A platinum electroplating solution, its method of preparation and its use in wafer electroplating

Abstract

The application belongs to the field of electroplating, and particularly relates to a platinum electroplating solution, a preparation method thereof and application thereof in wafer electroplating. The platinum electroplating solution comprises: a platinum salt, 0.02 mol / L in terms of platinum (II); the platinum salt is ethylenediamine platinum (II) chloride or ethylenediamine platinum (II) iodide; a complexing agent, 0.16-0.46 mol / L; the complex is a linear molecule with amino groups at both ends or 1,2-diaminocyclohexane; the number of carbons n between the two amino groups of the linear molecule with amino groups at both ends is selected from 2, 3 and 4; an electrolytic salt, 0.13-0.53 mol / L, the electrolytic salt comprises an ammonium carboxylate or an ammonium sulfate; a pH regulator adjusts the pH of the platinum electroplating solution to 7; and a solvent is ultrapure water. The platinum coating formed by the application has excellent morphology, uniform distribution, high purity and excellent compactness, and the produced wafer electronic product has excellent corrosion resistance, high-precision conductivity and high-quality electronic signal transmission performance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of wafer electroplating platinum, and particularly relates to a platinum electroplating solution, a preparation method thereof and application of the platinum electroplating solution in wafer electroplating. BACKGROUND

[0002] In the electroplating process on the wafer surface, platinum ions in the electroplating solution are electrochemically reacted on the wafer surface through an external current to form a platinum metal film. High-end platinum-plated semiconductor wafer products have very strict requirements on the purity, morphology, excellent compactness, high uniformity, high-precision conductivity, high-quality electronic signal transmission performance and strong corrosion resistance in various harsh environments of the platinum metal plating layer, and meeting the foregoing requirements is an important technical index for measuring the manufacturing process of the semiconductor wafer deposited with a nanometer platinum plating layer.

[0003] Currently, there is no report on using ethylenediamine platinum chloride or ethylenediamine platinum iodide as a platinum salt to prepare a platinum electroplating solution and apply the platinum electroplating solution to wafer electroplating to improve the quality of the platinum plating layer and the platinum-plated semiconductor wafer product.

[0004] Patent CN114752975A discloses an acidic electroplating solution of a 2-valence platinum (II) complex, free sulfuric acid or amino sulfonic acid and an anionic surfactant, which is extremely stable, has a long solution life, less impurity accumulation and can be used for plating thick platinum. Using the electroplating solution can process and manufacture high-purity platinum-plated products with compactness, high hardness, small stress, gloss and good corrosion resistance. Compared with comparative products 01-03, the porosity of examples 1-16 is reduced from 30.6-35.1% to 8.5-13.8%, and as the porosity of the platinum plating layer decreases, the corrosion resistance is improved to a certain extent. However, as can be seen from the application comparative example 3, the platinum electroplating solution based on CN114752975A has poor uniformity of the thickness of the platinum plating layer; the appearance detection result of the prepared platinum-plated semiconductor wafer product under a microscope 40 times and an electron microscope 300 times does not reach double excellence, the corrosion rate of the nitric acid vapor test for 2 hours is 1.9%, the purity of the platinum plating layer is 99.9167%, and the roughness of the platinum plating layer is 158 nm, which cannot meet the requirements of high corrosion resistance, high-precision conductivity and high-quality electronic signal transmission performance.

[0005] Patent CN114016097A discloses a plating liquid, and the preparation raw materials include: chloroplatinic acid hexahydrate and citrate; in the plating liquid, the concentration of citrate is 260-320 g / L. The plating liquid provided by the present application can form a platinum plating layer with uniform thickness and good appearance on the turbine blade when the turbine blade is electroplated in the above-mentioned plating liquid by adjusting the type of platinum source and conductive salt and the concentration of conductive salt. However, as can be seen from Example 4 of the present application, the platinum plating solution based on CN114016097A has poor uniformity of film thickness; the appearance detection results of the prepared platinum-plated semiconductor wafer product under a microscope 40 times and an electron microscope 300 times cannot reach double excellent, the corrosion rate of nitric acid vapor test for 2 hours is 2.3%, the purity of the platinum plating layer is 99.9025%, and the roughness of the platinum plating layer is 172 nm, which cannot meet the requirements of high corrosion resistance, high-precision conductivity and high-quality electronic signal transmission performance.

[0006] Patent CN114411215A discloses a platinum electroplating solution, and the platinum metal used is the corresponding platinum metal after dissolution of platinum salt, which is selected from one of sulfuric acid dinitrosyl platinous acid, potassium hexahydroxy platinic acid and tetraammine platinum sulfate. The platinum salt can be directly purchased in China, which makes the cost of platinum electroplating cheaper than the commercial platinum electroplating solution in the prior art by 25%, and the platinum electroplating solution is also suitable for hanging plating, and the plating layer has excellent hardness and corrosion resistance. However, as can be seen from Example 5 of the present application, the platinum plating solution based on CN114411215A has poor uniformity of film thickness; the appearance detection results of the prepared platinum-plated semiconductor wafer product under a microscope 40 times and an electron microscope 300 times cannot reach double excellent, the corrosion rate of nitric acid vapor test for 2 hours is 3.2%, the purity of the platinum plating layer is 99.8936%, and the roughness of the platinum plating layer is 185 nm, which cannot meet the requirements of high corrosion resistance, high-precision conductivity and high-quality electronic signal transmission performance.

[0007] In summary, the existing platinum electroplating solution applied to wafer electroplating cannot simultaneously realize that the platinum plating layer has excellent morphology, uniform distribution (film thickness Max-Min≤65 nm, film thickness error≤7.8%), high purity (≥99.99999%) and excellent density (roughness<130 nm), and the produced wafer electronic product has excellent corrosion resistance (nitric acid vapor corrosion rate for 2 hours is 0.0%), high-precision conductivity and high-quality electronic signal transmission performance. SUMMARY

[0008] [TECHNICAL PROBLEM]

[0009] The application provides a plating platinum solution based on a wafer, which can be applied to nanometer precision manufacturing of semiconductor wafer electronic products, and the platinum plating layer formed has excellent morphology, uniform distribution (film thickness Max-Min≤65nm, film thickness error≤7.8%), high purity (≥99.99999%) and excellent compactness (roughness<130nm), and the produced wafer electronic product has excellent corrosion resistance (corrosion rate is 0.0% after nitric acid vapor for 2 hours), high-precision conductivity and high-quality electronic signal transmission performance.

