Preparation method of water-based developer, water-based developer and application thereof

Abstract

The application discloses a preparation method of a water-based developing solution, the water-based developing solution and application thereof, and belongs to the technical field of developing solutions. The preparation method comprises the following steps: a first amount of sulfuric acid is mixed with a second amount of isopropyl alcohol to obtain an isopropyl alcohol solution; tetramethylammonium chloride is mixed with the isopropyl alcohol solution according to a first preset proportion, a third amount of sulfuric acid is added, and the precipitate is filtered and dried to obtain white crystalline solid tetramethylammonium sulfate; the solid tetramethylammonium sulfate is dissolved in water, a suspension of barium hydroxide is added to the water, the reaction mixture is filtered, a tetramethylammonium hydroxide solution is obtained and purified; and the purified tetramethylammonium hydroxide solution is mixed with water according to a second preset proportion, and stirring is performed to obtain the water-based developing solution. The application aims to provide a water-based developing solution to solve the problem that the conventional developing solution in the form of an organic solvent is inconvenient to use in a chip developing process.

Description

Technical Field

[0001] This invention relates to the field of developer preparation technology, specifically to a method for preparing a water-based developer, the water-based developer, and its applications. Background Technology

[0002] Photolithography is a technique that combines image copying and etching, encompassing methods such as optical, electron beam, ion beam, X-ray, and scanning tunneling microscopy (STM) nanolithography. The principle of optical lithography is similar to printing a photograph. The photoresist coated on the silicon wafer is analogous to photographic paper, and the mask is analogous to the film. Light of a specific wavelength is used to irradiate the photoresist. Photoresists possess both photosensitivity and etching resistance, i.e., positive and negative types. In positive photoresist, the exposed portions dissolve in the developer, leaving the unexposed layer; in negative photoresist, the exposed portions do not dissolve, while the unexposed layer is dissolved. After development, the lithographic pattern is revealed, as shown in the figure.

[0003] For chip development, the developer is typically an organic solvent, such as xylene. The main chemical principle utilized in the development process is the "like dissolves like" principle, for example, diazonium quinone / phenolic resin reacts with light to form carboxylic acid / phenolic resin. However, these substances are highly volatile and flammable. Even without an open flame, they can be ignited by static electricity carried by the human body during production. Furthermore, the development time is long, and the developer has high viscosity, easily leaving residues on the chip, requiring additional chip cleaning. Therefore, traditional organic solvent-based developers still present inconveniences in chip development. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide a method for preparing a water-based developer, the water-based developer and its application, and to solve the problem that organic solvent-based developers are inconvenient to use in the chip development process.

[0005] A first aspect of the present invention is to provide a method for preparing a water-based developer, the method comprising:

[0006] A first part of sulfuric acid and a second part of isopropanol are mixed to obtain an isopropanol solution. Tetramethylammonium chloride is mixed with the isopropanol solution according to a first preset ratio. A third part of sulfuric acid is added, the precipitate is filtered, and the precipitate is dried to obtain a white crystalline solid tetramethylammonium sulfate.

[0007] The solid tetramethylammonium sulfate was dissolved in water, a suspension of barium hydroxide was added to the water, the reaction mixture was filtered to obtain a tetramethylammonium hydroxide solution, which was then purified.

[0008] The purified tetramethylammonium hydroxide solution is mixed with water in a second preset ratio and stirred to obtain a water-based developer.

[0009] According to one aspect of the above technical solution, the steps of mixing a first portion of sulfuric acid with a second portion of isopropanol to obtain an isopropanol solution, mixing tetramethylammonium chloride with the isopropanol solution according to a first preset ratio, adding a third portion of sulfuric acid, filtering the precipitate, and drying the precipitate to obtain a white crystalline solid tetramethylammonium sulfate specifically include:

[0010] Select a first amount of sulfuric acid and a second amount of isopropanol, and mix the sulfuric acid and the isopropanol to obtain an isopropanol solution;

[0011] Tetramethylammonium chloride and the resulting isopropanol solution are mixed in a first preset ratio and poured into a three-necked flask for reflux at a first temperature for a first duration.

