Mercury cadmium telluride infrared detector and preparation method thereof

Abstract

The present application relates to the field of infrared detector chip preparation, and discloses a mercury cadmium telluride infrared detector and a preparation method thereof, including preparing a mercury cadmium telluride wafer that has been ion-implanted and has a composite passivation layer distributed on the surface; the composite passivation layer includes a stacked first passivation layer and a second passivation layer; removing the second passivation layer; making a patterned photoresist on the surface of the processed mercury cadmium telluride wafer; making a new second passivation layer on the surface of the reprocessed mercury cadmium telluride wafer; removing the patterned photoresist to form a through hole in the new second passivation layer; etching the first passivation layer and the mercury cadmium telluride wafer located below the through hole to form a contact hole; making an electrode to obtain a mercury cadmium telluride infrared detector. The new second passivation layer is not damaged by the ion implantation process, which can improve the device performance; the through hole is formed in the new second passivation layer by stripping the photoresist, which avoids the problem of poor uniformity of the contact hole depth caused by etching the second passivation layer, and is conducive to realizing a low-damage etching process.

Description

Technical Field

[0001] The present application relates to the field of infrared detector chip preparation, and in particular to a mercury cadmium telluride infrared detector and a preparation method thereof. Background Art

[0002] The preparation of infrared detector chips is the core of infrared detection technology. The processes for preparing chips mainly include semiconductor processes such as photolithography, wet chemistry, ion implantation, passivation, electrode preparation and dry etching.

[0003] The purpose of the ion implantation process is to form the PN junction of the chip. The ion implantation process is the process of high-energy ions bombarding the material surface, which inevitably causes a certain degree of damage to the zinc sulfide film layer in the composite passivation film on the chip surface. A large number of surface states will be formed at the interface between the damaged zinc sulfide film layer and the cadmium telluride film layer. These surface states are easily used as the recombination center of electron holes, generating a large amount of surface leakage current, resulting in poor chip performance, and in severe cases, chip pixel failure. In addition, when making contact holes, it is necessary to etch three layers of materials: zinc sulfide film layer, cadmium telluride film layer and mercury cadmium telluride. Mercury cadmium telluride is a relatively sensitive optoelectronic material and is very easy to cause etching damage. The etching bias of the dry etching process is the main factor causing etching damage. If the etching bias is controlled very low, it is difficult for the etchant to enter the contact hole, and the etching rate of the surface zinc sulfide layer is extremely low, and the process cannot be carried out effectively; if the etching bias increases, the corresponding etching damage increases, affecting the optoelectronic performance of the device. The uniformity of the contact hole depth will be affected by the consistency of photolithography and the uniformity of the surface passivation layer. At the same time, taking into account the differences in the dry etching process itself for etching multi-layer materials, the above multiple factors are combined, and there are differences in the consistency of the prepared contact hole depth. Since the bottom of the contact hole has been etched to the n-type region of mercury cadmium telluride, different hole depths will cause differences in metal electrode contact and differences in the n-type region. These factors will lead to poor response consistency of the detector chip.

[0004] Therefore, how to solve the above technical problems should be the focus of technical personnel in this field. Summary of the invention

[0005] The purpose of this application is to provide a mercury cadmium telluride infrared detector and a preparation method thereof, so as to avoid the generation of surface leakage current and improve the performance of the detector.

[0006] In order to solve the above technical problems, the present application provides a method for preparing a mercury cadmium telluride infrared detector, comprising:

[0007] Preparing an ion-implanted HgCdTe wafer with a composite passivation layer distributed on the surface; the composite passivation layer includes a first passivation layer and a second passivation layer stacked in a direction away from the surface of the HgCdTe wafer;

[0008] removing the second passivation layer to obtain a processed mercury cadmium telluride wafer;

[0009] Making a patterned photoresist on the surface of the treated mercury cadmium telluride wafer to obtain a re-treated mercury cadmium telluride wafer;

[0010] forming a new second passivation layer on the surface of the reprocessed mercury cadmium telluride wafer to obtain a mercury cadmium telluride wafer having a new composite passivation layer distributed on the surface;

[0011] removing the patterned photoresist and forming a through hole in the new second passivation layer;

[0012] Etching the first passivation layer and the mercury cadmium telluride wafer located below the through hole to form a contact hole;

[0013] Electrodes are made in the contact holes to derive the electrical properties of the PN junction of the mercury cadmium telluride wafer, thereby obtaining a mercury cadmium telluride infrared detector.

