Wet etching method for chromium-nickel-gold special metal and prepared wafer

Abstract

The invention discloses a wet etching method for chromium-nickel-gold special metal and a wafer manufactured by the wet etching method, and belongs to the technical field of semiconductor device manufacturing processes, and the wet etching method comprises the following steps: evaporating Cr / Ni / Au on the front surface of the wafer to obtain the wafer with a Cr / Ni / Au film; sequentially carrying out metal Au photoetching, hardening, bottom film coating and metal Au wet etching on the wafer with the Cr / Ni / Au thin film to obtain a treated wafer; and sequentially carrying out hardening, metal Cr / Ni wet etching and dry photoresist removal on the treated wafer to obtain the wafer with the Cr / Ni / Au pattern. The problem that the existing Au / Cr / Ni three-layer composite metal is poor in corrosion morphology can be solved.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor device manufacturing process, and specifically relates to a wet etching method for chromium-nickel-gold special metal and a wafer obtained. Background Art

[0002] In the field of semiconductor manufacturing, metallization layers are key components for building interconnections between electronic devices. They are not only required to have excellent electrical conductivity, but also good mechanical and chemical stability to ensure that the performance and reliability of electronic equipment are not affected in complex and changing manufacturing environments and long-term service conditions. Au (gold), as a precious metal, occupies a pivotal position in the semiconductor industry due to its excellent corrosion resistance, high conductivity and relatively low melting point. Especially in high-end integrated circuits, Au is often used as a conductive material for bonding wires, contact pads and certain specific structures. Its good conductivity and chemical inertness are essential to ensure low-resistance connections and long-term reliability of circuits.

[0003] However, it is often difficult to form a satisfactory metal contact interface when Au is directly applied to Si (silicon)-based materials of semiconductor devices, which is mainly attributed to the poor adhesion and reactivity between Au and Si. In order to improve the bonding strength between the Au layer and the Si substrate, the industry generally adopts the method of depositing one or more layers of transition metals between Au and Si, among which Cr (chromium) and Ni (nickel) are the most commonly used transition metal materials due to their good adhesion and barrier properties. Cr can significantly improve the adhesion between the Au layer and the Si substrate, while Ni acts as a diffusion barrier layer to effectively prevent Au atoms from diffusing into Si, thereby protecting the Si substrate from potential metal contamination and performance degradation.

[0004] At present, when processing Cr / Ni / Au three-layer composite metal structures, it is often difficult to accurately control the corrosion rate and corrosion morphology, resulting in uneven corrosion of the Cr / Ni layer, which not only affects the adhesion of the Au layer, but also may cause defects such as circuit short circuit or open circuit due to corrosion residues, seriously affecting the performance and yield of semiconductor devices. In addition, inappropriate corrosion conditions may also trigger the formation of intermetallic compounds, further deteriorating the quality of the metal contact interface. Summary of the invention

[0005] The purpose of the present invention is to provide a wet etching method for chromium-nickel-gold special metal and a wafer obtained to solve the problem of poor corrosion morphology of the current Cr / Ni / Au three-layer composite metal.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: In a first aspect, a wet etching method for chromium-nickel-gold special metal comprises the following steps: S1: Cr / Ni / Au is evaporated on the front side of the wafer to obtain a wafer with a Cr / Ni / Au thin film; S2: performing metal Au photolithography, hardening, primer film and metal Au wet etching on the wafer with Cr / Ni / Au thin film in S1 in sequence to obtain a processed wafer; S3: The wafer processed in S2 is subjected to film hardening, metal Cr / Ni wet etching and dry stripping in sequence to obtain a wafer with a Cr / Ni / Au pattern.

[0007] In some embodiments, in S1, the evaporated thickness of Cr is 40 nm to 100 nm, the evaporated thickness of Ni is 60 nm to 100 nm, and the evaporated thickness of Au is 600 nm to 900 nm.