[0012] Add the third portion of hydrochloric acid and stir. After cooling to room temperature, filter the mixture to obtain the precipitate.

[0013] The precipitate was dried at a second temperature to obtain a white crystalline solid, tetramethylammonium sulfate.

[0014] According to one aspect of the above technical solution, the first temperature is 75°C, the second temperature is 60°C, and the first duration is 30 minutes.

[0015] According to one aspect of the above technical solution, the steps of dissolving the solid tetramethylammonium sulfate in water, adding a suspension of barium hydroxide to the water, filtering the reaction mixture to obtain a tetramethylammonium hydroxide solution, and then purifying it specifically include:

[0016] The solid tetramethylammonium sulfate was dissolved in water, and a suspension of barium hydroxide was gradually added dropwise to the water. The reaction mixture was then filtered to obtain a tetramethylbarium hydroxide solution.

[0017] The tetramethylbarium hydroxide solution is passed through an exchange column packed with OH-type anion exchange resin to remove SO4. 2- The ions were purified to obtain the tetramethylbarium hydroxide solution.

[0018] According to one aspect of the above technical solution, the OH-type anion exchange resin is spherical particles, and the particle size of the OH-type anion exchange resin is +1.2mm < 5%.

[0019] According to one aspect of the above technical solution, the first preset ratio of the mixing of the tetramethylammonium chloride and the isopropanol solution is the solid-liquid ratio, which is 1:(3-6).

[0020] A second aspect of the present invention is to provide a water-based developer, which is prepared by the preparation method described in the above-described technical solution.

[0021] A third aspect of the present invention is to provide an application of a water-based developer in a semiconductor chip development process, wherein the water-based developer is the water-based developer described in the above-mentioned technical solution.

[0022] Among them, the OH generated by the dissociation of the water-based developer - Ions react with the Si element in the wafer of a semiconductor chip, causing the Si in a specific area to be etched and dissolved, thereby enabling the development of the wafer.

[0023] Compared with existing technologies, the advantages of using the water-based developer preparation method, the water-based developer, and its applications as shown in this invention are as follows:

[0024] An isopropanol solution is obtained by mixing a first portion of sulfuric acid with a second portion of isopropanol. Tetramethylammonium chloride is then mixed with the isopropanol solution, followed by the addition of a third portion of sulfuric acid. The mixture is filtered to obtain a precipitate, which is then dried to yield a white crystalline solid, tetramethylammonium sulfate. This precipitate is dissolved in water, and a suspension of barium hydroxide is added. The reaction mixture is then filtered to obtain a tetramethylbarium hydroxide solution, which is the main component of the water-based developer. This tetramethylbarium hydroxide solution is mixed with water and stirred to obtain the water-based developer. This water-based developer is non-toxic, does not introduce heavy metal ions, is compatible with IC processes, has a high and easily controllable development rate, low volatility, is non-flammable, and has high development efficiency. Therefore, the water-based developer is currently an ideal developer for photolithography processes. Attached Figure Description

[0025] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0026] Figure 1 This is a schematic flowchart illustrating the preparation method of the water-based developer shown in the embodiments of the present invention. Detailed Implementation

[0027] To make the objectives, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Several embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of the present invention will be more thorough and complete.

[0028] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0030] Please see Figure 1 The first aspect of the present invention is to provide a method for preparing a water-based developer, the method comprising steps S01-S03:

[0031] Step S01: Select a first amount of sulfuric acid and a second amount of isopropanol to mix to obtain an isopropanol solution. Mix tetramethylammonium chloride with the isopropanol solution according to a first preset ratio. Add a third amount of sulfuric acid, filter the precipitate, and dry the precipitate to obtain a white crystalline solid tetramethylammonium sulfate.

