A tetramethylammonium hydroxide developer and its preparation method and application

Abstract

The invention discloses a tetramethylammonium hydroxide developer, a preparation method thereof, and an application thereof. The developer comprises tetramethylammonium hydroxide, polyoxyethyl glycerol ether, ammonium citrate, and water, wherein the mass ratio of the polyoxyethyl glycerol ether to the ammonium citrate is 1:1-10. The developer is prepared by weighing the components according to a formula and then mixing them to obtain the tetramethylammonium hydroxide developer. The developer has excellent development results, low residue, and good storage stability during an etching process, and is suitable for use in the preparation of liquid crystal displays, printed circuit boards, and integrated circuits.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor display technology, and in particular to a tetramethylammonium hydroxide developer, a preparation method thereof, and an application thereof. Background Art

[0002] Tetramethylammonium hydroxide (TMAH), also known as tetramethylammonium hydroxide, is an organic base with an alkalinity equivalent to caustic soda. Due to its low decomposition temperature, gasification upon decomposition without leaving residue, complete ionization in water, and low metal content, it is widely used in the preparation of semiconductor devices such as liquid crystal displays, printed circuit boards, and integrated circuits. In these processes, to obtain fine patterns, radiation-sensitive compositions such as photoresists are often coated onto substrates to form a thin film. After exposure, the image is developed with a tetramethylammonium hydroxide developer to remove unwanted portions of the coating to obtain a good pattern.

[0003] Currently, one goal of the development process is to minimize the amount of developer corrosion on the unexposed positive resist film. However, actual development always involves some degree of corrosion on the unexposed resist. While this difference in solubility between exposed and unexposed areas makes the resist process feasible, it significantly negatively impacts the accuracy and efficiency of development. Therefore, a developer should be selected that meets the required yield without causing excessive resist thinning. Furthermore, the developer should also have sufficient dispersion stability to maintain the process within the growth environment.

[0004] However, current developers, especially those using tetramethylammonium hydroxide (TMAH) as an etchant, still have the following problems when used for processing fine patterns: i. When forming fine patterns, the developer may cause pattern collapse, resulting in uneven pattern edges and obvious burrs; ii. Due to the presence of suspended particles in the development process, the developed material is more likely to form crystal nuclei, resulting in scaling and residue, which affects the pattern effect; iii. The developer becomes turbid after a period of use, which greatly affects the performance of the developer. Summary of the Invention

[0005] The object of the present invention is to overcome the deficiencies of the prior art and provide an improved tetramethylammonium hydroxide developer, which can achieve excellent development results, less residue and better storage stability during the etching process.

[0006] The present invention also provides a method for preparing the tetramethylammonium hydroxide developer.

[0007] The present invention also provides an application of the tetramethylammonium hydroxide developer in photolithography, which can be used, for example, in the preparation of liquid crystal displays, printed circuit boards, and integrated circuits.

[0008] In order to achieve the above object, a technical solution adopted by the present invention is:

[0009] A tetramethylammonium hydroxide developer comprises tetramethylammonium hydroxide and water. The developer further comprises polyoxyethyl glycerol ether and ammonium citrate. The mass ratio of the polyoxyethyl glycerol ether to the ammonium citrate is 1:1-10.

[0010] In the present invention, ammonium citrate is also referred to as triammonium citrate.

[0011] According to some specific aspects of the present invention, the boiling point of the polyoxyethylene glycerol ether at 1 atmosphere is greater than 200° C., and the density at 25° C. is 1.1-1.2 g / mL.

[0012] According to some preferred aspects of the present invention, the mass percentage of the polyoxyethylene glycerol ether in the developer is 0.01-1.0% by mass.

[0013] According to some preferred aspects of the present invention, the mass percentage of the ammonium citrate in the developer is 0.01-1.0% by mass.

[0014] According to some preferred aspects of the present invention, the mass percentage of the tetramethylammonium hydroxide in the developer is 1.0-5.0% by mass.

[0015] According to some preferred aspects of the present invention, in the developer, based on mass percentage, the tetramethylammonium hydroxide accounts for 1.5-4.0%, the polyoxyethyl glycerol ether accounts for 0.02-0.5%, and the ammonium citrate accounts for 0.02-0.75%.

