppress the leakage of the surface of the infrared detector table and improve the overall passivation effect of the table, thereby effectively improving the reliability and stability of the infrared detector.

Description

Technical Field

[0001] The present disclosure relates to the field of semiconductor technology, and in particular to an infrared detector and a method for preparing the same. Background Art

[0002] Infrared detectors can be widely used in aerospace, infrared guidance and early warning, remote sensing, environmental protection, biomedicine and other fields. High-performance infrared detectors are developing towards larger array scales, smaller pixel sizes, higher operating temperatures, and multi-color applications. Among them, antimonide infrared photodetectors based on InAs / GaSb type II superlattices have the characteristics of fast response speed, low dark current, and high quantum efficiency. They play a key role in space infrared systems such as ballistic missile defense, infrared tracking and guidance. At present, a large number of institutions at home and abroad have invested a lot of resources in research in this field and have made great progress.

[0003] InAs / GaSb type II superlattice infrared detector chips usually adopt a table-type device structure, which has the following main problems: sidewall etching damage will occur during the table dry etching process, resulting in a large number of surface states, causing sidewall leakage current, resulting in poor reliability and stability of the infrared detector. Summary of the invention

[0004] In view of the defects of the prior art, the purpose of the present invention is to provide an infrared detector and a method for preparing the same, which can suppress the surface leakage of the infrared detector table and improve the overall passivation effect of the table by adopting corrosion treatment and a composite passivation layer structure, thereby effectively improving the reliability and stability of the infrared detector.

[0005] In order to achieve the above-mentioned objectives, on the one hand, the present disclosure provides a method for preparing an infrared detector, the preparation method comprising: S1, providing a substrate, and growing an epitaxial layer on the substrate; S2, etching the epitaxial layer by a dry etching process to form a detector mesa; S3, corroding the surface of the detector mesa according to the structure obtained in step S2; S4, sulfiding the surface of the detector mesa after the corrosion treatment to form a first passivation layer on the surface of the detector mesa, and then depositing a dielectric film on the surface of the detector mesa after the sulfidation treatment to form a second passivation layer; S5, opening the first passivation layer and the second passivation layer to expose the surface of the detector mesa, and forming a first electrode and a second electrode on the surface of the detector mesa; S6, providing a readout circuit, and connecting the first electrode and the second electrode to the readout circuit.

[0006] In one embodiment, the surface of the detector mesa includes a top surface, a side surface and a bottom surface of the mesa. The specific method of step S5 is: etching the first passivation layer and the second passivation layer covering the bottom surface of the mesa to leave a first electrode opening, etching the first passivation layer and the second passivation layer covering the top surface of the mesa to leave a second electrode opening; forming the first electrode on the surface of the detector mesa by a metal deposition process, the first electrode including a first part, a second part and a third part, so that at least part of the first part is formed in the first electrode opening, the second part is connected to the first part and extended to form on the second passivation layer covering the side surface of the mesa, and the third part is connected to the second part and extended to form on the second passivation layer covering the top surface of the mesa; and forming the second electrode in the second electrode opening by a metal deposition process.

[0007] In one embodiment, a specific method of step S6 is: connecting the third portion of the first electrode and the second electrode to the readout circuit.

[0008] In one embodiment, the epitaxial layer includes a first superlattice contact layer, a superlattice absorption layer, and a second superlattice contact layer that are sequentially grown on the substrate.

[0009] In one embodiment, the specific method of step S3 is: placing the structure obtained in step S2 into a phosphocitric acid aqueous solution for corrosion treatment, setting the corrosion temperature to less than 50° C. and the corrosion time to no more than 5 minutes.

[0010] In one embodiment, the specific method of step S4 is: placing the structure obtained in step S2 after corrosion treatment into a sodium sulfide / ethylene glycol solution for sulfidation treatment to form a first passivation layer, and then low-temperature depositing a silicon oxide or silicon nitride dielectric film on the structure after sulfidation treatment to form a second passivation layer, and the deposition temperature for depositing the second passivation layer is less than 250°C.

[0011] In one embodiment, the first superlattice contact layer is an N-type superlattice contact layer, and the second superlattice contact layer is a P-type superlattice contact layer; the first electrode is formed on the first superlattice contact layer, and the second electrode is formed on the second superlattice contact layer.

