Preparation method of tellurium-cadmium-mercury infrared detector chip

Abstract

The invention discloses a preparation method of a tellurium-cadmium-mercury infrared detector chip, and the method comprises the steps: providing a substrate which comprises a photoelectric material layer; sequentially forming a passivation layer and a dielectric layer on the photoelectric material layer; etching the dielectric layer and the passivation layer to form a through hole, and exposing the photoelectric material layer; a metal layer is formed on one side of the photoelectric material layer of the substrate and covers the dielectric layer and the photoelectric material layer in the through hole, and the metal layer comprises a laminated structure of a first metal layer and a second metal layer; the metal layer is covered with patterned positive photoresist, dry etching is conducted on the metal layer through ICP etching equipment, and a patterned metal electrode is formed; and removing the dielectric layer outside the position corresponding to the patterned metal electrode to form the tellurium-cadmium-mercury infrared detector chip. The photoresist film can be prevented from remaining on the metal surface, the solution can be prevented from reacting with the metal, the risk of electric leakage of the passivation layer is reduced, and the conductivity effect of the metal layer is improved.

Description

Technical Field

[0001] This application relates to the technical field of infrared detectors, and particularly to a method for preparing a mercury cadmium telluride infrared detector chip. Background Art

[0002] With the continuous popularization and development of infrared applications, advanced infrared detection technologies require detectors to have higher spatial resolution and better target recognition capabilities. An infrared detector is an optoelectronic device that converts infrared radiation into an electrical signal. The photoelectric reaction occurs only on the photosensitive element, and the subsequent signal processing process only involves electronics technology. Therefore, an infrared detection chip is the core component of an infrared detector.

[0003] During the production process of an infrared detection chip, when etching the metal layer to form metal electrodes, the existing technology is to use a lift-off process. A mask layer such as photoresist is used to protect the parts that need to be retained, and then a specific chemical solution or physical method is used to strip the metal material on the photoresist, thereby obtaining the required pattern. In this way, solvent residues may cause certain damage to the substrate material, which in turn affects the product performance. Summary of the Invention

[0004] To solve the problems existing in the prior art, the present invention provides a method for preparing a mercury cadmium telluride infrared detector chip.

[0005] The present invention provides a method for preparing a mercury cadmium telluride infrared detector chip, including the steps of: providing a substrate including a photoelectric material layer; sequentially forming a passivation layer and a dielectric layer on the photoelectric material layer; etching the dielectric layer and the passivation layer to form a through hole, exposing the photoelectric material layer; forming a metal layer on one side of the photoelectric material layer of the substrate, covering the dielectric layer and the photoelectric material layer in the through hole, the metal layer including a stacked structure of a first metal layer and a second metal layer; covering the metal layer with a patterned positive photoresist, and performing dry etching on the metal layer using an ICP etching device to form a patterned metal electrode, wherein the power range of the ICP etching is 200 - 600 w, and the radio frequency range used for the dry etching is 10 - 100 w; removing the dielectric layer except for the position corresponding to the patterned metal electrode to form the mercury cadmium telluride infrared detector chip.

[0006] Optionally, the photoelectric material layer is a mercury cadmium telluride layer.

[0007] Optionally, the material of the passivation layer includes zinc sulfide.

[0008] Optionally, the material of the dielectric layer includes silicon dioxide.

[0009] Optionally, removing the dielectric layer except the position corresponding to the patterned metal electrode includes: under the coverage of the patterned metal electrode, etching the dielectric layer with a hydrofluoric acid solution to etch away the dielectric layer except the position corresponding to the patterned metal electrode.

[0010] Optionally, the material of the first metal layer is platinum, and the material of the second metal layer is chromium.

[0011] Optionally, the gases used in the dry etching include: Cl2, BCl3, Ar. Among them, the flow rate range of Cl2 is 5 - 10 sccm, the flow rate range of BCl3 is 1 - 3 sccm, and the flow rate range of Ar is 5 - 10 sccm.

