Platinum electroplating solution, preparation method thereof and application of platinum electroplating solution in semiconductors

Abstract

The invention discloses a platinum electroplating solution as well as a preparation method and application thereof in a semiconductor. The platinum electroplating solution comprises the following raw materials: 0.5-10 g / L of platinum salt PEP, 15-35 g / L of ethylenediamine sulfate, 5.0-29 g / L of malonic acid, 5.0-40 g / L of ammonium acetate and the balance of ultrapure water and ammonia water. Adjusting the pH value of the platinum electroplating solution to 7.0 by using ammonia water; the method for preparing the coating comprises the following steps: S1, removing oil and acid from the semiconductor device to be processed; s2, corresponding electroplating conditions are selected, and a corresponding anode and an anode mask are configured; s3, electroplating is carried out; s4, automatically supplementing the platinum salt PEP solution in a linkage manner; s5, adjusting the pH value of the platinum electroplating solution; and S6, after the target coating thickness is reached or the preset electroplating time is reached, electroplating is stopped. The platinum metal film formed by the method has the advantages of excellent morphology, uniform distribution, high wear resistance and excellent compactness.

Description

Technical Field

[0001] The present invention relates to the field of electroplating technology, and particularly to a platinum electroplating solution, a preparation method thereof, and an application in semiconductors. Background Art

[0002] Semiconductor devices are important raw materials for integrated circuits. Electrochemical deposition of semiconductor devices is a special manufacturing technology in the nano-precision manufacturing process of semiconductor electronic components, and is the only key technology capable of realizing nano-scale electronic logic interconnection and the manufacturing and processing of micro-nano structures. Application fields include electroplating of semiconductor wafer chips, electroplating of semiconductor lead frames, electroplating of printed circuit boards, electroplating of connectors, microwave devices, and the manufacturing of other electronic components. It involves electrochemical deposition on the surface of semiconductor devices to form nano-scale metal films and microstructures.

[0003] In the microfabrication process on the surface of semiconductor devices, by applying an external current, metal ions in the electroplating solution, such as platinum ions, undergo an electrochemical reaction on the surface of the semiconductor device to form a platinum metal film. This method requires precise control of the uniform distribution, morphology, purity, and density of the platinum metal film in order to obtain high corrosion resistance, high-precision conductivity, and high-quality electronic signal transmission performance.

[0004] The miniaturization and multi-functionality of semiconductor electronic products continuously drive the development of integrated circuits towards finer circuit lines and smaller volumes. Its mainstream products are HDI (High Density Interconnect) boards and IC (Integrated Circuit) substrates. To meet the high-density and high-integration requirements of HDI and IC substrates, a nano-precision manufacturing technology for electronic electroplating has been developed in the semiconductor device manufacturing industry chain.

[0005] With the increasing demand for nano-precision manufacturing technology for electronic electroplating, it is particularly important to improve the electroplating process and continuously update the electroplating solution in the nano-precision manufacturing technology for electronic electroplating. High-end semiconductor device products have very strict requirements for the excellent density, high uniformity, and strong corrosion resistance in various harsh environments of the platinum metal coating. Meeting these requirements is an important technical indicator for measuring the manufacturing process of depositing nano-metal coatings on semiconductor devices.

[0006] So far, the existing platinum electroplating solutions can generally be divided into two major types, which are prepared from divalent platinum salts and tetravalent platinum salts.

[0007] Patent CN114752975 A discloses an acidic electroplating solution of divalent platinum salt that is extremely stable, has a long solution life, less impurity accumulation, and can be used for thick platinum plating. Using this electroplating solution, high-purity platinum-plated products with dense, high hardness, low stress, shiny, and good corrosion resistance can be processed and manufactured. So far, due to the stress of the coating electroplated from the acidic platinum electroplating solution, there have always been problems such as tiny pinholes and cracks in the platinum metal film, which seriously affect the wear resistance and insertion and extraction performance of the platinum coating.

[0008] Regarding the problems such as tiny pinholes and cracks in the platinum coating, the above patent has carried out comprehensive research work. Comparing the results of Examples 1-16 with those of Comparative Examples 1-3, the porosity is reduced from 30.6-35.1% to 8.5-13.8%. With the reduction of the porosity of the platinum coating, its corrosion resistance has been improved to a certain extent; however, obviously, its porosity range far from meets the requirements of strong wear resistance and excellent insertion and extraction performance necessary for semiconductor wafer electronic products.

[0009] Patent CN114016097 A discloses a platinum plating solution, its preparation method and application. A platinum plating solution, the preparation raw materials include: chloroplatinic acid hexahydrate and citrate; in the platinum plating solution, the concentration of citrate is 260-320 g / L. The platinum plating solution proposed by the present invention can form a platinum coating with uniform thickness and good appearance on the turbine blade by adjusting the types of platinum source and conductive salt, and the concentration of the conductive salt.

[0010] Patent CN114411215 A discloses a platinum electroplating solution and an electroplating method suitable for high-speed continuous electroplating. The platinum electroplating solution, calculated by mass concentration, contains: tetraammineplatinum sulfate 5-20 g / L, additive 20-60 g / L, and the additive is selected from one or more of fatty alcohol polyoxyethylene ether, sodium fatty alcohol polyoxyethylene ether sulfate, sodium dodecyl sulfate, and sodium o-sulfobenzaldehyde. The coating of the present invention has excellent hardness and corrosion resistance.

[0011] The above patents do not disclose any experimental data results regarding the purity, density, high wear resistance, excellent insertion and extraction performance, high-precision conductivity, and high-quality electronic signal transmission performance of the platinum coating.

