Hole opening method for passivation layer of tellurium-cadmium-mercury chip

Abstract

The invention provides a HgCdTe chip passivation layer trepanning method comprising the following steps: a HgCdTe chip to be trepanned is provided, and the HgCdTe chip successively comprises a substrate, a HgCdTe material layer and a passivation layer; a patterned photoresist is arranged on the surface of the passivation layer; the passivation layer is etched by adopting a dry etching process to form a groove, and the depth of the groove is smaller than the thickness of the passivation layer; corroding the side wall of the groove and the passivation layer below the groove by adopting a wet etching process until the tellurium-cadmium-mercury material layer below the passivation layer is exposed; and removing the photoresist on the surface of the passivation layer. According to the hole opening method of the tellurium-cadmium-mercury chip passivation layer, the problem of hole opening corrosion expansion of the passivation layer can be effectively solved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular, to a method for opening holes in a passivation layer of a mercury cadmium telluride 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 only occurs 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] In the preparation of mercury cadmium telluride infrared devices, currently, for the passivation hole opening of mercury cadmium telluride chips, the ZnS passivation layer on the surface of the mercury cadmium telluride material is processed using a wet etching process. After etching is completed, metal coating is performed to form a good ohmic contact with the mercury cadmium telluride material. Since the wet etching process cannot complete operations with smaller sizes, and factors such as the compactness of ZnS, the uniformity of photoresist, and the concentration of the etching solution will all affect the pore size of the passivation layer hole opening, the passivation rework rate of the prepared mercury cadmium telluride infrared device products is high due to over-etching in the wet etching process. The prior art cannot solve this problem. Summary of the Invention

[0004] In order to solve the problems existing in the prior art, the present invention provides a method for opening holes in a passivation layer of a mercury cadmium telluride chip.

[0005] The present invention provides a method for opening holes in a passivation layer of a mercury cadmium telluride chip, including the steps of: providing a mercury cadmium telluride chip to be opened with holes, the mercury cadmium telluride chip sequentially including a substrate, a mercury cadmium telluride material layer, and a passivation layer; setting a patterned photoresist on the surface of the passivation layer; etching the passivation layer using a dry etching process to form a trench, the depth of the trench being less than the thickness of the passivation layer; etching the sidewalls and the underlying passivation layer of the trench using a wet etching process until the mercury cadmium telluride material layer under the passivation layer is exposed; removing the photoresist on the surface of the passivation layer.

[0006] Optionally, the passivation layer material includes ZnS.

[0007] Optionally, etching the passivation layer using the dry etching process includes: etching using an ICP etching device, wherein the etching power range of the ICP upper electrode is 50 - 600 w, the etching power range of the RF lower electrode is 5 - 300 w, and the chamber pressure range is 1 - 10 pa.

[0008] Optionally, the gas used in the dry etching includes: Ar, H 2 、CH 4 、N 2, wherein the flow rate range of Ar is 5 - 20 sccm, and the flow rate of H 2 is in the range of 1 - 50 sccm, and the flow rate of CH 4 is in the range of 1 - 50 sccm, and the flow rate of N 2 is in the range of 1 - 20 sccm.

[0009] Optionally, the dry etching process for etching the passivation layer includes: etching using an ICP etching equipment, wherein the etching power of the ICP upper electrode is 350 w, the etching power of the RF lower electrode is 80 w, and the chamber pressure is 2.5 pa.

[0010] Optionally, the gas used in the dry etching includes: Ar, H 2 , CH 4 , N 2 , wherein the flow rate of Ar is 30 sccm, the flow rate of H 2 is 3 sccm, the flow rate of CH 4 is 5 sccm, and the flow rate of N 2 is 3 sccm.

[0011] Optionally, the solution used for the wet etching is a mixed solution composed of HCl and H 2 O, wherein the ratio range of HCl to H 2 O is 20:1 - 1:50.

[0012] Optionally, the etching time range for the wet etching process is 1 - 10 seconds.

[0013] Optionally, the solution used for the wet etching is a mixed solution composed of HCl and H 2 O, wherein the ratio of HCl to H 2 O is 2:1.

