Multicolor cryogenic infrared detector and method of making same

Abstract

The application provides a polychromatic refrigeration infrared detector and a preparation method thereof, and is applied to the field of semiconductor technology. Specifically, a first epitaxial layer of mercury cadmium telluride (MCT) and a second epitaxial layer are respectively grown on a first cadmium zinc telluride (CZT) substrate and a second cadmium zinc telluride substrate, a first PN junction is formed on the second epitaxial layer of the second cadmium zinc telluride substrate, then the first epitaxial layer of the first cadmium zinc telluride substrate is bonded with the first PN junction formed on the second epitaxial layer of the second cadmium zinc telluride substrate, and a second PN junction is formed on the upper surface of the first epitaxial layer, so that the interconnection of the PN junctions on different cadmium zinc telluride substrates can be realized, and the PN junctions on the cadmium zinc telluride material substrate can be bonded through the bonding process, and the refrigeration infrared detector can be prepared, thereby providing a reference for the preparation of the refrigeration infrared detector.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a multicolor cooled infrared detector and its fabrication method. Background Technology

[0002] Since its discovery, infrared radiation has become increasingly well-known and plays a vital role in fields such as information technology and communications, healthcare and life sciences, defense and aerospace. The infrared spectrum is invisible to the human eye, with wavelengths ranging from 0.75 micrometers to 10 micrometers, falling between visible red light and microwaves. Based on wavelength, it can be divided into four categories: near-infrared, mid-infrared, far-infrared, and extreme far-infrared. With the continuous promotion and development of infrared applications, advanced infrared detection technology demands detectors with higher spatial resolution and better target recognition capabilities. Infrared detection technology is also developing towards higher resolution and multi-band capabilities. Dual-color infrared detection marks the beginning of multi-band detection, leading to the development of dual-color infrared detectors and even higher-color multi-color infrared detectors. Dual-color infrared detectors can process two-band radiation information, while higher-color multi-color infrared detectors can process multi-band radiation information with more than two bands. Multi-color infrared detectors, including dual-color infrared detectors, significantly improve the system's anti-interference and target recognition capabilities.

[0003] Currently, various fabrication processes have been developed in the research and manufacturing of multicolor infrared detectors. However, there is a lack of methods for arbitrarily combining different wavelengths of mercury cadmium telluride substrates to fabricate multicolor cooled infrared detectors, and methods for achieving low-temperature and room-temperature PN junction interconnection on mercury cadmium telluride substrates of different wavelengths. Summary of the Invention

[0004] The purpose of this invention is to provide a multicolor cooled infrared detector and its fabrication method, which uses a bonding process to bond PN junctions formed on epitaxial layers of mercury cadmium telluride (MDT) of different wavelength bands, so as to achieve interconnection of low-temperature and room-temperature PN junctions on MDT epitaxial layers of different wavelength bands, thereby fabricating a multicolor cooled infrared detector.

[0005] In a first aspect, to solve the above-mentioned technical problems, the present invention provides a multicolor cooled infrared detector and its preparation method, comprising:

[0006] S1, providing a first cadmium zinc telluride substrate with a first epitaxial layer formed on its surface and a second cadmium zinc telluride substrate with a second epitaxial layer formed on its surface;

[0007] S2, forming a first PN junction corresponding to at least one band in the second epitaxial layer, and bonding the first epitaxial layer and the second epitaxial layer face to face to form an integrated device;

[0008] S3, remove the first zinc cadmium telluride substrate to re-expose the first epitaxial layer, and form a second PN junction corresponding to at least another wavelength in the first epitaxial layer, wherein the second PN junction is offset from the first PN junction;

[0009] S4, forming electrodes for electrically drawing out the second PN junction and the first PN junction respectively, to obtain a multicolor cooled infrared detector.

[0010] Furthermore, before bonding the first epitaxial layer and the second epitaxial layer face to face, the fabrication method of the multicolor cooled infrared detector provided by the present invention may further include:

[0011] A first alignment mark is formed on the surface of the first epitaxial layer or in the first epitaxial layer, and / or a second alignment mark is formed on the surface of the second epitaxial layer or in the second epitaxial layer; during the bonding process, the first epitaxial layer and the second epitaxial layer are placed face to face according to the first alignment mark and / or the second alignment mark.