[0012] In summary, in the field of platinum electroplating technology for semiconductor devices, there is an urgent need to find an electroplating solution and an electroplating equipment process solution to solve problems such as tiny pinholes and cracks in the platinum coating, especially to focus on solving the technical difficulty of the lack of wear resistance of the platinum coating and provide high-end semiconductor devices with excellent plug-and-play performance; it is expected to achieve that the obtained platinum coating has excellent uniform distribution, morphology, purity and compactness, meet the market demand for semiconductor device electronic products with excellent morphology, uniform distribution, high wear resistance and excellent compactness, and the produced semiconductor electronic products have excellent plug-and-play performance, corrosion resistance, high-precision conductivity and high-quality electronic signal transmission performance. Summary of the Invention

[0013] In view of the above problems existing in the prior art, the present invention provides a platinum electroplating solution, its preparation method and its application in semiconductors. The present invention can achieve precision manufacturing and processing of the nano-platinum coating on semiconductor electronic products. The formed platinum metal film has uniform distribution, morphology, compactness and high wear resistance, and the produced semiconductor electronic products have excellent plug-and-play performance, corrosion resistance, high-precision conductivity and high-quality electronic signal transmission performance.

[0014] The technical solution of the present invention is as follows: The first object of the present invention is to provide a platinum electroplating solution, which includes the following raw materials: 1.5 - 10 g / L of platinum salt PEP, 5 - 45 g / L of ethylenediamine sulfate, 5 - 29 g / L of malonic acid, 0.6 - 40 g / L of ammonium acetate, the balance being ultrapure water and ammonia water; the ammonia water adjusts the pH value of the platinum electroplating solution to 7.0; The structure of the platinum salt PEP is shown in formula (1): Formula (1).

[0015] The CAS number of the platinum salt PEP is: 41666-77-7.

[0016] In an embodiment of the present invention, the dosage of the platinum salt PEP is calculated as Pt.

[0017] In an embodiment of the present invention, the dosage of the platinum salt PEP is 1.5 - 9.5 g / L.

[0018] In an embodiment of the present invention, the dosage of the ethylenediamine sulfate is 5 - 35 g / L.

[0019] In an embodiment of the present invention, the dosage of the ethylenediamine sulfate is 15 - 35 g / L.

[0020] In an embodiment of the present invention, the dosage of the ethylenediamine sulfate is 25 g / L.

[0021] In one embodiment of the present invention, the amount of malonic acid used is 11~23 g / L.

[0022] In one embodiment of the present invention, the amount of malonic acid used is 17 g / L.

[0023] In one embodiment of the present invention, the amount of malonic acid used is 15 g / L.

[0024] In one embodiment of the present invention, the amount of ammonium acetate used is 20~30 g / L.

[0025] The second object of the present invention is to provide a method for preparing a coating using the above platinum electroplating solution, comprising the following steps: S1. Degrease and acid activate the semiconductor device to be processed; S2. Select corresponding electroplating conditions according to the electroplating area and form of the workpiece, and configure the corresponding anode and its anode mask; S3. Perform electroplating using the corresponding electrolytic power supply according to the workpiece; S4. During electroplating, regularly detect the platinum content in the platinum electroplating solution, and automatically add platinum salt PEP solution in linkage according to the difference between the test result and the standard concentration to maintain the platinum salt concentration in the electroplating solution; S5. During electroplating, regularly detect the pH value of the platinum electroplating solution, and add acid solution or alkali solution according to the difference between the test result and the set standard pH value of the solution; S6. After reaching the target coating thickness or the preset electroplating time, stop electroplating, and the semiconductor wafer completes the process of depositing a platinum coating.

[0026] In one embodiment of the present invention, in step S2, when electroplating with the platinum electroplating solution, the current density is 1.0~9.0 A / dm 2 , and the solution temperature is 45~55 °C.

[0027] In one embodiment of the present invention, in step S5, when the measured pH value is greater than 7, automatically add dilute sulfuric acid solution in linkage to lower the pH value to 7; when the measured pH value is less than 7, automatically add sodium hydroxide solution in linkage to raise the pH to 7.

[0028] In one embodiment of the present invention, in step S4, maintain the concentration of platinum salt PEP (calculated as Pt) in the electroplating solution at 1.5~10 g / L.

[0029] In one embodiment of the present invention, when automatically adding platinum salt PEP solution in S4, the ratio with the complexing agent ethylenediamine sulfate and the additive malonic acid is 1.5:25:17, that is, 1:16.6:11.3.

[0030] In one embodiment of the present invention, during the electroplating production process, as the platinum salt PEP is consumed, its concentration is periodically tested by an automatic analysis device, and then a platinum salt PEP component solution is automatically added in a linked manner. The prepared weight ratio of the automatically added platinum component solution is prepared as 1:16.6:11.3 and dissolved in 1000 mL of ultrapure water.

[0031] The third object of the present invention is to provide a coating prepared from the above platinum electroplating solution.

[0032] The fourth object of the present invention is to provide an application of the above platinum electroplating solution for preparing semiconductor device electronic products with a dense platinum coating, uniform film thickness distribution, and high purity.

[0033] The present invention detects the porosity of the platinum coating through a nitric acid vapor test to evaluate and determine the corrosion resistance of semiconductor device nanostructured electronic products.

[0034] Through the nitric acid vapor experiment of the platinum coating of the present invention, it is found by studying the ratio of the corroded area to the total area of the coating that the smaller the ratio of the corroded area of the platinum coating, the stronger the corrosion resistance of the platinum-plated product. Conversely, the larger the corroded area, the worse its corrosion resistance.

[0035] The present invention conducts a wear amount experiment on the platinum coating to evaluate and determine the friction resistance of semiconductor device nanostructured electronic products. From the mass wear amount of the platinum coating before and after the abrasion experiment, it can be seen that the smaller the difference value, the stronger its wear resistance.

[0036] The present invention conducts a plug-and-play experiment on semiconductor electronic products to evaluate and determine the friction resistance and plug-and-play performance of semiconductor device nanostructured electronic products. After conducting a plug-and-play experiment on a platinum-coated semiconductor electronic circuit board, its circuit impedance is tested. The smaller the impedance change value before and after the experiment, the better the plug-and-play performance of the platinum coating can be confirmed.