[0014] Optionally, the etching time for the wet etching process is 3 seconds.

[0015] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0016] A method for opening holes in a passivation layer of a mercury cadmium telluride chip provided by the present invention first forms a groove at the position where the hole needs to be opened in the passivation layer through dry etching, which can effectively reduce the over-etching problem caused by directly forming the passivation layer hole by wet etching, and improve the uniformity of the passivation layer hole in the mercury cadmium telluride infrared device product; then uses wet etching to remove the passivation layer on the side wall and below the groove to form a passivation layer hole, solving the damage to the mercury cadmium telluride material caused by dry etching and improving the product quality. Description of the Drawings

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those skilled in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0018] Figure 1 It is a schematic flowchart of a method for opening holes in a passivation layer of a mercury cadmium telluride chip in an embodiment of the present invention;

[0019] Figure 2 It is a schematic diagram of the preparation process using the method for opening holes in the passivation layer of the mercury cadmium telluride chip in an embodiment of the present invention. Detailed implementation manners

[0020] 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 described herein.

[0021] In the present invention, unless otherwise stated, the orientation terms such as "upper, lower" usually refer to the upper and lower in the normal use state of the device, and "inner, outer" refer to the inside and outside relative to the contour of the device. In addition, the terms "first, second, third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined with "first, second, 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. Since the drawings are descriptions of the same device, the same reference numerals in the drawings represent the same components.

[0022] Currently, in the process of preparing mercury cadmium telluride chips, wet etching is usually used to form holes in the passivation layer. That is, the passivation layer on the surface of the mercury cadmium telluride material is processed by the wet etching process. After the etching is completed, metal coating is carried out. Since the wet etching process cannot complete operations with smaller sizes, and factors such as the compactness of the passivation layer material, the uniformity of the photoresist, and the concentration of the etching solution will all affect the aperture size of the holes in the passivation layer, the passivation rework rate of the prepared mercury cadmium telluride infrared device products is high due to over-etching in the wet etching process.

[0023] Therefore, the present invention provides a method for opening holes in a passivation layer of a mercury cadmium telluride chip, which can effectively solve the above problems and greatly improve the performance of the infrared detection chip.

[0024] The present invention provides a method for opening holes in a passivation layer of a mercury cadmium telluride chip, comprising the steps of: providing a mercury cadmium telluride chip to be opened with holes, the mercury cadmium telluride chip sequentially comprising a substrate, a mercury cadmium telluride material layer, and a passivation layer; disposing a patterned photoresist on the surface of the passivation layer; etching the passivation layer by a dry etching process to form a trench, the depth of the trench being less than the thickness of the passivation layer; etching the sidewalls and the underlying passivation layer of the trench by a wet etching process until the mercury cadmium telluride material layer underlying the passivation layer is exposed; and removing the photoresist on the surface of the passivation layer.

[0025] The following further elaborates on specific examples of the present invention with reference to the accompanying drawings. Among them, substances not detailed in the examples can be optionally selected as any substances on the market that can achieve the corresponding functions.

[0026] The present invention provides a method for opening holes in a passivation layer of a mercury cadmium telluride chip. In one embodiment, the specific steps are as Figure 1 shown, in combination with Figure 1 - Figure 2 , the method for opening holes in the passivation layer of the mercury cadmium telluride chip comprises the following steps:

[0027] S1: Provide a mercury cadmium telluride chip to be opened with holes, the mercury cadmium telluride chip sequentially comprising a substrate, a mercury cadmium telluride material layer, and a passivation layer.

[0028] Specifically, as Figure 2 shown, the mercury cadmium telluride chip 100 sequentially comprises a substrate 110, a mercury cadmium telluride material layer 120, and a passivation layer 130.

[0029] In some embodiments, the passivation layer material is ZnS.

[0030] S2: Dispose a patterned photoresist on the surface of the passivation layer.

[0031] In one embodiment of the present invention, as Figure 2 shown, a photoresist layer is spin-coated on the surface of the passivation layer 130, and after exposure and development under a mask plate, a patterned photoresist layer 140 is obtained.