[0012] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0013] A method for preparing a mercury cadmium telluride infrared detector chip provided by the present invention forms a dielectric layer on the passivation layer to prevent the metal layer from directly contacting the photoresist above the passivation layer, avoiding the residue of the photoresist film above the passivation layer on the metal surface and the reaction between the solution and the metal, and greatly improving the conductivity effect between the two metal layers of the mercury cadmium telluride infrared detector chip. Description of the Drawings

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present application. For those skilled in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0015] Figure 1 It is a schematic diagram of an intermediate structure in the formation process of preparing an infrared detection chip in the prior art;

[0016] Figure 2 It is a schematic flowchart of a method for preparing a mercury cadmium telluride infrared detector chip according to an embodiment of the present disclosure;

[0017] Figures 3 - 9 It is a schematic diagram of an intermediate structure in the formation process of a mercury cadmium telluride infrared detector chip according to an embodiment of the present invention. Detailed Description of the Embodiments

[0018] The following will describe the preferred embodiments of the present invention in more detail. Although the following describes the preferred embodiments of the present invention, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein.

[0019] In the present invention, unless otherwise stated, the orientation terms such as "upper" and "lower" generally refer to the upper and lower in the normal use state of the device, and "inner" and "outer" refer to the relative to the contour of the device. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first", "second", and "third" may explicitly or implicitly include one or more of such features. In the description of the present invention, the meaning of "a plurality" is two or more, unless otherwise specifically defined. The present invention is an electrical device, so connection and interconnection both represent conductive interconnection. Since the drawings are descriptions of the same device, the same reference numerals in the drawings represent the same components.

[0020] As described in the background art, in the prior art, an infrared detection chip is prepared by a stripping process. The part to be retained is protected by a mask layer such as a photoresist, and then a specific chemical solution or physical method is used to strip the metal material on the photoresist. In this way, chemical reagents and solvent residues may cause certain damage to the substrate material. As Figure 1 shown, in the process of preparing an infrared detection chip in the prior art, a through hole is formed in the passivation layer 120 by a photolithography process, and a patterned metal electrode 140 is formed in the through hole. During the etching process, the through hole in the passivation layer 120 is easily contaminated by the solvent, and an oxide film is formed in the through hole. Subsequently, the oxide film in the through hole needs to be further processed. When the oxide film in the through hole is etched, it will affect the passivation layer 120 around the through hole, increasing the leakage risk. At the same time, during the formation of the metal electrode, the metal layer is easily in contact with the photoresist 160 on the surface of the passivation layer 120, thereby corroding the metal layer 140.

[0021] Therefore, the embodiments of the present disclosure provide a method for preparing a mercury cadmium telluride infrared detector chip, which can effectively solve the above problems and greatly improve the performance of the mercury cadmium telluride infrared detector chip.

[0022] The embodiments of the present disclosure provide a method for preparing a mercury cadmium telluride infrared detector chip, including the steps of: providing a substrate including a photoelectric material layer; sequentially forming a passivation layer and a dielectric layer on the photoelectric material layer; etching the dielectric layer and the passivation layer to form a through hole, exposing the photoelectric material layer; forming a metal layer on one side of the photoelectric material layer of the substrate, covering the dielectric layer and the photoelectric material layer in the through hole, the metal layer including a stacked structure of a first metal layer and a second metal layer; covering the metal layer with a patterned positive photoresist, and performing dry etching on the metal layer by using an ICP etching device to form a patterned metal electrode, wherein the power range of the ICP etching is 200 - 600 w, and the radio frequency range used for the dry etching is 10 - 100 w; removing the dielectric layer other than the position corresponding to the patterned metal electrode to form the mercury cadmium telluride infrared detector chip.

[0023] The specific examples of the present invention will be further described in detail below with reference to the accompanying drawings. Among them, substances not listed in detail in the embodiments can be optionally selected as any substances that can achieve the corresponding functions on the market.

[0024] This embodiment provides a method for preparing a mercury cadmium telluride infrared detector chip, and the specific steps are as Figure 2 shown Figures 3 to 9 FIG. is a schematic diagram of an intermediate structure in the formation process of a mercury cadmium telluride infrared detector chip according to an embodiment of the present disclosure. With reference to the accompanying drawings, the method for preparing the mercury cadmium telluride infrared detector chip includes the following steps:

[0025] S1: Provide a substrate, which includes a photoelectric material layer.