[0037] The beneficial technical effects of the present invention are as follows: The platinum salt PEP of the present invention has a five-membered and six-membered double-ring complex, ethylene diamine sulfate is used as a complexing agent for linear molecules with amino groups at both ends, malonic acid is used as an additive, and ammonium acetate is used as an electrolytic salt; by optimizing the platinum salt, complexing agent, and additive and controlling their optimal ratios, the present invention can achieve precise manufacturing and processing of the nano-platinum coating for semiconductor electronic products. The formed platinum metal film has uniform distribution, high wear resistance, and excellent denseness. The produced semiconductor electronic products have excellent plug-and-play performance, corrosion resistance, high-precision conductivity, and high-quality electronic signal transmission performance. Description of the Drawings

[0038] Figure 1 It is a coordinate diagram for measuring the film thickness of a semiconductor plating part; Figure 2Schematic diagram for expanding semiconductor device units; In the figure, 10 is a semiconductor plating, 11 is a semiconductor device unit, and 12 is a film thickness test point. Specific implementation mode

[0039] The present invention will be specifically described below with reference to the accompanying drawings and embodiments.

[0040] Testing method: In this embodiment, the semiconductor plating 10 is as Figure 1 shown, and platinum electroplating treatment is performed on one side of each semiconductor device unit 11 thereof.

[0041] The experimental piece of the semiconductor plating to be processed in this embodiment is as Figure 1 shown, made of copper alloy material with dimensions of 250×79.2 mm and a thickness of 0.127 mm; there are 96 semiconductor device units in total. The electroplating area of each unit is 0.5×10×7 = 35 mm 2 , so the total area of one side of a semiconductor plating is 96×35 mm 2 = 3360 mm 2 .

[0042] For electroplating, after the semiconductor plating 10 is subjected to alkaline degreasing and acid activation treatments, nickel bottom plating is performed with a nickel film thickness of 1300 - 700 nm; subsequently, a high-speed jet precision electroplating device is used, and the platinum electroplating solution in the embodiment is added to the mother tank of the electroplating device. During electroplating, the current density is 5.0 A / dm 2 , the bath temperature is 50°C, a positive and negative pulse power supply is used, and the plating is energized for 53 seconds. The target thickness of the platinum coating on the semiconductor plating 10 is set to 200 nm.

[0043] Testing of the platinum coating film thickness: Use the FISCHERSCOPE X-RAY XDV-SDD detector manufactured by Fischer to test according to Figure 2The black dots at the centers of the electroplating areas of each semiconductor device unit 11, i.e., the film thickness test points 12, have the following coordinates: for column I, 16 (10.0 mm, 6.5 mm), 15 (10.0, 24.0), 14 (10.0, 37.5), 13 (10.0, 55.5), 12 (10.0, 69.0), 11 (10.0, 87.0), 10 (10.0, 100.5), 9 (10.0, 118.0), 8 (10.0, 131.5), 7 (10.0, 149.0), 6 (10.0, 161.0), 5 (10.0, 178.5), 4 (10.0, 190.5), 3 (10.0, 208.0), 2 (10.0, 220.0), 1 (10.0, 237.5.0); for column II, 16 (22.0 mm, 6.5 mm), 15 (22.0, 24.0), 14 (22.0, 37.5), 13 (22.0, 55.5), 12 (22.0, 69.0), 11 (22.0, 87.0), 10 (22.0, 100.5), 9 (22.0, 118.0), 8 (22.0, 131.5), 7 (22.0, 149.0), 6 (22.0, 161.0), 5 (22.0, 178.5), 4 (22.0, 190.5), 3 (22.0, 208.0), 2 (22.0, 220.0), 1 (22.0, 237.5.0); for column III, 16 (34.0 mm, 6.5 mm), 15 (34.0, 24.0), 14 (34.0, 37.5), 13 (34.0, 55.5), 12 (34.0, 69.0), 11 (34.0, 87.0), 10 (34.0, 100.5), 9 (34.0, 118.0), 8 (34.0, 131.5), 7 (34.0, 149.0), 6 (34.0, 161.0), 5 (34.0, 178.5), 4 (34.0, 190.5), 3 (34.0, 208.0), 2 (34.0, 220.0), 1 (34.0, 237.5.0); for column IV, 16 (46.0 mm, 6.5 mm), 15 (46.0, 24.0), 14 (46.0, 37.5), 13 (46.0, 55.5), 12 (46.0, 69.0), 11 (46.0, 87.0), 10 (46.0, 100.5), 9 (46.0, 118.0), 8 (46.0, 131.5), 7 (46.0, 149.0), 6 (46.0, 161.0), 5 (46.0, 178.5), 4 (46.0, 190.5), 3 (46.0, 208.0), 2 (46.0, 220.0), 1 (46.0, 237.5.0); for column V, 16 (58.0 mm, 6.5 mm), 15 (58.0, 24.0), 14(58.0, 37.5), 13(58.0, 55.5), 12(58.0, 69.0), 11(58.0, 87.0), 10(58.0, 100.5), 9(58.0, 118.0), 8(58.0, 131.5), 7(58.0, 149.0) 6(58.0, 161.0), 5(58.0, 178.5), 4(58.0, 190.5), 3(58.0, 208.0), 2(58.0, 220.0), 1(58.0, 237.5.0); For column VI, 16(70.0mm, 6.5mm), 15(70.0, 24.0), 14(70.0, 37.5), 13(70.0, 55.5), 12(70.0, 69.0), 11(70.0, 87.0), 10(70.0, 100.5), 9(70.0, 118.0), 8(70.0, 131.5), 7(70.0, 149.0) 6(70.0, 161.0), 5(70.0, 178.5), 4(70.0, 190.5), 3(70.0, 208.0), 2(70.0, 220.0), 1(70.0, 237.5.0).