[0012] In order to achieve the above-mentioned purpose, on the other hand, the present disclosure provides an infrared detector, which is prepared using the above-mentioned method for preparing the infrared detector, and the infrared detector includes a substrate, an epitaxial layer, a first passivation layer, a second passivation layer, a first electrode, a second electrode, and a readout circuit. The epitaxial layer is arranged on the substrate, and the epitaxial layer is configured to be etched to form a detector mesa; the first passivation layer is arranged on the surface of the detector mesa; the second passivation layer is arranged on the first passivation layer; the first electrode and the second electrode are arranged on the surface of the detector mesa, and the first electrode and the second electrode are connected to the readout circuit.

[0013] In one embodiment, the surface of the detector table includes a table top, a table side and a table bottom. A first electrode opening is provided on the first passivation layer and the second passivation layer covering the table bottom, and a second electrode opening is provided on the first passivation layer and the second passivation layer covering the table top; the first electrode includes a first part, a second part and a third part; at least part of the first part is located in the first electrode opening, the second part is connected to the first part and extended to form on the second passivation layer covering the table side, the third part is connected to the second part and extended to form on the second passivation layer covering the table top, and the third part is connected to the readout circuit; the second electrode is located in the second electrode opening.

[0014] In one embodiment, the first passivation layer is a sulfide passivation layer, and the second passivation layer is a silicon oxide passivation layer or a silicon nitride passivation layer.

[0015] The beneficial effects of the present disclosure are as follows:

[0016] On the one hand, in the preparation method of the infrared detector according to the present disclosure, after the epitaxial layer is etched by a dry etching process to form a detector table, the surface of the detector table is sequentially subjected to corrosion treatment, sulfurization treatment to form a first passivation layer, and treatment to form a second passivation layer on the first passivation layer. The surface damage and oxide impurities caused by the dry etching of the detector table are removed by corrosion treatment, and the surface leakage of the device table is suppressed. Then, a composite passivation layer structure is formed by the first passivation layer and the second passivation layer to achieve stable passivation of the detector table, thereby improving the passivation quality of the infrared detector and effectively suppressing the leakage current on the surface of the detector table. Therefore, the corrosion treatment and the composite passivation layer structure can suppress the surface leakage of the infrared detector table and improve the overall passivation effect of the table, thereby effectively improving the reliability and stability of the infrared detector.

[0017] On the other hand, in the infrared detector according to the present disclosure, a first passivation layer and a second passivation layer are sequentially arranged on the surface of the detector table. The first passivation layer and the second passivation layer constitute a composite passivation layer structure to achieve stable passivation of the detector table, improve the passivation quality of the infrared detector, and effectively suppress the leakage current on the surface of the detector table. Therefore, the composite passivation layer structure can suppress the leakage current on the surface of the infrared detector table and improve the overall passivation effect of the table, thereby effectively improving the reliability and stability of the infrared detector. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a cross-sectional schematic diagram of an infrared detector according to the present disclosure.

[0019] FIG. 2A to FIG. 2F The present invention is a schematic diagram of a process for preparing an infrared detector according to the method for preparing an infrared detector disclosed in the present invention.

[0020] The reference numerals are described as follows:

[0021] 1 substrate 52 second part

[0022] 2 Epitaxial Layer 53 Part III

[0023] 21 first superlattice contact layer 6 second electrode

[0024] 22 Superlattice absorption layer 7 Readout circuit

[0025] 23 Second superlattice contact layer M detector table

[0026] 3 The first passivation layer M1 top surface

[0027] 4 Side of the second passivation layer M2 table

[0028] 5 Bottom surface of the first electrode M3 table

[0029] 51 first part P1 first electrode opening

[0030] P2 second electrode opening DETAILED DESCRIPTION

[0031] The accompanying drawings show embodiments of the present disclosure, and it will be understood that the disclosed embodiments are merely examples of the present disclosure, and the present disclosure can be implemented in various forms. Therefore, the specific details disclosed herein should not be interpreted as limiting, but merely as the basis for the claims and as a representative basis for teaching ordinary technicians in the field to implement the present disclosure in various ways.