[0026] As Figure 3 shown, provide a substrate 100, and the substrate 100 includes a photoelectric material layer 110. In an embodiment of the present invention, the substrate 100 is a cadmium zinc telluride substrate, and the photoelectric material layer 110 is a mercury cadmium telluride layer.

[0027] S2: Sequentially form a passivation layer and a dielectric layer on the photoelectric material layer.

[0028] First, form a passivation layer 120 on the surface of the photoelectric material layer 110. The passivation layer 120 can be formed by thermal evaporation. As a protective layer of the refrigeration infrared detector device, it can avoid damage to the device surface in subsequent processes, which is beneficial to the better progress of subsequent processes. For example, the device surface will not be contaminated or damaged in subsequent processes. In an embodiment of the present invention, the material of the passivation layer 120 is preferably zinc sulfide.

[0029] After that, form a dielectric layer 130 on the surface of the passivation layer 120. As Figure 4 shown, in some embodiments, the dielectric layer 130 can be formed by plasma enhanced chemical vapor deposition. In an embodiment of the present invention, the material of the dielectric layer 130 is preferably silicon dioxide. During the subsequent metal etching process, the silicon dioxide film as the dielectric layer 130 is in direct contact with the metal layer of the mercury cadmium telluride infrared detector chip, preventing the metal layer from contacting the photoresist above the passivation layer, and avoiding the corrosion of the metal layer by the photoresist layer above the passivation layer.

[0030] S3: Etch the dielectric layer and the passivation layer to form a through hole, exposing the photoelectric material layer.

[0031] Refer to Figure 5, in an embodiment of the present invention, a positive first photoresist is spin-coated on the surface of the dielectric layer 130, and then exposed and developed to form a patterned first photoresist layer. Then, relying on the shielding of the patterned first photoresist layer, the dielectric layer 130 and the passivation layer 120 are etched to form a via 131. After that, the first photoresist layer on the dielectric layer 130 is removed.

[0032] S4: A metal layer is formed on one side of the optoelectronic material layer of the substrate, covering the optoelectronic material layer in the dielectric layer and the via. The metal layer includes a stacked structure of a first metal layer and a second metal layer.

[0033] Specifically, as Figure 6 shown, using a thermal evaporation device, a first metal layer 141 is formed on the surface of the dielectric layer 130 and the optoelectronic material layer 110 in the via. Then, using a thermal evaporation device, a second metal layer 142 is formed on the surface of the first metal layer 141. The metal layer composed of the first metal layer 141 and the second metal layer 142 is used to form a metal electrode in the subsequent process.

[0034] In an embodiment of the present invention, the material of the first metal layer is preferably platinum, and the material of the second metal layer is preferably chromium.

[0035] S5: The metal layer is covered with a patterned positive photoresist, and the metal layer is dry-etched using an ICP etching device to form a patterned metal electrode. The power range of the ICP etching is 200 - 600 w, and the radio frequency range used for the dry etching is 10 - 100 w.

[0036] Specifically, first, a second photoresist is spin-coated on the second metal layer 142. The second photoresist is a positive photoresist, and then it is exposed and developed to form a patterned second photoresist layer 150, specifically referring to the structure shown in Figure 7 shown. Then, through the coverage of the patterned second photoresist, the second metal layer 142 and the first metal layer 141 are etched to form a patterned metal electrode 140, and the patterned second photoresist 150 is removed, as shown in Figure 8 shown. By protecting the patterned metal electrode 140 area with the patterned second photoresist 150, during the process of etching the excess metal layer using the lithography process, the optoelectronic material layer 110 is not easily in contact with the photoresist developing solvent, avoiding contamination of the prepared mercury cadmium telluride infrared detector chip. At the same time, by protecting the patterned metal electrode area with the patterned second photoresist, it is not easy to form an oxide film in the second via formed in the passivation layer, and there is no risk of leakage around the passivation layer via.

[0037] In some embodiments, when using a dry etching process, in the ICP etching process, the power range of the ICP etching is 200 - 600 w, the radio frequency range used for dry etching the first metal layer and the second metal layer is 10 - 100 w, and the pressure range used for dry etching the first metal layer and the second metal layer is 1 - 10 pa.