[0012] Furthermore, prior to the step of forming a first PN junction corresponding to at least one wavelength band in the second epitaxial layer, and bonding the first epitaxial layer and the second epitaxial layer face-to-face to form an integrated device, the fabrication method of the multicolor cooled infrared detector provided by the present invention may further include:

[0013] S2.1, a barrier layer is formed on the second epitaxial layer of the second zinc cadmium telluride substrate;

[0014] S2.2, perform photolithography and / or etching on the barrier layer to form an ion implantation opening in the barrier layer that exposes the second epitaxial layer;

[0015] S2.3, using the barrier layer as a mask, ion implantation is performed on the second epitaxial layer to form the first PN junction.

[0016] Furthermore, the step of forming a first PN junction corresponding to at least one wavelength band in the second epitaxial layer, and bonding the first epitaxial layer and the second epitaxial layer face to face, may specifically include:

[0017] S2.4, after the first PN junction is formed and before the bonding is performed, a first passivation layer is formed on the surface of the second epitaxial layer having the first PN junction;

[0018] S2.5, the first epitaxial layer is bonded to the first heterojunction PN junction formed on the second epitaxial layer of the second zinc cadmium telluride substrate using an adhesive material.

[0019] Furthermore, the step of forming a first PN junction corresponding to at least one wavelength band in the second epitaxial layer, and bonding the first epitaxial layer and the second epitaxial layer face to face, may specifically include:

[0020] S2.6, After the first PN junction is formed and before bonding is performed, a molten bonding layer is formed on the upper surface of the first PN junction;

[0021] S2.7, the first epitaxial layer of the first zinc cadmium telluride substrate and the first PN junction formed on the second epitaxial layer of the second zinc cadmium telluride substrate are bonded through the fused bonding layer;

[0022] Alternatively, in step S2, the bonding step may specifically include:

[0023] S2.8, After the first PN junction is formed and before bonding is performed, an organic material layer is formed on the upper surface of the first PN junction;

[0024] S2.9, using an adhesive material and passing through the organic material layer, the first epitaxial layer of the first zinc cadmium telluride substrate and the first PN junction formed on the second epitaxial layer of the second zinc cadmium telluride substrate are bonded together.

[0025] Furthermore, the material of the fused bonding layer can be silicon dioxide and / or silicon nitride, and the thickness of the fused bonding layer can be 1µm to 5µm.

[0026] Furthermore, after S3 and before S4, an aperture etching is performed on the surface of the first epitaxial layer facing away from the second epitaxial layer to expose the first alignment mark and / or the second alignment mark.

[0027] Furthermore, in step S4, the step of forming electrodes for electrically drawing out the second PN junction and the first PN junction, respectively, may include:

[0028] A second passivation layer is formed on the surface of the first epitaxial layer;

[0029] The film layer above the second PN junction and the film layer above the first PN junction are opened by two opening processes to form contact holes that expose the second PN junction and contact holes that expose the first PN junction.

[0030] The inner surface of each of the contact holes and a portion of the first epitaxial layer surrounding the contact holes are metallized to form metal interconnects;

[0031] Metal pillars are grown at corresponding locations on the metal interconnects to form electrodes for electrically drawing out the second PN junction and electrically drawing out the first PN junction, respectively.

[0032] Furthermore, the band may include short waves with wavelengths of 1µm to 3µm, or the band may include medium waves with wavelengths of 3µm to 6µm, or the band may include long waves with wavelengths of 6µm to 15µm.

[0033] In a second aspect, the present invention provides a multicolor cooled infrared detector, comprising:

[0034] A second zinc cadmium telluride substrate, wherein a second epitaxial layer and a first epitaxial layer bonded face-to-face with the second epitaxial layer are sequentially formed on the second zinc cadmium telluride substrate;

[0035] The first PN junction is located in the second epitaxial layer and corresponds to at least one wavelength band;

[0036] The second PN junction is located in the first epitaxial layer and corresponds to at least another band. The second PN junction is offset from the first PN junction.

