Infrared detector and infrared detector preparation method

Abstract

The present invention discloses an infrared detector and a method for preparing the infrared detector, which are applied to the field of optical detectors, and include: a substrate, and an absorption layer located on one side of the substrate, wherein a plurality of pixel regions arranged in an array are formed on the surface of the absorption layer on the side facing away from the substrate, and each pixel region has a pn junction formed thereon; a passivation layer is provided on the side of the absorption layer facing away from the substrate, and a lead-out electrode is provided on the passivation layer corresponding to each pn junction; an anti-reflection layer is provided on the side of the substrate facing away from the absorption layer; and a barrier region for blocking the diffusion of photogenerated carriers is formed at the edge region between the pixel regions arranged in adjacent arrays in the absorption layer. The present invention can reduce the problem of electrical crosstalk between adjacent pixel regions due to the lateral diffusion of photogenerated carriers by preparing a barrier region for blocking the diffusion of photogenerated carriers at the edge region between the pixel regions arranged in adjacent arrays in the absorption layer.

Description

Technical Field

[0001] The present invention relates to the field of optical detectors, and in particular to an infrared detector and a method for preparing the infrared detector. Background Art

[0002] Take mercury cadmium telluride infrared detector as an example. Mercury cadmium telluride infrared detector is an important material for making infrared detector. When the radiation signal acts on a certain unit to generate a response signal, a response signal will also appear on its adjacent unit. Regarding the existence of electrical crosstalk in mercury cadmium telluride devices, take the electrical crosstalk generated by the lateral diffusion of photogenerated carriers as an example. Specifically, after the incident radiation signal is converted into non-equilibrium carriers after being absorbed by the pixel, some non-equilibrium carriers will enter the adjacent pixel area through lateral diffusion, and will be received by the pn junction of the adjacent pixel to form a photocurrent output signal, forming crosstalk.

[0003] Therefore, how to solve the problem of electrical crosstalk caused by lateral diffusion of photogenerated carriers is a technical problem that technical personnel in this field need to solve urgently. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide an infrared detector and a method for preparing an infrared detector, which solves the problem in the prior art that photogenerated carriers diffuse laterally into adjacent pixel areas and are received by the pn junctions of adjacent pixels to form photocurrent output signals, thereby forming crosstalk.

[0005] In order to solve the above technical problems, the present invention provides an infrared detector, comprising:

[0006] A substrate, and an absorption layer located on one side of the substrate, wherein a surface of the absorption layer facing away from the substrate is formed with a plurality of pixel regions arranged in an array, and each of the pixel regions is correspondingly formed with a pn junction;

[0007] A passivation layer is provided on the side of the absorption layer facing away from the substrate, and a lead-out electrode is provided at each pn junction of the passivation layer;

[0008] An anti-reflection layer is provided on the side of the substrate facing away from the absorption layer;

[0009] A potential barrier region for blocking the diffusion of photogenerated carriers is formed in the edge region between adjacent array-arranged pixel regions in the absorption layer.

[0010] Optionally, the barrier region is formed on a side of the absorption layer close to the substrate, and the barrier region is formed by diffusing doping ions from the substrate into the absorption layer.

[0011] Optionally, the substrate is a substrate including cadmium zinc telluride and cadmium telluride;

[0012] The absorption layer is a mercury cadmium telluride absorption layer, and the cadmium ion concentration in the barrier region is higher than the cadmium ion concentration in other regions of the mercury cadmium telluride absorption layer.

[0013] Optionally, the anti-reflection layer is a zinc sulfide anti-reflection layer.

[0014] Optionally, the passivation layer includes a composite layer formed by stacking a cadmium telluride sub-passivation layer disposed on a side close to the mercury cadmium telluride absorption layer and a zinc sulfide sub-passivation layer disposed on a side away from the mercury cadmium telluride absorption layer.

[0015] The present invention also provides a method for preparing an infrared detector, which is used to prepare the infrared detector as described above, comprising:

[0016] A detector preform is provided, the detector preform comprising a substrate, an absorption layer prepared on one side of the substrate, and a passivation layer prepared on a side of the absorption layer facing away from the substrate; a plurality of pixel regions arranged in an array are formed on a surface of the absorption layer facing away from the substrate;

[0017] The edge area between the pixel areas arranged in adjacent arrays in the absorption layer is doped to form a barrier area that blocks the diffusion of photogenerated carriers, thereby completing the preparation of the infrared detector; an anti-reflection layer is provided on the side of the substrate facing away from the absorption layer.

[0018] Optionally, doping is performed on the edge region between adjacent array-arranged pixel regions in the absorption layer to form a barrier region that blocks the diffusion of photogenerated carriers. Before the preparation of the infrared detector is completed, the method further includes:

[0019] On the side of the substrate facing away from the absorption layer, a patterned barrier layer is prepared that only exposes a preset area of ​​the substrate; the preset area of ​​the substrate is an area of ​​the substrate corresponding to an edge area between adjacent array-arranged pixel areas;

[0020] The edge region between adjacent array-arranged pixel regions in the absorption layer is doped to form a barrier region for blocking the diffusion of photogenerated carriers, thereby completing the preparation of the infrared detector, including:

[0021] Through the patterned barrier layer, only the preset area of ​​the substrate is subjected to diffusion enhancement treatment, so that the doped ions at the preset area of ​​the substrate diffuse toward the absorption layer, and the barrier region is formed on the side of the absorption layer close to the substrate, thereby completing the preparation of the infrared detector.

[0022] Optionally, the substrate is a substrate including cadmium zinc telluride and cadmium telluride, and the absorption layer is a mercury cadmium telluride absorption layer;

[0023] The patterned barrier layer is used to perform diffusion enhancement treatment only on a preset area of ​​the substrate, so that doping ions at the preset area of ​​the substrate diffuse toward the absorption layer, and the barrier region is formed on a side of the absorption layer close to the substrate, thereby completing the preparation of the infrared detector, including:

[0024] The patterned barrier layer is used to enhance the mutual diffusion rate between the mercury ions in the mercury cadmium telluride absorption layer and the cadmium ions in the substrate by utilizing mercury pressure at high temperature, so as to form the barrier region on the side of the mercury cadmium telluride absorption layer close to the substrate, thereby completing the preparation of the infrared detector; the cadmium ion concentration in the barrier region is higher than the cadmium ion concentration in the remaining areas of the mercury cadmium telluride absorption layer.