[0014] Optionally, after forming a new second passivation layer on the surface of the reprocessed mercury cadmium telluride wafer, the method further comprises:

[0015] A metal layer is formed on the surface of the new second passivation layer.

[0016] Optionally, removing the patterned photoresist and forming a through hole in the new second passivation layer comprises:

[0017] removing the patterned photoresist and forming a through hole in the new second passivation layer and the metal layer;

[0018] Etching the first passivation layer and the mercury cadmium telluride wafer located below the through hole to form a contact hole comprises:

[0019] The metal layer is used as a mask, and the first passivation layer and the mercury cadmium telluride wafer located below the through hole are etched by dry etching to form a contact hole.

[0020] Optionally, etching the first passivation layer and the mercury cadmium telluride wafer located below the through hole by dry etching includes:

[0021] The first passivation layer and the mercury cadmium telluride wafer located below the through hole are etched by inductively coupled plasma etching, wherein the etching bias voltage ranges from 10V to 20V.

[0022] Optionally, forming a metal layer on the surface of the new second passivation layer comprises:

[0023] The metal layer is formed on the surface of the new second passivation layer by ion beam deposition, wherein the ion beam current ranges from 80 mA to 100 mA, and the ion beam voltage ranges from 400 V to 500 V.

[0024] Optionally, forming a metal layer on the surface of the new second passivation layer comprises:

[0025] A chromium metal layer is formed on the surface of the new second passivation layer.

[0026] Optionally, when the second passivation layer is a zinc sulfide layer, forming a new second passivation layer on the surface of the reprocessed mercury cadmium telluride wafer comprises:

[0027] A zinc sulfide layer is formed on the surface of the reprocessed mercury cadmium telluride wafer by magnetron sputtering.

[0028] Optionally, removing the second passivation layer includes:

[0029] The mercury cadmium telluride wafer is placed in a hydrochloric acid etching solution to etch and remove the second passivation layer.

[0030] Optionally, an electrode is fabricated in the contact hole to derive the electrical properties of the PN junction of the mercury cadmium telluride wafer, including:

[0031] Depositing an electrode layer on the surface of the mercury cadmium telluride wafer having the contact hole;

[0032] Making a patterned photoresist on the surface of the electrode layer;

[0033] Using the patterned photoresist as a mask, etching the electrode layer to form an electrode;

[0034] The patterned photoresist is removed.

[0035] The present application also provides a mercury cadmium telluride infrared detector, which is prepared by any of the above-mentioned methods for preparing a mercury cadmium telluride infrared detector.

[0036] The present application provides a method for preparing a mercury cadmium telluride infrared detector, comprising: preparing a mercury cadmium telluride wafer which has been ion-implanted and has a composite passivation layer distributed on its surface; the composite passivation layer comprises a first passivation layer and a second passivation layer stacked in a direction away from the surface of the mercury cadmium telluride wafer; removing the second passivation layer to obtain a processed mercury cadmium telluride wafer; making a patterned photoresist on the surface of the processed mercury cadmium telluride wafer to obtain a reprocessed mercury cadmium telluride wafer; making a new second passivation layer on the surface of the reprocessed mercury cadmium telluride wafer to obtain a mercury cadmium telluride wafer with a new composite passivation layer distributed on its surface; removing the patterned photoresist to form a through hole in the new second passivation layer; etching the first passivation layer and the mercury cadmium telluride wafer located below the through hole to form a contact hole; making an electrode in the contact hole to derive the electrical properties of the PN junction of the mercury cadmium telluride wafer to obtain a mercury cadmium telluride infrared detector.