[0008] In some embodiments, in S2, the coating thickness of the photoresist in the metal Au photolithography is 1.7 μm to 2.4 μm.

[0009] In some embodiments, in S2, the temperature of the hardening film is 110° C. to 150° C., and the time of the hardening film is 25 min to 50 min.

[0010] In some embodiments, in S2, the metal Au wet etching uses a gold etching solution, the gold etching solution is prepared by mixing 50g~200g iodine and 200g~400g potassium iodide solution, and the temperature of the gold etching solution is 25°C~60°C.

[0011] In some implementations, in S2, the metal Au wet etching time is 20 sec to 60 sec.

[0012] In some embodiments, in S3, the temperature of the hardening film is 110° C. to 150° C., and the time of the hardening film is 25 min to 50 min.

[0013] In some embodiments, in S3, the metal Cr / Ni wet corrosion uses a chromium-nickel corrosion solution, and the chromium-nickel corrosion solution is prepared by dissolving 20g~500g of cerium sulfate in 300mL~600mL of nitric acid aqueous solution. The temperature of the chromium-nickel corrosion solution is 25°C~60°C, and the time of the metal Cr / Ni wet corrosion is 20sec~40sec.

[0014] In some embodiments, in S3, the dry stripping adopts plasma stripping, and the time of the dry stripping is 90 minutes to 120 minutes.

[0015] In a second aspect, a wafer having a Cr / Ni / Au pattern is obtained by using the wet etching method.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a wet etching method for chromium-nickel-gold special metals, wherein Cr / Ni / Au is first evaporated on the front side of a wafer, and then the wafer with a Cr / Ni / Au thin film is subjected to metal Au photolithography, hardening, primer film and metal Au wet etching in sequence, and then hardening, metal Cr / Ni wet etching and dry degumming are performed in sequence to obtain a wafer with a Cr / Ni / Au pattern. The method enables the Cr / Ni / Au three-layer metal to have a good corrosion morphology and can be used in the corrosion process of Cr / Ni / Au products. The metal covering holes of the Cr / Ni / Au three-layer metal after etching by the method are intact under microscopic inspection, the graphic lines are neat, there is no excess residue, and the side etching amount is less than 3μm.

[0017] Furthermore, the present invention can obtain a structurally stable Cr / Ni / Au film by evaporating Cr / Ni / Au of a specific thickness on the front side of the wafer, wherein the evaporation thickness of Cr is 40nm~100nm, the evaporation thickness of Ni is 60nm~100nm, and the evaporation thickness of Au is 600nm~900nm, which helps to ensure the stability of subsequent processes and the quality of finished products.

[0018] Furthermore, in S2, the coating thickness of the photoresist in the metal Au lithography is 1.7 μm~2.4 μm, which ensures the clarity and accuracy of the lithography pattern and reduces errors and defects in the lithography process.

[0019] Furthermore, in S2, the hardening temperature is 110° C. to 150° C., and the hardening time is 25 min to 50 min, which helps to enhance the adhesion between the photoresist and the wafer and improve the stability of the photolithography pattern.

[0020] Furthermore, in S2, the metal Au is wet-etched using a gold etching solution, which is prepared by mixing 50g~200g of iodine and 200g~400g of potassium iodide solution. The temperature of the gold etching solution is 25°C~60°C. By controlling the composition and temperature of the gold etching solution, the wet etching process of Au is ensured to be stable and controllable, and the unnecessary Au parts can be effectively removed in a short time, while protecting the photolithography pattern from damage.

[0021] Furthermore, in S2, the time of the metal Au wet etching is 20 sec to 60 sec to avoid excessive corrosion.

[0022] Furthermore, in S3, the temperature of the hardening film is 110° C. to 150° C., and the time of the hardening film is 25 min to 50 min, so as to enhance the adhesion between the photoresist and the wafer.