[0025] Optionally, the patterned barrier layer is a zinc sulfide patterned barrier layer;

[0026] After the preparation of the infrared detector is completed, the patterned barrier layer is used to enhance the mutual diffusion rate of mercury ions in the mercury cadmium telluride absorption layer and cadmium ions in the substrate by mercury pressure at high temperature, so as to form the barrier region on the side of the mercury cadmium telluride absorption layer close to the substrate. The method further includes:

[0027] The zinc sulfide patterned barrier layer is removed, and a zinc sulfide anti-reflection layer is prepared on the side of the substrate facing away from the mercury cadmium telluride absorption layer.

[0028] Optionally, on a side of the substrate facing away from the absorption layer, a patterned barrier layer is prepared that only exposes a predetermined area of ​​the substrate, including:

[0029] On the side of the substrate facing away from the absorbent layer, an initial barrier layer is prepared;

[0030] The initial blocking layer is etched and removed along the edge area between the pixel areas corresponding to the adjacent array arrangement by using a dry etching process to obtain the patterned blocking layer.

[0031] It can be seen that the infrared detector provided by the present invention includes a substrate, and an absorption layer located on one side of the substrate, a plurality of pixel areas arranged in an array are formed on the surface of the absorption layer on the side facing away from the substrate, and each pixel area has a corresponding pn junction; a passivation layer is provided on the side of the absorption layer facing away from the substrate, and the passivation layer is provided with an extraction electrode corresponding to each pn junction; an anti-reflection layer is provided on the side of the substrate facing away from the absorption layer; a barrier area for blocking the diffusion of photogenerated carriers is formed at the edge area between the pixel areas arranged in adjacent arrays in the absorption layer. The present invention can reduce the problem of electrical crosstalk between adjacent pixel areas caused by the lateral diffusion of photogenerated carriers by preparing a barrier area for blocking the diffusion of photogenerated carriers at the edge area between the pixel areas arranged in adjacent arrays in the absorption layer.

[0032] In addition, the present invention also provides a method for preparing an infrared detector, which also has the above-mentioned beneficial effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention 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 invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0034] Figure 1 A schematic diagram of the structure of an infrared detector provided by an embodiment of the present invention;

[0035] Figure 2 An example diagram of the movement trend of photogenerated carriers in an existing infrared detector;

[0036] Figure 3 An exemplary diagram of the movement trend of photogenerated carriers in an infrared detector provided by an embodiment of the present invention;

[0037] Figure 4 A flowchart of a method for preparing an infrared detector provided by an embodiment of the present invention;

[0038] Figure 5 A schematic structural diagram of a mercury cadmium telluride preform provided in an embodiment of the present invention;

[0039] Figure 6 A schematic structural diagram of a mercury cadmium telluride preform after substrate thinning provided in an embodiment of the present invention;

[0040] Figure 7 A schematic structural diagram of a mercury cadmium telluride preform prepared with a zinc sulfide initial barrier layer provided in an embodiment of the present invention;

[0041] Figure 8 A schematic structural diagram of a mercury cadmium telluride (HgCdTe) workpiece to be treated provided by an embodiment of the present invention;

[0042] Fig. 9 A schematic diagram of the structure of a mercury cadmium telluride to-be-treated component observed from the bottom side according to an embodiment of the present invention;

[0043] Fig.10 A schematic diagram of the structure of a mercury cadmium telluride device with barrier region preparation provided in an embodiment of the present invention;

[0044] Fig.11 A schematic diagram of the structure of a mercury cadmium telluride device with an anti-reflection layer prepared according to an embodiment of the present invention;

[0045] Figure 1 ,as well as Figures 5 to 11 In the figure, the reference numerals are described as follows:

[0046] 1-pn junction region, 10-substrate, 11-thinned substrate, 20-absorption layer, 21-mercury cadmium telluride absorption layer, 30-pixel region, 31-edge region between adjacent pixel regions, 32-pixel center, 40-passivation layer, 41-cadmium telluride sub-passivation layer, 42-zinc sulfide sub-passivation layer, 50-export electrode, 60-anti-reflection layer, 70-barrier region, 80-zinc sulfide initial blocking layer, 81-removed portion of the zinc sulfide initial blocking layer, 82-zinc sulfide patterned blocking layer. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0048] Take mercury cadmium telluride infrared detectors as an example. Mercury cadmium telluride is an important material for making infrared detectors. Because its bandgap width is adjustable and the detection spectrum range extends from the short-wave band to the long-wave band, it has the advantage of high photoelectric detection efficiency and is widely used in military and civil fields such as early warning detection, infrared reconnaissance, and imaging guidance. The crosstalk problem in mercury cadmium telluride infrared detectors is that when the radiation signal acts on a certain pixel unit to generate a response signal, the pixel unit adjacent to the pixel unit also has a response signal.

[0049] The crosstalk of existing HgCdTe devices is generally divided into two types: optical crosstalk and electrical crosstalk. Optical crosstalk refers to the crosstalk caused by part of the radiation signal corresponding to the target pixel unit entering the pixel unit adjacent to the target pixel unit after transmission. Electrical crosstalk is divided into two types: one is that when the incident radiation signal is converted into unbalanced carriers by pixel absorption, part of the unbalanced carriers will enter the adjacent pixel unit area through lateral diffusion and be received by the pn junction of the adjacent pixel unit, forming a photocurrent output signal, that is, a crosstalk signal; the other is that in the process of pixel unit signal output, if there is surface leakage between pixel units and the series resistance of a certain pixel unit is large, part of the output signal of the pixel unit will be output to the signal output electrode of the adjacent pixel unit through the surface shunt resistance, forming crosstalk.