[0016] Furthermore, in the developer, in terms of mass percentage, the tetramethylammonium hydroxide accounts for 2.0-3.0%, the polyoxyethyl glycerol ether accounts for 0.05-0.25%, and the ammonium citrate accounts for 0.2-0.75%.

[0017] According to some preferred aspects of the present invention, the mass ratio of the tetramethylammonium hydroxide, the polyoxyethyl glycerol ether and the ammonium citrate is 1:0.3-0.5:0.15-0.25.

[0018] According to some preferred aspects of the present invention, the water is deionized water with a metal ion concentration of less than or equal to 1000 nanograms per liter.

[0019] According to a specific aspect of the present invention, in the developer, in terms of mass percentage, the tetramethylammonium hydroxide accounts for 2.2-2.4%, the polyoxyethyl glycerol ether accounts for 0.05-0.15%, the ammonium citrate accounts for 0.4-0.6%, and the balance is deionized water.

[0020] Another technical solution provided by the present invention is a method for preparing the above-mentioned tetramethylammonium hydroxide developer, which comprises: weighing each component according to a formula and then mixing to obtain the tetramethylammonium hydroxide developer.

[0021] In some embodiments of the present invention, the mixing operation is controlled to be performed at 20-30° C., for example, it can be performed at room temperature.

[0022] In some embodiments of the present invention, the mixing operation can be performed by stirring, and the stirring time can be 20-120 minutes.

[0023] Another technical solution provided by the present invention is a use of the above-mentioned tetramethylammonium hydroxide developer in the preparation of liquid crystal displays, printed circuit boards and integrated circuits.

[0024] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0025] The present invention is based on the problems of tetramethylammonium hydroxide as an etchant in the developer, such as pattern collapse, a lot of residue and poor storage stability. In practice, it is unexpectedly found that when polyoxyethyl glycerol ether and ammonium citrate are used in combination, on the one hand, not only the developer is better and faster to be evenly distributed on the plate, but also the developer system is more stable, thus avoiding the uneven edge and burr phenomenon of the pattern in the processing of fine patterns, which is beneficial to prevent the occurrence of pattern collapse and ensure better development effect; at the same time, the combination of the two can make the developed material less likely to form crystal nuclei, reduce the generation of residue, and can also The free metal ion content in the developer is significantly reduced; on the other hand, during use, the developer of the present invention can be stably and evenly dispersed for a long time, and turbidity will basically not occur. Research and analysis show that in the developer system of the present invention, after tetramethylammonium hydroxide is combined with polyoxyethylene glycerol ether and ammonium citrate, it dissociates in water to obtain large-volume organic groups, which reduces the charge per unit volume, thereby effectively reducing the influence on the formation of hydrogen bonds between hydroxyl groups, polyoxyethylene chains and water molecules, and ultimately increasing the number of hydrogen bonds, ensuring the dissolution effect, avoiding turbidity during use, and achieving long-term stable storage and use.

[0026] In addition, the developer of the present invention has a strong fault tolerance. Even if the actual content of tetramethylammonium hydroxide in the developer has a significant error compared to the theoretical content due to operator error, it will not cause a significant negative impact on the developing effect or residue of the developer. Specifically, under the formulation system of the present invention, the actual content of tetramethylammonium hydroxide can be selected in a wide range, which is conducive to industrial application. DETAILED DESCRIPTION

[0027] The above scheme is further described below in conjunction with specific examples; it should be understood that these examples are used to illustrate the basic principles, main features and advantages of the present invention, and the present invention is not limited to the scope of the following examples; the implementation conditions adopted in the examples can be further adjusted according to specific requirements, and the implementation conditions not specified are generally the conditions in routine experiments.

[0028] Unless otherwise specified in the following examples, all raw materials can be purchased from commercial sources or prepared by conventional methods in the art. Polyoxyethylene glycerol ether was purchased from Maclean, CAS: 31694-55-0.

[0029] Example 1

[0030] This example provides a developer solution, which comprises, by weight percentage, 2.0% of tetramethylammonium hydroxide (TMAH); 0.1% of polyoxyethylene glycerol ether (MF); 0.5% of ammonium citrate (AMC); and the balance being deionized water.

[0031] The preparation method is as follows: the ingredients are mixed at room temperature according to the above formula, and stirred for 60 minutes to obtain the product.