[0032] Step S02: Dissolve the solid tetramethylammonium sulfate in water, add a suspension of barium hydroxide to the water, filter the reaction mixture to obtain a tetramethylammonium hydroxide solution, and then purify it.

[0033] Step S03: The purified tetramethylammonium hydroxide solution is mixed with water in a second preset ratio and stirred to obtain a water-based developer.

[0034] In this invention, the steps of mixing a first portion of sulfuric acid with a second portion of isopropanol to obtain an isopropanol solution, mixing tetramethylammonium chloride with the isopropanol solution according to a first preset ratio, adding a third portion of sulfuric acid, filtering the precipitate, and drying the precipitate to obtain a white crystalline solid tetramethylammonium sulfate specifically include:

[0035] Select a first amount of sulfuric acid and a second amount of isopropanol, and mix the sulfuric acid and the isopropanol to obtain an isopropanol solution;

[0036] Tetramethylammonium chloride and the resulting isopropanol solution are mixed in a first preset ratio and poured into a three-necked flask for reflux at a first temperature for a first duration.

[0037] Add the third portion of hydrochloric acid and stir. After cooling to room temperature, filter the mixture to obtain the precipitate.

[0038] The precipitate was dried at a second temperature to obtain a white crystalline solid, tetramethylammonium sulfate.

[0039] In this invention, the first temperature is 75°C, the second temperature is 60°C, and the first duration is 30 minutes.

[0040] In this invention, the steps of dissolving the solid tetramethylammonium sulfate in water, adding a suspension of barium hydroxide to the water, filtering the reaction mixture to obtain a tetramethylammonium hydroxide solution, and then purifying it specifically include:

[0041] The solid tetramethylammonium sulfate was dissolved in water, and a suspension of barium hydroxide was gradually added dropwise to the water. The reaction mixture was then filtered to obtain a tetramethylbarium hydroxide solution.

[0042] The tetramethylbarium hydroxide solution is passed through an exchange column packed with OH-type anion exchange resin to remove SO4. 2- The ions were purified to obtain the tetramethylbarium hydroxide solution.

[0043] In this invention, the OH-type anion exchange resin is in the form of spherical particles, and the particle size of the OH-type anion exchange resin is +1.2mm < 5%.

[0044] In this invention, the first preset ratio of the mixing of the tetramethylammonium chloride and the isopropanol solution is the solid-liquid ratio, which is 1:(3-6).

[0045] A second aspect of the present invention is to provide a water-based developer prepared by the preparation method described in the first aspect above.

[0046] A third aspect of the present invention is to provide an application of a water-based developer in a semiconductor chip development process, wherein the water-based developer is the water-based developer described in the second aspect above.

[0047] Among them, the OH generated by the dissociation of the water-based developer - Ions react with the Si element in the wafer of a semiconductor chip, causing the Si in a specific area to be etched and dissolved, thereby enabling the development of the wafer.

[0048] Compared with existing technologies, the advantages of using the water-based developer preparation method, the water-based developer, and its applications as shown in this invention are as follows:

[0049] An isopropanol solution is obtained by mixing a first portion of sulfuric acid with a second portion of isopropanol. Tetramethylammonium chloride is then mixed with the isopropanol solution, followed by the addition of a third portion of sulfuric acid. The mixture is filtered to obtain a precipitate, which is then dried to yield a white crystalline solid, tetramethylammonium sulfate. This precipitate is dissolved in water, and a suspension of barium hydroxide is added. The reaction mixture is then filtered to obtain a tetramethylbarium hydroxide solution, which is the main component of the water-based developer. This tetramethylbarium hydroxide solution is mixed with water and stirred to obtain the water-based developer. This water-based developer is non-toxic, does not introduce heavy metal ions, is compatible with IC processes, has a high and easily controllable development rate, low volatility, is non-flammable, and has high development efficiency. Therefore, the water-based developer is currently an ideal developer for photolithography processes.