[0037] It can be seen that in the preparation method of the present application, after ion implantation, the damaged second passivation layer of the mercury cadmium telluride wafer with a composite passivation layer distributed on the surface is removed, and a patterned photoresist is made on the processed mercury cadmium telluride wafer. The patterned photoresist is used to make contact holes in the subsequent process, and then a new second passivation layer is made, and then contact holes and electrodes are made. The new second passivation layer is not damaged by the ion implantation process, so the surface state will not be formed at the interface between the first passivation layer and the first passivation layer, thereby avoiding the generation of surface leakage current, improving the performance of the mercury cadmium telluride wafer, and thus improving the performance of the mercury cadmium telluride infrared detector. Furthermore, in the present application, a patterned photoresist is produced before growing a new second passivation layer, and a through hole is formed in the new second passivation layer by removing the patterned photoresist. The through hole is a part of the contact hole, and there is no need to etch the new second passivation layer when producing the contact hole, thereby avoiding the problem of poor uniformity of the contact hole depth caused by etching zinc sulfide. At the same time, it is conducive to realizing a low-damage etching process, and only the first passivation layer and mercury cadmium telluride need to be etched, thereby reducing the number of etching layers.

[0038] In addition, the present application also provides a mercury cadmium telluride infrared detector having the above advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present application or the technical solutions of 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 some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0040] Figure 1 A flow chart of a method for preparing a mercury cadmium telluride infrared detector provided in an embodiment of the present application;

[0041] Figure 2 A flow chart of another method for preparing a mercury cadmium telluride infrared detector provided in an embodiment of the present application;

[0042] Figures 3 to 11 A process flow chart of a method for preparing a mercury cadmium telluride infrared detector provided in an embodiment of the present application. DETAILED DESCRIPTION

[0043] In order to enable those skilled in the art to better understand the present application, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0044] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0045] As described in the background technology section, in the related technology, when preparing mercury cadmium telluride infrared detectors, ion implantation will cause a certain degree of damage to the zinc sulfide film layer on the surface of the chip, resulting in the formation of a large number of surface states at the interface between the zinc sulfide film layer and the cadmium telluride film layer, thereby generating leakage current and affecting the performance of the chip.

[0046] In view of this, the present application provides a method for preparing a mercury cadmium telluride infrared detector, please refer to Figure 1 , the method comprising:

[0047] Step S101: preparing an ion-implanted HgCdTe wafer with a composite passivation layer distributed on the surface; the composite passivation layer comprises a first passivation layer and a second passivation layer stacked in a direction away from the surface of the HgCdTe wafer.

[0048] The second passivation layer is an insulating film layer, which is used to isolate the performance of the mercury cadmium telluride material from the influence of the outside world.

[0049] As an implementation method, the first passivation layer may be a cadmium telluride layer, and the second passivation layer may be a zinc sulfide layer.

[0050] As an implementation method, preparing an ion-implanted HgCdTe wafer having a composite passivation layer distributed on the surface includes:

[0051] A photoresist pattern for photolithography ion implantation is formed on the surface of a mercury cadmium telluride wafer with a composite passivation layer, the mercury cadmium telluride wafer is placed in an ion implanter for a boron ion implantation process, and the photoresist on the surface of the mercury cadmium telluride wafer is removed after the implantation.

[0052] Step S102: removing the second passivation layer to obtain a processed mercury cadmium telluride wafer.

[0053] It should be noted that the present embodiment does not limit the method for removing the second passivation layer, and the method can be set at will.

[0054] As an implementation method, the second passivation layer can be removed by wet etching. The etching solution has a high selectivity to the second passivation layer, and the etching time can be controlled to stop the etching at the interface between the second passivation layer and the first passivation layer.