[0010] [Technical concept]

[0011] In order to provide a plating platinum solution based on a wafer, which can be applied to nanometer precision manufacturing of semiconductor wafer electronic products, and the platinum plating layer formed has excellent morphology, uniform distribution and excellent compactness, and the produced wafer electronic product has excellent corrosion resistance, high-precision conductivity and high-quality electronic signal transmission performance, the application develops a plating platinum solution based on a wafer with stable performance and long service life, and the application adopts ethylenediamine platinum (II) chloride or ethylenediamine platinum (II) iodide, such as a cyclic platinum salt, preferably a linear molecule with amino groups at both ends of a complexing agent or 1,2-diaminocyclohexane, which can form a cyclic complex (for example, formula 1) with platinum (II) in the platinum salt, and is beneficial to moving the equilibrium reaction (for example, reaction one) of the reaction of generating a cyclic complex and the dissociation reaction of the cyclic complex towards the direction of generating a stable cyclic complex, so as to be beneficial to maintaining the stability of the cyclic complex in the platinum plating solution. In the plating process, platinum (II) is electrolytically reduced to deposit zero-valent platinum (0) to form a platinum plating layer by obtaining electrons on the cathode surface, and the electrolytic equilibrium moves towards the direction of decomposition of the cyclic complex. The stability of the cyclic complex is improved, that is, the decomposition rate of the cyclic complex is reduced, when the decomposition rate of the cyclic complex is less than the speed of electrolytic reduction of zero-valent platinum (0) by obtaining electrons on the cathode surface, the deposited platinum particles are uniformly and orderly arranged, the platinum metal lattice formed is compact and defect-free, and excellent platinum plating layer is obtained; therefore, the platinum plating layer formed has excellent morphology, uniform distribution and excellent compactness, and the produced wafer electronic product has excellent corrosion resistance, high-precision conductivity and high-quality electronic signal transmission performance.

[0012] Further, by the preferred addition of the additive, it is found that when the additive contains both carboxyl and at least one of α-amino group, β-amino group or γ-amino group, from the structural characteristics of the α-amino group, β-amino group and γ-amino group of the additive, it is known that N in the amino group has strong electronegativity, can be mutually attracted with the positive ion of platinum (II), and form N-Pt covalent bond; at the same time, the hydroxyl oxygen O of the carboxylic acid also has strong electronegativity, is also mutually attracted with the positive ion of platinum (II), and form O-Pt covalent bond; when the formed N-Pt and O-Pt covalent bonds are the same Pt, the formed compound is a cyclic complex with excellent stability (such as, for example, formula 2), which also helps to alleviate and maintain the decomposition rate of the cyclic complex to be less than the speed of being electrolytically reduced and deposited as zero-valent platinum (0) on the cathode surface to obtain electrons, thereby being conducive to maintaining the stability of the platinum electroplating solution, and further promoting the platinum coating layer to have better compactness and corrosion resistance to nitric acid vapor;

[0013] The present application also optimizes the concentration of the complexing agent and the additive to maintain the decomposition rate of the cyclic complex to be less than the speed of being electrolytically reduced and deposited as zero-valent platinum (0) on the cathode surface to obtain electrons, thereby being conducive to maintaining the stability of the platinum electroplating solution, and ultimately achieving a platinum coating layer with nanoscale compact morphology, uniform distribution, extremely high purity and excellent compactness, and a platinum-coated semiconductor wafer product with a compact platinum coating layer, uniform film thickness distribution and high purity.

[0014]

[0015]

[0016] [Technical scheme]

[0017] On the one hand, a platinum electroplating solution is provided, which includes the following components at the following concentrations:

[0018] Platinum salt: 0.02 mol / L calculated as platinum (II); the platinum salt is at least one of ethylenediamine platinum (II) chloride or ethylenediamine platinum (II) iodide;

[0019] Complexing agent: 0.16-0.46 mol / L; the complexing agent is at least one of a linear molecule with amino groups at both ends or 1,2-diaminocyclohexane, and the complexing agent can form a cyclic complex (such as formula 1) with platinum through two amino groups; the number of carbons n between the two amino groups of the linear molecule with amino groups at both ends is selected from 2, 3, 4;

[0020] Electrolytic salt: 0.33 mol / L, the electrolytic salt includes at least one of ammonium carboxylate or ammonium sulfate;

[0021] pH adjuster, adjusting the pH of the platinum electroplating solution to 7;

[0022] Solvent: ultrapure water, the balance.

[0023] In some embodiments, the platinum electroplating solution further comprises:

[0024] an additive: 2-5 mmol / L; the additive is at least one of an alpha-amino acid, a beta-amino acid, or a gamma-amino acid; the additive is capable of forming a ring complex with platinum via the amino group and the carboxyl group (e.g., Formula 2);

[0025] In other embodiments, a platinum electroplating solution is provided, comprising components at the following concentrations:

[0026] a platinum salt: 0.01-0.05 mol / L as platinum (II); the platinum salt is at least one of ethylenediamine platinum (II) chloride or ethylenediamine platinum (II) iodide;

[0027] a complexing agent: at least one of a linear molecule with amino groups at both ends or 1,2-diaminocyclohexane; the complexing agent is capable of forming a ring complex with platinum via the two amino groups (e.g., Formula 1); the linear molecule with amino groups at both ends has a carbon number n between the two amino groups selected from 2, 3, 4;

[0028] an additive: at least one of an alpha-amino acid, a beta-amino acid, or a gamma-amino acid; the additive is capable of forming a ring complex with platinum via the amino group and the carboxyl group (e.g., Formula 2);

[0029] an electrolytic salt: 0.13-0.53 mol / L; the electrolytic salt is at least one of an ammonium carboxylate or an ammonium sulfate;

[0030] a pH adjuster to adjust the pH of the platinum electroplating solution to 7;

[0031] a solvent: ultra-pure water, the balance;

[0032] wherein the molar ratio of the complexing agent: the additive: the platinum salt is (8-23):(0.1-0.25):1.