[0023] Furthermore, in S3, the metal Cr / Ni wet corrosion adopts a chromium-nickel corrosion solution, which is prepared by dissolving 20g~500g of cerium sulfate in 300mL~600mL of nitric acid aqueous solution, the temperature of the chromium-nickel corrosion solution is 25°C~60°C, and the metal Cr / Ni wet corrosion time is 20sec~40sec, ensuring that unnecessary Cr / Ni parts can be removed in a short time while maintaining the integrity and accuracy of the photolithography pattern.

[0024] Furthermore, in S3, dry stripping adopts plasma stripping, and the time of the dry stripping is 90 minutes to 120 minutes, which can effectively remove the photoresist residue on the wafer and avoid the pollution and damage caused by the traditional stripping method. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A flow chart of a wet etching method for nickel-chromium-gold special metal provided in an embodiment of the present invention; Figure 2 The SEM image of the Cr / Ni / Au three-layer metal corrosion morphology obtained for the embodiment of the present invention. DETAILED DESCRIPTION

[0026] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0027] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0028] In the present invention, unless otherwise specified, all the embodiments and preferred implementation methods mentioned herein can be combined with each other to form a new technical solution.

[0029] In the present invention, unless otherwise specified, all technical features and preferred features mentioned herein can be combined with each other to form a new technical solution.

[0030] In the present invention, unless otherwise specified, the components or preferred components involved can be combined with each other to form a new technical solution.

[0031] In the present invention, unless otherwise specified, the numerical range "a-b" represents an abbreviation of any combination of real numbers between a and b, wherein a and b are both real numbers.

[0032] The “range” disclosed in the present invention is in the form of a lower limit and an upper limit, which can be one or more lower limits, and one or more upper limits, respectively.

[0033] In the present invention, the term "and / or" used herein refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0034] In the present invention, unless otherwise specified, each reaction or operation step can be carried out sequentially or in accordance with the sequence. Preferably, the reaction method herein is carried out sequentially.

[0035] Unless otherwise specified, the professional and scientific terms used herein have the same meanings as those familiar to those skilled in the art. In addition, any method or material similar or equivalent to the described content may also be applied to the present invention.

[0036] The present invention will be further described below in conjunction with the accompanying drawings: like Figure 1 As shown, the present invention discloses a wet etching method for chromium-nickel-gold special metal, comprising the following steps: Step 1: Cr / Ni / Au is evaporated on the front side of the wafer to obtain a wafer with a Cr / Ni / Au thin film; Step 2: sequentially performing metal Au photolithography, hardening, primer film and metal Au wet etching on the wafer having the Cr / Ni / Au thin film obtained in step 1 to obtain a processed wafer; Step 3: The wafer processed in step 2 is subjected to hardening, metal CrNi wet etching and dry stripping in sequence to obtain a wafer with a Cr / Ni / Au pattern.

[0037] Preferably, in step 1, the evaporation thickness ranges of the three metal layers of Cr / Ni / Au are 40nm-100nm, 60nm-100nm, and 600nm-900nm, respectively.

[0038] Preferably, in step 2, the coating thickness of the photoresist for metal Au lithography is 1.7 μm to 2.4 μm, the temperature of the hardening film is 110° C. to 150° C., the time of the hardening film is 25 min to 50 min, and the metal Au wet etching adopts a gold etching solution, the gold etching solution is prepared by mixing 50 g to 200 g of iodine and 200 g to 400 g of potassium iodide solution, the temperature of the gold etching solution is 25° C. to 60° C., and the time of the metal Au wet etching is 20 sec to 60 sec.

[0039] Preferably, in step 3, the temperature of the hardening film is 110°C to 150°C, the time of the hardening film is 25min to 50min, the metal Cr / Ni wet corrosion adopts a chromium-nickel corrosion solution, the chromium-nickel corrosion solution is prepared by dissolving 20g to 500g of cerium sulfate in 300mL to 600mL of nitric acid aqueous solution, the temperature of the chromium-nickel corrosion solution is 25°C to 60°C, the time of the metal Cr / Ni wet corrosion is 20sec to 40sec, dry degumming adopts plasma degumming, and the time of the dry degumming is 90min to 120min.