[0055] As an implementation method, when the second passivation layer is a zinc sulfide layer, removing the second passivation layer includes:

[0056] The mercury cadmium telluride wafer is placed in a hydrochloric acid etching solution to etch and remove the second passivation layer.

[0057] Zinc sulfide reacts with the hydrochloric acid solution, completely corroding the zinc sulfide layer.

[0058] Step S103: forming a patterned photoresist on the surface of the treated mercury cadmium telluride wafer to obtain a re-treated mercury cadmium telluride wafer.

[0059] The surface of the processed mercury cadmium telluride wafer is coated with a photoresist, and then exposed and developed to form a patterned photoresist.

[0060] The patterned photoresist includes a plurality of photoresist cylinders, each of which is located directly above the n-type region in the mercury cadmium telluride wafer. The diameter of the photoresist cylinder may range from 2 μm to 4 μm, and the height may range from 4 μm to 5 μm, including the end values.

[0061] Step S104: forming a new second passivation layer on the surface of the reprocessed HgCdTe wafer to obtain a HgCdTe wafer having a new composite passivation layer distributed on the surface.

[0062] The new composite passivation layer includes the first passivation layer and the new second passivation layer.

[0063] It should be noted that the preparation method of the new second passivation layer is not limited in this embodiment and depends on the circumstances.

[0064] As an implementation method, when the second passivation layer is a zinc sulfide layer, forming a new second passivation layer on the surface of the reprocessed mercury cadmium telluride wafer includes:

[0065] A zinc sulfide layer is formed on the surface of the reprocessed mercury cadmium telluride wafer by magnetron sputtering.

[0066] When zinc sulfide is grown by magnetron sputtering, the growth temperature may be in the range of 60°C to 80°C, and the sputtering power may be in the range of 300W to 400W. For example, the temperature may be 60°C, 65°C, 70°C, 75°C, 80°C, etc., and the sputtering power may be 300W, 330W, 360W, 400W, etc.

[0067] Step S105: removing the patterned photoresist and forming a through hole in the new second passivation layer.

[0068] The patterned photoresist can be removed by using an acetone solution. When removing the patterned photoresist, the new second passivation layer on the patterned photoresist is also stripped and removed. Using the stripping method to remove the new second passivation layer in the contact hole not only simplifies the process complexity of dry etching to make the contact hole, but also completely avoids the influence of the new second passivation layer on the uniformity of the contact hole depth.

[0069] The through hole is part of the contact hole. It is relatively simple to use the method of stripping the photoresist. There is no need to etch the new second passivation layer. The number of layers etched when making the contact hole can be reduced, the etching difficulty can be reduced, and the problem of poor uniformity of the contact hole depth caused by etching zinc sulfide can be avoided. At the same time, it is conducive to realizing a low-damage etching process.

[0070] Step S106: etching the first passivation layer and the HgCdTe wafer below the through hole to form a contact hole.

[0071] The first passivation layer and the mercury cadmium telluride wafer at the bottom of the through hole are etched to form a contact hole. When the material of the first passivation layer is cadmium telluride, cadmium telluride and mercury cadmium telluride are similar in material, and etching is relatively easy.

[0072] Step S107: making electrodes in the contact holes, deriving electrical properties of the PN junction of the mercury cadmium telluride wafer, and obtaining a mercury cadmium telluride infrared detector.

[0073] As an implementation method, an electrode is fabricated in the contact hole to obtain the electrical properties of the PN junction of the mercury cadmium telluride wafer, including:

[0074] Step S1071: depositing an electrode layer on the surface of the HgCdTe wafer having the contact hole.

[0075] The electrode layer is located on the surface of the entire HgCdTe wafer and in the contact holes.

[0076] The electrode layer may be a composite metal layer, for example, a Cr / Au / Pt composite metal electrode layer.

[0077] Step S1072: making a patterned photoresist on the surface of the electrode layer.