[0033] In some embodiments, the molar ratio of the complexing agent: the additive: the platinum salt is 15.5:0.175:1.

[0034] In some embodiments, the linear molecule with amino groups at both ends comprises: an ethylenediamine compound, a 1,3-propanediamine compound, a 1,4-butanediamine compound, or a tris-tetraethylenediamine; the ethylenediamine compound, the 1,3-propanediamine compound, or the 1,4-butanediamine compound comprises a corresponding hydrochloride (salt) or sulfate (salt).

[0035] In some embodiments, the ethylenediamine compound comprises at least one of ethylenediamine, ethylenediamine hydrochloride, or ethylenediamine sulfate.

[0036] In some embodiments, the 1,3-propanediamine compound comprises 1,3-propanediamine hydrochloride.

[0037] In some embodiments, the 1,4-butanediamine compound comprises 1,4-butanediamine bis-hydrochloride.

[0038] In some embodiments, the ammonium carboxylate salt comprises at least one of ammonium formate, ammonium acetate, ammonium propionate, ammonium butyrate, and ammonium 2-hydroxyacetate.

[0039] In some embodiments, the additive comprises at least one of aminoacetic acid, DL-serine, N-(2-aminoethyl)glycine, N-(3-aminopropyl)glycine, glycine sodium salt hydrate, beta-alanine hydroiodide, gamma-aminobutyric acid, 2,5-diaminopentanoic acid, or sarcosine.

[0040] In some embodiments, the total content of impurity metals of the platinum salt is required to be ≤0.1 ppm; and the solvent is ultrapure water that meets the highest grade EW-I of the national electronic grade water standard, with a resistivity of ≥18 MΩ*cm (25°C).

[0041] In another aspect, a method for preparing the aforementioned platinum electroplating solution is provided, which comprises the following steps:

[0042] (1) ultrapure water is added in a container, and under heating and stirring conditions, a complexing agent is added in small amounts and multiple times, and after complete dissolution and mixing, an electrolytic salt is added in small amounts and multiple times, and after complete dissolution and mixing, a pH adjuster is used to adjust the pH value of the solution to 7 to obtain solution A;

[0043] (2) under heating and stirring conditions, the platinum salt is added in small amounts and multiple times to solution A, and after complete dissolution and mixing, a pH adjuster is used to adjust the pH value of the solution to 7, and ultrapure water is added to constant volume.

[0044] In another aspect, the aforementioned platinum electroplating solution is provided for use in wafer electroplating.

[0045] In some embodiments, a method for forming a platinum nanostructure coating on the surface of a semiconductor wafer is provided, which uses the aforementioned platinum electroplating solution as an electroplating processing solution; and the method comprises the following steps:

[0046] S1, oil removal and acid activation treatment are performed on the semiconductor wafer to be processed;

[0047] S2, the corresponding electroplating conditions are selected according to the electroplating area and the form of the plated part, and the corresponding anode and anode mask are configured, and the current density of the platinum electroplating solution is 1.0-9.0 A / dm 2 , the solution temperature is 45-55°C; the electroplating is performed according to the corresponding electrolytic power source selected according to the plated part; and the electroplating is ended when the preset platinum film thickness is reached.

[0048] In the batch plating process, the concentration of platinum (II) in the platinum plating solution, the concentration of complexing agent, additive, etc., and the pH value are monitored at regular intervals. According to the difference between the test results and the initial concentration of each component in the platinum plating solution, the automatic replenishment is linked to maintain the same formula of the platinum plating solution.

[0049] In some embodiments, the electrolytic power supply includes one of a positive reverse pulse power supply or a single pulse power supply.

[0050] [Advantages]

[0051] The present application provides a platinum plating solution, which innovatively uses ethylenediamine platinum (II) chloride or ethylenediamine platinum (II) iodide, a linear molecule with two amino groups at both ends or a specific complexing agent such as 1,2-diaminocyclohexane. The carbon number n between the two amino groups of the linear molecule with two amino groups at both ends is selected from 2, 3, and 4. The platinum plating solution at a specific concentration ratio can be used for nanometer precision manufacturing of semiconductor wafer electronic products. The formed platinum plating layer has excellent morphology, uniform distribution (film thickness Max-Min ≤ 65 nm, film thickness error ≤ 7.8%), high purity (≥ 99.99999%), and excellent density (roughness < 130 nm). The produced wafer electronic product has excellent corrosion resistance (corrosion rate of 0.0% in nitric acid vapor for 2 hours), high-precision conductivity, and high-quality electronic signal transmission performance, overcoming the technical difficulty that existing platinum plating solutions cannot simultaneously achieve the aforementioned effects. BRIEF DESCRIPTION OF DRAWINGS

[0052] Figure 1 The figure shows the film thickness test position of the semiconductor wafer plated part. Wherein: 10-semiconductor wafer plated part; 11-plating area; 12-center black dot●. DETAILED DESCRIPTION

[0053] Test method:

[0054] Platinum plating layer film thickness test: using Fischer's FISCHERSCOPE X-RAY XDV-SDD detector Figure 1 The platinum plating layer film thickness at the center black dot● of each plating area 11 of I~VII of the semiconductor wafer plated part is tested by Fischer's FISCHERSCOPE X-RAY XDV-SDD detector

[0055] I column 6 (3.24, 18.38), 10 (3.24, 10.16), 14 (3.24, 6.52);

[0056] II column 3 (5.55, 16.54), 7 (5.55, 12.86), 13 (5.55, 7.43), 17 (5.55, 3.80);

[0057] Column III 2 (7.86 mm, 17.46 mm), 6 (7.86, 18.38), 10 (7.86, 10.16), 14 (7.86, 6.52), 18 (7.86, 2.89);

[0058] Column IV 1 (10.16 mm, 18.35 mm), 5 (10.16, 14.71), 9 (10.16, 11.07), 11 (10.16, 9.25), 15 (10.16, 5.61), 19 (10.16, 1.97);

[0059] Column V 4 (12.47 mm, 15.62 mm), 8 (12.47, 12), 12 (12.47, 8.36), 16 (12.47, 4.72);

[0060] Column VI 3 (14.78 mm, 16.54 mm), 7 (14.78, 12.90), 13 (12.47, 7.44), 17 (12.47, 3.80);

[0061] Column VII 6 (14.78 mm, 18.38 mm), 10 (17.09, 10.16), 14 (17.09, 6.52).