[0032] Example 2

[0033] This example provides a developer solution, which comprises, by weight percentage, 2.2% of tetramethylammonium hydroxide (TMAH); 0.1% of polyoxyethylene glycerol ether (MF); 0.5% of ammonium citrate (AMC); and the balance being deionized water.

[0034] The preparation method is the same as that in Example 1.

[0035] Example 3

[0036] This example provides a developer solution, which comprises, by weight percentage, 2.38% of tetramethylammonium hydroxide (TMAH); 0.1% of polyoxyethylene glycerol ether (MF); 0.5% of ammonium citrate (AMC); and the balance being deionized water.

[0037] The preparation method is the same as that in Example 1.

[0038] Example 4

[0039] This example provides a developer solution, which comprises, by weight percentage, 2.4% of tetramethylammonium hydroxide (TMAH); 0.1% of polyoxyethylene glycerol ether (MF); 0.5% of ammonium citrate (AMC); and the balance being deionized water.

[0040] The preparation method is the same as that in Example 1.

[0041] Example 5

[0042] This example provides a developer solution, which comprises, by weight percentage, 3.0% tetramethylammonium hydroxide (TMAH); 0.1% polyoxyethylene glycerol ether (MF); 0.5% ammonium citrate (AMC); and the balance deionized water.

[0043] The preparation method is the same as that in Example 1.

[0044] Example 6

[0045] This example provides a developer solution, which comprises, by weight percentage, 2.38% of tetramethylammonium hydroxide (TMAH); 0.15% of polyoxyethylene glycerol ether (MF); 0.6% of ammonium citrate (AMC); and the balance being deionized water.

[0046] The preparation method is the same as that in Example 1.

[0047] Example 7

[0048] This example provides a developer solution, which comprises, by weight percentage, 2.38% of tetramethylammonium hydroxide (TMAH); 0.15% of polyoxyethylene glycerol ether (MF); 0.5% of ammonium citrate (AMC); and the balance being deionized water.

[0049] The preparation method is the same as that in Example 1.

[0050] Example 8

[0051] This example provides a developer solution, which comprises, by weight percentage, 2.38% of tetramethylammonium hydroxide (TMAH); 0.10% of polyoxyethylene glycerol ether (MF); 0.4% of ammonium citrate (AMC); and the balance being deionized water.

[0052] The preparation method is the same as that in Example 1.

[0053] Comparative Example 1

[0054] The process is basically the same as Example 1, except that polyoxyethylene glycerol ether (MF) and ammonium citrate (AMC) are not added, and the content of deionized water is adjusted accordingly.

[0055] Comparative Example 2

[0056] The process is basically the same as Example 1, except that polyoxyethylene glycerol ether (MF) is not added and the content of deionized water is adjusted accordingly.

[0057] Comparative Example 3

[0058] The process is basically the same as Example 1, except that ammonium citrate (AMC) is not added and the content of deionized water is adjusted accordingly.

[0059] Comparative Example 4

[0060] The method is basically the same as Example 1, except that polyoxyethyl glycerol ether (MF) is replaced by an equal amount of naphthol polyoxyethylene ether.

[0061] Comparative Example 5

[0062] The process is basically the same as Example 1, except that polyoxyethylene glycerol ether (MF) is replaced with an equal amount of nonylphenol polyoxyethylene ether.

[0063] Comparative Example 6

[0064] The process is basically the same as Example 1, except that polyoxyethylene glycerol ether (MF) is replaced with castor oil polyoxyethylene ether in an equal amount.

[0065] Comparative Example 7

[0066] The method is basically the same as Example 1, except that ammonium citrate (AMC) is replaced by an equal amount of sodium citrate.

[0067] Comparative Example 8

[0068] The process is basically the same as Example 1, except that ammonium citrate (AMC) is replaced by an equal amount of ammonium carbonate.

[0069] Comparative Example 9

[0070] The method is basically the same as Example 1, except that ammonium citrate (AMC) is replaced by an equal amount of triethanolammonium.

[0071] Comparative Example 10

[0072] The process is basically the same as Example 1, except that tetramethylammonium hydroxide is replaced with an equal amount of potassium hydroxide.

