High-temperature-resistant semiconductor platinum etching solution, preparation method and application thereof

Abstract

This invention relates to a high-temperature resistant platinum etching solution for semiconductors, comprising the following components by weight: 8-15 parts hydrochloric acid; 30-50 parts hydrogen peroxide; 0.1-1 parts composite stabilizer; 0.01-0.1 parts surfactant; and 30-40 parts ultrapure water. The invention also discloses a method for preparing the above-mentioned platinum etching solution. The organophosphonic acid stabilizer of this invention utilizes the advantage of containing phosphate groups in its structure, allowing it to form complexes with metal ions and exhibiting good stability. The addition of a carboxylic acid stabilizer further complexes the remaining metal ions, enhancing the stability of the addition system. The surfactant further improves the etching rate, and its complexing effect further stabilizes the system. Simultaneously, both the composite stabilizer and the surfactant possess high-temperature resistance, resulting in a platinum etching system with superior stability and high-temperature resistance.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor manufacturing processes, and particularly relates to a high-temperature resistant semiconductor platinum etching solution, its preparation method and application. Background Technology

[0002] Platinum (Pt) is well-suited for high-temperature reaction processes due to its high melting point (1772°C) and its inert properties, and is used in the IC industry to form PtSi.

[0003] Platinum is widely used in MEMS applications requiring high-temperature processes due to these properties, and when used as an electrode material, it helps prevent oxidation and diffusion problems. However, due to its inert nature, platinum is one of the most difficult materials to form using standard etching techniques.

[0004] Currently, aqua regia, a mixture of hydrochloric acid and nitric acid, is commonly used to etch platinum films on semiconductor devices. CN112753093A discloses an etching solution for removing alloyed aluminum platinum, but the etching rate is slow, it is volatile at high temperatures, has high toxicity, and the etching solution itself contains strong acid, making it complex to handle.

[0005] Hydrogen peroxide is easily decomposed by metal ions at high temperatures, which reduces its content and affects the etching rate. The reaction formula is as follows:

[0006]

[0007] Therefore, it is necessary to develop a platinum etching solution that can stably etch platinum sheets at high temperatures for extended periods, improve the platinum etching rate, and produce a uniform etched surface, in order to solve the aforementioned technical challenges and process platinum film devices. Summary of the Invention

[0008] The technical problems solved by this invention are: the inability of platinum etching solution to stably etch platinum sheets for a long time, the low platinum etching rate, and the uneven etching surface.

[0009] In view of the technical problems existing in the prior art, the present invention designs a high-temperature resistant semiconductor platinum etching solution, its preparation method and application.

[0010] To solve the aforementioned technical problems, the present invention adopts the following solution:

[0011] A high-temperature resistant semiconductor platinum etching solution, characterized in that it comprises the following components by weight:

[0012]

[0013] The composite stabilizer includes organophosphonic acid stabilizers and carboxylic acid stabilizers;

[0014] The mass ratio of the organophosphonic acid stabilizer to the carboxylic acid stabilizer is 1:2-5.

[0015] Furthermore, the organophosphonic acid stabilizer is one or more of cyclohexanehexaphosphate, hydroxyethylidene diphosphonic acid, methylene phosphonate, ethylenediaminetetramethylenephosphonic acid, diethylenetriaminepentamethylenephosphonic acid, and triethylenetetraaminehexamethylenephosphonic acid.

[0016] Furthermore, the carboxylic acid stabilizer is one or more of 1,4-cyclohexanedibutyric acid, cyclohexane-1,2,4,5-tetracarboxylic acid, N-methylcyclohexanecarboxylic acid, N-methylcyclopentanecarboxylic acid, and tartaric acid.

[0017] Furthermore, the organophosphonic acid stabilizer is cyclohexanehexaphosphate;

[0018] The carboxylic acid stabilizer is 1,4-cyclohexanedibutyric acid.