[0037] Electrodes are located on the electrical surfaces of the first PN junction and the second PN junction, and are used to electrically lead out the first PN junction and the second PN junction, respectively.

[0038] Compared with the prior art, the technical solution provided by the present invention has at least one of the following beneficial effects:

[0039] In the method for fabricating a multicolor cooled infrared detector provided by this invention, a first epitaxial layer and a second epitaxial layer are grown on a first zinc cadmium telluride (CdT) substrate and a second CdT substrate, respectively. A first PN junction is formed on the second epitaxial layer of the second CdT substrate. Then, the first epitaxial layer of the first CdT substrate and the first PN junction formed on the second epitaxial layer of the second CdT substrate are bonded together. A second PN junction is then formed on the upper surface of the first epitaxial layer. This allows for the interconnection of PN junctions of different mercury cadmium telluride (MCH) epitaxial layers. Furthermore, by bonding the PN junctions on the MCH material using a bonding process, a cooled infrared detector can be fabricated, thus providing a valuable reference for the fabrication of cooled infrared detectors.

[0040] Furthermore, in the fabrication method of the multicolor cooled infrared detector provided by the present invention, after forming the first PN junction and before bonding, a first passivation layer is formed on the upper surface of the first PN junction, which can improve the hole isolation effect between the first PN junction and the first epitaxial layer. In addition, after forming the second PN junction and before two aperture etchings, a second passivation layer is formed on the upper surface of the integrated device after forming the second PN junction, which can prevent leakage current from occurring on the surface of the second PN junction. Attached Figure Description

[0041] Figure 1 This is a schematic flowchart of a method for preparing a multicolor cooled infrared detector according to an embodiment of the present invention;

[0042] Figures 2a to 2g This is a schematic diagram of the fabrication process of a multicolor cooled infrared detector according to an embodiment of the present invention.

[0043] The accompanying figure is labeled as follows:

[0044] 100 - First cadmium zinc telluride substrate; 200 - Second cadmium zinc telluride substrate;

[0045] 110 - First outer mercury cadmium telluride epitaxial layer; 210 - Second outer mercury cadmium telluride epitaxial layer;

[0046] 210n - First PN junction; 110n - Second PN junction;

[0047] 220 - First passivation layer; 230 - Third passivation layer;

[0048] 240 - Metal interconnect; 250 - Electrode;

[0049] 101 - An opening formed after etching the location of the first alignment mark A and / or the second alignment mark B;

[0050] 102 - Exposes the contact hole of the second PN junction 110n;

[0051] A - First alignment mark; B - Second alignment mark. Detailed Implementation

[0052] As described in the background section, various fabrication methods have been developed in the research and manufacturing of multicolor infrared detectors. However, there is a lack of methods for arbitrarily combining different wavelengths of cadmium zinc telluride substrates to fabricate multicolor cooled infrared detectors, and methods for achieving low-temperature and room-temperature PN junction interconnection on cadmium zinc telluride substrates of different wavelengths.

[0053] To this end, the present invention provides a multicolor cooled infrared detector and its fabrication method, which uses a bonding process to bond PN junctions formed on cadmium zinc telluride substrates of different wavelengths to achieve low-temperature and room-temperature interconnection of PN junctions on mercury cadmium telluride epitaxial layers of different wavelengths, thereby fabricating a multicolor cooled infrared detector.

[0054] refer to Figure 1 , Figure 1 This is a flowchart illustrating a method for fabricating a multicolor cooled infrared detector according to an embodiment of the present invention. The method includes the following steps:

[0055] Step S1: Provide a first cadmium zinc telluride substrate with a first epitaxial layer formed on its surface and a second cadmium zinc telluride substrate with a second epitaxial layer formed on its surface.

[0056] Step S2: A first PN junction corresponding to at least one band is formed in the second epitaxial layer, and the first epitaxial layer and the second epitaxial layer are bonded face to face to form an integrated device;

[0057] Step S3: Remove the first zinc cadmium telluride substrate to re-expose the first epitaxial layer, and form a second PN junction corresponding to at least another wavelength in the first epitaxial layer, wherein the second PN junction is offset from the first PN junction.

