Masking composition and mask for etching processing

Abstract

Provided is a technique relating to a mask composition capable of forming a mask having a thicker film. One embodiment of the present invention is a mask composition. The mask composition includes a metal hydroxide and a solvent. The metal hydroxide is dispersed or dissolved in the solvent.

Description

Technical Field

[0001] This invention relates to a mask composition and a mask for etching processes. Background Technology

[0002] In recent years, electronic materials, represented by semiconductors such as LSI (Large Scale Integration), have been advancing towards miniaturization and high precision as they become more integrated. In particular, the development of technology for manufacturing nanoscale micro-patterns is underway.

[0003] As a method for manufacturing fine patterns, etching using masks is generally employed. In particular, dry etching is widely known as a technique for forming patterns with even higher precision due to its extremely high etching accuracy.

[0004] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2012-185484 Summary of the Invention The problem the invention aims to solve In 3D packaging used with the miniaturization of electronic devices, deep vias need to be formed. The formation of deep vias requires highly durable masks, and in some applications, both durability and thick film coating properties of the masks are required.

[0005] The present invention was made in view of the above-mentioned problems, and its object is to provide a mask composition capable of forming a thick film mask.

[0006] means for solving problems One aspect of the present invention is a mask composition. This mask composition comprises a metal hydroxide and a solvent, wherein the metal hydroxide is dispersed or dissolved in the solvent.

[0007] In the mask composition described above, the mass of the mask composition when heated at 120°C for 3 hours can be 0.1% to 50.0% of the total mass of the mask composition.

[0008] The ratio of the mass of the mask composition heated at 120°C for 3 hours to the mass of the mask composition heated at 120°C for 3 hours and then further heated at 500°C for 30 minutes can be 60 to 100 by mass.

[0009] The content of the metal element constituting the metal hydroxide can be 25 to 70% by mass, relative to the mask composition when the mask composition is heated at 120°C for 3 hours.

[0010] The pH of the mask composition described above can be 10-14. The viscosity ratio at 20 rpm to that at 200 rpm can be 1-15. The viscosity at 20 rpm can be 1-100 mPa·s.

[0011] Another aspect of the invention is an etching mask. This etching mask contains flake-like metal hydroxides, which are stacked such that the normal direction of the flake surfaces is substantially the same as the film thickness direction.

[0012] In the etching mask described above, the film thickness can be 1 μm or more.

[0013] The effects of the invention According to the present invention, a technique is provided for a mask composition capable of forming a thicker film. Attached Figure Description

[0014] Figure 1 This is a schematic diagram showing the mask forming process based on the pattern transfer method. Detailed Implementation

[0015] Hereinafter, embodiments of the present invention will be described in detail. Furthermore, in this specification, unless otherwise specified, the use of "a~b" in the description of numerical ranges indicates a or more and b or less.

[0016] (Mask composition) The mask composition of the embodiments comprises a metal hydroxide and a solvent. Details of the mask composition of the embodiments are described below.

[0017] As a metal hydroxide, one or more can be selected from the group consisting of aluminum hydroxide, zinc hydroxide, silicon hydroxide, chromium hydroxide, and magnesium hydroxide. Therefore, by using these metal hydroxides, both etching resistance and thick film properties can be achieved simultaneously. Furthermore, magnesium hydroxide is preferably used as the metal hydroxide, as it improves etching resistance, allows for deep etching, and, whether in its magnesium hydroxide state or in its magnesium oxide state after heating, it can be dissolved by acid washing or the like, thus facilitating mask removal.

[0018] As a solvent, one or more polar solvents selected from the group consisting of water, methanol, and ethanol can be used. This allows for the formation of a more uniform coating film while maintaining the solubility of the metal hydroxide in the solvent; from the viewpoint of solubility and film thickness, water is preferred.

[0019] The aforementioned metal hydroxide is dispersed or dissolved in the aforementioned solvent. The mask composition of the embodiment may simultaneously contain both a metal hydroxide dispersed in the aforementioned solvent and a metal hydroxide dissolved in the aforementioned solvent.

[0020] The preferred mass of the mask composition heated at 120°C for 3 hours is 0.1% to 50.0% by mass relative to the total mass of the mask composition, more preferably 1.0% to 30.0% by mass, further preferably 2.0% to 30.0% by mass, and most preferably 2.0% to 10.0% by mass. By setting it to the above range, both coating properties and thick film properties can be achieved simultaneously.