[0019] Furthermore, the surfactant is a sulfonate surfactant.

[0020] Furthermore, the surfactant is a symmetrical diaromatic ether sulfonate, which has the following structure:

[0021]

[0022] Where n has a value between 2 and 6.

[0023] This invention also discloses a method for preparing a high-temperature resistant semiconductor platinum etching solution, characterized by comprising the following steps:

[0024] Step 1: Weigh out ultrapure water, hydrochloric acid, and hydrogen peroxide separately and add them to a container in sequence to obtain a mixed solution;

[0025] Step 2: Continue to add composite stabilizer and surfactant to the mixed solution prepared in Step 1, and stir for 5-10 minutes until all materials are completely dissolved to obtain high-temperature resistant semiconductor platinum etching solution.

[0026] This invention also discloses an etching method using a high-temperature resistant semiconductor platinum etching solution, characterized by comprising the following steps:

[0027] Step 1: Prepare a 60-70% (w / w) aqueous solution of the high-temperature resistant semiconductor platinum etching solution with ultrapure water. Then, use this aqueous solution to soak the platinum wafer at 70-80℃ for 60-80 minutes to obtain the soaked platinum wafer.

[0028] Step 2: Rinse the soaked platinum wafer twice in ultrapure water and purge it with nitrogen gas to complete the etching process of the platinum wafer.

[0029] This invention also discloses the use of a high-temperature resistant semiconductor platinum etching solution in the etching of platinum wafers, thin-film platinum resistance thermometers, and platinum film temperature sensors.

[0030] In this invention, to further optimize the etching effect, hydrochloric acid is preferably 10-15 parts; hydrogen peroxide is preferably 35-45 parts; composite stabilizer is preferably 0.1-0.5 parts; surfactant is preferably 0.01-0.05 parts; and ultrapure water is preferably 30-40 parts.

[0031] It should be noted that in the etching method of the present invention, the concentration of the high-temperature resistant semiconductor platinum etching solution can be any concentration of 60-70%, such as 60%, 64%, 66%, 68%, etc.; the immersion temperature can be any temperature between 70-80℃, such as 72℃, 74℃, 76℃, 78℃, etc.; and the immersion time can be any duration between 60-80min, such as 61min, 63min, 68min, 72min, 77min, etc. The selection of these durations does not affect the effect of the platinum etching solution of the present invention.

[0032] In this invention, the surfactant has the following functions:

[0033] Symmetrical biaromatic ether sulfonate molecules contain symmetrical benzenesulfonic acid groups at both ends, with the benzene rings connected by ether bonds. This gives the component high-temperature resistance, allowing it to be used stably at high temperatures.

[0034] Secondly, the sulfonic acid groups can also complex metal ions through coordination. The resulting complexes are more stable due to the interaction between van der Waals forces and surrounding molecules, thus increasing the stability of the system.

[0035] Third, the addition of this component can adjust the interfacial tension between the high-temperature resistant semiconductor platinum etching solution of the present invention and the metal surface, thereby reducing the interfacial tension between the etching solution and the metal surface, reducing the cohesive force of the liquid, making it easier to wet the metal surface, increasing the dielectric transfer rate, and thus increasing the etching rate.

[0036] In summary, the addition of surfactants in this invention not only improves interfacial properties but also further enhances the high-temperature resistance and stability of the high-temperature resistant semiconductor platinum etching solution.

[0037] In this invention, cyclohexanehexaphosphate and 1,4-cyclohexanedibutyric acid are used as the most preferred composite stabilizers to adsorb metal ions in the solution as dual stabilizers of hydrogen peroxide.

[0038] Among them, cyclohexanehexaphosphate has a cyclic structure, which can be added to high-temperature solution systems. It is not easily decomposed, and it contains phosphate groups around itself, which can form complexes with metal ions at multiple sites. It has excellent stability and the strongest ability to capture metal ions.