[0078] The patterned photoresist is located above the contact hole. The patterned photoresist includes a plurality of photoresist cylinders, each of which is located above a corresponding contact hole, and the diameter of the photoresist cylinder may range from 6 μm to 8 μm, and the height may range from 3 μm to 4 μm.

[0079] Step S1073: using the patterned photoresist as a mask, etching the electrode layer to form an electrode.

[0080] An electrode is distributed in each contact hole, and the electrode is in contact with the N-type region of the mercury cadmium telluride wafer.

[0081] Step S1074: removing the patterned photoresist.

[0082] The patterned photoresist can be removed using an acetone solution.

[0083] In the preparation method of this embodiment, after ion implantation, the damaged second passivation layer is removed from the mercury cadmium telluride wafer with a composite passivation layer on the surface, and a patterned photoresist is made on the treated mercury cadmium telluride wafer. The patterned photoresist is used for subsequent contact hole fabrication, and then a new second passivation layer is fabricated, and then contact holes and electrodes are fabricated. The new second passivation layer is not damaged by the ion implantation process, so the surface state will not be formed at the interface between the first passivation layer and the first passivation layer, thereby avoiding the generation of surface leakage current, improving the performance of the mercury cadmium telluride wafer, and thus improving the performance of the mercury cadmium telluride infrared detector. Moreover, in the present embodiment, a patterned photoresist is produced before growing a new second passivation layer, and a through hole is formed in the new second passivation layer by removing the patterned photoresist. The through hole is a part of the contact hole, and there is no need to etch the new second passivation layer when producing the contact hole. This avoids the problem of poor uniformity of the contact hole depth caused by etching zinc sulfide, and is conducive to realizing a low-damage etching process. Only the first passivation layer and mercury cadmium telluride need to be etched, thereby reducing the number of etching layers and reducing the difficulty of etching.

[0084] Please refer to Figure 2 Based on the above embodiments, in one embodiment of the present application, a method for preparing a mercury cadmium telluride infrared detector includes:

[0085] Step S201: preparing an ion-implanted HgCdTe wafer with a composite passivation layer distributed on the surface; the composite passivation layer comprises a first passivation layer and a second passivation layer stacked in a direction away from the surface of the HgCdTe wafer.

[0086] Step S202: removing the second passivation layer to obtain a processed mercury cadmium telluride wafer.

[0087] Step S203: forming a patterned photoresist on the surface of the treated mercury cadmium telluride wafer to obtain a re-treated mercury cadmium telluride wafer.

[0088] Step S204: forming a new second passivation layer on the surface of the reprocessed HgCdTe wafer to obtain a HgCdTe wafer having a new composite passivation layer distributed on the surface.

[0089] Step S205: forming a metal layer on the surface of the new second passivation layer.

[0090] The thickness of the metal layer may range from 500Å to 1000Å. For example, the thickness of the metal layer may be 500Å, 600Å, 700Å, 800Å, 900Å, 1000Å, etc.

[0091] The metal layer serves as a protective layer and also as a mask for subsequent etching to form contact holes. Compared with photoresist used as a mask, the thickness of the metal mask layer is much lower than that of the photoresist, and the etchant can easily enter the through hole, so the cadmium telluride layer (first passivation layer) and the mercury cadmium telluride layer can be etched with a low bias voltage to prepare contact holes with high uniformity and low damage without causing obvious etching damage. At the same time, the etching and electrode deposition processes can be closely connected to improve the ohmic contact between the mercury cadmium telluride material and the metal electrode.

[0092] It should be noted that the type of the metal layer is not limited in this embodiment.

[0093] As an implementation method, forming a metal layer on the surface of the new second passivation layer includes:

[0094] A chromium metal layer is formed on the surface of the new second passivation layer. The chromium metal layer has good stability and low cost.

[0095] In other embodiments of the present application, the metal layer may also be a platinum metal layer, a palladium metal layer, etc.