[0021] The ratio of the mass of the mask composition heated at 120°C for 3 hours to the mass of the mask composition heated at 120°C for 3 hours and then further heated at 500°C for 30 minutes is preferably 60-100% by mass, more preferably 65-100% by mass. By setting it to the above range, a mask composition with high etch resistance that is independent of the etch time can be provided.

[0022] The mask composition is heated to become a mask composed of metal hydroxide. Furthermore, it is further heated to become a metal oxide mask. Specifically, the mass of the mask composition after heating at 120°C for 3 hours depends primarily on the metal hydroxide, while the mass after heating at 120°C for 3 hours and then at 500°C for 30 minutes depends primarily on the metal oxide. As described above, the minimal change in mass during heating at high temperature (500°C) improves the etching resistance of the mask.

[0023] Regarding the mask composition of the embodiment, after drying, the mass content (%) of the metal element constituting the metal hydroxide relative to the mass of the dried product can be 25-70% by mass, 30-65% by mass, or 35-65% by mass, and the molar content (%) can be 10-20 mol%. This further improves the dry etching resistance of the mask formed using the mask composition. The aforementioned mass content (%) and molar content (%) can be calculated by comparing the contents before and after drying when the mask composition is dried in a hot air dryer at 120°C for 3 hours.

[0024] Regarding the aforementioned mass content (%), the solid components obtained by drying the mask composition with acid or the like are prepared into an aqueous solution and analyzed using ICP-MS (Inductively Coupled Plasma Mass Spectrometry), thereby enabling the identification and quantification of metallic elements. For example, calculations can be performed using an ICP mass spectrometer (Shimadzu Corporation, ICPM-8500). Furthermore, the aforementioned molar content (%) is calculated not only based on the analysis results of ICP-MS but also further clarified by elemental analysis, thereby determining the composition.

[0025] The pH of the mask composition can be 7 to 14, preferably 10 to 14. Therefore, by setting the pH within the above range, the viscosity shear rate dependence in the mask composition is adjusted, resulting in a mask composition with good coatability and thick film properties.

[0026] The mask composition of the embodiment preferably has a viscosity ratio of 1 to 15 at 23°C and 20 rpm to that at 23°C and 200 rpm. As a result, the smoothness (coating property) of the coated film after coating and drying is improved, and as a result, a mask capable of forming a thick film is formed.

[0027] The mask composition described above enables the formation of thicker and more uniform masks.

[0028] (use) The mask composition of this embodiment is suitable for forming masks based on a pattern transfer method. Hereinafter, the outline of the pattern transfer method using the mask composition of this embodiment will be described.

[0029] Figure 1 This is a schematic diagram illustrating the mask forming process based on the pattern transfer method.

[0030] like Figure 1 As shown in (a), photoresist 20 is patterned on the etchable material 10, such as a silicon wafer, by photolithography.

[0031] Next, as Figure 1 As shown in (b), a mask composition 30 is coated on the opening portion of the photoresist 20. The coating method for the mask composition 30 is not particularly limited, and examples include spraying, spin coating, dip coating, and roll coating.

[0032] Next, as Figure 1 As shown in (c), a drying process (e.g., 120°C, 3 hours) is performed to cure the mask composition, forming an etching mask 32 made of metal hydroxide. Thereafter, the metal hydroxide can be oxidized by reheating (e.g., 500°C, 30 minutes) to form an etching mask 32 made of metal oxide.

[0033] Next, as Figure 1 As shown in (d), the photoresist is removed to obtain an etching mask 32 formed by transferring the photoresist pattern.

[0034] (Etching mask) The etching mask used in the embodiment preferably contains flake-like metal hydroxides or metal oxides, more preferably the flake-like metal hydroxides or metal oxides are stacked, and even more preferably the flake-like metal hydroxides or metal oxides are stacked in such a way that the normal direction of the flake surface is approximately the same as the film thickness direction.

[0035] The aforementioned flake-like metal hydroxide or metal oxide preferably contains magnesium. Specifically, it preferably contains one or more selected from magnesium hydroxide and magnesium oxide. Therefore, the etching mask of the embodiment can include gaps whose normal direction is approximately the same as the film thickness direction, which can alleviate the thermal stress generated on the etching mask. As a result, an etching mask suitable for heating the etched object can be provided.

[0036] The thickness of the etching mask in the embodiment is preferably 0.2 μm or more and 10 μm or less, more preferably 0.5 μm or more and 10 μm or less, and especially preferably 1 μm or more and 10 μm or less.