[0044] Analyze the Max, Min, Ave., Max - Min of the platinum plating film thickness data and the film thickness error value.

[0045] The calculation formula for the platinum film thickness error is as follows.

[0046]

[0047] Appearance inspection of platinum - plated semiconductor device products: For appearance inspection, observe with a 40 - fold optical microscope and a 5000 - fold magnification electron microscope, and judge the results according to the following criteria; Excellent: The platinum - plated layer should be uniform, smooth, without bubbles, pockmarks, scratches, non - plating, non - infiltration, etc. Defects, and it is evaluated as excellent.

[0048] Good: For the platinum - plated layer, in terms of uniformity, smoothness, no bubbles, no pockmarks, no scratches, no non - plating, no non - infiltration, etc., the defect area < 3% of the overall test area, and it is evaluated as good.

[0049] Medium: For the platinum - plated layer, in terms of uniformity, smoothness, no bubbles, no pockmarks, no scratches, no non - plating, no non - infiltration, etc., the defect area > 3% of the overall test area and the defect area < 5% of the overall test area, and it is evaluated as medium.

[0050] Poor: For the platinum - plated layer, in terms of uniformity, smoothness, no bubbles, no pockmarks, no scratches, no non - plating, no non - infiltration, etc., the defect area > 5% of the overall test area, and it is evaluated as unqualified.

[0051] Nitric Acid Vapor Test and Detection of Platinum-Plated Semiconductor Device Products: Detect according to the implementation method of national standard GB / T 19351-2003; Cut each sample of the embodiment into four chips as a group, with an experimental time of 2 hours. After the test, use the 3D profilometer VR-6000 manufactured by Keyence to detect the corrosion area caused by micro pinholes and slits. The percentage of the corrosion area in the total area of the plating area is called the corrosion rate; The lower the corrosion rate, the fewer the micro pinholes and slits, and the higher the corrosion resistance of the platinum-plated metal; On the contrary, the higher the corrosion rate, the more the micro pinholes and slits, and the lower the corrosion resistance of the platinum-plated metal.

[0052] Surface Roughness Test of Platinum Coating on Platinum-Plated Semiconductor Device Products: Detect according to the implementation method of national standard GB / T3505-2000. The surface roughness is detected by using the 3D profilometer VR-6000 manufactured by Keyence, and the result is expressed by the Ra arithmetic mean value in nm.

[0053] Wear Amount Test of Platinum Coating on Platinum-Plated Semiconductor Device Products: Implement according to national standard GB-T 12444-2006 and test with a CSM ball friction and wear test equipment.

[0054] Contact Resistance Test of Platinum Coating Electrical Contacts on Printed Circuit Boards of Platinum-Plated Semiconductor Devices: Test according to the national standard "Measurement Method for Contact Resistance of Precious Metal Electrical Contacts" GB / T 15078-2021. Test samples: 1. Samples of printed circuit boards of platinum-plated semiconductor devices before and after nitric acid vapor test; 2. Samples of printed circuit boards of platinum-plated semiconductor devices before and after plugging and unplugging experiments.

[0055] Plugging and Unplugging Experiment Conditions: 1000 times; Inserting and pulling out is counted as one time.

[0056] Discrimination Criteria: 1. Average Resistance Difference △Ω before and after the experiment: 0 mΩ ≤ △Ω ≤ 0.5 mΩ is excellent; 2. 0.5 mΩ < △Ω ≤ 1.0 mΩ is good; 3. 1.0 mΩ < △Ω ≤ 5.0 mΩ is qualified; 4. 5.0 mΩ < △Ω ≤ ∞ mΩ is unqualified.

[0057] Example 1 A platinum electroplating solution includes the components shown in Table 1 below: Table 1

[0058] The preparation method of the above platinum electroplating solution includes the following steps: (1) Add 350 mL of ultrapure water to a container. Under the conditions of heating and stirring at 50 °C, add the complexing agent ethylenediamine sulfate in small portions and multiple times. After dissolving and mixing evenly, add the additive malonic acid in small portions and multiple times. After dissolving and mixing evenly, add the electrolytic salt ammonium acetate in small portions and multiple times, and dissolve and mix evenly. Detect and adjust the pH value of the solution to 7 to obtain Solution A: When the pH value of the solution is lower than 7, adjust it to 7 with ammonia water until it reaches 7; when the pH value of the solution is higher than 7, adjust it to 7 with dilute sulfuric acid solution until it reaches 7. (2) Under the conditions of heating and stirring, add the platinum salt PEP to Solution A in small portions and multiple times. After dissolving and mixing evenly, detect and adjust the pH value of the solution to 7 again, and add ultrapure water to make the volume up to 1000 mL.

[0059] The application of the above platinum electroplating solution in the electroplating of semiconductor devices includes the following steps: (1) The semiconductor workpiece 10 to be electroplated, see Figure 1 .

[0060] (2) Install the semiconductor workpiece 10 to be processed in the electroplating equipment. Use the above platinum electroplating solution for electroplating, and use a positive and negative pulse electroplating power supply. Electroplate under the electroplating conditions shown in Table 2 below. During the electroplating process, regularly detect the platinum content in the platinum electroplating solution. According to the difference between the test result and the standard concentration of Pt ions in management, automatically add the platinum salt complex PEP solution in a linked manner to maintain the concentration of platinum salt PEP in the electroplating solution at 1.5 g / L (by weight of Pt).

[0061] (3) The preparation method of the automatically added platinum salt complex PEP solution is as follows: The ratio of platinum salt complex PEP, complexing agent ethylenediamine sulfate, and additive malonic acid is 1:16.6:11.3, and it can be prepared by dissolving in 1000 mL of ultrapure water; for example, when preparing a 1.5 g / L solution of platinum salt complex PEP (by weight of Pt), the concentration of ethylenediamine sulfate is 25 g / L, and the concentration of malonic acid is 15 g / L; make it up to 1000 ml solution with ultrapure water.