[0062] The platinum plating layer film thickness data Max, Min, Ave., Max-Min and film thickness error value were analyzed.

[0063] The platinum film thickness error calculation formula is as follows.

[0064]

[0065] Appearance detection of platinum-plated semiconductor wafer product: appearance detection, 40 times optical microscope and electron microscope magnification 5000 times observation, the results are judged according to the following standard:

[0066] Excellent: the platinum plating layer should be uniform, smooth, no bubbles, no pockmarks, no scratches, no plating leakage, no plating penetration and other defects, and be evaluated as excellent;

[0067] Good: according to the evaluation of defect area of platinum plating layer uniformity, smoothness, bubbles, pockmarks, scratches, plating leakage, plating penetration and other aspects, the defect area < 3% of the overall test area, and be evaluated as good;

[0068] Medium: according to the evaluation of defect area of platinum plating layer uniformity, smoothness, bubbles, pockmarks, scratches, plating leakage, plating penetration and other aspects, the defect area > 3% of the overall test area, and the defect area < 5% of the overall test area, and be evaluated as medium;

[0069] Unqualified: According to the uniformity, smoothness, bubbles, pitting, scratches, plating leakage, plating penetration and other aspects of the platinum plating layer, the defect area is evaluated, and the defect area is > 5% of the overall test area, which is evaluated as unqualified.

[0070] Nitric acid vapor test and detection of platinum-plated semiconductor wafer products: according to the method of national standard GB / T 19351-2003; each sample in the example is cut into four chips as a group, the experimental time is 2 hours, after the test, the corrosion area caused by the micro pinholes and slits is detected by the 3D profile measuring instrument VR-6000 manufactured by KQNS, the percentage of the corroded area to 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.

[0071] Surface roughness test of platinum-plated semiconductor wafer product: according to the method of national standard GB / T 3505-2000, the surface roughness is detected by the 3D profile measuring instrument VR-6000 manufactured by KQNS, and the result is expressed by Ra arithmetic mean value (unit: nm); the larger the roughness, the more uneven the surface, and the lower the uniformity of the plating layer.

[0072] Purity test of platinum-plated semiconductor wafer product: according to the test of national chemical industry standard HG / T 5747-2020, the Hitachi spectrophotometer PS3500DD II / ICP-AES is used for detection, and the detection limit of the equipment is ≤0.1ppb. The purity calculation formula of the platinum plating layer is as follows. The higher the purity of the platinum plating layer, the better the nitric acid vapor corrosion resistance of the surface, and the more it can meet the high corrosion resistance requirement of the semiconductor wafer electronic product; on the contrary, the lower the purity, the worse the corrosion resistance.

[0073]

[0074] In the embodiments and comparative examples of the present application, the total content of impurity metals in the platinum salt is required to be ≤0.1ppm; the solvent ultrapure water adopts the highest grade EW-I of national electronic grade water standard, and the resistivity is ≥18MΩ*cm (25℃) of ultrapure water.

[0075] Example 1

[0076] 1. A platinum electroplating solution comprising components in the following concentrations, wherein the platinum concentration is 3.9 g / L:

[0077]

[0078] 2. A preparation method of the above platinum electroplating solution, comprising the following steps:

[0079] (1) In the container, add ultrapure water, under the condition of heating (such as temperature setting at 50℃) and stirring, add complexing agent hydrochloric acid ethylenediamine in small quantities for several times, completely dissolve and mix, then add electrolytic salt ammonium formate in small quantities for several times, completely dissolve and mix; adjust the pH value of the solution to 7 by using pH regulator, to obtain solution A;

[0080] Wherein, the pH regulator can include at least one of lye and / or acid liquor; when the pH value of the solution is <7, use lye to adjust the pH value to 7; when the pH value of the solution is >7, use acid liquor to adjust the pH value to 7; the lye can be ammonia water; the acid liquor can be dilute sulfuric acid solution;

[0081] (2) Under the condition of heating (such as temperature setting at 50℃) and stirring, add platinum salt ethylenediamine platinum (II) chloride to solution A in small quantities for several times, completely dissolve and mix, then adjust the pH value of the solution to 7 by using pH regulator, add ultrapure water to constant volume.

[0082] 3. The application of the above platinum electroplating solution in semiconductor wafer electroplating, comprising the following steps:

[0083] (1) The semiconductor wafer plating piece 10 to be electroplated (see Figure 1 ) is prepared. The semiconductor wafer plating piece 10 to be electroplated is prepared by using a wafer with a diameter of 8 inches and a thickness of 0.35 mm as raw material, pasting dry film on one side and protecting the other side with 3M electroplating special adhesive tape; the side with dry film is sequentially subjected to the following operations: 1) mask exposure, 2) development, 3) film removal, 4) neutralization, 5) cleaning, and 6) drying, to obtain a single-sided experimental piece with 52 electroplating areas 11, the dry film still protecting the areas outside the electroplating areas, only the 52 electroplating areas 11 contacting the platinum electroplating solution during electroplating, the area of each plating area being 35 mm 2 , and the total surface area of the plating areas being 52×35=1820 mm 2 ; bottom nickel with a film thickness in the range of 780-830 nm is plated on the electroplating areas, to obtain the semiconductor wafer plating piece 10 to be electroplated.