[0032] S3: Etch the passivation layer by a dry etching process to form a trench, the depth of the trench being less than the thickness of the passivation layer.

[0033] After that, a dry etching process is used to etch the passivation layer 130 on the mercury cadmium telluride chip. The specific steps include: using the shielding of the patterned photoresist layer 140 to etch the passivation layer 130 on the mercury cadmium telluride chip, forming a trench 131 in the passivation layer 130. The dry etching does not etch through the passivation layer 130, and a part of the passivation layer 130 is reserved under the trench 131. Because the dry etching has good uniformity, using the dry etching process to etch away part of the passivation layer can reduce the time for wet etching to form an opening, improve the uniformity of the opening of the mercury cadmium telluride chip product, and can reduce the problem of over-etching of the passivation layer opening caused by factors such as the concentration of the etching solution during the formation of the passivation layer through-hole by wet etching.

[0034] In some embodiments, an ICP etching device can be used to etch the passivation layer of the mercury cadmium telluride chip. The etching power range of the ICP upper electrode can be 50 - 600w, the etching power range of the RF lower electrode can be 5 - 300w, and the chamber pressure range can be 1 - 10pa.

[0035] In an embodiment of the present invention, an ICP etching device is used to dry-etch the passivation layer of the mercury cadmium telluride chip. The etching power of the ICP upper electrode is 350w, the etching power of the RF lower electrode is 80w, and the chamber pressure is 2.5pa.

[0036] In some embodiments, the gas used in the dry etching may include: Ar, H 2 、CH 4 、N 2 Among them, the flow rate range of Ar is 5 - 20sccm, the flow rate range of H 2 is 1 - 50sccm, the flow rate range of CH 4 is 1 - 50sccm, and the flow rate range of N 2 is 1 - 20sccm.

[0037] Preferably, in an embodiment of the present invention, the gas used in the dry etching includes Ar, H 2 、CH 4 、N 2 Among them, the flow rate of Ar is 30sccm, the flow rate of H 2 is 3sccm, the flow rate of CH 4 is 5sccm, and the flow rate of N 2 is 3sccm.

[0038] S4: Use a wet etching process to etch the sidewalls and the underlying passivation layer of the trench until the mercury cadmium telluride material layer under the passivation layer is exposed.

[0039] In an embodiment of the present invention, the solution used in the wet etching is HCl and H 2A mixed solution composed of O is used to perform wet etching on the sidewalls of the trench 131 and the remaining passivation layer 130 below, as Figure 2 shown, etching the passivation layer on the sidewalls of the trench 131 and removing the remaining passivation layer 130 below the trench 131, exposing the mercury cadmium telluride material layer 120 below the passivation layer 130, and forming a through hole 132. Compared with completely forming an opening in the passivation layer by wet etching, in the technical solution of the present invention, a wet etching process is adopted after dry etching. Since the thickness to be etched is reduced, the time of wet etching and the amount of wet etching solution can be reduced, thereby improving the over-etching caused by wet etching solution corrosion; at the same time, by using the wet etching process to etch the passivation layer on the sidewalls and below of the trench, problems such as rough burrs and micro-grooves generated by the previous dry etching process in the passivation layer can be effectively avoided.

[0040] In some embodiments, the solution used for the wet etching is a mixed solution composed of HCl and H 2 O, where the ratio range of HCl and H 2 O is 20:1 - 1:50.

[0041] Preferably, in an embodiment of the present invention, the solution used for the wet etching is a mixed solution composed of HCl and H 2 O, where the ratio of HCl and H 2 O is 2:1.

[0042] In some embodiments, the etching time range of the wet etching process is 1 - 10 seconds.

[0043] Preferably, in an embodiment of the present invention, the etching time of the wet etching process is 3 seconds.

[0044] S5: Remove the photoresist on the surface of the passivation layer.

[0045] In some embodiments, a solvent stripping bath can be used to remove the photoresist 140 on the surface of the passivation layer, referring to Figure 2 , so as to form an opening in the passivation layer.