[0050] Example 1

[0051] The first embodiment of the present invention provides a method for preparing a water-based developer, the preparation method comprising steps S11-S13:

[0052] Step S11: Select a first amount of sulfuric acid and a second amount of isopropanol to mix to obtain an isopropanol solution. Mix tetramethylammonium chloride with the isopropanol solution according to a first preset ratio. Add a third amount of sulfuric acid, filter the precipitate, and dry the precipitate to obtain a white crystalline solid tetramethylammonium sulfate.

[0053] Step S12: Dissolve the solid tetramethylammonium sulfate in water, add a suspension of barium hydroxide to the water, filter the reaction mixture to obtain a tetramethylammonium hydroxide solution, and then purify it.

[0054] Step S13: The purified tetramethylammonium hydroxide solution is mixed with water according to a second preset ratio and stirred to obtain a water-based developer.

[0055] It should be noted that tetramethylammonium chloride (TMAC) has the molecular formula C4H. 12 ClN is a white crystalline solid that is volatile and hygroscopic.

[0056] In this embodiment, firstly, a first portion of sulfuric acid and a second portion of isopropanol are mixed to obtain an isopropanol solution. Then, the aforementioned tetramethylammonium chloride is mixed with the obtained isopropanol solution. The first preset ratio of the tetramethylammonium chloride to the isopropanol solution is the solid-liquid ratio, which is 1:4. A third portion of sulfuric acid is then added, and the mixture is allowed to stand and filtered to obtain a precipitate in the solution. Since the precipitate is obtained from the solution, it has a certain degree of moisture. Therefore, the precipitate needs to be dried to obtain a dry, white crystalline solid tetramethylammonium sulfate (TMAHS).

[0057] The first part is 50 ml of sulfuric acid (H2SO4), the second part is 80 ml of isopropanol, the third part is 20 g of tetramethylammonium chloride, and the fourth part is also 50 ml of sulfuric acid. The white crystalline solid tetramethylammonium sulfate obtained by drying the precipitate weighs 160 g.

[0058] Specifically, the steps of mixing a first portion of sulfuric acid with a second portion of isopropanol to obtain an isopropanol solution, mixing tetramethylammonium chloride with the isopropanol solution according to a first preset ratio, adding a third portion of sulfuric acid, filtering the precipitate, and drying the precipitate to obtain a white crystalline solid tetramethylammonium sulfate include:

[0059] Select a first amount of sulfuric acid and a second amount of isopropanol, and mix the sulfuric acid and the isopropanol to obtain an isopropanol solution;

[0060] Tetramethylammonium chloride and the resulting isopropanol solution are mixed in a first preset ratio and poured into a three-necked flask for reflux at a first temperature for a first duration.

[0061] Add the third portion of hydrochloric acid and stir. After cooling to room temperature, filter the mixture to obtain the precipitate.

[0062] The precipitate was dried at a second temperature to obtain a white crystalline solid, tetramethylammonium sulfate.

[0063] The first temperature is 75°C, the second temperature is 60°C, and the first duration is 30 minutes.

[0064] Next, the dry, white crystalline solid tetramethylammonium sulfate is dissolved in water and stirred to ensure complete dissolution. A suspension of barium hydroxide is then added to the water. The reaction mixture is filtered to remove impurities, yielding a tetramethylammonium hydroxide solution. This tetramethylammonium hydroxide solution is then purified to obtain a tetramethylammonium hydroxide solution with higher purity.

[0065] Specifically, the purification steps for the tetramethylammonium hydroxide solution include:

[0066] The tetramethylammonium hydroxide solution was poured into an exchange column packed with OH-type anion exchange resin to remove SO4 from the tetramethylammonium hydroxide solution. 2- Ions were used to obtain a high-purity tetramethylammonium hydroxide solution, which is the main component of the water-based developer in this embodiment.

[0067] Finally, the purified tetramethylammonium hydroxide solution was mixed with water and stirred to obtain a water-based developer.