[0062] (4) During the electroplating process, regularly detect the pH value of the platinum electroplating solution. According to the difference between the test result and the set standard pH value of the solution, add acid solution or alkali solution; specifically, when the measured pH value is greater than 7, automatically add dilute sulfuric acid solution in a linked manner to lower the pH value to 7; when the measured pH value is less than 7, automatically add sodium hydroxide solution in a linked manner to raise the pH to 7; obtain the semiconductor device product plated with platinum.

[0063] Table 2

[0064] The results of the platinum coating film thickness (unit: nm) of the semiconductor device product plated with platinum in Example 1 are shown in Table 3.

[0065] Table 3

[0066] As can be seen from Table 3, the platinum electroplating solution of Example 1 was applied to the electrochemical deposition of platinum on semiconductor devices, and the film thickness range of the platinum coating on the surface of the obtained platinum-plated semiconductor device products was 202 - 214 nm; the difference between the maximum film thickness and the minimum film thickness of Max - Min was 12 nm; the error of its maximum value compared with the target set value of 200 nm was (214 - 200) / 200 = 7.0%. This confirmed that the platinum electroplating solution of Example 1 achieved a uniform film thickness distribution with a film thickness error ≤ 7.0%.

[0067] Examples 2 - 9 A platinum electroplating solution, referring to Example 1, the difference is only that the concentration of the complexing agent ethylenediamine sulfate is adjusted according to Table 4.

[0068] Table 4

[0069] The preparation method of the above platinum electroplating solution refers to Example 1.

[0070] The application of the above platinum electroplating solution in semiconductor device electroplating refers to Example 1.

[0071] Test Example 1: The platinum coating film thickness (unit: nm) of the platinum-plated semiconductor device products obtained in Examples 1 - 9 was detected, and the results are shown in Table 5.

[0072] Table 5

[0073] As can be seen from Table 5, the platinum electroplating solutions of Examples 1 - 9 were applied to the electrochemical deposition of platinum on semiconductor devices, and the film thickness range of the platinum coatings on the surfaces of the obtained platinum-plated semiconductor wafer products was 201 - 214 nm; the difference between the maximum film thickness and the minimum film thickness of Max - Min was 9 - 12 nm; the error of its maximum value compared with the target set value of 200 nm was 5.5 - 7.0%; the electroplating platinum solutions of Examples 1 - 9 showed excellent film thickness distribution uniformity.

[0074] The appearance inspection, nitric acid vapor test, platinum coating friction and wear weight, and roughness test results of the platinum-plated semiconductor device products obtained in Examples 1 - 9 are shown in Table 6.

[0075] Table 6

[0076] As can be seen from Table 6, when the platinum electroplating solutions of Examples 1-9 are applied to electrochemically deposit platinum on semiconductor devices, in the obtained platinum-plated semiconductor device products, the 300-fold appearance detection of the platinum metal film by electron microscope is excellent, the corrosion rate in the nitric acid vapor experiment for 2 hours is 0.0%, and the roughness of the platinum coating is 189-195 nm; further, its wear weight is only 0.6-0.9 mg; the above results confirm that the platinum metal films formed by the platinum-plated semiconductor device products prepared in Examples 1-9 have excellent morphology, uniform distribution, high purity and excellent compactness, and the produced semiconductor device electronic products have excellent corrosion resistance, thus better ensuring the high-precision conductivity and high-quality electronic signal transmission performance of the platinum-plated semiconductor device products. It can be seen that the concentration of the complexing agent ethylenediamine sulfate in the present invention has a significant influence on the comprehensive performance of the platinum coating, and the optional range of the concentration of the complexing agent ethylenediamine sulfate is 5-45 g / L; the most preferred range is 15-35 g / L; among them, 25 g / L of Example 5 can be used as the most preferred example.

[0077] Optimization of the dosage of additives in Examples 10-18 For the platinum electroplating solutions of Examples 10-18, referring to Example 1, the difference is only that the concentration of the complexing agent ethylenediamine sulfate is fixed at 25 g / L, ammonium acetate (electrolytic salt) is 30 g / L, and different concentrations of the additive malonic acid are further added to the platinum electroplating solution, and the concentration of the additive is adjusted according to Table 7.

[0078] Table 7

[0079] The preparation method of the above platinum electroplating solution refers to Example 1.

[0080] The application of the above platinum electroplating solution in semiconductor device electroplating refers to Example 1 Test Example 2: The platinum coating thickness (nm) of the platinum-plated semiconductor device products obtained in Examples 10-18 was detected, and the results are shown in Table 8.

[0081] Table 8

[0082] As can be seen from Table 8, when the platinum electroplating solutions of Examples 10-18 are applied to electrochemically deposit platinum on semiconductor devices, the thickness range of the platinum coating on the surface of the obtained platinum-plated semiconductor device products is 201-213 nm; the difference between the maximum film thickness and the minimum film thickness is 9-12 nm; the error of its maximum value compared with the target set value of 200 nm is 5.5-6.5%; it shows that the electroplating platinum solutions of Examples 10-18 achieve excellent film thickness distribution uniformity.

[0083] The appearance inspection, nitric acid vapor test, friction and wear test, and roughness test results of the platinum-plated semiconductor device products obtained in Examples 10 to 18 are shown in Table 9.

[0084] Table 9

[0085] From the appearance inspection results, nitric acid vapor corrosion rate inspection results, and surface roughness test results of platinum coatings in Examples 10 to 18 in Table 9, the 300-fold appearance inspection of the platinum metal film by electron microscope is excellent, the corrosion rate in the nitric acid vapor experiment for 2 hours is 0.0%, the roughness of the platinum coating is 191 - 195 nm, and further, the friction and wear test result of its platinum coating is only 0.6 - 0.9 mg; the above results confirm that the platinum metal film formed by the platinum-plated semiconductor device products prepared in Examples 10 to 18 has excellent morphology, uniform distribution, excellent compactness and pluggability, and the produced semiconductor device electronic products have excellent corrosion resistance, thus better ensuring the high-precision conductivity and high-quality electronic signal transmission performance of the platinum-plated semiconductor device products. It can be seen that the concentration of additive malonic acid in the present invention has a significant impact on the comprehensive performance of the platinum coating, and the optional concentration range of additive malonic acid is 5 - 29 g / L; the most preferred range is 11 - 23 g / L; among which 17 g / L in Example 14 can be used as the most preferred example.