[0084] (2) The semiconductor wafer plating piece 10 to be electroplated is installed in the electroplating equipment, and electroplating is performed using the above platinum electroplating solution and a positive and negative pulse electroplating power source, under the following electroplating conditions, to obtain a platinum-plated semiconductor wafer product.

[0085]

[0086]

[0087] Examples 2-11: Optimization of the concentration of complexing agent hydrochloric acid ethylenediamine

[0088] 1. A platinum electroplating solution, referring to Example 1, with the only difference being that the concentration of the complexing agent ethylenediamine hydrochloride is adjusted according to Table 1.

[0089] Table 1

[0090]

[0091] 2. A method for preparing the platinum electroplating solution, referring to Example 1.

[0092] 3. The application of the platinum electroplating solution in the electroplating of semiconductor wafers, referring to Example 1.

[0093] Test Example 1

[0094] The platinum plating layer thickness (unit: nm) of the platinum-plated semiconductor wafer products obtained in Examples 1-11 was detected, and the results are shown in Table 2.

[0095] Table 2

[0096]

[0097]

[0098] The appearance detection, nitric acid vapor test, platinum plating layer roughness and platinum purity test results of the platinum-plated semiconductor wafer products obtained in Examples 1-11 are shown in Table 3.

[0099] Table 3

[0100]

[0101] From Tables 2 and 3, it can be seen that:

[0102] On the basis of the platinum electroplating solution of Example 1, the change in the concentration of the complexing agent ethylenediamine hydrochloride has a significant effect on the comprehensive performance of the platinum-plated semiconductor wafer products:

[0103] In Examples 3-9, when the concentration of the complexing agent ethylenediamine hydrochloride is 0.16-0.46 mol / L, the appearance detection results of the platinum-plated semiconductor wafer products under a microscope 40 times and an electron microscope 300 times are both excellent, the corrosion rate of the nitric acid vapor test for 2 hours is 0.0%, the purity of the platinum plating layer is >99.9999%, the roughness of the platinum plating layer is <130 nm, the thickness index Max-Min of the platinum plating layer is ≤65 nm, and the thickness error is ≤7.8%. Therefore, it can be seen that the platinum-plated semiconductor wafer products prepared in Examples 3-9 form a platinum metal plating layer with uniform thickness distribution, high purity, high density, excellent corrosion resistance and excellent morphology, and based on this, the platinum-plated semiconductor wafer products better guarantee high-precision conductivity and high-quality electronic signal transmission performance.

[0104] The concentration of the complexing agent ethylenediamine hydrochloride in Examples 1-2 is 0.05 mol / L and 0.11 mol / L respectively, both of which are lower than 0.16 mol / L, and the appearance test results of the platinum-coated semiconductor wafer products prepared by using the platinum electroplating solutions of Examples 1-2 under a microscope at 40 times and an electron microscope at 300 times cannot reach double-optimality, the corrosion rates of the platinum-coated semiconductor wafer products prepared by using the platinum electroplating solutions of Examples 1-2 in the nitric acid vapor test for 2 hours are 2.7% and 0.8% respectively, the purity of the platinum coating is lower than 99.9999%, and the roughness of the platinum coating is 137 nm and 131 nm respectively; the concentration of the complexing agent ethylenediamine hydrochloride in Examples 10-11 is 0.51 mol / L and 0.56 mol / L respectively, both of which are higher than 0.46 mol / L, and the appearance test results of the platinum-coated semiconductor wafer products prepared by using the platinum electroplating solutions of Examples 10-11 under a microscope at 40 times and an electron microscope at 300 times cannot reach double-optimality, the corrosion rates of the platinum-coated semiconductor wafer products prepared by using the platinum electroplating solutions of Examples 10-11 in the nitric acid vapor test for 2 hours are 0.6% and 1.1% respectively, the purity of the platinum coating is lower than 99.9999%, and the roughness of the platinum coating is 129 nm and 136 nm respectively; thus, it can be seen that when the concentration of the complexing agent ethylenediamine hydrochloride in the platinum electroplating solution of Example 1 is lower than 0.16 mol / L or higher than 0.46 mol / L, the purity, compactness and corrosion resistance of the platinum coating of the platinum-coated semiconductor wafer product prepared by using the platinum electroplating solution are low, and the quality of the platinum-coated semiconductor wafer product is reduced, so that the high-precision conductivity and high-quality electronic signal transmission performance cannot be achieved.

[0105] In conclusion, the concentration of the complexing agent ethylenediamine hydrochloride in the present application has a significant influence on the comprehensive performance of the platinum coating, and the concentration of the complexing agent ethylenediamine hydrochloride can be selected in the range of 0.16-0.46 mol / L, preferably in the range of 0.21-0.41 mol / L, and most preferably in the range of 0.26-0.36 mol / L.

[0106] Optimization of the concentration of the additive aminoacetic acid in Examples 12-22

[0107] 1. The platinum electroplating solutions of Examples 12-22 are the same as those of Example 1, except that the concentration of the complexing agent ethylenediamine hydrochloride is 0.31 mol / L, and different concentrations of the additive aminoacetic acid are added to the platinum electroplating solutions, and the concentration of the additive is adjusted according to Table 4.

[0108] Table 4

[0109]

[0110] 2. The preparation method of the above platinum electroplating solution is the same as that of Example 1, except that after the platinum salt ethylenediamine platinum (II) chloride is added and completely dissolved and mixed, the additive is added and completely dissolved and mixed.

[0111] 3. The application of the above platinum electroplating solution in the electroplating of semiconductor wafers is the same as that of Example 1.

[0112] Test Example 2:

[0113] The platinum plating layer thickness (nm) of the platinum plated semiconductor wafer products obtained in Examples 12-22 was detected, and the results are shown in Table 5.

[0114] Table 5

[0115]

[0116]

[0117] The appearance detection, nitric acid vapor test, platinum plating layer roughness and platinum purity test results of the platinum plated semiconductor wafer products obtained in Examples 12-22 are shown in Table 6.