[0068] It should be noted again that this water-based developer is used for wafer development of semiconductor chips, specifically:

[0069] The entire box of wafers is immersed in the water-based developer and agitated to a certain extent. The temperature of the water-based developer is controlled between 15-25℃ during the development process. To ensure development quality, the water-based developer is replaced before the reaction rate between the developer and the photoresist on the wafer surface changes significantly. Furthermore, after the photoresist is dissolved by the water-based developer, the wafer surface is rinsed with deionized water to remove any residual deionized water. Therefore, developing wafers using this water-based developer is quick and unaffected by environmental factors.

[0070] The water-based developer was used to develop the wafers. After testing, the development linewidth was 1µm ± 0.15µm, which meets the product process requirements.

[0071] In summary, the beneficial effects of using the water-based developer prepared in this embodiment to develop semiconductor chip wafers are as follows:

[0072] The water-based developer prepared in the above embodiments is non-toxic, does not introduce heavy metal ions, is compatible with semiconductor manufacturing processes (i.e., IC processes), has a high development rate and is easy to control, has low volatility, is non-flammable, and has high development efficiency. Therefore, the water-based developer provided in this embodiment has superior performance in all aspects for developing wafers and is currently an ideal developer in photolithography processes.

[0073] Example 2

[0074] The second embodiment of the present invention provides a method for preparing a water-based developer, the method comprising steps S21-S23:

[0075] Step S21: Select a first part of sulfuric acid and a second part of isopropanol to mix to obtain an isopropanol solution. Mix tetramethylammonium chloride with the isopropanol solution according to a first preset ratio. Add a third part of sulfuric acid, filter the precipitate, and dry the precipitate to obtain a white crystalline solid tetramethylammonium sulfate.

[0076] Step S22: Dissolve the solid tetramethylammonium sulfate in water, add a suspension of barium hydroxide to the water, filter the reaction mixture to obtain a tetramethylammonium hydroxide solution, and then purify it.

[0077] Step S23: The purified tetramethylammonium hydroxide solution is mixed with water in a second preset ratio and stirred to obtain a water-based developer.

[0078] It should be noted that tetramethylammonium chloride (TMAC) has the molecular formula C4H. 12 ClN is a white crystalline solid that is volatile and hygroscopic.

[0079] In this embodiment, firstly, a first portion of sulfuric acid and a second portion of isopropanol are mixed to obtain an isopropanol solution. Then, the aforementioned tetramethylammonium chloride is mixed with the obtained isopropanol solution. The first preset ratio of the tetramethylammonium chloride to the isopropanol solution is the solid-liquid ratio, which is 1:5. A third portion of sulfuric acid is then added, and the mixture is allowed to stand and filtered to obtain a precipitate in the solution. Since the precipitate is obtained from the solution, it has a certain degree of moisture. Therefore, the precipitate needs to be dried to obtain a dry, white crystalline solid tetramethylammonium sulfate (TMAHS).

[0080] The first part is 100 ml of sulfuric acid (H2SO4), the second part is 100 ml of isopropanol, the third part is 20 g of tetramethylammonium chloride, and the fourth part is also 100 ml of sulfuric acid. The white crystalline solid tetramethylammonium sulfate obtained by drying the precipitate weighs 230 g.

[0081] Specifically, the steps of mixing a first portion of sulfuric acid with a second portion of isopropanol to obtain an isopropanol solution, mixing tetramethylammonium chloride with the isopropanol solution according to a first preset ratio, adding a third portion of sulfuric acid, filtering the precipitate, and drying the precipitate to obtain a white crystalline solid tetramethylammonium sulfate include:

[0082] Select a first amount of sulfuric acid and a second amount of isopropanol, and mix the sulfuric acid and the isopropanol to obtain an isopropanol solution;

[0083] Tetramethylammonium chloride and the resulting isopropanol solution are mixed in a first preset ratio and poured into a three-necked flask for reflux at a first temperature for a first duration.