[0050] The present invention mainly solves the problem of crosstalk caused by lateral diffusion of photogenerated carriers in electrical crosstalk. In view of this problem, the existing common technical solutions for reducing lateral diffusion of carriers and avoiding crosstalk include the following: (1) forming an n+ layer at the edge of the pixel of the np device to capture diffused photogenerated carriers; (2) forming a gradient absorption layer with components from large to small from the infrared signal incident surface to the pn junction component to increase the longitudinal movement of photogenerated carriers; (3) increasing the width of the pn junction depletion layer to increase the probability of photogenerated carriers being captured. Although the above solution (1) reduces the problem of device crosstalk, the photogenerated carriers are captured by the n+ layer formed at the edge of the pixel and are not captured by the pn junction to form an optical signal, thereby reducing the quantum efficiency of the device. The use of solutions (2) and (3) alone cannot fundamentally solve the crosstalk problem, and the component gradient absorption layer set in solution (2) can only be obtained by molecular beam epitaxy. This process is complex and difficult to control, which limits the application of this solution. The method of increasing the depletion layer width in solution (3) usually adopts a low doping concentration preparation method, and the preparation process of low doping concentration devices is difficult, which also limits the application of this solution.

[0051] Therefore, how to solve the problem of electrical crosstalk caused by lateral diffusion of photogenerated carriers while ensuring the detection efficiency of the device and avoiding the high difficulty of device preparation affecting the application is a technical problem that technical personnel in this field urgently need to solve.

[0052] The present invention forms a barrier region for blocking the diffusion of photogenerated carriers at the edge region between adjacent array-arranged pixel regions in the absorption layer, thereby reducing the problem of electrical crosstalk between adjacent pixel regions caused by lateral diffusion of photogenerated carriers. The following embodiments may be referred to:

[0053] Please refer to Figure 1 , Figure 1 A schematic diagram of the structure of an infrared detector provided by an embodiment of the present invention. The infrared detector may include:

[0054] A substrate 10, and an absorption layer 20 located on one side of the substrate 10, wherein a plurality of pixel regions 30 arranged in an array are formed on a surface of the absorption layer 20 facing away from the substrate 10, and each pixel region 30 has a corresponding pn junction;

[0055] A passivation layer 40 is disposed on the side of the absorption layer 20 facing away from the substrate 10, and a lead-out electrode 50 is disposed at each pn junction of the passivation layer 40;

[0056] An anti-reflection layer 60 is disposed on the side of the substrate 10 facing away from the absorption layer 20;

[0057] A potential barrier region 70 for blocking the diffusion of photogenerated carriers is formed in the edge region between adjacent array-arranged pixel regions 30 in the absorption layer 20 .

[0058] It should be noted that, in this embodiment, the absorption layer 20 is generally prepared by epitaxial growth of the substrate 10, and the pn junction formed at the pixel region 30 on the surface of the absorption layer 20 facing away from the substrate 10 is generally prepared by an ion doping process and is formed by combining a P-type semiconductor material and an N-type semiconductor material, wherein the pn junction region 1 is as shown in FIG. Figure 1 As shown in . In this embodiment, a passivation layer 40 is prepared on the surface of the absorption layer 20. On the one hand, it is to reduce or eliminate dangling bonds and defects on the surface of the absorption layer 20, prevent the generation of surface states, and then reduce the recombination rate on the surface of the absorption layer 20, thereby ensuring the sensitivity and response speed of the detector, and ensuring the performance of the detector; on the other hand, the introduction of the passivation layer 40 can also significantly reduce the dark current of the device, improve the signal-to-noise ratio of the detector, and ensure the detection capability of the detector. In this embodiment, by setting a lead-out electrode 50 at each pn junction in the passivation layer 40, the lead-out electrodes 50 between adjacent pixel units can be avoided from being connected. Generally, the lead-out electrode 50 is prepared by etching a hole in the passivation layer 40 and filling it to ensure the convenience of preparing the lead-out electrode 50. In addition, an anti-reflection layer 60 is arranged on the outer side of the substrate 10 of the detector, that is, on the side of the substrate 10 facing away from the absorption layer 20, which can improve the detector's light absorption efficiency and reduce the reflection loss of light when entering the detector, thereby increasing the detector's light absorption efficiency. By reducing the reflection of light entering the detector, the imaging quality can be improved under low light conditions, and the structure inside the detector can be protected, thereby enhancing the environmental adaptability and reliability of the detector. The defect of electrical crosstalk caused by the lateral diffusion of photogenerated carriers in the existing infrared detector in this embodiment can be referred to Figure 2 , Figure 2 is an example diagram of the movement trend of photogenerated carriers in an existing infrared detector; and the infrared detector with a barrier region in the present application can prevent the lateral diffusion of photogenerated carriers. For details, please refer to Figure 3 , Figure 3 This is an example diagram of the migration trend of photogenerated carriers in an infrared detector provided by an embodiment of the present invention.

[0059] In view of the problem of electrical crosstalk in the detector caused by the lateral diffusion of photogenerated carriers proposed in this embodiment, in this embodiment, the edge region 31 between the adjacent pixel regions 30 arranged in the absorption layer 20 is set. Figure 1As shown in , a barrier region 70 is formed to block the diffusion of photogenerated carriers. It should be further explained that in this embodiment, by setting the barrier region 70 at the edge region between the adjacent array-arranged pixel regions 30 in the absorption layer 20, the lateral diffusion of photogenerated carriers is blocked, and the photogenerated carriers are not captured, so that the loss of photogenerated carriers can be avoided. While the lateral diffusion of photogenerated carriers is weakened, the longitudinal diffusion of photogenerated carriers is not affected, or the longitudinal movement of photogenerated carriers is enhanced through the corresponding structure, and the photogenerated carriers are more likely to move to the pn junction of the corresponding pixel region 30, while reducing or even preventing the photogenerated carriers from moving to the adjacent pixel region 30, thereby reducing the problem of electrical crosstalk of the detector.