[0032] In order to make the purpose, technical solutions and advantages of the embodiments of the present disclosure clearer, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, rather than all of the embodiments.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by technicians in the technical field of the present disclosure; the terms used in the specification of the application herein are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure; the terms "including" and "having" in the specification and claims of the present disclosure and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions. In the description of the present disclosure, unless otherwise clearly specified and limited, the terms "first", "second", "third", etc. in the specification and claims of the present disclosure or the above-mentioned figures are used to distinguish different objects, rather than to describe a specific order or a primary and secondary relationship, and cannot be understood as indicating or implying relative importance. The terms "connected" and "connected" should be understood in a broad sense, for example, "connected" can be a fixed connection, a detachable connection, an integral connection, an electrical connection, or a signal connection; "connected" can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present disclosure can be understood according to specific circumstances.

[0034] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present disclosure. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0035] The term "and / or" in this article is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0036] The term “plurality” appearing in the present disclosure means two or more (including two).

[0037] The infrared detector and the method for preparing the infrared detector according to the present disclosure are described in detail below with reference to the accompanying drawings.

[0038] Reference Figure 1-2FAccording to the present disclosure, the infrared detector includes a substrate 1, an epitaxial layer 2, a first passivation layer 3, a second passivation layer 4, a first electrode 5, a second electrode 6, and a readout circuit 7. The epitaxial layer 2 is disposed on the substrate 1, and the epitaxial layer 2 is configured to be etched to form a detector mesa M. The first passivation layer 3 is disposed on the surface of the detector mesa M, and the second passivation layer 4 is disposed on the first passivation layer 3. The first electrode 5 and the second electrode 6 are disposed on the surface of the detector mesa M, and the first electrode 5 and the second electrode 6 are connected to the readout circuit 7.

[0039] In the infrared detector according to the present disclosure, a first passivation layer 3 and a second passivation layer 4 are sequentially arranged on the surface of the detector table M. The first passivation layer 3 and the second passivation layer 4 constitute a composite passivation layer structure to achieve stable passivation of the detector table M, improve the passivation quality of the infrared detector, and effectively suppress the leakage current on the surface of the detector table M. Therefore, the composite passivation layer structure can suppress the leakage current on the surface of the infrared detector table and improve the overall passivation effect of the table, thereby effectively improving the reliability and stability of the infrared detector.

[0040] Reference Figure 1-2F In the illustrated example, specifically, the surface of the detector table M includes a table top surface M1 , a table side surface M2 , and a table bottom surface M3 .

[0041] like Figure 1 As shown, in some embodiments, a first electrode opening P1 is provided on the first passivation layer 3 and the second passivation layer 4 covering the mesa bottom surface M3, and a second electrode opening P2 is provided on the first passivation layer 3 and the second passivation layer 4 covering the mesa top surface M1. The first electrode opening P1 is provided to expose the mesa bottom surface M3, and the first electrode 5 is provided on the surface of the detector mesa M through the first electrode opening P1; the second electrode opening P2 is provided to expose the mesa top surface M1, and the second electrode 6 is provided on the surface of the detector mesa M through the second electrode opening P2.

[0042] Reference Figure 1In the example of , the first electrode 5 includes a first part 51, a second part 52 and a third part 53. At least a part of the first part 51 is located in the first electrode opening P1, the second part 52 is connected to the first part 51 and is extended to form on the second passivation layer 4 covering the side surface M2 of the table, the third part 53 is connected to the second part 52 and is extended to form on the second passivation layer 4 covering the top surface M1 of the table, and the third part 53 is connected to the readout circuit 7. The second electrode 6 is located in the second electrode opening P2. Usually, the upper electrode and the lower electrode of the table-type infrared detector are respectively located on the top surface and the bottom surface of the detector table, which will cause a step difference between the upper electrode and the lower electrode, and there is a problem that the upper electrode and the lower electrode cannot be turned on at the same time in the process of connecting the upper electrode and the lower electrode to the readout circuit respectively. In the infrared detector disclosed in the present invention, at least a portion of the first portion 51 of the first electrode 5 is formed on the bottom surface M3 of the mesa through the first electrode opening P1, and the first electrode 5 extends to the second passivation layer 4 covering the top surface M1 of the mesa through the second portion 52 and the third portion 53 in sequence, and the second electrode 6 is located on the top surface M1 of the mesa, so that the third portion 53 of the first electrode 5 and the second electrode 6 connected to the readout circuit 7 are both on the top surface M1 of the mesa. Since the third portion 53 of the first electrode 5 and the second electrode 6 are respectively interconnected with the readout circuit 7, the interconnection process step difference is reduced through the coplanar structure of the first electrode 5 and the second electrode 6, so as to ensure the conductive effect of the flip-chip interconnection with the readout circuit 7, and improve the mechanical and electrical properties of the interconnection between the first electrode 5 and the second electrode 6 and the readout circuit 7, thereby improving the reliability of the interconnection between the first electrode 5 and the second electrode 6 and the readout circuit 7.