[0046] In Figure 2 the shown embodiment, the depth of the trench formed in the passivation layer by the dry etching process is less than the thickness of the passivation layer, that is, the dry etching process does not etch through the passivation layer. In different embodiments, the depth of the trench formed by etching the passivation layer using the dry etching process can be determined according to actual needs, and the present invention does not limit this.

[0047] A method for opening holes in a passivation layer of a mercury cadmium telluride chip provided by the present invention can effectively reduce the problem of over-etching caused by only using wet etching to form holes in the passivation layer by first using a dry etching process and then using a wet etching process, and reduce the problem of high passivation rework rate of the product due to over-etching of wet etching. At the same time, after dry etching, a wet etching process is used to etch the side wall and below of the through hole of the passivation layer, which also solves the problems of rough burrs, micro-grooves, material damage, etc. generated during dry etching of the passivation layer.

[0048] The above are only embodiments of the present application, and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present application, such as the mutual combination of technical features between various embodiments, or direct or indirect application in other related technical fields, are equally included in the patent protection scope of the present application.

Claims

1. A method for opening a hole in a passivation layer of a mercury cadmium telluride chip, characterized in that: Includes steps: Providing a mercury cadmium telluride chip to be opened, wherein the mercury cadmium telluride chip sequentially comprises a substrate, a mercury cadmium telluride material layer and a passivation layer; Disposing a patterned photoresist on the surface of the passivation layer; Etching the passivation layer using a dry etching process to form a groove, wherein the depth of the groove is less than the thickness of the passivation layer; Etching the sidewall of the trench and the passivation layer thereunder by a wet etching process until the mercury cadmium telluride material layer thereunder is exposed; The photoresist on the surface of the passivation layer is removed.

2. The method for opening a hole in a passivation layer of a mercury cadmium telluride chip according to claim 1, characterized in that: The passivation layer material includes ZnS.

3. The method for opening a hole in a passivation layer of a mercury cadmium telluride chip according to claim 1, characterized in that: The dry etching process for etching the passivation layer includes: etching with ICP etching equipment, wherein the etching power range of the ICP upper electrode is 50-600W, the etching power range of the RF lower electrode is 5-300W, and the chamber pressure range is 1-10Pa.

4. The method for opening a hole in a passivation layer of a mercury cadmium telluride chip according to claim 3, characterized in that: The gases used for the dry etching include: Ar, H2, CH4, and N2, wherein the flow rate range of Ar is 5-20 sccm, the flow rate range of H2 is 1-50 sccm, the flow rate range of CH4 is 1-50 sccm, and the flow rate range of N2 is 1-20 sccm.

5. The method for opening a hole in a passivation layer of a mercury cadmium telluride chip according to claim 3, characterized in that: The dry etching process for etching the passivation layer includes: etching with ICP etching equipment, wherein the etching power of the ICP upper electrode is 350W, the etching power of the RF lower electrode is 80W, and the chamber pressure is 2.5Pa.

6. The method for opening a hole in a passivation layer of a mercury cadmium telluride chip according to claim 5, characterized in that: The gases used in the dry etching include: Ar, H2, CH4, and N2, wherein the flow rate of Ar is 30 sccm, the flow rate of H2 is 3 sccm, the flow rate of CH4 is 5 sccm, and the flow rate of N2 is 3 sccm.

7. The method for opening a hole in a passivation layer of a mercury cadmium telluride chip according to claim 1, characterized in that: The solution used for the wet etching is a mixed solution of HCl and H2O, wherein the ratio of HCl to H2O is in the range of 20:1-1:

50.

8. The method for opening a hole in a passivation layer of a mercury cadmium telluride chip according to claim 7, characterized in that: The etching time range of the wet etching process is 1-10 seconds.

9. The method for opening a hole in a passivation layer of a mercury cadmium telluride chip according to claim 8, characterized in that: The solution used for the wet etching is a mixed solution of HCl and H2O, wherein the ratio of HCl to H2O is 2:

1.

10. The method for opening a hole in a passivation layer of a mercury cadmium telluride chip according to claim 9, characterized in that: The etching time of the wet etching process is 3 seconds.

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