[0060] The specific structure of the barrier region 70 is not limited in this embodiment, as long as it can block the lateral diffusion of photogenerated carriers. The preparation method of the barrier region 70 is also not limited in this embodiment, for example, the barrier region 70 can be prepared in the absorption layer 20 by ion implantation, or other methods can be used to prepare the barrier region 70.

[0061] Furthermore, in order to improve the convenience of preparing the barrier region 70 , the barrier region 70 may be formed on a side of the absorption layer 20 close to the substrate 10 , and the barrier region 70 is formed by diffusing doped ions from the substrate 10 into the absorption layer 20 .

[0062] It should be noted that in this embodiment, the barrier region 70 is formed on the side of the absorption layer 20 close to the substrate 10, so as to facilitate the diffusion of doped ions into the absorption layer 20 through the substrate 10 to form the barrier region 70, which can avoid grooving the substrate 10, improve the convenience of device preparation, and reduce the damage caused by device preparation.

[0063] Furthermore, in order to ensure that the barrier region 70 for blocking the lateral diffusion of photogenerated carriers in the infrared detector is smoothly prepared, the substrate 10 may be set to be a substrate 10 including cadmium zinc telluride and cadmium telluride;

[0064] The absorption layer 20 is a mercury cadmium telluride absorption layer, and the cadmium ion concentration in the barrier region 70 is higher than the cadmium ion concentration in other regions of the mercury cadmium telluride absorption layer.

[0065] It should be noted that, in a feasible embodiment, the substrate 10 is set to be a substrate 10 including cadmium zinc telluride and cadmium telluride, and the absorption layer 20 is correspondingly set to be a mercury cadmium telluride absorption layer prepared by epitaxial growth on the substrate 10. At this time, the barrier region 70 is set to be a high-concentration cadmium ion region, that is, the larger band gap width of cadmium ions is utilized to increase the energy consumed by the photogenerated carriers to move in the lateral direction, and the number of photogenerated carriers moving in the lateral direction can be reduced. In this embodiment, the barrier region 70 is set to be a high-concentration cadmium ion region, that is, the cadmium ion concentration in the barrier region 70 is higher than the cadmium ion concentration in the remaining regions of the mercury cadmium telluride absorption layer, so as to promote the photogenerated carriers to move in the longitudinal direction to the pn junction.

[0066] Furthermore, in order to ensure the convenience of manufacturing the infrared detector, the anti-reflection layer 60 may be a zinc sulfide anti-reflection layer.

[0067] It should be noted that the zinc sulfide anti-reflection layer provided in this embodiment can, on the one hand, improve the detector's absorption efficiency of light and reduce the reflection loss of light when entering the detector. At the same time, when the mercury pressure is used to enhance the mutual diffusion of cadmium ions of cadmium telluride in the substrate 10 and mercury ions in the mercury cadmium telluride absorption layer, zinc sulfide can serve as a barrier layer for mercury, so that the mercury pressure in the area where zinc sulfide is provided cannot act on the substrate 10, and the mercury pressure in the area not covered by zinc sulfide acts on the substrate 10, thereby enhancing the mutual diffusion rate of cadmium ions and mercury ions in the area. Therefore, in this embodiment, the anti-reflection layer 60 is provided as a zinc sulfide anti-reflection layer, which can also be used as a mercury barrier layer to improve the functionality of zinc sulfide. It should be further explained that when utilizing mercury pressure to enhance the mutual diffusion rate between the cadmium ions of the cadmium telluride in the substrate 10 and the mercury ions in the mercury cadmium telluride absorption layer, the prepared zinc sulfide layer needs to be patterned to expose the substrate 10 at the edge area between the pixel areas 30 corresponding to the adjacent array arrangement, so as to realize the preparation of the above-mentioned barrier area 70. After the preparation of the barrier area 70, a zinc sulfide layer can be prepared again to fill the gap in the patterned zinc sulfide layer, or the patterned zinc sulfide layer can be removed, and the entire surface of the zinc sulfide layer can be prepared again as the anti-reflection layer 60.

[0068] Furthermore, in order to reduce the recombination rate on the surface of the mercury cadmium telluride absorption layer and reduce the dark current of the device, the passivation layer 40 can be provided to include a composite layer formed by stacking a cadmium telluride sub-passivation layer disposed on a side close to the mercury cadmium telluride absorption layer and a zinc sulfide sub-passivation layer disposed on a side away from the mercury cadmium telluride absorption layer.

[0069] It should be noted that in this embodiment, the passivation layer 40 is composed of a cadmium telluride layer and a zinc sulfide layer stacked in a direction from the mercury cadmium telluride absorption layer back to the substrate 10 and pointing outward, which can protect the mercury cadmium telluride absorption layer, eliminate surface damage of the mercury cadmium telluride absorption layer, and ensure the performance of the device.

[0070] The infrared detector provided by the embodiment of the present invention comprises a substrate 10, and an absorption layer 20 located on one side of the substrate 10, wherein a plurality of pixel regions 30 arranged in an array are formed on the surface of the absorption layer 20 on the side facing away from the substrate 10, and each pixel region 30 forms a pn junction correspondingly; a passivation layer 40 is provided on the side facing away from the substrate 10 of the absorption layer 20, and an extraction electrode 50 is provided on the passivation layer 40 corresponding to each pn junction; an anti-reflection layer 60 is provided on the side facing away from the absorption layer 20 of the substrate; a barrier region 70 for blocking the diffusion of photogenerated carriers is formed at the edge region between the pixel regions 30 arranged in adjacent arrays in the absorption layer 20. The present invention can reduce the problem of electrical crosstalk between adjacent pixel regions 30 caused by the lateral diffusion of photogenerated carriers by preparing a barrier region 70 for blocking the diffusion of photogenerated carriers at the edge region between the pixel regions 30 arranged in adjacent arrays in the absorption layer 20.