[0043] like Figure 1 As shown, in some embodiments, a portion of the first portion 51 of the first electrode 5 is formed in the first electrode opening P1, and another portion of the first portion 51 of the first electrode 5 is extended and formed on the second passivation layer 4 covering the mesa bottom surface M3. Of course, in other embodiments, the first portion 51 of the first electrode 5 may also be entirely formed in the first electrode opening P1.

[0044] Reference Figure 1-2F In the example shown, the epitaxial layer 2 may include a first superlattice contact layer 21, a superlattice absorption layer 22, and a second superlattice contact layer 23 that are sequentially grown on the substrate 1. The first superlattice contact layer 21 may have a thickness of 100-500 nm and a doping concentration greater than 5×10 17 / cm 3 The thickness of the superlattice absorption layer 22 may be 1-4 μm. The thickness of the second superlattice contact layer 23 may be 100-500 nm, and the doping concentration may be greater than 5×10 17 / cm 3 The substrate 1 may be an N-type substrate, such as an N-type GaSb substrate, but is not limited thereto. Figures 1 to 2FIn the example shown, the first superlattice contact layer 21 of the epitaxial layer 2 is an N-type superlattice contact layer, and the second superlattice contact layer 23 is a P-type superlattice contact layer. For example, the first superlattice contact layer 21 may be an Si-doped InAs / InSb N-type superlattice contact layer, and the doping concentration may be 5×10 18 / cm 3 The superlattice absorption layer 22 can be an undoped InAs / GaSb superlattice absorption layer, and the second superlattice contact layer 23 can be a Be-doped InAs / GaSb P-type superlattice contact layer, and the doping concentration can be 5×10 18 / cm 3 In other embodiments, the first superlattice contact layer 21 may be a P-type superlattice contact layer, and the second superlattice contact layer 23 may be an N-type superlattice contact layer.

[0045] like Figure 1 As shown, in some embodiments, the first electrode 5 and the second electrode 6 are both formed on the epitaxial layer 2. Specifically, the first electrode 5 is formed on the first superlattice contact layer 21, and the second electrode 6 is formed on the second superlattice contact layer 23. The first superlattice contact layer 21 is an N-type superlattice contact layer, and the second superlattice contact layer 23 is a P-type superlattice contact layer. Figure 1 In the embodiment, the first portion 51 of the first electrode 5 is formed on the first superlattice contact layer 21 through the first electrode opening P1, and the first electrode 5 is connected to the readout circuit 7 through the third portion 53, and the second electrode 6 is formed on the second superlattice contact layer 23 through the second electrode opening P2 and connected to the readout circuit 7, thereby improving the conductive effect of the first electrode 5 and the second electrode 6 being interconnected with the readout circuit 7, respectively, and avoiding the influence of the step difference formed by the mesa on the interconnection effect. In addition, in other embodiments, the first electrode 5 can be formed on the substrate 1, and the second electrode 6 can be formed on the epitaxial layer 2.

[0046] In the infrared detector according to the present disclosure, the first passivation layer 3 may be a sulfide passivation layer, and the second passivation layer 4 may be a silicon oxide passivation layer or a silicon nitride passivation layer. The sulfide passivation layer can reduce the surface state of the detector table M formed by etching to suppress the leakage current on the table surface, and the silicon oxide passivation layer or the silicon nitride passivation layer can protect the sulfide passivation layer to make the passivation effect stable and lasting. The double-layer passivation layer effectively improves the passivation quality of the infrared detector and realizes efficient and stable passivation of the etched table. Among them, the thickness of the first passivation layer 3 is greater than 1nm, specifically 30nm, and the thickness of the second passivation layer 4 can be 100-300nm, but is not limited thereto.