[0096] It should also be noted that the manufacturing method of the metal layer is not limited in this embodiment.

[0097] As an implementation method, forming a metal layer on the surface of the new second passivation layer includes:

[0098] The metal layer is formed on the surface of the new second passivation layer by ion beam deposition, wherein the ion beam current ranges from 80 mA to 100 mA, and the ion beam voltage ranges from 400 V to 500 V.

[0099] For example, the ion beam current can be 80 mA, 90 mA, 100 mA, etc., and the ion beam voltage can be 400 V, 450 V, 500 V, etc.

[0100] Step S206: removing the patterned photoresist and forming through holes in the new second passivation layer and the metal layer.

[0101] When removing the patterned photoresist, the new second passivation layer and the metal layer on the patterned photoresist are stripped off together, thereby forming a through hole in the new second passivation layer and the metal layer. Using the stripping method to remove the new second passivation layer in the contact hole not only simplifies the process complexity of dry etching to make the contact hole, but also completely avoids the influence of the new second passivation layer on the uniformity of the depth of the contact hole.

[0102] Step S207: using the metal layer as a mask, etching the first passivation layer and the mercury cadmium telluride wafer located below the through hole by dry etching to form a contact hole, wherein the area where the contact hole is located includes the area where the patterned photoresist is located.

[0103] The area where the patterned photoresist is located is also the area where the through hole is located.

[0104] The dry etching method includes but is not limited to an inductively coupled plasma etching method, an ion beam etching method, and a reactive ion etching method.

[0105] As an implementation method, etching the first passivation layer and the mercury cadmium telluride wafer located below the through hole by dry etching includes:

[0106] The first passivation layer and the mercury cadmium telluride wafer located below the through hole are etched by inductively coupled plasma etching, wherein the etching bias voltage ranges from 10V to 20V, including end values.

[0107] The etching gas during inductively coupled plasma etching can be Ar, H2 and CH4, wherein:

[0108] The Ar flow rate range can be 15 sccm (standard cubic centimeter per minute) ~ 20 sccm, including the endpoint values; the H2 flow rate range can be 10 sccm ~ 15 sccm, including the endpoint values; the CH4 flow rate range can be 2 sccm ~ 5 sccm, including the endpoint values.

[0109] The etching bias voltage can be 10V, 12V, 14V, 16V, 18V, 20V, etc., and can be set according to the specific situation.

[0110] Compared with ion beam etching and reactive ion etching, the inductively coupled plasma etching method can reduce etching damage while ensuring a good etching rate.

[0111] Step S208: making electrodes in the contact holes, deriving electrical properties of the PN junction of the mercury cadmium telluride wafer, and obtaining a mercury cadmium telluride infrared detector.

[0112] The preparation method of the mercury cadmium telluride infrared detector of the present application is introduced below using a specific case.

[0113] Step 1: Please refer to Figure 3 , photolithography ion implantation pattern on the surface of mercury cadmium telluride wafer 1 with double-layer composite passivation layer (cadmium telluride layer 2 and zinc sulfide layer 3), that is, forming patterned photoresist 4 on the surface of mercury cadmium telluride wafer, placing mercury cadmium telluride wafer 1 in ion implantation machine for boron ion implantation process, and removing patterned photoresist 4 on the surface of mercury cadmium telluride wafer 1 after implantation;

[0114] Step 2: Please refer to Figure 4, immerse the mercury cadmium telluride wafer 1 in a hydrochloric acid etching solution to completely etch away the zinc sulfide layer 3 on its surface that has been bombarded;

[0115] Step 3: Please refer to Figure 5 , photolithography contact hole patterns on the surface of the cadmium telluride layer 2, that is, forming a patterned photoresist 4 on the surface of the cadmium telluride layer 2, and preparing a photoresist cylinder with a diameter of 2-4 μm and a height of 4-5 μm just above the corresponding n-type region;