[0086] In summary, in Examples 1 to 9, the concentration range of complexing agent ethylenediamine sulfate is preferably 5 - 45 g / L, in Examples 10 to 18, the concentration range of additive malonic acid is preferably 5 - 29 g / L, the concentration of platinum salt PEP is 1.5 g / L, and the concentration of electrolytic salt is 20 - 30 g / L.

[0087] As can be seen from the results in Table 5 and Table 8, the prepared electroplating platinum solution in Example 14 has excellent comprehensive performance, and its composition is shown in Table 10.

[0088] Table 10

[0089] As can be seen from Table 10, the weight ratio of platinum salt PEP:ethylenediamine sulfate:malonic acid is 1.5:25:17, that is, 1:16.6:11.3. Based on this, in the electroplating production process of the platinum electroplating solution in the present invention, as the platinum salt is consumed, its concentration is tested regularly by an automatic analysis device, and then an automatic supplementary platinum component solution is added. The prepared weight ratio of the automatic supplementary platinum component solution is prepared according to 1:16.6:11.3 and dissolved in 1000 mL of ultrapure water.

[0090] Before and after the nitric acid vapor experiment on the platinum-coated semiconductor electronic circuit board of Example 14, the circuit board resistance test results are shown in Tables 11 and 12, with the unit of mΩ.

[0091] Table 11

[0092] Table 12

[0093] Before and after 1000 plugging and unplugging experiments on the platinum-plated semiconductor electronic circuit board of Example 14, the difference results of the circuit board resistance test are shown in Table 13, with the unit of mΩ.

[0094] Table 13

[0095] As can be seen from Tables 11 - 13, through the resistance tests before and after the nitric acid vapor experiment and the plugging and unplugging experiment on the platinum-plated circuit board of Example 14, the resistance difference results are 0.11 - 0.29 mΩ and 0.12 - 0.35 mΩ respectively, which confirms that the platinum plating solution of the present invention, the semiconductor electronic circuit board prepared has excellent electrical conductivity even after severe nitric acid vapor experiments and plugging and unplugging experiments.

[0096] Comparative Examples 1 - 8 Except for the different concentrations of the complexing agent ethylenediamine sulfate in Comparative Examples 1 - 4 and Example 14, the other components are the same. Except for the different concentrations of the additive malonic acid in Comparative Examples 5 - 8 and Example 5, the other components are the same. The detailed preparation concentrations of Comparative Examples 1 - 8 are shown in Table 14.

[0097] Table 14

[0098] According to the same method as in Example 1, a platinum electroplating solution was prepared, and a platinum-plated product of a semiconductor device was prepared. The results of appearance inspection, nitric acid vapor test, friction and wear test, and roughness test of the platinum coating are shown in Table 15.

[0099] Table 15

[0100] As can be seen from Table 15, when the usage amounts of the complexing agent and the additive are lower or higher than the practical usage amount range of the present invention, the results of the coating appearance inspection can only reach poor, medium, and good; the corrosion rate in the nitric acid vapor experiment for 2 hours is 0.8% - 3.5%, the roughness of the platinum coating is 192 - 217 nm, and the results of the friction and wear experiment of the platinum coating show that the wear weight is 1.1 - 2.2 mg; therefore, the low or high content of the complexing agent and the additive directly leads to the reduction of the performance of the platinum coating.

[0101] The above results further confirmed that in Examples 10 - 18, the concentration range of the complexing agent ethylenediamine sulfate was preferably 5 - 45 g / L, in Examples 10 - 18, the concentration range of the additive malonic acid was preferably 5 - 29 g / L, the concentration of platinum salt PEP was 1.5 g / L, and the concentration of the electrolytic salt was 20 - 30 g / L.

[0102] For Comparative Example 9, referring to Example 14, ethylenediamine hydrochloride was used instead of ethylenediamine sulfate, and propionic acid was used instead of malonic acid; for Comparative Example 10, referring to Example 14, dichlorodiammineplatinum (II) was used instead of PEP; for Comparative Example 11, a platinum electroplating solution was prepared according to Example 1 in CN114752975 A; for Comparative Example 12, a platinum electroplating solution was prepared according to Example 2 in CN114016097 A; for Comparative Example 13, a platinum electroplating solution was prepared according to Example 3 in CN114411215 A; for Comparative Example 14, a platinum electroplating solution was prepared according to Example 17 in CN119082815 A.

[0103] The formulations of Comparative Examples 9 - 14 are shown in Table 16 below.

[0104] Table 16

[0105] For the preparation methods of the platinum electroplating solutions in the above Comparative Examples 9 - 10, referring to Example 1, and for the preparation methods of the platinum electroplating solutions in Comparative Examples 11 - 14, referring to the corresponding patent documents.

[0106] For the application of the above platinum electroplating solution in the electroplating of semiconductor devices, referring to Example 1.

[0107] Test Example 3: The platinum coating film thickness (unit: nm) of the platinum - plated semiconductor device products obtained in Comparative Examples 9 - 14 was detected, and the results are shown in Table 17.