[0047] Reference Figure 1-2FAccording to the preparation method of the infrared detector disclosed in the present invention, the method comprises: S1, providing a substrate 1, growing an epitaxial layer 2 on the substrate 1; S2, etching the epitaxial layer 2 by a dry etching process to form a detector mesa M; S3, corroding the surface of the detector mesa M according to the structure obtained in step S2; S4, sulfurizing the surface of the detector mesa M after the corrosion treatment to form a first passivation layer 3 on the surface of the detector mesa M, and then depositing a dielectric film on the surface of the detector mesa M after the sulfurization treatment to form a second passivation layer 4; S5, openings are formed in the first passivation layer 3 and the second passivation layer 4 to expose the surface of the detector mesa M, and a first electrode 5 and a second electrode 6 are formed on the surface of the detector mesa M; S6, providing a readout circuit 7, and connecting the first electrode 5 and the second electrode 6 to the readout circuit 7.

[0048] In the preparation method of the infrared detector according to the present disclosure, after the epitaxial layer 2 is etched by a dry etching process to form a detector mesa M, the surface of the detector mesa M is sequentially subjected to corrosion treatment, sulfurization treatment to form a first passivation layer 3, and a treatment to form a second passivation layer 4 on the first passivation layer 3. The surface damage and oxide impurities caused by the dry etching of the detector mesa M are removed by corrosion treatment, and the surface leakage of the device mesa is suppressed. Then, a composite passivation layer structure is formed by the first passivation layer 3 and the second passivation layer 4 to achieve stable passivation of the detector mesa M, improve the passivation quality of the infrared detector, and effectively suppress the leakage current on the surface of the detector mesa M. Therefore, the corrosion treatment and the composite passivation layer structure can suppress the surface leakage of the infrared detector mesa and improve the overall passivation effect of the mesa, thereby effectively improving the reliability and stability of the infrared detector.

[0049] Reference Figure 1 , Figure 2A and Figure 2B , the growth of the epitaxial layer 2 on the substrate 1 can be achieved by molecular beam epitaxy technology.

[0050] Reference Figure 1 and Figure 2C In some embodiments, the epitaxial layer 2 is etched to form a detector mesa M, and the mesa top surface M1 and the mesa side surface M2 of the etched detector mesa M may form a cubic shape or a cylindrical shape, and the etching depth reaches the first superlattice contact layer 21 of the epitaxial layer 2. However, it is not limited to this, and the mesa top surface M1 and the mesa side surface M2 may also form a terraced shape or a truncated cone shape. In other embodiments, the etching depth may also reach the substrate 1.

[0051] In some embodiments, the specific method of step S3 is: placing the structure obtained in step S2 into a phosphocitric acid aqueous solution for corrosion treatment, setting the corrosion temperature to less than 50° C. and the corrosion time to no more than 5 minutes. The ratio of phosphoric acid, citric acid and water in the phosphocitric acid aqueous solution can be: 1g: 1g: 2ml, but is not limited thereto.

[0052] Reference Figure 1 and Figure 2D In some embodiments, the specific method of step S4 is: placing the structure obtained in step S2 after the corrosion treatment into a sodium sulfide / ethylene glycol solution for sulfurization treatment to form a first passivation layer 3, and then depositing a silicon oxide or silicon nitride dielectric film on the structure after the sulfurization treatment at a low temperature to form a second passivation layer 4, and the deposition temperature for depositing the second passivation layer 4 is less than 250°C. The first passivation layer 3 is formed by an anodic sulfurization reaction between the etched dangling bonds on the surface of the detector mesa M and the sulfur atoms in the sodium sulfide / ethylene glycol solution to generate ultra-thin sulfides, thereby reducing the surface state of the surface of the detector mesa M. The second passivation layer 4 can protect the unstable sulfur atoms of the first passivation layer 3, and realize the efficient and stable passivation of the detector mesa M obtained by etching through a double-layer passivation layer structure.