[0071] In addition, in the embodiment of the present invention, the barrier region 70 is formed on the side of the absorption layer 20 close to the substrate 10, so that the doped ions are diffused into the absorption layer 20 through the substrate 10 to form the barrier region 70, which can avoid the substrate 10 from being grooved, improve the convenience of device preparation, and reduce the damage caused by device preparation; the substrate 10 is set to be a substrate 10 including cadmium zinc telluride and cadmium telluride, the absorption layer 20 is a mercury cadmium telluride absorption layer, and the cadmium ion concentration of the barrier region 70 is higher than that of the remaining regions in the mercury cadmium telluride absorption layer. The cadmium ion concentration at the infrared detector is ensured to ensure the smooth preparation of the barrier region 70 for blocking the lateral diffusion of photogenerated carriers in the infrared detector, thereby improving the simplicity of preparation; by setting the anti-reflection layer 60 as a zinc sulfide anti-reflection layer, the convenience and adaptability of the preparation of the infrared detector are ensured; by setting the passivation layer 40 to be composed of a cadmium telluride layer and a zinc sulfide layer stacked in a direction in which the mercury cadmium telluride absorption layer is back to the substrate 10 and points outward, the mercury cadmium telluride absorption layer can be protected, the surface damage of the mercury cadmium telluride absorption layer can be eliminated, and the performance of the device can be ensured.

[0072] A method for preparing an infrared detector provided in an embodiment of the present invention is introduced below. The method for preparing an infrared detector described below is used to prepare the infrared detector as described above, and can be referred to in correspondence with the infrared detector described above.

[0073] Please refer to Figure 4 , Figure 4 A flowchart of a method for preparing an infrared detector provided by an embodiment of the present invention, the method may include:

[0074] S101: providing a detector preform, the detector preform comprising a substrate, an absorption layer prepared on one side of the substrate, and a passivation layer prepared on a side of the absorption layer facing away from the substrate; a plurality of pixel regions arranged in an array are formed on a surface of the absorption layer facing away from the substrate.

[0075] The executor of this embodiment is an infrared detector preparation device. It should be noted that the detector preform in this embodiment includes a substrate, an absorption layer epitaxially grown on the surface of the substrate, and a passivation layer prepared on the side of the absorption layer facing away from the substrate, and the surface of the absorption layer facing away from the substrate is divided into a plurality of pixel areas arranged in an array, and a pn junction is subsequently prepared in each pixel area. In addition, the detector preform in this embodiment may also include other functional structures, which are not limited here. Further, in this embodiment, the substrate is set as a thinned substrate, and the thinned substrate can be specifically set to a thickness of 20 microns to 100 microns.

[0076] S102: performing doping treatment on the edge area between adjacent array-arranged pixel areas in the absorption layer to form a barrier area that blocks the diffusion of photogenerated carriers, thereby completing the preparation of the infrared detector; an anti-reflection layer is provided on the side of the substrate facing away from the absorption layer.

[0077] It should be noted that in this embodiment, by performing diffusion doping treatment on the edge area between the pixel areas of adjacent arrays in the absorption layer, the specified ions can be doped into the edge area between the pixel areas of adjacent arrays, thereby forming a barrier area that blocks the diffusion of photogenerated carriers. Specifically, the barrier area can block the lateral movement of photogenerated carriers, thereby completing the preparation of the infrared detector. This embodiment does not limit the specific method of doping the corresponding ions in the edge area between the pixel areas of adjacent arrays, as long as it can be doped to form the above-mentioned barrier area. Correspondingly, this embodiment does not limit the specific preparation time of the anti-reflection layer set on the side of the substrate facing away from the absorption layer. The preparation of the anti-reflection layer can be completed in the provided detector preform, or the anti-reflection layer can be prepared on the side of the substrate facing away from the absorption layer after the preparation of the above-mentioned barrier area is completed.

[0078] It should be further explained that in the manufacturing process of the mercury cadmium telluride infrared detector in this embodiment, the subsequent ion implantation, electrode growth, and interconnection processes are no different from the conventional mercury cadmium telluride device process, and the infrared detector is manufactured at this point. Specifically, each pixel area is formed corresponding to a pn junction, and the passivation layer is provided with a lead-out electrode at each pn junction.

[0079] Furthermore, in order to ensure that the barrier region is successfully prepared, a doping process is performed on the edge region between the pixel regions arranged in adjacent arrays in the absorption layer to form a barrier region that blocks the diffusion of photogenerated carriers. Before the preparation of the infrared detector is completed, the following steps may also be included:

[0080] On the side of the substrate facing away from the absorption layer, a patterned barrier layer is prepared that exposes only a preset area of ​​the substrate; the preset area of ​​the substrate is an area in the substrate corresponding to an edge area between pixel areas arranged in adjacent arrays;

[0081] Accordingly, the above-mentioned doping treatment is performed on the edge region between the pixel regions arranged in adjacent arrays in the absorption layer to form a barrier region that blocks the diffusion of photogenerated carriers, thereby completing the preparation of the infrared detector, which may include:

[0082] By patterning the barrier layer, only the preset area of ​​the substrate is subjected to diffusion enhancement treatment, so that the doped ions in the preset area of ​​the substrate diffuse to the absorption layer, forming a barrier region on the side of the absorption layer close to the substrate, and completing the preparation of the infrared detector.

[0083] It should be noted that in this embodiment, a graphic barrier layer that only exposes a preset area of ​​the substrate is prepared on the side of the substrate facing away from the absorption layer. Specifically, the graphic barrier layer is in the area covering the substrate, that is, the area outside the preset area, so as to prevent the process of enhancing the diffusion of doped ions in the substrate into the absorption layer from taking effect. Since there is no graphic barrier layer to block the preset area, the diffusion enhancement process can promote the designated doped ions in the substrate to diffuse into the absorption layer, thereby forming a potential barrier region on the side of the absorption layer close to the substrate and at the edge area between adjacent array-arranged pixel areas, thereby completing the preparation of the infrared detector.