[0039] Furthermore, 1,4-cyclohexanedibutyric acid also has a cyclic structure, can withstand high temperatures, and has a carboxylic acid group. Its carboxyl group forms a coordinate bond with metal ions, which further complexes the remaining metal ions that were not captured and complexed by cyclohexanehexaphosphate, forming a stable complex.

[0040] The two work together in a progressive and synergistic manner to form a highly efficient complexing system, which controls the side effects of metal ions at the source, effectively slows down the decomposition of hydrogen peroxide, and ensures the concentration advantage of hydrogen peroxide in the system, thus making it more conducive to accelerating the etching rate of platinum.

[0041] It should be noted that, in this invention, unless otherwise specified, the specific meaning of "comprising" in relation to composition definition and description includes both open-ended meanings such as "comprising," "including," etc., and closed-ended meanings such as "composed of," etc., and similar meanings.

[0042] This invention provides a high-temperature resistant semiconductor platinum etching solution, its preparation method, and its application, which have the following beneficial effects:

[0043] (1) The high-temperature semiconductor platinum etching solution of the present invention is environmentally friendly, efficient and has low volatilization loss. It uses hydrogen peroxide instead of traditional nitric acid as an oxidant to oxidize platinum, which is not only safe but also speeds up the etching rate. After etching, the wafer can be rinsed with ultrapure water, which is harmless to the environment and human body.

[0044] (2) The high-temperature resistant semiconductor platinum etching solution of the present invention has unique advantages in the use of composite stabilizers:

[0045] Firstly, organophosphonic acid stabilizers, by utilizing the advantage of containing phosphate groups in their structure, can form complexes with metal ions, thus exhibiting good stability.

[0046] Secondly, the use of carboxylic acid stabilizers can help the metal ions form coordinate bonds with their carboxyl groups, allowing the metal ions that were not captured and complexed by organophosphonic acid stabilizers to be further complexed, forming stable complexes.

[0047] Third, both organophosphonic acid stabilizers and carboxylic acid stabilizers have high temperature resistance.

[0048] The simultaneous addition of these two stabilizers enables the high-temperature resistant semiconductor platinum etching solution of the present invention to have better high-temperature resistance, while also increasing the etching rate and having longer-term stability.

[0049] (3) The addition of surfactants in this invention has unique advantages:

[0050] Firstly, surfactants not only possess excellent high-temperature resistance, but their sulfonic acid groups can also complex metal ions through coordination. The resulting complexes are further stabilized due to van der Waals forces and interactions with surrounding molecules. This helps to mitigate the decomposition of hydrogen peroxide and, in conjunction with the composite stabilizer, further stabilizes the etching system.

[0051] Secondly, it can reduce the interfacial tension between the etching solution and the metal surface, reduce the cohesive force of the liquid, make it easier to wet the metal surface, increase the medium transfer rate, and thus increase the etching rate.

[0052] Therefore, the addition of surfactants in this invention not only improves the interfacial properties, but also further enhances the high-temperature resistance of the high-temperature semiconductor platinum etching solution and improves the stability of the etching system. Attached Figure Description

[0053] Figure 1 : A microscope image of a platinum wafer before etching, magnified 50 times;

[0054] Figure 2 : A microscope image magnified 50 times after etching with the platinum etching solution prepared in Example 1 of this invention;

[0055] Figure 3 : A microscope image magnified 50 times after a platinum wafer was etched using the platinum etching solution prepared in Comparative Example 1 of this invention. Detailed Implementation

[0056] The present invention will be further described below with reference to specific embodiments and accompanying drawings:

[0057] Table 1 Examples 1-6

[0058]

[0059] Table 2 Comparative Examples 1-4

[0060]

[0061] Regarding the preparation method of the high-temperature resistant semiconductor platinum etching solution of the present invention

[0062] It includes the following steps:

[0063] Step 1: Weigh out ultrapure water, hydrochloric acid, and hydrogen peroxide separately and add them to a container in sequence to obtain a mixed solution;

[0064] Step 2: Continue to add composite stabilizer and surfactant to the mixed solution prepared in Step 1, and stir for 6 minutes until all materials are completely dissolved to obtain high-temperature resistant semiconductor platinum etching solution.