[0118] Table 6

[0119]

[0120] From Tables 5 and 6, it can be seen that:

[0121] Based on the platinum plating solution of Example 6 (concentration of complexing agent ethylenediamine hydrochloride is 0.31 mol / L), the concentration of the additive glycine has a significant effect on the comprehensive performance of the platinum plated semiconductor wafer product:

[0122] When the concentration of the additive glycine in Examples 14-20 is 2-5 mmol / L, the appearance detection results of the platinum plated semiconductor wafer product under a microscope 40 times and an electron microscope 300 times are both excellent, the corrosion rate of the nitric acid vapor test for 2 hours is 0.0%, the purity of the platinum plating layer is >99.9999%, the roughness of the platinum plating layer is <130 nm, the thickness index Max-Min of the platinum plating layer is ≤65 nm, and the thickness error is ≤7.8%. Therefore, the platinum plated semiconductor wafer product prepared in Examples 14-20 has a platinum metal plating layer with uniform thickness distribution, high purity, high density, excellent corrosion resistance and excellent morphology, which better ensures that the platinum plated semiconductor wafer product has high-precision conductivity and high-quality electronic signal transmission performance.

[0123] The concentration of the additive aminoacetic acid in Examples 12-13 is 0.1 mmol / L and 1.5 mmol / L respectively, both of which are lower than 2 mmol / L, and the appearance detection result of the prepared platinum-plated semiconductor wafer product under a microscope 40 times and an electron microscope 300 times cannot reach double excellent, the corrosion rate of the nitric acid vapor test for 2 hours is 2.3% and 0.6%, the purity of the platinum plating layer is lower than 99.9999%, and the roughness of the platinum plating layer is 136 nm and 127 nm respectively; the concentration of the additive aminoacetic acid in Examples 21-22 is 5.5 mmol / L and 6 mmol / L respectively, both of which are higher than 5 mmol / L, and the appearance detection result of the prepared platinum-plated semiconductor wafer product under a microscope 40 times and an electron microscope 300 times cannot reach double excellent, the corrosion rate of the nitric acid vapor test for 2 hours is 0.5% and 0.9%, the purity of the platinum plating layer is lower than 99.9999%, and the roughness of the platinum plating layer is 126 nm and 133 nm respectively; it can be seen that when the concentration of the additive aminoacetic acid in the platinum electroplating solution based on Example 6 is lower than 2 mmol / L or higher than 5 mmol / L, the purity of the platinum metal plating layer of the prepared platinum-plated semiconductor wafer product is lower, the compactness is lower, the corrosion resistance is lower, the quality of the obtained platinum-plated semiconductor wafer product is reduced, and high-precision conductivity and high-quality electronic signal transmission performance are difficult to achieve.

[0124] In conclusion, the concentration of the additive aminoacetic acid in the application has a significant influence on the comprehensive performance of the platinum plating layer, and the concentration of the additive aminoacetic acid can be selected in the range of 2-5 mmol / L; the preferred scheme of Example 17 is that the platinum electroplating solution comprises the following components with the following concentrations.

[0125]

[0126] As can be seen from Comparative Examples 1-11 and Examples 12-22, the addition of trace amounts (millimolar level) of the additive aminoacetic acid helps to reduce the roughness of the platinum plating layer and improve the compactness of the platinum plating layer, thereby better ensuring that the platinum-plated semiconductor wafer product achieves high-precision conductivity and high-quality electronic signal transmission performance.

[0127] In summary, in the present application, the concentration of ethylenediamine platinum (II) chloride is 0.02 mol / L, the concentration range of the complexing agent hydrochloric acid ethylenediamine is 0.16-0.46 mol / L, and the concentration range of the additive aminoacetic acid is 2-5 mmol / L; therefore, the molar ratio of the complexing agent hydrochloric acid ethylenediamine: the additive aminoacetic acid: ethylenediamine platinum (II) chloride is (0.16-0.46):(0.002-0.005):0.02, i.e. the molar ratio of the complexing agent hydrochloric acid ethylenediamine: the additive aminoacetic acid: ethylenediamine platinum is (8-23):(0.1-0.25):1. When the concentration of ethylenediamine platinum (II) chloride is changed, the concentration of the complexing agent hydrochloric acid ethylenediamine and the concentration of the additive aminoacetic acid need to be calculated according to the above-mentioned ratio in the platinum electroplating solution of the present application. According to Example 17, preferably, the molar ratio of the complexing agent hydrochloric acid ethylenediamine: the additive aminoacetic acid: ethylenediamine platinum (II) chloride is 0.31:0.0035:0.02=15.5:0.175:1.

[0128] Examples 23-27

[0129] 1. The platinum electroplating solution of Examples 23-27, wherein the concentrations of the platinum salt, the complexing agent, the electrolyte salt, and the additive in Example 17 remain unchanged, and the only difference is that the types of the components are changed, as shown in Table 7.

[0130] Table 7

[0131]

[0132] 2. The preparation method of the platinum electroplating solution, which refers to Example 17.

[0133] 3. The application of the platinum electroplating solution in semiconductor wafer electroplating, which refers to Example 1.

[0134] Comparative Examples 1-5

[0135] 1. The platinum electroplating solution of Comparative Examples 1-2, wherein the concentrations of the platinum salt, the complexing agent, the electrolyte salt, and the additive in Example 17 remain unchanged, and the only difference is that:

[0136] In Comparative Example 1, ethylamine hydrochloride is used instead of hydrochloric acid ethylenediamine, and acetic acid is used instead of aminoacetic acid.

[0137] In Comparative Example 2, dichlorodiammine platinum (II) is used instead of ethylenediamine platinum (II) chloride.

[0138] In Comparative Example 3, the platinum electroplating solution is prepared according to Patent CN114752975A.

[0139] In Comparative Example 4, the platinum electroplating solution is prepared according to Patent CN114016097A.

[0140] In Comparative Example 5, the platinum electroplating solution is prepared according to Patent CN114411215A.

[0141] The platinum electroplating solution formulations of Comparative Examples 1-5 are shown in Table 8:

[0142] Table 8

[0143]

[0144]

[0145] 2. The preparation methods of the platinum electroplating solutions of Comparative Examples 1-2 above are referred to Example 1, and the preparation methods of the platinum electroplating solutions of Comparative Examples 3-5 are referred to the corresponding patent documents.