[0084] Furthermore, in order to ensure that the barrier region is successfully prepared and to improve the convenience of preparation, the substrate may be a substrate including cadmium zinc telluride and cadmium telluride, and the absorption layer may be a mercury cadmium telluride absorption layer;

[0085] The above-mentioned patterned barrier layer is used to perform diffusion enhancement treatment only on the preset area of ​​the substrate, so that the doping ions at the preset area of ​​the substrate diffuse to the absorption layer, and a barrier region is formed on the side of the absorption layer close to the substrate to complete the preparation of the infrared detector, which may include:

[0086] By patterning the barrier layer, the mutual diffusion rate between the mercury ions in the mercury cadmium telluride absorption layer and the cadmium ions in the substrate is enhanced by mercury pressure at high temperature, so as to form a barrier region on the side of the mercury cadmium telluride absorption layer close to the substrate, thereby completing the preparation of the infrared detector; the cadmium ion concentration in the barrier region is higher than the cadmium ion concentration in the rest of the mercury cadmium telluride absorption layer.

[0087] It should be noted that in this embodiment, the substrate is set to include cadmium zinc telluride and cadmium telluride, and the absorption layer is set to a mercury cadmium telluride absorption layer. At this time, the cadmium ions of the cadmium telluride in the substrate are diffused into the mercury cadmium telluride to form a high-concentration cadmium ion area. The wide bandgap width of the cadmium element can prevent the lateral movement of photogenerated carriers, thereby making it easy for photogenerated carriers to move longitudinally, and promoting the movement of photogenerated carriers to the pn junction prepared in the pixel area. The high-concentration cadmium ion area mentioned in this embodiment is the above-mentioned barrier area, which is specifically manifested in that the cadmium ion concentration in the barrier area is higher than the cadmium ion concentration in the remaining areas of the mercury cadmium telluride absorption layer, and the specific parameters of the cadmium ion concentration are not specifically limited in this embodiment. In this embodiment, the barrier region is prepared by specifically using mercury pressure at high temperature to enhance the mutual diffusion rate of mercury ions in the mercury cadmium telluride absorption layer and cadmium ions in the substrate, and the patterned barrier layer covers the area of ​​the substrate, and the barrier layer forms a barrier effect on mercury, so the patterned barrier layer covers the area of ​​the substrate, and the diffusion of cadmium ions cannot be enhanced, thereby realizing the formation of a high-concentration cadmium ion barrier region at the edge area between the pixel areas arranged in adjacent arrays in the mercury cadmium telluride absorption layer. In this embodiment, the mercury pressure enhancement treatment at high temperature can be specifically set to perform mercury saturation heat treatment at a temperature of 250 degrees Celsius to 400 degrees Celsius, and the treatment time is set to between 0.5 hours and 12 hours.

[0088] Furthermore, in order to ensure the smooth preparation of the barrier region and the functionality of the infrared detector, the above-mentioned patterned barrier layer can be set as a zinc sulfide patterned barrier layer;

[0089] By patterning the barrier layer, the mutual diffusion rate of mercury ions in the mercury cadmium telluride absorption layer and cadmium ions in the substrate is enhanced by mercury pressure at high temperature, so as to form a barrier region on the side of the mercury cadmium telluride absorption layer close to the substrate. After the preparation of the infrared detector is completed, the following may also be included:

[0090] The zinc sulfide patterned barrier layer is removed, and a zinc sulfide anti-reflection layer is formed on the side of the substrate facing away from the mercury cadmium telluride absorption layer.

[0091] It should be noted that in this embodiment, high temperature mercury pressure is used to act on the exposed substrate of the zinc sulfide patterned barrier layer to enhance the diffusion of cadmium ions in the substrate to the mercury cadmium telluride absorption layer to form the above-mentioned barrier region, and then the zinc sulfide patterned barrier layer is removed, and a zinc sulfide anti-reflection layer is prepared on the side of the substrate facing away from the mercury cadmium telluride absorption layer, and the zinc sulfide anti-reflection layer forms a uniform and dense structure on the surface of the substrate without gaps, so as to reduce the reflectivity of light entering the detector. In this embodiment, it can be specifically arranged on the side of the substrate facing away from the mercury cadmium telluride absorption layer, and a zinc sulfide patterned barrier layer of 0.1 micron to 1 micron can be prepared by a magnetron sputtering process or a thermal evaporation process.

[0092] Further, in a feasible embodiment, the above-mentioned step of preparing a patterned barrier layer that only exposes a predetermined area of ​​the substrate on the side of the substrate facing away from the absorption layer may include:

[0093] On the side of the substrate facing away from the absorbent layer, an initial barrier layer is prepared;

[0094] The initial blocking layer is etched and removed along the edge area between the pixel areas corresponding to the adjacent array arrangement by using a dry etching process to obtain a patterned blocking layer.

[0095] In this embodiment, a uniform and dense initial barrier layer is first prepared on the side of the substrate facing away from the absorption layer, and then the initial barrier layer is etched and removed along the edge area between the pixel areas corresponding to adjacent array arrangements using a dry etching process to obtain a patterned barrier layer, thereby ensuring that the patterned barrier layer is successfully prepared.

[0096] The infrared detector preparation method provided by the embodiment of the present invention includes providing a detector preform, the detector preform includes a substrate, an absorption layer prepared on one side of the substrate, and a passivation layer prepared on the side of the absorption layer facing away from the substrate; a plurality of pixel regions arranged in an array are formed on the surface of the absorption layer facing away from the substrate, each pixel region has a corresponding pn junction, and the passivation layer is provided with a lead-out electrode corresponding to each pn junction, and the edge region between the pixel regions arranged in adjacent arrays in the absorption layer is doped to form a barrier region that blocks the diffusion of photogenerated carriers, and the preparation of the infrared detector is completed, and an anti-reflection layer is provided on the side of the substrate facing away from the absorption layer. The present invention can reduce the problem of electrical crosstalk between adjacent pixel regions caused by lateral diffusion of photogenerated carriers by preparing a barrier region that blocks the diffusion of photogenerated carriers at the edge region between the pixel regions arranged in adjacent arrays in the absorption layer.