[0073] Performance Testing

[0074] 1. The pH values ​​and metal ion data of various developing solutions prepared at room temperature are shown in Table 1.

[0075] Table 1

[0076]

[0077] 2. The developers prepared in Examples 1-8 and Comparative Examples 1-10 were subjected to photolithographic development. The specific operation process was as follows: a negative photoresist was coated on a clean glass substrate, dried, and then exposed through a mask. The mask line width was 30 μm, and the exposure energy was set to 200 ml / cm 2 The exposed glass substrate was placed in a developing tank and sprayed with the developer prepared in Examples 1-8 and Comparative Examples 1-10 for 30 seconds at a developing temperature of 25°C. The substrate was then rinsed with deionized water and dried. The residue and edge flatness were observed under an optical microscope, and the process and results were evaluated.

[0078] 2.1 Development Results

[0079] Use a 50x microscope to observe the flatness of the pattern edges on the photoresist board after development: O: indicates a clean, flat, and burr-free pattern edge; #: indicates a dirty or uneven pattern edge with burrs; X: indicates a dirty, uneven pattern edge with burrs. See Table 2 for the specific results.

[0080] 2.2. Development residue

[0081] The patterned areas of the photoresist plate after development were observed using a 200x microscope to determine if there was any residue: O: no residue; #: little residue; X: much residue. The specific results are shown in Table 2.

[0082] Table 2

[0083]

[0084] 3. Stability during use

[0085] 50 ml of each developer prepared in Examples 1-8 and Comparative Examples 1-10 was added to a 100 ml beaker, and a thermometer was inserted. The beakers were then placed in a container of water so that the water level was higher than the developer level. The beakers were then slowly heated to observe whether the developer became turbid within a certain temperature and maintenance time range.

[0086] See Table 3 for specific results.

[0087] Table 3

[0088]

[0089] In Table 3 above, "slightly turbid" and "turbid" both indicate relative degrees relative to the transparent and non-turbid samples of Examples 1-8.

[0090] The above embodiments are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made in accordance with the spirit of the present invention are intended to be covered by the scope of protection of the present invention.

[0091] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

Claims

1. A tetramethylammonium hydroxide developer, comprising tetramethylammonium hydroxide and water, characterized in that: The developer further comprises polyoxyethyl glycerol ether and ammonium citrate, wherein the mass ratio of the polyoxyethyl glycerol ether to the ammonium citrate is 1:1-10; in terms of mass percentage, the mass percentage of the tetramethylammonium hydroxide in the developer is 1.0-5.0%, the mass percentage of the polyoxyethyl glycerol ether in the developer is 0.01-1.0%, and the mass percentage of the ammonium citrate in the developer is 0.01-1.0%.

2. The tetramethylammonium hydroxide developer according to claim 1, wherein The boiling point of the polyoxyethylene glycerol ether at 1 atmosphere is greater than 200° C., and the density at 25° C. is 1.1-1.2 g / mL.

3. The tetramethylammonium hydroxide developer according to claim 1, wherein Calculated by mass percentage, in the developer, the tetramethylammonium hydroxide accounts for 1.5-4.0%, the polyoxyethyl glycerol ether accounts for 0.02-0.5%, and the ammonium citrate accounts for 0.02-0.75%.

4. The tetramethylammonium hydroxide developer according to claim 3, wherein Calculated by mass percentage, in the developer, the tetramethylammonium hydroxide accounts for 2.0-3.0%, the polyoxyethyl glycerol ether accounts for 0.05-0.25%, and the ammonium citrate accounts for 0.2-0.75%.

5. The tetramethylammonium hydroxide developer according to claim 1, wherein The mass ratio of the tetramethylammonium hydroxide to the ammonium citrate is 1:0.15-0.

25.

6. The tetramethylammonium hydroxide developer according to claim 1, wherein The water is deionized water with a metal ion concentration of less than or equal to 1000 nanograms per liter.

7. A method for preparing the tetramethylammonium hydroxide developer according to any one of claims 1 to 6, characterized in that: The preparation method comprises: weighing each component according to a formula, and then mixing them to obtain the tetramethylammonium hydroxide developer.

8. Use of the tetramethylammonium hydroxide developer according to any one of claims 1 to 6 in the preparation of liquid crystal displays, printed circuit boards and integrated circuits.

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