[0058] Step S4: Form electrodes for electrically drawing out the second PN junction and electrically drawing out the first PN junction, respectively, to obtain a multicolor cooled infrared detector.

[0059] Specifically, this invention provides a method for fabricating a multicolor cooled infrared detector. Specifically, a first epitaxial layer and a second epitaxial layer are grown on a first zinc cadmium telluride (CdT) substrate and a second CdT substrate, respectively. A first PN junction is formed on the second epitaxial layer of the second CdT substrate. Then, the first epitaxial layer on the first CdT substrate and the first PN junction formed on the second epitaxial layer of the second CdT substrate are bonded together. A second PN junction is then formed on the upper surface of the first epitaxial layer, thereby enabling the interconnection of PN junctions on different mercury cadmium telluride (MCH) epitaxial layers. Furthermore, by bonding the PN junctions on the MCH substrate using a bonding process, a cooled infrared detector can be fabricated, thus providing a valuable reference for the fabrication of cooled infrared detectors.

[0060] The preparation method of the multicolor cooled infrared detector proposed in this invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of this invention will become clearer from the following description. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of this invention.

[0061] Figures 2a to 2g This is a schematic diagram of the fabrication process of a multicolor cooled infrared detector according to an embodiment of the present invention.

[0062] In step S1, please refer to the following for details. Figure 2aAs shown, a first cadmium zinc telluride substrate 100 with a first epitaxial layer 110 formed on its surface and a second cadmium zinc telluride substrate 200 with a second epitaxial layer 210 formed on its surface are provided. In this embodiment of the invention, both the first cadmium zinc telluride substrate 100 and the second cadmium zinc telluride substrate 200 can be CZT material substrates, and can also be at least one of other materials such as germanium, silicon germanide, silicon carbide, gallium arsenide, or indium gallium dichromate. Furthermore, the material of the first epitaxial layer 110 and the second epitaxial layer 210 can be mercury cadmium telluride (MCT).

[0063] In this embodiment, a first cadmium zinc telluride substrate 100 and a second cadmium zinc telluride substrate 200 made of cadmium zinc telluride material can be provided firstly. Then, a thin film process, such as epitaxial growth process MBE or LPE process, is used to form a first epitaxial layer 110 of a certain thickness on the surface of the first cadmium zinc telluride substrate 100 and a second epitaxial layer 210 on the surface of the second cadmium zinc telluride substrate 200.

[0064] In step S2, please refer to the following for details. Figures 2b to 2e As shown, a first PN junction 210n corresponding to at least one band is formed in the second epitaxial layer 210, and the first epitaxial layer 110 and the second epitaxial layer 210 are bonded face to face to form an integrated device.

[0065] The band may include short waves with wavelengths of 1µm to 3µm, or medium waves with wavelengths of 3µm to 6µm, or long waves with wavelengths of 6µm to 15µm.

[0066] In this embodiment, after forming the epitaxial layers 110 and 210, the second epitaxial layer 210 can be subjected to photolithography and / or etching processes to form an NPN structure (or PNP structure) for a multicolor cooled infrared detector in the second epitaxial layer 210. Specifically, since the present invention forms a multicolor cooled infrared detector, the first PN junction 210n formed in the second epitaxial layer 210 corresponds to a different wavelength band than the second PN junction 110n formed in the first epitaxial layer 110 in subsequent steps, so as to achieve the requirement of not blocking light. The PN junction can be at least one of NonP, PonN, PIN, etc. The present invention can be any two different optoelectronic devices that can be freely combined using mature adhesive / bonding processes to realize dual-color or multicolor devices with different wavelengths and applications.

[0067] For details, see Figure 2b As shown, in this embodiment of the invention, a method for forming the first PN junction 210n is provided, specifically including the following steps:

[0068] Step S2.1: A barrier layer (not shown) is formed on the second epitaxial layer 210 of the second zinc cadmium telluride substrate 200;

[0069] Step S2.2: Photolithography is performed on the barrier layer to form an ion implantation opening (not shown) in the barrier layer that exposes the second epitaxial layer 210;

[0070] Step S2.3: Using the barrier layer as a mask, ion implantation is performed on the second epitaxial layer 210 to form the first PN junction 210n.