[0097] In addition, the embodiment of the present invention ensures that the barrier region is successfully prepared by preparing a patterned barrier layer that only exposes a preset area of ​​the substrate on the side of the substrate facing away from the absorption layer; the substrate is set to include cadmium zinc telluride and cadmium telluride, and the absorption layer is set to be a mercury cadmium telluride absorption layer, and the cadmium ions of the cadmium telluride in the substrate are diffused into the mercury cadmium telluride to form a high-concentration cadmium ion area as the above-mentioned barrier region, thereby ensuring that the above-mentioned barrier region is successfully prepared and the convenience of preparation is improved; high-temperature mercury pressure is used to act on the exposed substrate of the zinc sulfide patterned barrier layer to enhance the diffusion of cadmium ions in the substrate at this location into the mercury cadmium telluride absorption layer to form the above-mentioned barrier region, thereby ensuring that the barrier region is successfully prepared and the functionality of the infrared detector is guaranteed; a uniform and dense initial barrier layer is first prepared on the side of the substrate facing away from the absorption layer, and then the initial barrier layer is etched and removed by a dry etching process along the edge area between the pixel areas corresponding to the adjacent array arrangement to obtain a patterned barrier layer, thereby improving the convenience of preparing the patterned barrier layer.

[0098] In a feasible embodiment, the above infrared detector preparation method may specifically include the following steps:

[0099] Step S1: providing a mercury cadmium telluride preform, and sequentially preparing a cadmium telluride sub-passivation layer 41 and a zinc sulfide sub-passivation layer 42 on the surface of the mercury cadmium telluride absorption layer 21 in the mercury cadmium telluride preform by using a magnetron sputtering process / thermal evaporation process; the mercury cadmium telluride preform includes a substrate 10, and a mercury cadmium telluride absorption layer 21 prepared on one side of the substrate 10, and a surface of the mercury cadmium telluride absorption layer 21 facing away from the substrate is divided into a plurality of pixel areas 30 arranged in an array.

[0100] The mercury cadmium telluride preform provided in step S1 can be referred to Figure 5 , Figure 5 A schematic structural diagram of a mercury cadmium telluride preform provided in an embodiment of the present invention.

[0101] Step S2: performing back thinning treatment on the substrate 10 in the mercury cadmium telluride preform to obtain a thinned substrate 11, and the thickness of the thinned substrate 11 is specifically 20 micrometers to 100 micrometers.

[0102] The thinned substrate in step S2 can be referred to Figure 6 , Figure 6 A schematic structural diagram of a mercury cadmium telluride preform after substrate thinning provided in an embodiment of the present invention.

[0103] Step S3: using a magnetron sputtering process / thermal evaporation process, a zinc sulfide initial barrier layer 80 with a thickness of 0.1 micrometer to 1 micrometer is formed on the surface of the thinned substrate 11 facing away from the mercury cadmium telluride absorption layer 21 .

[0104] The initial zinc sulfide barrier layer prepared in step S3 can be referred to Figure 7 , Figure 7 A schematic structural diagram of a mercury cadmium telluride preform prepared with a zinc sulfide initial barrier layer provided in an embodiment of the present invention.

[0105] Step S4: using a dry etching process, etching away a portion of the zinc sulfide initial barrier layer at the edge region between the pixel regions 30 arranged in adjacent arrays to form a zinc sulfide patterned barrier layer 82, thereby obtaining a mercury cadmium telluride to-be-processed component.

[0106] The mercury cadmium telluride to be processed component prepared in step S4 can refer to Figure 8 , Figure 8 The structure diagram of a mercury cadmium telluride to be treated component provided by an embodiment of the present invention. The zinc sulfide initial barrier layer removal portion 81 is as shown in FIG. Figure 8 In addition, the etched structure can be further referenced Fig. 9 , Fig. 9 A schematic diagram of the structure of a mercury cadmium telluride to be treated member observed from the bottom side according to an embodiment of the present invention, wherein the edge region 31 between adjacent pixel regions surrounds a pixel region 30, the center of the pixel region 30 is a pixel center 32, and a pn junction is generally provided at the pixel center 32.

[0107] Step S5: performing mercury saturation heat treatment on the mercury cadmium telluride workpiece at a temperature of 250 degrees Celsius to 400 degrees Celsius, and the treatment time is set to 0.5 hours to 12 hours, so as to form a barrier region 70 at the edge area between the adjacent array-arranged pixel areas 30 in the mercury cadmium telluride absorption layer 21, close to the side of the thinned substrate 11; and the cadmium ion concentration in the barrier region 70 is higher than the cadmium ion concentration in the remaining areas of the mercury cadmium telluride absorption layer 21.

[0108] The potential barrier region prepared in step S5 can refer to Fig.10 , Fig.10 A schematic diagram of the structure of a mercury cadmium telluride device with barrier region preparation provided in an embodiment of the present invention.

[0109] Step S6: using hydrochloric acid to completely corrode the zinc sulfide patterned barrier layer 82 on the surface of the thinned substrate 11 facing away from the mercury cadmium telluride absorption layer 21 , and re-grow a zinc sulfide layer of corresponding thickness as the anti-reflection layer 60 according to different wavelength requirements.

[0110] The anti-reflection layer prepared in step S6 can refer to Fig.11 , Fig.11 A schematic structural diagram of a mercury cadmium telluride device with an anti-reflection layer prepared according to an embodiment of the present invention.

[0111] It should be noted that in the preparation process of the mercury cadmium telluride infrared detector in this embodiment, the subsequent ion implantation, electrode growth, and interconnection processes are no different from the conventional mercury cadmium telluride device process. In this embodiment, the barrier effect of the zinc sulfide layer on mercury is used to manufacture areas with inconsistent mercury pressure, and the promotion effect of mercury on the mutual diffusion of cadmium ions and mercury ions is used to form a regional high-component barrier region 70 in the mercury cadmium telluride absorption layer 21, that is, the barrier region 70 is manufactured by using the effect of mercury pressure on the mutual diffusion rate of cadmium ions and mercury ions at high temperature to achieve the blocking of the lateral diffusion of photogenerated carriers. Compared with the existing methods for reducing electrical crosstalk, this embodiment has the following advantages: 1) It is more applicable and is suitable for mercury cadmium telluride materials obtained by various growth methods such as liquid phase epitaxy and molecular beam epitaxy; 2) The method of preparing the barrier region 70 between pixels is more effective than the method of blocking photogenerated carriers by the method of gradient component absorption layer, increasing the width of the pn junction depletion layer, and the n+ region, and can act on mercury cadmium telluride devices together with other methods.