[0040] Embodiment 1 A wet etching method for chromium-nickel-gold special metals comprises the following steps: Step 1: Cr / Ni / Au is evaporated on the front side of the wafer for metal layer preparation, and a wafer having Cr / Ni / Au thin films is obtained. The evaporation thickness of the three layers of Cr / Ni / Au metal is 55nm, 70nm, and 850nm, respectively. Step 2: The wafer with the Cr / Ni / Au film obtained in step 1 is subjected to metal Au photolithography, hardening, primer and metal Au wet etching in sequence to obtain a processed wafer, wherein the coating thickness of the photoresist for the metal Au photolithography is 2.4 μm, the hardening temperature is 150° C., the hardening time is 50 min, the metal Au wet etching adopts a gold etching solution, the gold etching solution is prepared by mixing 50 g of iodine and 200 g of potassium iodide solution, the etching solution temperature for the metal Au wet etching is 45° C., and the metal Au wet etching time is 60 sec; Step 3: The processed wafer obtained in step 2 is subjected to hardening, metal CrNi wet etching and dry stripping in sequence to obtain a wafer with a Cr / Ni / Au pattern, wherein the hardening temperature is 150°C, the hardening time is 30 minutes, the metal Cr / Ni wet etching adopts a chromium-nickel corrosion solution, and the chromium-nickel corrosion solution is prepared by dissolving 20g of cerium sulfate in 300mL of nitric acid aqueous solution, the temperature of the chromium-nickel corrosion solution is 50°C, the metal Cr / Ni wet etching time is 30 seconds, and the dry stripping adopts plasma stripping, and the dry stripping time is 120 minutes.

[0041] Embodiment 2 A wet etching method for chromium-nickel-gold special metals comprises the following steps: Step 1: Cr / Ni / Au is evaporated on the front side of the wafer for metal layer preparation, and a wafer having Cr / Ni / Au thin films is obtained. The evaporation thickness of the three layers of Cr / Ni / Au metal is 45nm, 75nm, and 800nm, respectively. Step 2: The wafer with the Cr / Ni / Au film obtained in step 1 is subjected to metal Au photolithography, hardening, primer and metal Au wet etching in sequence to obtain a processed wafer, wherein the coating thickness of the photoresist for the metal Au photolithography is 1.7 μm, the hardening temperature is 150° C., the hardening time is 50 min, the metal Au wet etching adopts a gold etching solution, the gold etching solution is prepared by mixing 130 g of iodine and 300 g of potassium iodide solution, the etching solution temperature for the metal Au wet etching is 50° C., and the metal Au wet etching time is 50 sec; Step 3: The processed wafer obtained in step 2 is subjected to hardening, metal CrNi wet etching and dry stripping in sequence to obtain a wafer with a Cr / Ni / Au pattern, wherein the hardening temperature is 150°C, the hardening time is 30 minutes, the metal Cr / Ni wet etching adopts a chromium-nickel corrosion solution, and the chromium-nickel corrosion solution is prepared by dissolving 50g of cerium sulfate in 450mL of nitric acid aqueous solution, the temperature of the chromium-nickel corrosion solution is 60°C, the metal Cr / Ni wet etching time is 25 seconds, and the dry stripping adopts plasma stripping, and the dry stripping time is 120 minutes.