[0071] In this embodiment, the material of the barrier layer can be at least one of zinc sulfide, cadmium telluride, silicon dioxide, or silicon nitride. Furthermore, after step S2.3, in which the barrier layer is used as a mask to perform ion implantation on the second epitaxial layer 210 to form the first PN junction 210n, the etched barrier layer can be removed.

[0072] For further details, please refer to [link / reference]. Figure 2c As shown, in order to facilitate the accurate bonding of the first zinc-cadmium telluride substrate 100 and the second zinc-cadmium telluride substrate 200 together, this embodiment of the invention also proposes to first form alignment marks on the first epitaxial layer 110 and the second epitaxial layer 210 respectively, and then determine the accuracy of the bonding of the two zinc-cadmium telluride substrates based on whether the formed alignment marks are aligned. Specifically, this may include the following steps:

[0073] A first alignment mark A is formed on the surface of the first epitaxial layer 110 or in the first epitaxial layer 110, and / or a second alignment mark B is formed on the surface of the second epitaxial layer 210 or in the second epitaxial layer 210; during the bonding process, the first epitaxial layer 110 and the second epitaxial layer 210 are placed face to face according to the first alignment mark A and / or the second alignment mark B.

[0074] In this embodiment, a patterned photoresist layer (not shown) can be formed on the surface of the second epitaxial layer 210, wherein the pattern is an overlay mark pattern. Then, the patterned photoresist layer is exposed and developed to form the second alignment mark B on the surface of the second epitaxial layer 210. Similarly, the first alignment mark A can also be formed in the first epitaxial layer 110. This is prior art, and the present invention will not describe it in detail.

[0075] After forming the first alignment mark A and the second alignment mark B respectively, the first epitaxial layer 110 and the second epitaxial layer 210 can be bonded face-to-face based on the two pairs of alignment marks formed. Specifically, the present invention provides a specific method for bonding the two, which may include the following steps:

[0076] Step S2.4, see details. Figure 2d As shown, after the first PN junction 210n is formed and before the bonding is performed, a first passivation layer 220 is formed on the surface of the second epitaxial layer 210 having the first PN junction 210n.

[0077] Step S2.5, see details. Figure 2e As shown, the first epitaxial layer 110 is bonded to the first PN junction 210n formed on the second epitaxial layer 210 of the second zinc cadmium telluride substrate 200 using an adhesive material.

[0078] In this embodiment, after the first PN junction 210n is formed and before bonding, a fused bonding layer (not shown) can be formed on the upper surface of the first PN junction 210n; then, the first epitaxial layer 110 of the first zinc cadmium telluride substrate 100 and the first PN junction 210n formed on the second epitaxial layer 210 of the second zinc cadmium telluride substrate 200 are bonded through the fused bonding layer.

[0079] The material of the fused bonding layer can be silicon dioxide and / or silicon nitride, and the thickness of the fused bonding layer can be 1µm to 5µm.

[0080] In this embodiment, when bonding the first epitaxial layer 110 and the second epitaxial layer 210, a silicon dioxide layer and / or a silicon nitride layer can be formed on the surface of both the first epitaxial layer 110 and the second epitaxial layer 210. Then, the two silicon dioxide layers and / or silicon nitride layers are transformed into a single film structure by means of melting, molecular diffusion, etc., thereby realizing the bonding of the first epitaxial layer 110 and the second epitaxial layer 210.

[0081] In this embodiment of the invention, a first epitaxial layer 110 and a second epitaxial layer 210 are first grown on a first zinc cadmium telluride substrate 100 and a second zinc cadmium telluride substrate 200, respectively. A first PN junction 210n is formed on the second epitaxial layer 210 of the second zinc cadmium telluride substrate 200. Then, the first epitaxial layer of the first zinc cadmium telluride substrate 100 is bonded to the first PN junction 210n formed on the second epitaxial layer 210 of the second zinc cadmium telluride substrate 200. A second PN junction 110n is then formed on the upper surface of the first epitaxial layer 110. This allows for the interconnection of PN junctions on different mercury cadmium telluride epitaxial materials. Furthermore, by bonding the PN junctions on the mercury cadmium telluride epitaxial materials using a bonding process, a cooled infrared detector can be fabricated, thus providing a reference value for the fabrication of cooled infrared detectors.