[0146] 3. The application of the platinum electroplating solutions above in semiconductor wafer electroplating is referred to Example 1.

[0147] Test Example 3:

[0148] The platinum plating layer film thickness (unit: nm) of the platinum-plated semiconductor wafer products obtained from Examples 23-27 and Comparative Examples 1-5 was detected, and the results are shown in Table 9.

[0149] Table 9

[0150] Max Min Ave. Max-Min Film thickness error % Example 23 1071 1017 1057 56 7.1 Example 24 1072 1018 1055 54 7.2 Example 25 1069 1014 1056 55 6.9 Example 26 1070 1015 1059 55 7.0 Example 27 1068 1016 1058 52 6.8 Comparative Example 1 1097 1019 1063 78 9.7 Comparative Example 2 1086 1020 1068 66 8.6 Comparative Example 3 1117 1018 1079 99 11.7 Comparative Example 4 1128 1017 1083 111 12.8 Comparative Example 5 1141 1021 1091 120 14.1

[0151] The appearance detection, nitric acid vapor test, platinum plating layer roughness and platinum purity test results of the platinum-plated semiconductor wafer products obtained from Examples 23-27 and Comparative Examples 1-5 are shown in Table 10.

[0152] Table 10

[0153]

[0154]

[0155] From Tables 9 and 10, it can be seen that:

[0156] As can be seen from Examples 17, 23-27, in the platinum plating solution of the present application, under the premise that the platinum salt concentration is 0.02 mol / L, the complexing agent concentration is 0.31 mol / L, the electrolytic salt concentration is 0.33 mol / L, the additive concentration is 3.5 mmol / L, and the solution pH is adjusted to 7, the type of platinum salt can be selected from at least one of ethylenediamine platinum (II) chloride or ethylenediamine platinum iodide and other cyclic platinum salts, the complexing agent can be selected from at least one of ethylenediamine hydrochloride, ethylenediamine sulfate, 1,3-propanediamine hydrochloride, 1,4-butanediamine bis-hydrochloride, 1,2-diaminocyclohexane, or tris-tetraethylenediamine, the additive can be selected from at least one of aminoacetic acid, DL-serine, N-(2-aminoethyl) glycine, beta-alanine hydrogen iodide, gamma-aminobutyric acid, and 2,5-diaminopentanoic acid, and the electrolytic salt can be selected from at least one of ammonium formate, ammonium acetate, ammonium propionate, ammonium butyrate, or ammonium 2-hydroxyacetate. Based on the foregoing platinum plating solution, the appearance detection results of the platinum-plated semiconductor wafer product prepared under 40 times of a microscope and 300 times of an electron microscope are double excellent, the platinum plating layer has no micro pinholes and cracks, and has a flat, smooth, and dense surface state, the corrosion rate of the platinum-plated semiconductor wafer product in the nitric acid vapor test for 2 hours is 0.0%, the purity of the platinum plating layer is >99.9999%, the roughness of the platinum plating layer is <130 nm, the film thickness index Max-Min of the platinum plating layer is ≤65 nm, and the film thickness error is ≤7.8%, so it can be seen that the platinum-plated semiconductor wafer product forms a platinum metal plating layer with uniform film thickness distribution, high purity, high density, excellent corrosion resistance, and excellent morphology, and thus better ensures that the platinum-plated semiconductor wafer product realizes high-precision conductivity and high-quality electronic signal transmission performance.

[0157] However, in Comparative Example 1, ethylamine hydrochloride is used to replace ethylenediamine hydrochloride, and acetic acid is used to replace aminoacetic acid based on Example 17, and as a result, the film thickness index Max-Min of the platinum plating layer is 78 nm, and the film thickness error is 9.7%, which is significantly increased compared with Examples 1-27, indicating that the platinum plating layer has poor film thickness uniformity; in addition, the appearance detection results of the platinum-plated semiconductor wafer product prepared under 40 times of a microscope and 300 times of an electron microscope cannot reach double excellent, the corrosion rate of the platinum-plated semiconductor wafer product in the nitric acid vapor test for 2 hours is 1.7%, the purity of the platinum plating layer is lower than 99.9999%, and the roughness of the platinum plating layer is 142 nm; the comprehensive performance is far worse than that of Examples 23-27, and cannot meet the requirements of high corrosion resistance, high-precision conductivity, and high-quality electronic signal transmission performance. Comparative Example 1 confirms that the key technical means for achieving the excellent effects of the present application includes: using ethylenediamine hydrochloride and other linear molecules with amino groups at both ends or 1,2-diaminocyclohexane as a complexing agent, or using alpha-amino acid, beta-amino acid, and gamma-amino acid and other amino carboxylic acid compounds as an additive.

[0158] Comparative Example 2 was based on Example 17, using a non-cyclic platinum salt, dichloro diammine platinum (II) instead of the cyclic platinum salt, ethylenediamine platinum (II) chloride, and the platinum coating had a film thickness index Max-Min of 66 nm and a film thickness error of 8.6%, which was significantly larger than Examples 1-27, indicating poor uniformity of the platinum coating film thickness. In addition, the appearance of the platinum-coated semiconductor wafer product under a microscope at 40 times and under an electron microscope at 300 times was not double-optimal, the corrosion rate of the nitric acid vapor test was 2.4% for 2 hours, the purity of the platinum coating was less than 99.9999%, and the roughness of the platinum coating was 151 nm, respectively. The platinum coating could not have excellent morphology, uniform distribution, high purity, and excellent compactness, and the comprehensive performance was much worse than Examples 23-27, and could not meet the requirements of high corrosion resistance, high-precision conductivity, and high-quality electronic signal transmission performance. Comparative Example 2 confirmed that the key technical means to achieve the excellent effects of the present application included the use of a cyclic platinum salt.