[0053] Reference Figure 1 , Figure 2E and Figure 2FIn some embodiments, the specific method of step S5 is: etching the first passivation layer 3 and the second passivation layer 4 covering the bottom surface M3 of the mesa to leave a first electrode opening P1, etching the first passivation layer 3 and the second passivation layer 4 covering the top surface M1 of the mesa to leave a second electrode opening P2; forming a first electrode 5 on the surface of the detector mesa M by a metal deposition process, the first electrode 5 including a first part 51, a second part 52 and a third part 53, so that at least part of the first part 51 is formed in the first electrode opening P1, the second part 52 is connected to the first part 51 and extends to form on the second passivation layer 4 covering the side surface M2 of the mesa, and the third part 53 is connected to the second part 52 and extends to form on the second passivation layer 4 covering the top surface M1 of the mesa; and forming a second electrode 6 in the second electrode opening P2 by a metal deposition process. Usually, the upper electrode and the lower electrode of the table-type infrared detector are respectively located on the top and bottom surfaces of the detector table, which will cause a step difference between the upper electrode and the lower electrode, and there is a problem that the upper electrode and the lower electrode cannot be turned on at the same time during the interconnection process with the readout circuit. In the preparation method of the infrared detector according to the present disclosure, after the step S5 is processed, at least part of the first part 51 of the first electrode 5 is formed on the bottom surface M3 of the table through the first electrode opening P1, and the third part 53 of the first electrode 5 is formed on the second passivation layer 4 covering the top surface M1 of the table, so that the first electrode 5 is led from the first part located on the bottom surface M3 of the table to the third part 53. Since the third part 53 of the first electrode 5 and the second electrode 6 are both on the top surface M1 of the table, the first electrode 5 and the second electrode 6 are coplanar. The first electrode 5 and the second electrode 6 are respectively connected to the readout circuit 7 through the flip-chip interconnection process. The coplanar first electrode 5 and the second electrode 6 structure ensure the conductive effect of the flip-chip interconnection with the readout circuit 7, reduce the step difference formed by the table, and improve the interconnection reliability. The first passivation layer 3 and the second passivation layer 4 may be etched by a dry etching process to leave the first electrode opening P1 and the second electrode opening P2 .

[0054] Reference Figure 1 In some embodiments, the specific method of step S6 is: connecting the third portion 53 of the first electrode 5 and the second electrode 6 to the readout circuit 7. The third portion 53 of the first electrode 5 coplanar with the second electrode 6 and the second electrode 6 are interconnected with the readout circuit 7 to solve the interconnection step difference problem, so as to achieve a simpler and more reliable flip-chip interconnection process.

[0055] Reference Figures 1 to 2F, an embodiment of the infrared detector of the present invention is prepared according to the preparation method of the infrared detector of the present invention. The substrate 1 is an N-type GaSb substrate, the first superlattice contact layer 21 is a Si-doped InAs / InSb N-type superlattice contact layer, the superlattice absorption layer 22 is an undoped InAs / GaSb superlattice absorption layer, and the second superlattice contact layer 23 is a Be-doped InAs / GaSb P-type superlattice contact layer.