[0116] Step 4: Please refer to Figure 6 , placing the photolithographic HgCdTe wafer 1 into a magnetron sputtering device, regrowing a new zinc sulfide layer 5 on the surface thereof, and then using an ion beam deposition device to prepare a chromium metal layer 6 on the surface of the new zinc sulfide layer 5, wherein the thickness of the chromium metal layer 6 is controlled to be 500Å~1000Å;

[0117] Step 5: Please refer to Figure 7 , placing the mercury cadmium telluride wafer 1 in acetone, stripping off the new zinc sulfide layer 5 and the chromium metal layer 6 on the surface of the patterned photoresist 4, and forming a through hole 7 in the new zinc sulfide layer 5 and the chromium metal layer 6 on the surface of the mercury cadmium telluride wafer 1;

[0118] Step 6: Please refer to Figure 8 , placing the mercury cadmium telluride wafer 1 into an ICP etching (inductively coupled plasma etching) device, using an Ar / H2 / CH4 gas combination as etching gas, and etching bias voltage between 10V and 20V, etching the cadmium telluride layer 2 and the mercury cadmium telluride material with a low etching bias voltage, while no obvious etching damage is generated;

[0119] Step 7: Please refer to Fig. 9 After the etching is completed, the mercury cadmium telluride wafer 1 is directly placed in an electrode deposition device to grow a Cr / Au / Pt composite metal electrode layer 9 to bring out the pn junction electrical properties of the mercury cadmium telluride wafer 1;

[0120] Step 8: Please refer to Fig.10 After the composite metal electrode layer 9 is grown, an electrode pattern is photolithographically formed on the surface of the mercury cadmium telluride wafer 1, that is, a patterned photoresist 4 is formed on the surface of the mercury cadmium telluride wafer 1, and a photoresist cylinder with a diameter of 6-8 μm and a height of 3-4 μm is prepared directly above the corresponding contact hole;

[0121] Step 9: Please refer to Fig.11 The HgCdTe wafer 1 with the electrode pattern photolithography is etched away in an ion beam etching device to remove the composite metal electrode layer 9 not covered by the patterned photoresist to form an electrode 10, so that the pixels are isolated, and finally the surface photoresist is removed to complete the preparation of the HgCdTe device.

[0122] The preparation method in this application has the following advantages:

[0123] First, the zinc sulfide layer is regrown to restore the bombarded zinc sulfide layer to a state of stable physical and chemical properties. At the same time, the zinc sulfide layer in the contact hole is removed by the stripping process, which simplifies the process complexity of dry etching the multi-layer dielectric film in the contact hole and completely avoids the influence of the zinc sulfide layer on the uniformity of the contact hole depth. Second, the chromium metal layer is used as a protective layer and a mask. The thickness of the chromium metal mask layer is much lower than the thickness of the photoresist. The etchant can easily enter the contact hole, and the cadmium telluride and mercury cadmium telluride layers can be etched with low bias voltage to prepare highly uniform and less damaged contact holes. At the same time, the etching and electrode deposition processes can be closely connected to improve the ohmic contact between the mercury cadmium telluride material and the metal electrode, thereby improving the response consistency of the chip and laying a solid foundation for the consistency of the detector performance.

[0124] The present application also provides a mercury cadmium telluride infrared detector, which is manufactured using the method for manufacturing the mercury cadmium telluride infrared detector described in any of the above embodiments.

[0125] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0126] The mercury cadmium telluride infrared detector and its preparation method provided by the present application are introduced in detail above. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the scheme and core ideas of the present application. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the scope of protection of the present application.