[0159] Comparative Examples 3-5 used existing platinum electroplating solutions and were applied in semiconductor wafer electroplating according to the method of Example 1. It was found that the platinum coating had a film thickness index Max-Min of 99-120 nm and a film thickness error of 11.7-14.1%, which was significantly larger than Examples 1-27, indicating poor uniformity of the platinum coating film thickness. In addition, the appearance of the platinum-coated semiconductor wafer product under a microscope at 40 times and under an electron microscope at 300 times was not double-optimal, the corrosion rate of the nitric acid vapor test was 1.9-3.2% for 2 hours, the purity of the platinum coating was less than 99.9999%, and the roughness of the platinum coating was 158-185 nm, respectively. The comprehensive performance was much worse than Examples 23-27, and could not meet the requirements of high corrosion resistance, high-precision conductivity, and high-quality electronic signal transmission performance. Comparison showed that the platinum-coated semiconductor wafer product prepared by the method of the present application formed a platinum metal coating with uniform film thickness distribution, high purity, high compactness, excellent corrosion resistance, and excellent morphology, which better ensured that the platinum-coated semiconductor wafer product achieved high-precision conductivity and high-quality electronic signal transmission performance, and had a significant advantage over Comparative Examples 3-5.

[0160] In summary, to prepare a platinum-coated semiconductor wafer product that forms a platinum metal coating with uniform film thickness distribution, high purity, high compactness, excellent corrosion resistance, and excellent morphology, which better ensures that the platinum-coated semiconductor wafer product achieves high-precision conductivity and high-quality electronic signal transmission performance, the platinum electroplating solution provided by the present application must at least meet the following requirements: the platinum salt is a cyclic platinum salt, the complexing agent is a complexing agent with amino groups at both ends, and the additive is an amino carboxylic acid compound.

[0161] The above examples are not intended to limit the scope of the present application, nor are the described steps intended to limit the order in which they are performed. Modifications apparent to one skilled in the art in light of the above teachings are intended to fall within the scope of the claims.

Claims

1. A platinum electroplating solution, characterized in that, The components include the following concentrations: Divalent platinum salt: 0.02 mol / L in terms of divalent platinum; the divalent platinum salt is at least one of ethylenediamine platinum chloride or ethylenediamine platinum iodide; Complexing agent: 0.16-0.46 mol / L; the complexing agent is at least one of a linear molecule with amino groups at both ends or 1,2-diaminocyclohexane; the linear molecule with amino groups at both ends includes: ethylenediamine compounds, 1,3-propanediamine compounds, 1,4-butanediamine compounds, or triethylenetetramine; the ethylenediamine compounds, 1,3-propanediamine compounds, or 1,4-butanediamine compounds include corresponding hydrochlorides or sulfates; Electrolytic salt: 0.33 mol / L, the electrolytic salt includes at least one of ammonium carboxylate or ammonium sulfate; pH adjuster, adjust the pH of the platinum electroplating solution to 7; Solvent: ultrapure water, the balance.

2. The platinum electroplating solution of claim 1, wherein, Also includes: Additive: 2-5 mmol / L; the additive includes at least one of aminoacetic acid, DL-serine, N-(2-aminoethyl) glycine, N-(3-aminopropyl) glycine, glycine sodium salt hydrate, beta-alanine hydrogen iodide, gamma-aminobutyric acid, 2,5-diaminopentanoic acid, or sarcosine; the additive can form a cyclic complex with platinum through the amino and carboxyl groups.

3. The platinum electroplating solution of claim 1, wherein, The ethylenediamine compounds include at least one of ethylenediamine, ethylenediamine hydrochloride, or ethylenediamine sulfate.

4. A platinum electroplating solution characterized in that, The components include the following concentrations: Divalent platinum salt: 0.01-0.05 mol / L in terms of divalent platinum; the divalent platinum salt is at least one of ethylenediamine platinum chloride or ethylenediamine platinum iodide; Complexing agent: at least one of a linear molecule with amino groups at both ends or 1,2-diaminocyclohexane; the linear molecule with amino groups at both ends includes: ethylenediamine compounds, 1,3-propanediamine compounds, 1,4-butanediamine compounds, or triethylenetetramine; the ethylenediamine compounds, 1,3-propanediamine compounds, or 1,4-butanediamine compounds include corresponding hydrochlorides or sulfates; Additive: includes at least one of aminoacetic acid, DL-serine, N-(2-aminoethyl) glycine, N-(3-aminopropyl) glycine, glycine sodium salt hydrate, beta-alanine hydrogen iodide, gamma-aminobutyric acid, 2,5-diaminopentanoic acid, or sarcosine; Electrolytic salt: 0.13-0.53 mol / L, the electrolytic salt is at least one of ammonium carboxylate or ammonium sulfate; pH adjuster, adjust the pH of the platinum electroplating solution to 7; Solvent: ultrapure water, the balance; The molar ratio of the complexing agent: the additive: the platinum salt is (8-23): (0.1-0.25):

1.

5. The platinum electroplating solution of claim 4, wherein, The molar ratio of the complexing agent: the additive: the platinum salt is 15.5: 0.175:

1.

6. The platinum electroplating solution of claim 4, wherein, The ethylenediamine compounds include at least one of ethylenediamine, ethylenediamine hydrochloride, or ethylenediamine sulfate.

7. The platinum electroplating solution of claim 4, wherein, The ammonium carboxylate includes: at least one of ammonium formate, ammonium acetate, ammonium propionate, ammonium butyrate, and ammonium 2-hydroxyacetate.

8. The method of preparing a platinum electroplating solution according to claim 1, characterized in that, The components include the following concentrations: (1) Add ultrapure water into a container, under the condition of heating and stirring, add complexing agent in small amount for several times, completely dissolve and mix, then add electrolytic salt in small amount for several times, completely dissolve and mix; adjust the pH value of the solution to 7 by using pH regulator, to obtain solution A; (2) Under the condition of heating and stirring, add platinum salt into solution A in small amount for several times, completely dissolve and mix, then adjust the pH value of the solution to 7 by using pH regulator, and add ultrapure water to constant volume.

9. Use of the platinum electroplating solution according to any one of claims 1-7 in wafer electroplating.

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