[0084] Add the third portion of hydrochloric acid and stir. After cooling to room temperature, filter the mixture to obtain the precipitate.

[0085] The precipitate was dried at a second temperature to obtain a white crystalline solid, tetramethylammonium sulfate.

[0086] The first temperature is 75°C, the second temperature is 60°C, and the first duration is 30 minutes.

[0087] Next, the dry, white crystalline solid tetramethylammonium sulfate is dissolved in water and stirred to ensure complete dissolution. A suspension of barium hydroxide is then added to the water. The reaction mixture is filtered to remove impurities, yielding a tetramethylammonium hydroxide solution. This tetramethylammonium hydroxide solution is then purified to obtain a tetramethylammonium hydroxide solution with higher purity.

[0088] Specifically, the purification steps for the tetramethylammonium hydroxide solution include:

[0089] The tetramethylammonium hydroxide solution was poured into an exchange column packed with OH-type anion exchange resin to remove SO4 from the tetramethylammonium hydroxide solution. 2- Ions were used to obtain a high-purity tetramethylammonium hydroxide solution, which is the main component of the water-based developer in this embodiment.

[0090] Finally, the purified tetramethylammonium hydroxide solution was mixed with water and stirred to obtain a water-based developer.

[0091] It should be noted again that this water-based developer is used for wafer development of semiconductor chips, specifically:

[0092] The entire box of wafers is immersed in the water-based developer and agitated to a certain extent. The temperature of the water-based developer is controlled between 15-25℃ during the development process. To ensure development quality, the water-based developer is replaced before the reaction rate between the developer and the photoresist on the wafer surface changes significantly. Furthermore, after the photoresist is dissolved by the water-based developer, the wafer surface is rinsed with deionized water to remove any residual deionized water. Therefore, developing wafers using this water-based developer is quick and unaffected by environmental factors.

[0093] The water-based developer was used to develop the wafers. After testing, the development linewidth was 1µm ± 0.15µm, which meets the product process requirements.

[0094] In summary, the beneficial effects of using the water-based developer prepared in this embodiment to develop semiconductor chip wafers are as follows:

[0095] The water-based developer prepared in the above embodiments is non-toxic, does not introduce heavy metal ions, is compatible with semiconductor manufacturing processes (i.e., IC processes), has a high development rate and is easy to control, has low volatility, is non-flammable, and has high development efficiency. Therefore, the water-based developer provided in this embodiment has superior performance in all aspects for developing wafers and is currently an ideal developer in photolithography processes.

[0096] Example 3

[0097] The third embodiment of the present invention provides a method for preparing a water-based developer, the method comprising steps S31-S33:

[0098] Step S31: Select a first part of sulfuric acid and a second part of isopropanol to mix to obtain an isopropanol solution. Mix tetramethylammonium chloride with the isopropanol solution according to a first preset ratio. Add a third part of sulfuric acid, filter the precipitate, and dry the precipitate to obtain a white crystalline solid tetramethylammonium sulfate.

[0099] Step S32: Dissolve the solid tetramethylammonium sulfate in water, add a suspension of barium hydroxide to the water, filter the reaction mixture to obtain a tetramethylammonium hydroxide solution, and then purify it.

[0100] Step S33: The purified tetramethylammonium hydroxide solution is mixed with water in a second preset ratio and stirred to obtain a water-based developer.

[0101] It should be noted that tetramethylammonium chloride (TMAC) has the molecular formula C4H. 12 ClN is a white crystalline solid that is volatile and hygroscopic.

[0102] In this embodiment, firstly, a first portion of sulfuric acid and a second portion of isopropanol are mixed to obtain an isopropanol solution. Then, the aforementioned tetramethylammonium chloride is mixed with the obtained isopropanol solution. The first preset ratio of the tetramethylammonium chloride to the isopropanol solution is the solid-liquid ratio, which is 1:6. A third portion of sulfuric acid is then added, and the mixture is allowed to stand and filtered to obtain a precipitate in the solution. Since the precipitate is obtained from the solution, it has a certain degree of moisture. Therefore, the precipitate needs to be dried to obtain a dry, white crystalline solid tetramethylammonium sulfate (TMAHS).