[0065] Etching method of the high-temperature resistant semiconductor platinum etching solution of the present invention

[0066] It includes the following steps:

[0067] Step 1: Prepare a 65% (w / w) aqueous solution of the high-temperature resistant semiconductor platinum etching solution with ultrapure water. Then, use this aqueous solution to soak the platinum wafer at 80°C for 60 minutes to obtain the soaked platinum wafer.

[0068] Step 2: Rinse the soaked platinum wafer twice in ultrapure water and purge it with nitrogen gas to complete the etching process of the platinum wafer.

[0069] Regarding performance testing and explanation:

[0070] The test method for performance stability is as follows:

[0071] The etching solution was stored at room temperature away from light, and the etching effect of the initial solution and the etching solution after 7 days of storage were examined to evaluate their respective stability.

[0072] The test method for performance 2 etching effect is as follows:

[0073] The etching solutions of the above-described embodiments and comparative examples of the present invention were used to etch platinum wafers, and the surface morphology of the etched platinum wafers under an optical microscope was observed to examine the etching effect of the etching solution.

[0074] The etching process includes the following steps:

[0075] Step 1: Immerse the platinum wafer in the etching solution at 80°C for 60 minutes to obtain the immersed platinum wafer;

[0076] Step 2: Rinse the soaked platinum wafer twice in ultrapure water and purge it with nitrogen gas to complete the etching process of the platinum wafer.

[0077] The ultrapure water used in step 2 is deionized water with a resistance of at least 18 MΩ.

[0078] The test method for performance 3 metal etching rate is as follows:

[0079] A four-probe thickness gauge was used to record the thickness of Pt before and after etching, and the etching rate of platinum was calculated. The specific testing method was as follows: First, the thickness of a 2×2cm wafer (with a Pt metal layer deposited on it) before etching was measured using a four-probe thickness gauge. Then, the wafer was immersed in an etching solution at 80℃ for 60 minutes. After etching, the thickness of the platinum wafer after etching was measured using the four-probe thickness gauge. The etching rate was calculated from the change in film thickness before and after etching. Right now The etching rate of platinum was investigated by measuring the etching solution per minute ( / min).

[0080] Table 3 Test Results

[0081]

[0082] Analysis and explanation of the test results:

[0083] As can be seen from the test data in Table 3, the etching effect of the etching solution prepared in the comparative example decreased significantly after 7 days, reaching 3-4.5 / min.

[0084] The high-temperature resistant semiconductor platinum etching solution prepared using the embodiments of the present invention showed a decrease in etching effect of no more than 2 / min after 7 days of storage.

[0085] As can be seen from the above comparison, the high-temperature resistant semiconductor platinum etching solution of the present invention has better stability.

[0086] Further comparison can be made using the accompanying diagrams in the instruction manual:

[0087] Figure 1 This is an optical microscope image of a platinum wafer before etching, magnified 50 times.

[0088] Figure 2 This is an optical microscope image magnified 50 times after a platinum wafer was etched using the platinum etching solution prepared in Example 1 of this invention.

[0089] Figure 3 This is an optical microscope image magnified 50 times after a platinum wafer was etched using the platinum etching solution prepared in Comparative Example 1 of this invention.

[0090] from Figure 2 As can be seen from the above, the surface morphology of the platinum wafer after etching with the high-temperature resistant semiconductor platinum etching solution prepared in Example 1 of the present invention is completely and uniformly etched.

[0091] from Figure 3 As can be seen from the above, the surface morphology of the platinum wafer etched using the aqua regia system in Comparative Example 1 of this invention is not completely etched and is uneven.