[0112] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0113] In addition, it should be noted that, in this article, relationships 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 "include", "comprises" or any other variations are intended to cover non-exclusive inclusion, so that a process, method, article or device that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0114] The above is a detailed introduction to an infrared detector and a method for preparing an infrared detector provided by the present invention. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea; at the same time, for a general technician in this field, according to the idea of ​​the present invention, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. An infrared detector, characterized in that: include: A substrate, and an absorption layer located on one side of the substrate, wherein a surface of the absorption layer facing away from the substrate is formed with a plurality of pixel regions arranged in an array, and each of the pixel regions is correspondingly formed with a pn junction; A passivation layer is provided on the side of the absorption layer facing away from the substrate, and a lead-out electrode is provided at each pn junction of the passivation layer; An anti-reflection layer is provided on the side of the substrate facing away from the absorption layer; A potential barrier region for blocking the diffusion of photogenerated carriers is formed in the edge region between adjacent array-arranged pixel regions in the absorption layer.

2. The infrared detector according to claim 1, characterized in that: The barrier region is formed on a side of the absorption layer close to the substrate, and the barrier region is formed by diffusing doping ions from the substrate into the absorption layer.

3. The infrared detector according to claim 2, characterized in that: The substrate is a substrate including cadmium zinc telluride and cadmium telluride; The absorption layer is a mercury cadmium telluride absorption layer, and the cadmium ion concentration in the barrier region is higher than the cadmium ion concentration in other regions of the mercury cadmium telluride absorption layer.

4. The infrared detector according to claim 3, characterized in that: The anti-reflection layer is a zinc sulfide anti-reflection layer.

5. The infrared detector according to claim 3, characterized in that: The passivation layer comprises a composite layer formed by stacking a cadmium telluride sub-passivation layer disposed on a side close to the mercury cadmium telluride absorption layer and a zinc sulfide sub-passivation layer disposed on a side away from the mercury cadmium telluride absorption layer.

6. A method for preparing an infrared detector, characterized in that: Used to prepare the infrared detector according to any one of claims 1 to 5, comprising: A detector preform is provided, the detector preform comprising a substrate, an absorption layer prepared on one side of the substrate, and a passivation layer prepared on a side of the absorption layer facing away from the substrate; a plurality of pixel regions arranged in an array are formed on a surface of the absorption layer facing away from the substrate; The edge area between the pixel areas arranged in adjacent arrays in the absorption layer is doped to form a barrier area that blocks the diffusion of photogenerated carriers, thereby completing the preparation of the infrared detector; an anti-reflection layer is provided on the side of the substrate facing away from the absorption layer.

7. The method for preparing an infrared detector according to claim 6, characterized in that: Doping is performed on the edge region between adjacent array-arranged pixel regions in the absorption layer to form a barrier region that blocks the diffusion of photogenerated carriers. Before the preparation of the infrared detector is completed, the method further includes: On the side of the substrate facing away from the absorption layer, a patterned barrier layer is prepared that only exposes a preset area of ​​the substrate; the preset area of ​​the substrate is an area of ​​the substrate corresponding to an edge area between adjacent array-arranged pixel areas; The edge region between adjacent array-arranged pixel regions in the absorption layer is doped to form a barrier region for blocking the diffusion of photogenerated carriers, thereby completing the preparation of the infrared detector, including: Through the patterned barrier layer, only the preset area of ​​the substrate is subjected to diffusion enhancement treatment, so that the doped ions at the preset area of ​​the substrate diffuse toward the absorption layer, and the barrier region is formed on the side of the absorption layer close to the substrate, thereby completing the preparation of the infrared detector.

8. The method for preparing an infrared detector according to claim 7, characterized in that: The substrate is a substrate including cadmium zinc telluride and cadmium telluride, and the absorption layer is a mercury cadmium telluride absorption layer; The patterned barrier layer is used to perform diffusion enhancement treatment only on a preset area of ​​the substrate, so that doping ions at the preset area of ​​the substrate diffuse toward the absorption layer, and the barrier region is formed on a side of the absorption layer close to the substrate, thereby completing the preparation of the infrared detector, including: The patterned barrier layer is used to enhance the mutual diffusion rate between the mercury ions in the mercury cadmium telluride absorption layer and the cadmium ions in the substrate by utilizing mercury pressure at high temperature, so as to form the barrier region on the side of the mercury cadmium telluride absorption layer close to the substrate, thereby completing the preparation of the infrared detector; the cadmium ion concentration in the barrier region is higher than the cadmium ion concentration in the remaining areas of the mercury cadmium telluride absorption layer.

9. The method for preparing an infrared detector according to claim 8, characterized in that: The patterned barrier layer is a zinc sulfide patterned barrier layer; After the preparation of the infrared detector is completed, the patterned barrier layer is used to enhance the mutual diffusion rate of mercury ions in the mercury cadmium telluride absorption layer and cadmium ions in the substrate by mercury pressure at high temperature, so as to form the barrier region on the side of the mercury cadmium telluride absorption layer close to the substrate. The method further includes: The zinc sulfide patterned barrier layer is removed, and a zinc sulfide anti-reflection layer is prepared on the side of the substrate facing away from the mercury cadmium telluride absorption layer.

10. The method for preparing an infrared detector according to claim 7, characterized in that: On the side of the substrate facing away from the absorption layer, a patterned barrier layer is prepared to expose only a predetermined area of ​​the substrate, comprising: On the side of the substrate facing away from the absorbent layer, an initial barrier layer is prepared; The initial blocking layer is etched and removed along the edge area between the pixel areas corresponding to the adjacent array arrangement by using a dry etching process to obtain the patterned blocking layer.

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