[0108] Table 17

[0109] As can be seen from Table 17, Comparative Example 9 is obtained by replacing ethylenediamine sulfate with ethylamine hydrochloride and replacing malonic acid with propionic acid in the best Embodiment 14 of the present invention; Comparative Example 10 shows the test results of the platinum coating film thickness of platinum plating solution using dichlorodiammineplatinum instead of ethylplatinum salt PEP. The film thickness errors are 9.5% and 10.5%, which are significantly increased compared with 5.5% of Embodiment 14. The comparison between Comparative Example 9 and Embodiment 14 confirms that for the platinum electroplating solution based on the present invention, when the complexing agent and additive malonic acid of the diamino structure at both ends are omitted, the film thickness uniformity decreases significantly, and a platinum coating with excellent morphology, uniform distribution, high purity and excellent compactness cannot be obtained, and the semiconductor device electronic products produced have a platinum coating with excellent corrosion resistance; the comparison between Comparative Example 10 and Embodiment 14 confirms that for the platinum electroplating solution based on the present invention, when using non-cyclic platinum salt dichlorodiammineplatinum, the film thickness uniformity decreases significantly, and a platinum coating with excellent morphology, uniform distribution, high purity and excellent compactness cannot be obtained, and the wafer electronic products produced have a platinum coating with excellent corrosion resistance.

[0110] Comparative Examples 11 to 13 are platinum electroplating solutions in prior art patents. Their film thickness errors of 17.5% to 19.5% are much larger than the film thickness errors of 5.5% to 7.0% in Embodiments 27 to 31 of the present invention. It can be seen that the method of the present invention has significant advantages over Comparative Examples 11 to 13 in improving the film thickness uniformity and obtaining a platinum coating with excellent morphology, uniform distribution, high purity and excellent compactness.

[0111] Comparative Example 14 is a platinum electroplating solution developed earlier, with a film thickness error of 7.5%, which is inferior to the film thickness error of 5.5% in Embodiment 14 in Table 8.

[0112] The experimental comparison results of the appearance, nitric acid vapor, friction and wear, and surface roughness of the platinum coatings in Embodiments 10 to 18 and Comparative Examples 1 to 14 are shown in Table 18.

[0113] Table 18

[0114] Note: The three-component elements are defined as the conjugate effect of platinum salt PEP, ethylenediamine sulfate, and malonic acid.

[0115] As can be seen from Table 18, the appearance detection results of Examples 10 to 18 are excellent. The corrosion rate results of the nitric acid vapor experiment show extremely strong corrosion resistance. The roughness of the platinum coating is in the range of 191 to 195 nm, with a flat, smooth and dense surface state. The weight difference results before and after the friction and wear experiment are only in the range of 0.7 to 0.9 mg. Therefore, the platinum coating of the semiconductor device provided by the electroplating platinum solution of the present invention has excellent uniform distribution, morphology, excellent denseness and pluggability, especially excellent friction resistance, providing an important preparation method for the high-performance pluggable electronic materials required by high-end semiconductor electronic components; it can meet the market demand for semiconductor device electronic products with high corrosion resistance, high-precision conductivity and high-quality electronic signal transmission performance.

[0116] On the other hand, for Comparative Examples 1 to 8, since the concentration of their complexing agents or additives is lower or higher than the locked concentration range of the present invention, therefore, their appearance monitoring results can only reach poor, medium and good. The corrosion rate results of the nitric acid vapor experiment show 0.8 to 3.5%, failing to reach the excellent level of 0.0%. The roughness of the platinum coating is in the relatively rough range of 192 to 217 nm, and the weight difference results before and after the friction and wear experiment in the range of 1.1 to 2.2 mg are far beyond 0.7 to 0.9 mg of the present invention.

[0117] Furthermore, for Comparative Examples 9 to 13, which are representatives of the existing platinum electroplating technology, the micro-pinholes and micro-cracks existing in the platinum coating are not completely solved, resulting in defective appearance detection results, as manifested in the results of the nitric acid vapor corrosion experiment, that is, having a corrosion rate of 1.9 to 3.6%; further, the roughness of the platinum coating is in the range of 225 to 294 nm, which is consistent with the uneven distribution result of the platinum film thickness; the weight difference results before and after its friction and wear experiment are 2.3 to 3.9 mg, further deeply confirming the problems of micro-pinholes and micro-cracks existing in the prior art.

[0118] In addition, for the preparation method provided by Comparative Example 14, although the problems of micro-pinholes and micro-cracks existing in the platinum coating are solved, however, since the formulation of its electroplating solution does not have the "three-component elements" of the present invention, therefore, the weight difference result before and after its friction and wear experiment is 1.8 mg. Although it has a better result compared with Comparative Examples 9 to 13, but compared with the weight difference result range of only 0.7 to 0.9 mg of the present invention, the difference is relatively large, resulting in the semiconductor device electronic products prepared by the comparative examples described in Table 18 being difficult to meet the high-performance market demand for semiconductor device electronic products with excellent pluggability, high corrosion resistance, high-precision conductivity and high-quality electronic signal transmission performance.

[0119] Furthermore, for the platinum-plated layer electronic circuit boards obtained in Examples 10 to 18 and Comparative Examples 1 to 14, the test results of the average resistance difference before and after the nitric acid vapor experiment and the average resistance difference before and after the plugging and unplugging experiment are shown in Table 19.

[0120] Table 19

[0121] As can be seen from Table 19, according to the discrimination criteria for the average resistance difference before and after the nitric acid vapor experiment and the plugging and unplugging experiment of the platinum-plated layer electronic circuit board, the discrimination results of Examples 10 to 18 of the present invention are excellent; it realizes that the platinum-plated layer has excellent friction resistance, and provides an important preparation method for the high-performance plugging and unplugging performance electronic materials required by high-end semiconductor electronic components; the platinum electroplating solution technology of the present invention can meet the market demand for manufacturing semiconductor device electronic products with high corrosion resistance, high-precision conductivity and high-quality electronic signal transmission performance.