[0082] Alternatively, the present invention also provides a method for bonding the first epitaxial layer 110 and the second epitaxial layer 210 face-to-face, specifically including the following steps:

[0083] S2.8, After the first PN junction is formed and before bonding is performed, an organic material layer is formed on the upper surface of the first PN junction;

[0084] S2.9, using an adhesive material and passing through the organic material layer, the first epitaxial layer of the first zinc cadmium telluride substrate and the first PN junction formed on the second epitaxial layer of the second zinc cadmium telluride substrate are bonded together.

[0085] In this embodiment, organic adhesives and materials such as BCB / POB can be used to bond the first epitaxial layer 110 and the second epitaxial layer 210, or SiN SiO2 in a fusion state can be bonded to the substrate. The present invention does not specifically limit the specific bonding methods.

[0086] Furthermore, in the method for preparing the multicolor cooled infrared detector provided by the present invention, when bonding with adhesive material, after forming the first PN junction 210n and before bonding, a first passivation layer 220 is formed on the upper surface of the first PN junction 210n, which can improve the hole isolation effect between the first PN junction 210n and the first epitaxial layer 110.

[0087] In step S3, see details. Figure 2f As shown, the first zinc cadmium telluride substrate 100 is removed to re-expose the first epitaxial layer 110, and a second PN junction 110n corresponding to at least another wavelength band is formed in the first epitaxial layer 110, and the second PN junction 110n is offset from the first PN junction 210n.

[0088] In this embodiment, after removing the first zinc cadmium telluride substrate 100, a photoresist layer can be formed on the surface where the first epitaxial layer 110 is re-exposed. Then, photolithography and / or etching are performed on the photoresist layer to form a plurality of ion implantation openings that expose the first epitaxial layer 110. For example, the present invention forms three ion implantation openings. Then, an ion implantation process is performed on the photoresist layer containing the plurality of ion implantation openings that expose the first epitaxial layer 110 to form a second PN junction 110n corresponding to at least another wavelength in the first epitaxial layer 110.

[0089] Furthermore, such as Figure 2f As shown, after the second PN junction 110n in step S3, an aperture etching can be performed on the surface of the first epitaxial layer 110 facing away from the second epitaxial layer 210, at the location of the first alignment mark A and / or the second alignment mark B, as shown. Figure 2f As shown in 101, the first alignment mark A and / or the second alignment mark B are exposed.

[0090] In step S4, see details. Figure 2g As shown, electrodes are formed for electrically leading out the second PN junction 110n and the first PN junction 210n, respectively, to obtain a multicolor cooled infrared detector.

[0091] In this embodiment, after forming the second PN junction 110n in the first epitaxial layer 110 in step S3, a second passivation layer (not shown) can be formed on the surface of the first epitaxial layer 110; then, the film layer above the second PN junction 110n and the film layer above the first PN junction 210n are opened through a two-stage aperture process (wherein, by... Figure 2g It is understood that the thickness of the film layer above the second PN junction 110n is less than the thickness of the film layer above the first PN junction 210n, to form a contact hole 102 exposing the second PN junction 110n and a contact hole (not shown) exposing the first PN junction 210n; then a third passivation layer 230 of a certain thickness is formed on the inner surface of each contact hole and on the surface of the first epitaxial layer 110 around the contact hole to avoid the problem of interconnection of the subsequently formed electrodes; wherein, the third passivation layer 230 can be at least one of silicon dioxide, silicon nitride, or zinc sulfide. Afterwards, the inner surface of each contact hole and part of the first epitaxial layer 110 around the contact hole are metallized to form metal interconnects 240; and flip-flop interconnect metal pillars are grown at the corresponding positions of the metal interconnects 240 to form electrodes 250 for electrically leading out the second PN junction 110n and the first PN junction 210n, respectively.