[0042] Embodiment 3 A wet etching method for chromium-nickel-gold special metals comprises the following steps: Step 1: Cr / Ni / Au is evaporated on the front side of the wafer for metal layer preparation, and a wafer having Cr / Ni / Au thin films is obtained. The evaporation thickness of the three layers of Cr / Ni / Au metal is 55nm, 80nm, and 800nm, respectively. Step 2: The wafer with the Cr / Ni / Au film obtained in step 1 is subjected to metal Au photolithography, hardening, primer and metal Au wet etching in sequence to obtain a processed wafer, wherein the coating thickness of the photoresist for the metal Au photolithography is 1.7 μm, the hardening temperature is 130° C., the hardening time is 40 min, the metal Au wet etching adopts a gold etching solution, the gold etching solution is prepared by mixing 200 g of iodine and 400 g of potassium iodide solution, the etching solution temperature for the metal Au wet etching is 40° C., and the metal Au wet etching time is 50 sec; Step 3: The wafer processed in step 2 is subjected to hardening, metal CrNi wet etching and dry stripping in sequence to obtain a wafer with a Cr / Ni / Au pattern, wherein the hardening temperature is 130°C, the hardening time is 30 minutes, the metal Cr / Ni wet etching adopts a chromium-nickel corrosion solution, and the chromium-nickel corrosion solution is prepared by dissolving 100g of cerium sulfate in 600mL of nitric acid aqueous solution, the temperature of the chromium-nickel corrosion solution is 25°C, the metal Cr / Ni wet etching time is 40 seconds, and the dry stripping adopts plasma stripping, and the dry stripping time is 120 minutes.

[0043] Embodiment 4 A wet etching method for chromium-nickel-gold special metals comprises the following steps: Step 1: Cr / Ni / Au is evaporated on the front side of the wafer for metal layer preparation, and a wafer having Cr / Ni / Au thin films is obtained. The evaporation thickness of the three layers of Cr / Ni / Au metal is 100nm, 100nm, and 900nm, respectively. Step 2: The wafer with the Cr / Ni / Au thin film obtained in step 1 is subjected to metal Au photolithography, hardening, primer and metal Au wet etching in sequence to obtain a processed wafer, wherein the coating thickness of the photoresist for the metal Au photolithography is 2.0 μm, the hardening temperature is 110° C., the hardening time is 25 min, the metal Au wet etching adopts a gold etching solution, the gold etching solution is prepared by mixing 50 g of iodine and 200 g of potassium iodide solution, the etching solution temperature for the metal Au wet etching is 25° C., and the metal Au wet etching time is 20 sec; Step 3: The wafer processed in step 2 is subjected to hardening, metal CrNi wet etching and dry stripping in sequence to obtain a wafer with a Cr / Ni / Au pattern, wherein the hardening temperature is 110°C, the hardening time is 25 minutes, the metal Cr / Ni wet etching adopts a chromium-nickel corrosion solution, and the chromium-nickel corrosion solution is prepared by dissolving 200g of cerium sulfate in 300mL of nitric acid aqueous solution, the temperature of the chromium-nickel corrosion solution is 40°C, the metal Cr / Ni wet etching time is 20 seconds, and the dry stripping adopts plasma stripping, and the dry stripping time is 90 minutes.

[0044] Embodiment 5 A wet etching method for chromium-nickel-gold special metals comprises the following steps: Step 1: Cr / Ni / Au is evaporated on the front side of the wafer for metal layer preparation, and a wafer having Cr / Ni / Au thin films is obtained. The evaporation thickness of the three layers of Cr / Ni / Au metal is 40nm, 60nm, and 600nm, respectively. Step 2: The wafer with the Cr / Ni / Au thin film obtained in step 1 is subjected to metal Au photolithography, hardening, primer and metal Au wet etching in sequence to obtain a processed wafer, wherein the coating thickness of the photoresist for the metal Au photolithography is 1.7 μm, the hardening temperature is 110° C., the hardening time is 30 min, the metal Au wet etching adopts a gold etching solution, the gold etching solution is prepared by mixing 50 g of iodine and 200 g of potassium iodide solution, the etching solution temperature for the metal Au wet etching is 60° C., and the metal Au wet etching time is 40 sec; Step 3: The wafer processed in step 2 is subjected to hardening, metal CrNi wet etching and dry stripping in sequence to obtain a wafer with a Cr / Ni / Au pattern, wherein the hardening temperature is 110°C, the hardening time is 50 minutes, the metal Cr / Ni wet etching adopts a chromium-nickel corrosion solution, and the chromium-nickel corrosion solution is prepared by dissolving 500g of cerium sulfate in 600mL of nitric acid aqueous solution, the temperature of the chromium-nickel corrosion solution is 40°C, the metal Cr / Ni wet etching time is 25 seconds, and the dry stripping adopts plasma stripping, and the dry stripping time is 116 minutes.