[0092] from Figure 2 and Figure 3The comparison shows that the platinum etching solution prepared using Example 1 of the present invention has a better etching effect on platinum wafers.

[0093] The organophosphonic acid stabilizer of this invention utilizes the advantage of containing phosphate groups in its structure, allowing it to form complexes with metal ions and exhibiting good stability. The addition of a carboxylic acid stabilizer further complexes the remaining metal ions, enhancing the system's stability. Furthermore, the addition of a surfactant increases the etching rate, and its complexing effect further stabilizes the system. Simultaneously, both the composite stabilizer and the surfactant possess high-temperature resistance, resulting in superior stability and high-temperature resistance for the entire platinum etching system.

[0094] The present invention has been described above by way of example with reference to the embodiments and accompanying drawings. Obviously, the implementation of the present invention is not limited to the above-described manner. Any improvements made by adopting the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. A high-temperature-resistant semiconductor platinum etching solution, characterized by comprising: a platinum etching agent; a complexing agent; and a pH adjuster. Based on parts by weight, it includes the following components: 8-15 parts hydrochloric acid; 30-50 parts hydrogen peroxide; 0.1-1 part of composite stabilizer; Surfactant 0.01-0.1 parts; 30-40 parts ultrapure water; The composite stabilizer includes organophosphonic acid stabilizers and carboxylic acid stabilizers; The mass ratio of the organophosphonic acid stabilizer to the carboxylic acid stabilizer is 1:2-5; The surfactant is a symmetrical diaromatic ether sulfonate, which has the following structure: Where n has a value between 2 and 6.

2. The high-temperature resistant semiconductor platinum etching solution according to claim 1, characterized in that: The organophosphonic acid stabilizers are one or more of cyclohexanehexaphosphate, hydroxyethylidene diphosphonic acid, methylene phosphonate, ethylenediaminetetramethylenephosphonic acid, diethylenetriaminepentamethylenephosphonic acid, and triethylenetetraaminehexamethylenephosphonic acid.

3. The high-temperature resistant semiconductor platinum etching solution according to claim 2, characterized in that: The carboxylic acid stabilizer is one or more of 1,4-cyclohexanedibutyric acid, cyclohexane-1,2,4,5-tetracarboxylic acid, N-methylcyclohexanecarboxylic acid, N-methylcyclopentanecarboxylic acid, and tartaric acid.

4. The high-temperature resistant semiconductor platinum etching solution according to claim 3, characterized in that: The organophosphonic acid stabilizer is cyclohexanehexaphosphate; The carboxylic acid stabilizer is 1,4-cyclohexanedibutyric acid.

5. A method of preparing the high-temperature-resistant semiconductor platinum etching solution according to any one of claims 1 to 4, characterized by Includes the following steps: Step 1: Weigh out ultrapure water, hydrochloric acid, and hydrogen peroxide separately and add them to a container in sequence to obtain a mixed solution; Step 2: Continue to add composite stabilizer and surfactant to the mixed solution prepared in Step 1, and stir for 5-10 minutes until all materials are completely dissolved to obtain high-temperature resistant semiconductor platinum etching solution.

6. An etching method of the high-temperature-resistant semiconductor platinum etching solution according to any one of claims 1 to 4, characterized by Includes the following steps: Step 1: Prepare a 60-70% (w / w) aqueous solution of the high-temperature resistant semiconductor platinum etching solution with ultrapure water. Then, use this aqueous solution to soak the platinum wafer at 70-80℃ for 60-80 minutes to obtain the soaked platinum wafer. Step 2: Rinse the soaked platinum wafer twice in ultrapure water and purge it with nitrogen gas to complete the etching process of the platinum wafer.

7. The use of the high-temperature resistant semiconductor platinum etching solution according to any one of claims 1-4 in the etching of platinum wafers, thin-film platinum resistance thermometers, and platinum film temperature sensors.

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