[0103] The first portion of sulfuric acid, i.e. H2SO4, is 150 ml; the second portion of isopropanol is 120 ml; tetramethylammonium chloride is 20 g; and the third portion of sulfuric acid, also 150 ml, is added. The white crystalline solid tetramethylammonium sulfate obtained by drying the precipitate is weighed to be 268 g.

[0104] Specifically, the steps of mixing a first portion of sulfuric acid with a second portion of isopropanol to obtain an isopropanol solution, mixing tetramethylammonium chloride with the isopropanol solution according to a first preset ratio, adding a third portion of sulfuric acid, filtering the precipitate, and drying the precipitate to obtain a white crystalline solid tetramethylammonium sulfate include:

[0105] Select a first amount of sulfuric acid and a second amount of isopropanol, and mix the sulfuric acid and the isopropanol to obtain an isopropanol solution;

[0106] Tetramethylammonium chloride and the resulting isopropanol solution are mixed in a first preset ratio and poured into a three-necked flask for reflux at a first temperature for a first duration.

[0107] Add the third portion of hydrochloric acid and stir. After cooling to room temperature, filter the mixture to obtain the precipitate.

[0108] The precipitate was dried at a second temperature to obtain a white crystalline solid, tetramethylammonium sulfate.

[0109] The first temperature is 75°C, the second temperature is 60°C, and the first duration is 30 minutes.

[0110] Next, the dry, white crystalline solid tetramethylammonium sulfate is dissolved in water and stirred to ensure complete dissolution. A suspension of barium hydroxide is then added to the water. The reaction mixture is filtered to remove impurities, yielding a tetramethylammonium hydroxide solution. This tetramethylammonium hydroxide solution is then purified to obtain a tetramethylammonium hydroxide solution with higher purity.

[0111] Specifically, the purification steps for the tetramethylammonium hydroxide solution include:

[0112] The tetramethylammonium hydroxide solution was poured into an exchange column packed with OH-type anion exchange resin to remove SO4 from the tetramethylammonium hydroxide solution. 2- Ions were used to obtain a high-purity tetramethylammonium hydroxide solution, which is the main component of the water-based developer in this embodiment.

[0113] Finally, the purified tetramethylammonium hydroxide solution was mixed with water and stirred to obtain a water-based developer.

[0114] It should be noted again that this water-based developer is used for wafer development of semiconductor chips, specifically:

[0115] The entire box of wafers is immersed in the water-based developer and agitated to a certain extent. The temperature of the water-based developer is controlled between 15-25℃ during the development process. To ensure development quality, the water-based developer is replaced before the reaction rate between the developer and the photoresist on the wafer surface changes significantly. Furthermore, after the photoresist is dissolved by the water-based developer, the wafer surface is rinsed with deionized water to remove any residual deionized water. Therefore, developing wafers using this water-based developer is quick and unaffected by environmental factors.

[0116] The water-based developer was used to develop the wafers. After testing, the development linewidth was 1µm ± 0.15µm, which meets the product process requirements.

[0117] In summary, the beneficial effects of using the water-based developer prepared in this embodiment to develop semiconductor chip wafers are as follows:

[0118] The aqueous developer solution prepared in the above embodiments is non-toxic, does not introduce heavy metal ions, is compatible with semiconductor manufacturing processes (i.e., IC processes), has a high development rate that is easy to control, low volatility, is non-flammable, and has high development efficiency. Therefore, the aqueous developer solution provided in this embodiment has superior performance in all aspects for developing wafers and is currently an ideal developer solution for photolithography processes. Table 1 shows the preparation parameters of the white crystalline solid tetramethylammonium sulfate (TMAHS) used in the preparation of the aqueous developer solution in this invention.