[0038] Preferably, in an embodiment of the present invention, when forming a metal electrode using a dry etching process, the power of the ICP etching used is 400 w, the radio frequency used is 60 w, and the pressure used is 6 pa.

[0039] In some embodiments, the gases used for the dry etching include: Cl2, BCl3, Ar. Among them, the flow rate range of Cl2 is 5 - 10 sccm, the flow rate range of BCl3 is 1 - 3 sccm, and the flow rate range of Ar is 5 - 10 sccm. In an embodiment of the present invention, the flow rate of Cl2 is preferably 8 sccm, the flow rate of BCl3 is preferably 2 sccm, and the flow rate of Ar is preferably 8 sccm.

[0040] S6: Remove the dielectric layer except for the position corresponding to the patterned metal electrode to form the mercury cadmium telluride infrared detector chip.

[0041] In some embodiments, the removal of the dielectric layer except for the position corresponding to the patterned metal electrode includes: under the coverage of the patterned metal electrode, using a hydrofluoric acid solution to etch the dielectric layer, and etching away the dielectric layer except for the position corresponding to the patterned metal electrode.

[0042] Specifically, in an embodiment of the present invention, as Figure 9 shown, use a hydrofluoric acid solution to etch away the dielectric layer 130 except for the position corresponding to the patterned metal electrode, and remove the dielectric layer 130 except for the position corresponding to the patterned metal electrode to form the mercury cadmium telluride infrared detector chip.

[0043] The method for preparing the mercury cadmium telluride infrared detector chip provided by the present disclosure can effectively avoid the residue of the photoresist film on the metal surface and the reaction between the solution and the metal, and also avoid the risk of leakage of the passivation layer in the subsequent preparation process, which can greatly improve the conductivity effect of the contact between the two metals before and after.

[0044] The above are only the embodiments of the present application, and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the content of the specification and drawings of the present application, such as the mutual combination of technical features between embodiments, or direct or indirect application in other related technical fields, shall be equally included in the patent protection scope of the present application.

Claims

1. A method for preparing a mercury cadmium telluride infrared detector chip, characterized in that: The method comprises the steps of: providing a substrate comprising a photoelectric material layer; forming a passivation layer and a dielectric layer in sequence on the photoelectric material layer; Etching the dielectric layer and the passivation layer to form a through hole to expose the photoelectric material layer; Forming a metal layer on one side of the optoelectronic material layer of the substrate to cover the dielectric layer and the optoelectronic material layer in the through hole, wherein the metal layer includes a stacked structure of a first metal layer and a second metal layer; Covering the metal layer with a patterned positive photoresist, and dry-etching the metal layer with an ICP etching device to form a patterned metal electrode, wherein the power range of the ICP etching is 200-600w, and the radio frequency range used in the dry etching is 10-100w; The dielectric layer other than the position corresponding to the patterned metal electrode is removed to form the mercury cadmium telluride infrared detector chip.

2. The method for preparing a mercury cadmium telluride infrared detector chip according to claim 1, characterized in that: The photoelectric material layer is a mercury cadmium telluride layer.

3. The method for preparing the mercury cadmium telluride infrared detector chip according to claim 1, characterized in that: The material of the passivation layer includes zinc sulfide.

4. The method for preparing a mercury cadmium telluride infrared detector chip according to claim 1, characterized in that: The material of the dielectric layer includes silicon dioxide.

5. The method for preparing the mercury cadmium telluride infrared detector chip according to claim 4, characterized in that: The removing of the dielectric layer outside the position corresponding to the patterned metal electrode comprises: etching the dielectric layer with a hydrofluoric acid solution under the cover of the patterned metal electrode, and etching away the dielectric layer outside the position corresponding to the patterned metal electrode.

6. The method for preparing a mercury cadmium telluride infrared detector chip according to claim 1, characterized in that: The material of the first metal layer is platinum, and the material of the second metal layer is chromium.

7. The method for preparing a mercury cadmium telluride infrared detector chip according to claim 1, characterized in that: The gases used in the dry etching include: Cl2, BCl3, and Ar, wherein the flow rate range of Cl2 is 5-10 sccm, the flow rate range of BCl3 is 1-3 sccm, and the flow rate range of Ar is 5-10 sccm.

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