[0056] Reference Figures 1 to 2F First, an epitaxial layer 2 is grown on an N-type GaSb substrate by molecular beam epitaxy technology. The epitaxial layer 2 is made of InAs / GaSb superlattice epitaxial material. The growth method of the epitaxial layer 2 on the N-type GaSb substrate 1 is as follows: a Si-doped InAs / InSb N-type superlattice contact layer with a thickness of 300 nm is grown on the N-type GaSb substrate 1, and the doping concentration is 5×10 18 / cm 3 ; On the Si-doped InAs / InSb N-type superlattice contact layer, an undoped InAs / GaSb superlattice absorption layer with a thickness of 2 μm is grown; On the undoped InAs / GaSb superlattice absorption layer, a Be-doped InAs / GaSb P-type superlattice contact layer with a thickness of 300 nm is grown, with a doping concentration of 5×10 18 / cm 3. Secondly, the epitaxial layer 2 is etched by a dry etching process to form a detector mesa M, the etching gas is Cl2 / Ar or BCl3 / CH4 / H2 / Ar, and the etching depth reaches the first superlattice contact layer 21 of the epitaxial layer 2. Next, the etched mesa structure is placed in a phosphocitric acid aqueous solution for corrosion treatment, the corrosion temperature is less than 50°C, the corrosion time does not exceed 5min, and the ratio of phosphoric acid, citric acid and water in the phosphocitric acid aqueous solution is 1g:1g:2ml, because after dry etching, the surface of the detector mesa M may have surface dangling bonds caused by etching damage and oxide impurities generated by the reaction of the surface with air, and the corrosion treatment can effectively remove the damage and oxide impurities on the surface of the detector mesa M. Then, the mesa structure after the corrosion treatment is first placed in a sodium sulfide / ethylene glycol solution for sulfidation treatment, and a first passivation layer 3 is prepared on the surface of the detector mesa M. The first passivation layer 3 is a sulfide passivation layer, and the thickness of the first passivation layer 3 is 30nm. After the sulfurization treatment is completed, the mesa structure continues to deposit a dielectric film at a low temperature to form a second passivation layer 4, the deposition temperature is less than 250°C, the thickness of the second passivation layer 4 is 100-300nm, and the second passivation layer 4 is a silicon oxide passivation layer or a silicon nitride passivation layer. The first passivation layer 3 and the second passivation layer 4 constitute a double-layer composite passivation layer, thereby effectively improving the passivation quality of the device. After the passivation is completed, the first passivation layer 3 and the second passivation layer 4 are opened to expose the surface of the detector mesa M, and a first electrode opening P1 is opened above the bottom surface M3 of the mesa so that the first electrode opening P1 is located above the first superlattice contact layer 21, and a second electrode opening P2 is opened above the top surface M1 of the mesa so that the second electrode opening P2 is located above the second superlattice contact layer 23. The opening size of the first electrode opening P1 and the second electrode opening P2 is 6-12um. Next, the first electrode 5 and the second electrode 6 are prepared on the surface of the detector mesa M by a metal deposition process. The materials of the first electrode 5 and the second electrode 6 are Ti (50 nm) / Pt (50 nm) / Au (100 nm).The second electrode 6 is formed in the second electrode opening P2, so that the second electrode 6 is located in the second superlattice contact layer 23, so that the second superlattice contact layer 23 is connected to the second electrode 6, and the first electrode 5 is formed so that the first portion 51 of the first electrode 5 is located in the first electrode opening P1 so that the first portion 51 is located in the first superlattice contact layer 21, so that the first superlattice contact layer 21 is connected to the first electrode 5, and the second portion 52 of the first electrode 5 extends along the second passivation layer 4 covering the side surface M2 of the mesa, and the third portion 53 of the first electrode 5 The second passivation layer 4 covering the top surface M1 of the mesa is extended to lead the first electrode 5 located in the first superlattice contact layer 21 from the bottom surface M3 of the mesa to the top surface M1 of the mesa. The third part 53 of the first electrode 5 connected to the readout circuit 7 and the second electrode 6 are both located on the top surface M1 of the mesa, forming an electrode structure with a coplanar design, thereby reducing the step difference formed by the mesa, ensuring the conductive effect of the flip-chip interconnection with the readout circuit 7, and improving the mechanical and electrical properties of the interconnection between the first electrode 5 and the second electrode 6 and the readout circuit 7, thereby improving the interconnection reliability. Finally, the readout circuit 5 and the first electrode 5 and the second electrode 6 are efficiently interconnected at the same time through the flip-chip interconnection process to realize the reading of the infrared detector signal.

[0057] The above detailed description describes multiple exemplary embodiments, but this document is not intended to be limited to the explicitly disclosed combinations. Therefore, unless otherwise stated, the various features disclosed herein may be combined together to form multiple additional combinations that are not shown for the sake of simplicity.

[0058] The above description is only a preferred embodiment of the present disclosure and is not intended to limit the present disclosure. For those skilled in the art, the present disclosure may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A method for preparing an infrared detector, characterized in that: The preparation method comprises: S1, providing a substrate (1), and growing an epitaxial layer (2) on the substrate (1); S2, etching the epitaxial layer (2) by a dry etching process to form a detector mesa (M); S3, performing corrosion treatment on the surface of the detector table (M) according to the structure obtained in step S2; S4, performing a sulfurization treatment on the surface of the detector mesa (M) after the corrosion treatment to form a first passivation layer (3) on the surface of the detector mesa (M), and then depositing a dielectric film on the surface of the detector mesa (M) after the sulfurization treatment to form a second passivation layer (4); S5, openings are formed on the first passivation layer (3) and the second passivation layer (4) to expose the surface of the detector mesa (M), and a first electrode (5) and a second electrode (6) are formed on the surface of the detector mesa (M); S6, providing a readout circuit (7), and connecting the first electrode (5) and the second electrode (6) to the readout circuit (7); in, The specific method of step S3 is: placing the structure obtained in step S2 into a phosphocitric acid aqueous solution for corrosion treatment, setting the corrosion temperature to less than 50° C. and the corrosion time to no more than 5 minutes; The first passivation layer (3) is a sulfide passivation layer, and the second passivation layer (4) is a silicon oxide passivation layer or a silicon nitride passivation layer.