Claims

1. A method for preparing a mercury cadmium telluride infrared detector, characterized in that: include: preparing an ion-implanted HgCdTe wafer having a composite passivation layer distributed on the surface; The composite passivation layer comprises a first passivation layer and a second passivation layer stacked in a direction away from the surface of the mercury cadmium telluride wafer, the first passivation layer is a cadmium telluride layer, and the second passivation layer is a zinc sulfide layer; the mercury cadmium telluride wafer is obtained by forming a photoresist pattern for photolithography ion implantation on the surface of the mercury cadmium telluride wafer with the composite passivation layer, placing the mercury cadmium telluride wafer in an ion implanter for a boron ion implantation process, and removing the photoresist on the surface of the mercury cadmium telluride wafer after the implantation; removing the second passivation layer to obtain a processed mercury cadmium telluride wafer; Making a patterned photoresist on the surface of the treated mercury cadmium telluride wafer to obtain a re-treated mercury cadmium telluride wafer; The patterned photoresist includes a plurality of photoresist cylinders, each of which is located directly above the n-type region in the mercury cadmium telluride wafer; forming a new second passivation layer on the surface of the reprocessed mercury cadmium telluride wafer to obtain a mercury cadmium telluride wafer having a new composite passivation layer distributed on the surface; removing the patterned photoresist and forming a through hole in the new second passivation layer; Etching the first passivation layer and the mercury cadmium telluride wafer located below the through hole to form a contact hole; Electrodes are made in the contact holes to derive the electrical properties of the PN junction of the mercury cadmium telluride wafer, thereby obtaining a mercury cadmium telluride infrared detector.

2. The preparation method according to claim 1, characterized in that After forming a new second passivation layer on the surface of the reprocessed mercury cadmium telluride wafer, the method further comprises: A metal layer is formed on the surface of the new second passivation layer.

3. The preparation method according to claim 2, characterized in that: Removing the patterned photoresist and forming a through hole in the new second passivation layer comprises: removing the patterned photoresist and forming a through hole in the new second passivation layer and the metal layer; Etching the first passivation layer and the mercury cadmium telluride wafer located below the through hole to form a contact hole comprises: The metal layer is used as a mask, and the first passivation layer and the mercury cadmium telluride wafer located below the through hole are etched by dry etching to form a contact hole.

4. The preparation method according to claim 3, characterized in that: Etching the first passivation layer and the mercury cadmium telluride wafer located below the through hole by dry etching includes: The first passivation layer and the mercury cadmium telluride wafer located below the through hole are etched by inductively coupled plasma etching, wherein the etching bias voltage ranges from 10V to 20V.

5. The preparation method according to claim 2, characterized in that: Producing a metal layer on the surface of the new second passivation layer comprises: The metal layer is formed on the surface of the new second passivation layer by ion beam deposition, wherein the ion beam current ranges from 80 mA to 100 mA, and the ion beam voltage ranges from 400 V to 500 V.

6. The preparation method according to claim 2, characterized in that: Producing a metal layer on the surface of the new second passivation layer comprises: A chromium metal layer is formed on the surface of the new second passivation layer.

7. The preparation method according to claim 1, characterized in that: When the second passivation layer is a zinc sulfide layer, forming a new second passivation layer on the surface of the reprocessed mercury cadmium telluride wafer comprises: A zinc sulfide layer is formed on the surface of the reprocessed mercury cadmium telluride wafer by magnetron sputtering.

8. The preparation method according to claim 7, characterized in that: Removing the second passivation layer includes: The mercury cadmium telluride wafer is placed in a hydrochloric acid etching solution to etch and remove the second passivation layer.

9. The preparation method according to any one of claims 1 to 8, characterized in that: The electrodes are fabricated in the contact holes to obtain the electrical properties of the PN junction of the HgCdTe wafer, including: Depositing an electrode layer on the surface of the mercury cadmium telluride wafer having the contact hole; Making a patterned photoresist on the surface of the electrode layer; Using the patterned photoresist as a mask, etching the electrode layer to form an electrode; The patterned photoresist is removed.

10. A mercury cadmium telluride infrared detector, characterized in that: The mercury cadmium telluride infrared detector is prepared by the preparation method of the mercury cadmium telluride infrared detector according to any one of claims 1 to 9.

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