[0045] Embodiment 6 A wet etching method for chromium-nickel-gold special metals comprises the following steps: Step 1: Cr / Ni / Au is evaporated on the front side of the wafer for metal layer preparation, and a wafer having Cr / Ni / Au thin films is obtained. The evaporation thickness of the three layers of Cr / Ni / Au metal is 40nm, 60nm, and 600nm, respectively. Step 2: The wafer with the Cr / Ni / Au thin film obtained in step 1 is subjected to metal Au photolithography, hardening, primer and metal Au wet etching in sequence to obtain a processed wafer, wherein the coating thickness of the photoresist for the metal Au photolithography is 1.7 μm, the hardening temperature is 110° C., the hardening time is 30 min, the metal Au wet etching adopts a gold etching solution, the gold etching solution is prepared by mixing 50 g of iodine and 200 g of potassium iodide solution, the etching solution temperature for the metal Au wet etching is 60° C., and the metal Au wet etching time is 40 sec; Step 3: The wafer processed in step 2 is subjected to hardening, metal CrNi wet etching and dry stripping in sequence to obtain a wafer with a Cr / Ni / Au pattern, wherein the hardening temperature is 110°C, the hardening time is 50 minutes, the metal Cr / Ni wet etching adopts a chromium-nickel corrosion solution, and the chromium-nickel corrosion solution is prepared by dissolving 260 g of cerium sulfate in 350 mL of nitric acid aqueous solution, the temperature of the chromium-nickel corrosion solution is 40°C, the metal Cr / Ni wet etching time is 25 seconds, and the dry stripping adopts plasma stripping, and the dry stripping time is 116 minutes.

[0046] like Figure 2 As shown, after wet etching of Cr-Ni-Au in Example 3, microscopic examination shows that the metal covering holes on the surface are intact, the graphic lines are neat, there is no excess residue, and the side etching amount is less than 3 μm.

[0047] The above embodiment provides a wet etching method for chromium-nickel-gold special metals, by accurately controlling the evaporation thickness of the three layers of Cr / Ni / Au metal to be 40nm~100nm, 60nm~100nm, 600nm~900nm, and the coating thickness of the photoresist to be 1.7μm~2.4μm, and also controlling the composition, temperature, and corrosion time of the gold corrosion solution and the high nickel corrosion solution, so as to achieve a fine process of the corrosion process, ensure the uniformity and consistency of the corrosion process, avoid problems such as metal layer residue or excessive corrosion caused by uneven corrosion, thereby improving the manufacturing quality and yield of semiconductor devices. After the wafer is processed by this method, the adhesion between the Cr / Ni transition layer and the Au layer is significantly improved, and the impurities and residues that affect the adhesion are effectively removed, while retaining the good bonding interface between the Cr / Ni layer and the Au layer, thereby enhancing the adhesion of the metal layer. The method can avoid unnecessary chemical reactions of the metal layer during the corrosion process by precisely controlling the corrosion time and temperature and selecting a suitable corrosion solution, thereby reducing the generation of intermetallic compounds; the method can reduce the manufacturing cost of semiconductor devices by optimizing the corrosion process and reducing unnecessary material consumption. At the same time, since the method improves production efficiency and yield, it also further reduces the cost of unit products.