[0119] Table 1

[0120]

[0121] Please refer to Table 1 and Examples 1 to 3, which show the parameters of the white crystalline solid tetramethylammonium sulfate (TMAHS) prepared in the preparation of water-based developer in this invention. It can be seen that in the first example, when TMAC:isopropanol:H2SO4=1:4:5, the input-output ratio of white crystalline solid tetramethylammonium sulfate (TMAHS) is optimal. That is, more TMAHS can be produced with less raw material input, thereby effectively improving the input-output ratio of water-based developer.

[0122] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0123] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A method for preparing a water-based developer, characterized in that, The method includes: A first part of sulfuric acid and a second part of isopropanol are mixed to obtain an isopropanol solution. Tetramethylammonium chloride is mixed with the isopropanol solution in a first preset ratio. A third part of hydrochloric acid is added, the precipitate is filtered, and the precipitate is dried to obtain a white crystalline solid tetramethylammonium sulfate. The solid tetramethylammonium sulfate was dissolved in water, and a suspension of barium hydroxide was added to the water. The reaction mixture was filtered to obtain a tetramethylammonium hydroxide solution, which was then purified. Purification was performed using an exchange column packed with OH-type anion exchange resin to remove... ion; The purified tetramethylammonium hydroxide solution is mixed with water in a second preset ratio and stirred to obtain a water-based developer. Wherein, the first preset ratio is the solid-liquid ratio of tetramethylammonium chloride to isopropanol solution, which is 1:(3-6), and the second preset ratio is the volume ratio of purified tetramethylammonium hydroxide solution to water.

2. The method for preparing the water-based developer according to claim 1, characterized in that, The steps of mixing a first portion of sulfuric acid with a second portion of isopropanol to obtain an isopropanol solution, mixing tetramethylammonium chloride with the isopropanol solution according to a first preset ratio, adding a third portion of hydrochloric acid, filtering the precipitate, and drying the precipitate to obtain a white crystalline solid tetramethylammonium sulfate specifically include: Select a first amount of sulfuric acid and a second amount of isopropanol, and mix the sulfuric acid and the isopropanol to obtain an isopropanol solution; Tetramethylammonium chloride and the resulting isopropanol solution were mixed in a first preset ratio and poured into a three-necked flask for reflux at a first temperature for a first duration. Add the third portion of hydrochloric acid and stir. After cooling to room temperature, filter the mixture to obtain the precipitate. The precipitate was dried at a second temperature to obtain a white crystalline solid, tetramethylammonium sulfate.

3. The method for preparing the water-based developer according to claim 2, characterized in that, The first temperature is 75°C, the second temperature is 60°C, and the first duration is 30 minutes.

4. The method for preparing the water-based developer according to claim 1, characterized in that, The steps of dissolving the solid tetramethylammonium sulfate in water, adding a suspension of barium hydroxide to the water, filtering the reaction mixture to obtain a tetramethylammonium hydroxide solution, and then purifying it specifically include: The solid tetramethylammonium sulfate was dissolved in water, and a suspension of barium hydroxide was gradually added dropwise to the water. The reaction mixture was then filtered to obtain a tetramethylbarium hydroxide solution. The tetramethylbarium hydroxide solution is passed through an exchange column packed with OH-type anion exchange resin to remove SO4. 2- The ions were purified to obtain the tetramethylbarium hydroxide solution.

5. The method for preparing the water-based developer according to claim 4, characterized in that, The OH-type anion exchange resin is in the form of spherical particles, and the particle size of the OH-type anion exchange resin is +1.2mm < 5%.

6. A water-based developer, characterized in that, The water-based developer is prepared by any one of the preparation methods according to claims 1-5.

7. The application of the water-based developer according to claim 6 in semiconductor chip development processes; in, The water-based developer dissociates to produce Ions react with the Si element in the wafer of a semiconductor chip, causing the Si in a specific area to be etched and dissolved, thereby enabling the development of the wafer.

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