[0092] The two-stage etching process may include: through-hole etching technology (TSV, TGV, etc.), inductively coupled plasma etching, and / or reactive ion etching.

[0093] In this embodiment, the electrodes formed on the upper surfaces of the exposed first alignment mark A and / or the second alignment mark B serve as the common electrodes of the multicolor cooled infrared detector provided by the present invention. Since the fabrication method of the multicolor cooled infrared detector provided by the present invention also forms a second passivation layer on the upper surface of the integrated device after the formation of the second PN junction 110n and before the two aperture etchings, leakage current can be prevented from occurring on the surface of the second PN junction 110n.

[0094] Furthermore, based on the fabrication method of the multicolor cooled infrared detector described above, the present invention also provides a multicolor cooled infrared detector, which specifically may include:

[0095] A second zinc cadmium telluride substrate 200, on which a second epitaxial layer 210 and a first epitaxial layer 110 bonded face-to-face with the second epitaxial layer are sequentially formed;

[0096] The first PN junction 210n is located in the second epitaxial layer 210 and corresponds to at least one wavelength band;

[0097] The second PN junction 110n is located in the first epitaxial layer 110 and corresponds to at least another band. The second PN junction 110n is offset from the first PN junction 210n.

[0098] Electrode 240 is located on the electrical surfaces of the first PN junction 210n and the second PN junction 110n, and is used to electrically lead out the first PN junction 210n and the second PN junction 110n, respectively.

[0099] In summary, the fabrication method of the multicolor cooled infrared detector provided by this invention involves growing a first epitaxial layer and a second epitaxial layer on a first zinc cadmium telluride (CdT) substrate and a second CdT substrate, respectively, and forming a first PN junction on the second epitaxial layer of the second CdT substrate. Then, the first epitaxial layer on the first CdT substrate and the first PN junction formed on the second epitaxial layer of the second CdT substrate are bonded together. A second PN junction is then formed on the upper surface of the first epitaxial layer, thereby enabling the interconnection of PN junctions of different CdT epitaxial layers. Furthermore, by bonding the PN junctions on the superlattice material substrate using a bonding process, a cooled infrared detector can be fabricated, thus providing valuable reference for the fabrication of cooled infrared detectors.

[0100] Furthermore, in the fabrication method of the multicolor cooled infrared detector provided by the present invention, after forming the first PN junction and before bonding, a first passivation layer is formed on the upper surface of the first PN junction, which can improve the hole isolation effect between the first PN junction and the first epitaxial layer. In addition, after forming the second PN junction and before two aperture etchings, a second passivation layer is formed on the upper surface of the integrated device after forming the second PN junction, which can prevent leakage current from occurring on the surface of the second PN junction.

[0101] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of protection of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the scope of protection of the present invention.

[0102] It should be noted that although the present invention has been disclosed above with reference to preferred embodiments, these embodiments are not intended to limit the present invention. For any person skilled in the art, many possible variations and modifications can be made to the technical solutions of the present invention based on the disclosed technical content, or equivalent embodiments can be modified accordingly, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the present invention shall still fall within the scope of protection of the present invention.