[0048] In summary, the present method has significant advantages over existing methods, including accurate control of the corrosion process, improving the adhesion of the metal layer, reducing the generation of intermetallic compounds, improving production efficiency and reducing costs. These advantages are mainly due to the accurate control of key parameters by the method, the optimized corrosion conditions and subsequent processing steps, and good repeatability and stability. First, by accurately controlling the evaporation thickness of the three-layer metal of Cr / Ni / Au and the coating thickness of the photoresist, the uniformity and consistency of the corrosion process are ensured, and the problems such as residual or excessive corrosion of the metal layer are effectively avoided, and the manufacturing quality and yield of semiconductor devices are significantly improved. Secondly, the method achieves fine control of the corrosion process by optimizing the composition, temperature and corrosion time of the corrosion solution, which not only improves the adhesion between the metal layers, but also effectively reduces the generation of intermetallic compounds, further improving the performance and reliability of semiconductor devices. Therefore, the wet corrosion method of chromium-nickel-gold special metal provided by the present invention shows significant advantages in accurately controlling the corrosion process, improving the adhesion of the metal layer, reducing the generation of intermetallic compounds, improving production efficiency and reducing costs.

[0049] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A wet etching method for chromium-nickel-gold special metals, characterized in that: The following steps are involved: S1: Cr / Ni / Au is evaporated on the front side of the wafer to obtain a wafer with a Cr / Ni / Au thin film; S2: performing metal Au photolithography, hardening, primer film and metal Au wet etching on the wafer with Cr / Ni / Au thin film in S1 in sequence to obtain a processed wafer; S3: The wafer processed in S2 is subjected to film hardening, metal Cr / Ni wet etching and dry stripping in sequence to obtain a wafer with a Cr / Ni / Au pattern.

2. The wet etching method of chromium-nickel-gold special metal according to claim 1, characterized in that: In S1, the evaporation thickness of Cr is 40nm~100nm, the evaporation thickness of Ni is 60nm~100nm, and the evaporation thickness of Au is 600nm~900nm.

3. The wet etching method for chromium-nickel-gold special metal according to claim 1, characterized in that: In S2, the coating thickness of the photoresist in the metal Au photolithography is 1.7 μm to 2.4 μm.

4. The wet etching method for chromium-nickel-gold special metal according to claim 1, characterized in that: In S2, the temperature of the hardening film is 110°C to 150°C, and the time of the hardening film is 25min to 50min.

5. The wet etching method for chromium-nickel-gold special metal according to claim 1, characterized in that: In S2, the metal Au wet etching adopts a gold etching solution, the gold etching solution is prepared by mixing 50g~200g of iodine and 200g~400g of potassium iodide solution, and the temperature of the gold etching solution is 25°C~60°C.

6. The wet etching method for chromium-nickel-gold special metal according to claim 1, characterized in that: In S2, the metal Au wet etching time is 20 sec to 60 sec.

7. The wet etching method for chromium-nickel-gold special metal according to claim 1, characterized in that: In S3, the temperature of the hardening film is 110° C. to 150° C., and the time of the hardening film is 25 min to 50 min.

8. The wet etching method for chromium-nickel-gold special metal according to claim 1, characterized in that: In S3, the metal Cr / Ni wet corrosion adopts a chromium-nickel corrosion solution, and the chromium-nickel corrosion solution is prepared by dissolving 20g~500g of cerium sulfate in 300mL~600mL of nitric acid aqueous solution. The temperature of the chromium-nickel corrosion solution is 25°C~60°C, and the metal Cr / Ni wet corrosion time is 20sec~40sec.

9. The wet etching method for chromium-nickel-gold special metal according to claim 1, characterized in that: In S3, the dry debonding adopts plasma debonding, and the time of the dry debonding is 90 minutes to 120 minutes.

10. A wafer having a Cr / Ni / Au pattern, characterized in that: The method is obtained by using the wet etching method described in any one of claims 1 to 9.

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