[0122] On the other hand, for Comparative Examples 1 to 8, since the concentration of their complexing agents or additives is lower or higher than the locked concentration range of the present invention, therefore, the average resistance difference before and after their nitric acid vapor experiment is 0.71 to 0.93 mΩ, only reaching good, qualified and unqualified, which is far from the experimental results of the present invention of 0.16 to 0.20 mΩ, and the average resistance difference before and after the plugging and unplugging experiment of the platinum coating is 0.95 to 2.71 mΩ, far inferior to the experimental results of the present invention of 0.18 to 0.22 mΩ.

[0123] Furthermore, as representatives of the existing platinum electroplating technology, Comparative Examples 9 to 13 did not completely solve the micro-pinholes and micro-cracks existing in the platinum coating, resulting in an average resistance difference of 0.62 to 4.13 mΩ before and after their nitric acid vapor corrosion experiment, only reaching qualified and unqualified, which is very different from the experimental results of the present invention of 0.16 to 0.20 mΩ; similarly, the average resistance difference before and after the plugging and unplugging experiment of the platinum coating is 1.58 to 6.21 mΩ, far inferior to the excellent experimental results of the present invention of 0.18 to 0.22 mΩ.

[0124] In addition, for the preparation method provided in Comparative Example 14, although it solved the problems of micro-pinholes and micro-cracks existing in the platinum coating, however, since the formula of its electroplating solution does not have the "three-component elements" described in the present invention, therefore, its average resistance difference before and after the nitric acid vapor corrosion experiment is 0.31 mΩ, only reaching good, which has a certain gap compared with the experimental results of the present invention of 0.16 to 0.20 mΩ; similarly, the average resistance difference before and after the plugging and unplugging experiment of the platinum coating is 0.73 mΩ, far inferior to the excellent experimental results of the present invention of 0.18 to 0.22 mΩ.

[0125] In summary, based on the platinum electroplating solution provided by the present invention, if the formulated components can meet the "component three elements", namely the combination of platinum salt PEP, ethylenediamine sulfate and malonic acid, the semiconductor device electronic products with nanostructured platinum coatings electrochemically deposited have excellent uniform distribution, high wear resistance and excellent denseness, especially excellent friction resistance. Through the average difference results of the resistance before and after the nitric acid vapor experiment and the plugging and unplugging experiment of the platinum layer printed circuit board, the goal of providing an important preparation method for high-performance plugging and unplugging performance electronic materials required for high-end semiconductor electronic components is achieved; it can meet the production and manufacturing requirements of high corrosion resistance, high-precision conductivity and high-quality electronic signal transmission performance; further, although the formulated components of the platinum electroplating solutions in Comparative Examples 1 to 8 meet the three elements, due to the concentration of their complexing agents or additives exceeding the locked concentration range of the present invention, there is an obvious gap in the comprehensive performance of their platinum coatings compared with the present invention.

[0126] Further, as representatives of the existing platinum electroplating technology, in Comparative Examples 9 to 13, since the formulated components of the platinum electroplating solution do not meet the above-mentioned three elements, there is a significant gap in the comprehensive performance of their platinum coatings compared with the present invention.

[0127] In addition, although the preparation method provided in Comparative Example 14 solves the problems of micro-pinholes and micro-cracks in the platinum coating, since the formulation of its electroplating solution does not have the "component three elements" described in the present invention, there is also an obvious gap in the comprehensive performance of its platinum coating compared with the present invention.

[0128] The embodiments provided above are not intended to limit the scope covered by the present invention, nor are the described steps intended to limit their execution order. Obvious improvements made by those skilled in the art to the present invention in combination with the existing common general knowledge also fall within the protection scope defined by the claims of the present invention.

Claims

1. A platinum electroplating solution, characterized in that: The method comprises the following raw materials: 1.5-10 g / L of platinum salt PEP, 5-45 g / L of ethylenediamine sulfate, 5-29 g / L of malonic acid, 0.6-40 g / L of ammonium acetate, and the remainder of ultrapure water and ammonia water; the pH value of the platinum electroplating solution is adjusted to 7.0 by the ammonia water; The structure of platinum salt PEP is shown in formula (1): Formula (1).

2. The platinum electroplating solution according to claim 1, characterized in that The amount of platinum salt PEP used is calculated as Pt.

3. The platinum electroplating solution according to claim 1, characterized in that The dosage of platinum salt PEP is 1.5~9.5 g / L.

4. The platinum electroplating solution according to claim 1, characterized in that The dosage of ethylenediamine sulfate is 5~35 g / L.

5. The platinum electroplating solution according to claim 1, characterized in that The dosage of malonic acid is 11~23 g / L.

6. The platinum electroplating solution according to claim 1, characterized in that The dosage of ammonium acetate is 20~30 g / L.

7. A method for preparing a coating using the platinum electroplating solution according to any one of claims 1 to 6, characterized in that: The steps include: S1. Degreasing and acid activation treatment of the semiconductor device to be processed; S2. Select corresponding electroplating conditions according to the electroplating area and the form of the plated part, and configure the corresponding anode and its anode mask; S3, selecting a corresponding electrolytic power source according to the plated part to carry out electroplating; S4. During the electroplating process, the platinum content in the platinum electroplating solution is regularly tested, and according to the difference between the test result and the standard concentration, the platinum salt PEP solution is automatically added to maintain the platinum salt concentration in the electroplating solution; S5. During the plating process, the pH value of the platinum electroplating solution is regularly tested, and acid or alkali solution is added according to the difference between the test result and the set standard pH value of the solution; S6. When the target coating thickness is reached or the preset electroplating time is reached, the electroplating is stopped, and the semiconductor wafer completes the process of depositing the platinum coating.

8. The method according to claim 7, characterized in that In step S2, the current density of the platinum solution during electroplating is 1.0-9.0 A / dm 2 , the solution temperature is 45~55 ℃.

9. The method according to claim 7, characterized in that: In step S5, when the measured pH value is greater than 7, dilute sulfuric acid solution is automatically added to reduce the pH value to 7; when the measured pH value is less than 7, sodium hydroxide solution is automatically added to increase the pH value to 7.

Images