[0103] In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, without necessarily requiring or implying any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0104] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A method for fabricating a multicolor cooled infrared detector, characterized in that, include: S1, providing a first cadmium zinc telluride substrate with a first epitaxial layer formed on its surface and a second cadmium zinc telluride substrate with a second epitaxial layer formed on its surface; S2, forming a first PN junction corresponding to at least one band in the second epitaxial layer, and bonding the first epitaxial layer and the second epitaxial layer face to face to form an integrated device; S3, remove the first zinc cadmium telluride substrate to re-expose the first epitaxial layer, and form a second PN junction corresponding to at least another wavelength in the first epitaxial layer, wherein the second PN junction is offset from the first PN junction; S4, forming electrodes for electrically drawing out the second PN junction and electrically drawing out the first PN junction respectively, to obtain a multicolor cooled infrared detector. In step S2, the bonding process specifically includes: After the first PN junction is formed and before the bonding is performed, a first passivation layer is formed on the surface of the second epitaxial layer having the first PN junction; The first epitaxial layer is bonded to the first PN junction formed on the second epitaxial layer of the second zinc cadmium telluride substrate using an adhesive material; Alternatively, in step S2, the bonding step specifically includes: After the first PN junction is formed and before bonding is performed, a molten bonding layer is formed on the upper surface of the first PN junction; The first epitaxial layer of the first zinc cadmium telluride substrate is bonded to the first PN junction formed on the second epitaxial layer of the second zinc cadmium telluride substrate through the fused bonding layer; Alternatively, in step S2, the bonding step specifically includes: After the first PN junction is formed and before bonding is performed, an organic material layer is formed on the upper surface of the first PN junction; The first PN junction formed on the first epitaxial layer of the first zinc cadmium telluride substrate and the second epitaxial layer of the second zinc cadmium telluride substrate is bonded using an adhesive material and through the organic material layer.

2. The method for preparing a multicolor cooled infrared detector as described in claim 1, characterized in that, Before bonding the first epitaxial layer and the second epitaxial layer face to face, the method further includes: A first alignment mark is formed on the surface of the first epitaxial layer or in the first epitaxial layer, and / or a second alignment mark is formed on the surface of the second epitaxial layer or in the second epitaxial layer; during the bonding process, the first epitaxial layer and the second epitaxial layer are placed face to face according to the first alignment mark and / or the second alignment mark.

3. The method for preparing a multicolor cooled infrared detector as described in claim 2, characterized in that, The method described in S2 further includes: A barrier layer is formed on the second epitaxial layer of the second zinc cadmium telluride substrate; The barrier layer is photolithographically etched to form an ion implantation opening in the barrier layer that exposes the second epitaxial layer; Using the barrier layer as a mask, ion implantation is performed on the second epitaxial layer to form the first PN junction.

4. The method for preparing a multicolor cooled infrared detector as described in claim 1, characterized in that, The material of the fused bonding layer is silicon dioxide and / or silicon nitride, and the thickness of the fused bonding layer is 1µm to 5µm.

5. The method for preparing a multicolor cooled infrared detector as described in claim 2, characterized in that, After S3 and before S4, an aperture etching is performed on the surface of the first epitaxial layer facing away from the second epitaxial layer to expose the first alignment mark and / or the second alignment mark.

6. The method for preparing a multicolor cooled infrared detector as described in claim 1, characterized in that, In step S4, the step of forming electrodes for electrically drawing out the second PN junction and the first PN junction respectively includes: A second passivation layer is formed on the surface of the first epitaxial layer; The film layer above the second PN junction and the film layer above the first PN junction are opened by two opening processes to form contact holes that expose the second PN junction and contact holes that expose the first PN junction. The inner surface of each of the contact holes and a portion of the first epitaxial layer surrounding the contact holes are metallized to form metal interconnects; Flip-bonded interconnect metal pillars are grown at corresponding locations on the metal interconnects to form electrodes for electrically leading out the second PN junction and electrically leading out the first PN junction, respectively.

7. The method for preparing a multicolor cooled infrared detector as described in claim 1, characterized in that, The band includes short waves with wavelengths of 1µm to 3µm, or medium waves with wavelengths of 3µm to 6µm, or long waves with wavelengths of 6µm to 15µm.

8. A multicolor cooled infrared detector prepared according to the preparation method of any one of claims 1 to 7, characterized in that, include: A second zinc cadmium telluride substrate, wherein a second epitaxial layer and a first epitaxial layer bonded face-to-face with the second epitaxial layer are sequentially formed on the second zinc cadmium telluride substrate; A first PN junction is located in the second epitaxial layer and corresponds to at least one wavelength band; a first passivation layer is formed on the surface of the second epitaxial layer of the first PN junction; The second PN junction is located in the first epitaxial layer and corresponds to at least another band. The second PN junction is offset from the first PN junction. Electrodes are located on the electrical surfaces of the first PN junction and the second PN junction, and are used to electrically lead out the first PN junction and the second PN junction, respectively.

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