2. The method for preparing an infrared detector according to claim 1, characterized in that: The surface of the detector table (M) includes a table top surface (M1), a table side surface (M2) and a table bottom surface (M3). The specific method of step S5 is: The first passivation layer (3) and the second passivation layer (4) covering the bottom surface (M3) of the mesa are etched to leave a first electrode opening (P1), and the first passivation layer (3) and the second passivation layer (4) covering the top surface (M1) of the mesa are etched to leave a second electrode opening (P2); The first electrode (5) is formed on the surface of the detector mesa (M) by a metal deposition process, wherein the first electrode (5) comprises a first portion (51), a second portion (52) and a third portion (53), so that at least a portion of the first portion (51) is formed in the first electrode opening (P1), the second portion (52) is connected to the first portion (51) and is extended to form on the second passivation layer (4) covering the side surface (M2) of the mesa, and the third portion (53) is connected to the second portion (52) and is extended to form on the second passivation layer (4) covering the top surface (M1) of the mesa; And the second electrode (6) is formed in the second electrode opening (P2) by a metal deposition process.

3. The method for preparing an infrared detector according to claim 2, characterized in that: The specific method of step S6 is: connecting the third portion (53) of the first electrode (5) and the second electrode (6) to the readout circuit (7).

4. The method for preparing an infrared detector according to any one of claims 1 to 3, characterized in that: The epitaxial layer (2) comprises a first superlattice contact layer (21), a superlattice absorption layer (22) and a second superlattice contact layer (23) which are sequentially grown on the substrate (1).

5. The method for preparing an infrared detector according to claim 1, characterized in that: The specific method of step S4 is: placing the structure obtained in step S2 after the corrosion treatment into a sodium sulfide / ethylene glycol solution for sulfidation treatment to form a first passivation layer (3), and then low-temperature depositing a silicon oxide or silicon nitride dielectric film on the structure after the sulfidation treatment to form a second passivation layer (4), and the deposition temperature for depositing the second passivation layer (4) is less than 250°C.

6. The method for preparing an infrared detector according to claim 4, characterized in that: The first superlattice contact layer (21) is an N-type superlattice contact layer, and the second superlattice contact layer (23) is a P-type superlattice contact layer; The first electrode (5) is formed on the first superlattice contact layer (21), and the second electrode (6) is formed on the second superlattice contact layer (23).

7. An infrared detector, characterized in that: The infrared detector is prepared by the method for preparing the infrared detector according to any one of claims 1 to 6, wherein the infrared detector comprises a substrate (1), an epitaxial layer (2), a first passivation layer (3), a second passivation layer (4), a first electrode (5), a second electrode (6) and a readout circuit (7); The epitaxial layer (2) is arranged on the substrate (1), and the epitaxial layer (2) is configured to be etched to form a detector mesa (M); the first passivation layer (3) is arranged on the surface of the detector mesa (M); the second passivation layer (4) is arranged on the first passivation layer (3); The first electrode (5) and the second electrode (6) are arranged on the surface of the detector table (M), and the first electrode (5) and the second electrode (6) are connected to the readout circuit (7).

8. The infrared detector according to claim 7, characterized in that: The surface of the detector table (M) includes a table top surface (M1), a table side surface (M2) and a table bottom surface (M3); A first electrode opening (P1) is provided on the first passivation layer (3) and the second passivation layer (4) covering the bottom surface (M3) of the mesa, and a second electrode opening (P2) is provided on the first passivation layer (3) and the second passivation layer (4) covering the top surface (M1) of the mesa; The first electrode (5) comprises a first part (51), a second part (52) and a third part (53); at least part of the first part (51) is located in the first electrode opening (P1); the second part (52) is connected to the first part (51) and is extended to form on the second passivation layer (4) covering the side surface (M2) of the mesa; the third part (53) is connected to the second part (52) and is extended to form on the second passivation layer (4) covering the top surface (M1) of the mesa; and the third part (53) is connected to the readout circuit (7); the second electrode (6) is located in the second electrode opening (P2).

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