[0037] Even when the etching mask of the embodiment is thickened, the film thickness is uniform, and it exhibits superior etching resistance compared to conventional masks.

[0038] The above describes embodiments of the present invention, but these are examples of the present invention, and various other structures can also be used.

[0039] Example The present invention will now be described through examples and comparative examples, but the present invention is not limited thereto.

[0040] The raw materials and formulations (parts by weight) shown in Table 1 were mixed and stirred to prepare the mask compositions for each embodiment and each comparative example.

[0041] <Example 1> Magnesium acetate tetrahydrate (manufactured by Fujifilm and Koko Pure Chemical Industries, Ltd.) was dissolved in water to prepare a 0.1 mol / L aqueous solution, resulting in 500 mL of magnesium acetate aqueous solution. Similarly, ammonia solution (manufactured by Fujifilm and Koko Pure Chemical Industries, Ltd.) was diluted with water to prepare a 3 mol / L ammonia solution. While stirring, the 3 mol / L ammonia solution was added dropwise to the magnesium acetate aqueous solution to prepare a colloidal suspension. The pH of this colloidal suspension was 11. The colloidal suspension was then centrifuged at 10,000 rpm for 30 minutes using a high-speed centrifuge (AS ONE, AS185H) to separate the colloidal suspension. A precipitate was formed in the collected colloidal suspension. The supernatant (impurities) of the collected colloidal suspension was then removed using a pipette, and water was added to the remaining precipitate to disperse it, creating a coating solution to remove impurities. Then, the coating solution (10.0g) was transferred to an aluminum dish (15.0g), and the aluminum dish was placed in a hot air dryer set to 120°C. After drying for 3 hours, the aluminum dish was removed. At this point, the mass of the removed aluminum dish was 15.50g.

[0042] <Examples 2-4> Except for changing the amount of water added to the precipitate, the coatings of Examples 2-4 were prepared in the same manner as in Example 1. Furthermore, the mass of the aluminum dish after drying at 120°C for 3 hours is shown in Table 1.

[0043] <Comparative Example 1> Magnesium acetate tetrahydrate (made by Fujifilm and Kojun Pharmaceutical) was dissolved in water to form a 0.1 mol / L aqueous solution to prepare a coating. The coating solution (10.0 g) was then transferred to an aluminum dish (15.0 g), which was placed in a hot air dryer set to 120°C and dried for 3 hours. The aluminum dish was then removed. The mass of the removed aluminum dish was 15.21 g.

[0044] <Comparative Example 2> Magnesium oxide powder (manufactured by Tateho Ozark Technical Ceramics, Inc., PUREMAG FNM-G), with an average primary particle size of approximately 500 nm, was dispersed in water to prepare a coating. The coating solution (10.0 g) was then transferred to an aluminum dish (15.0 g), which was placed in a hot air dryer set to 120°C and dried for 3 hours. The aluminum dish was then removed. The mass of the removed aluminum dish was 15.50 g.

[0045] [Table 1]

[0046] The pH of each mask composition was determined. The results are shown in Table 1.

[0047] Each mask composition was placed in a hot air dryer at 120°C for 3 hours. The resulting samples were analyzed using an ICP mass spectrometer (Shimadzu ICPM-8500) to calculate the mass content %. The results are shown in Table 1.

[0048] The viscosity was measured at 23°C and 200 rpm using a rheometer (BROOKFIELD, Rhometer R / S PLUS) and at 23°C and 20 rpm, respectively. The ratio of the viscosity at 20 rpm to that at 200 rpm was calculated. The results are shown in Table 1.

[0049] Each mask composition was spin-coated (1500 rpm, 30 seconds) onto an excimer-treated Si substrate to obtain a coating. The coating was then heated at 120°C for 3 hours to obtain a test sample of the mask.

[0050] The particles contained in the test sample were observed using an electron microscope (Hitachi High Technology Co., Ltd. SU5000). The particle size and shape were determined by averaging 20 random particles. Additionally, the cross-section of the test sample was observed to confirm the mask shape and film thickness. The results are shown in Table 1.

[0051] <Mass content % of metal elements in the mask composition after heating and drying at 120°C for 3 hours> The mass content of metal elements in the mask composition after heating and drying at 120°C for 3 hours was calculated based on the mass (10.0 g) of each coating liquid prepared according to Examples 1-4 and Comparative Examples 1 and 2, and the mass of each aluminum dish holding the mask composition after heating and drying at 120°C for 3 hours.

[0052] <Mass change rate after heating at 500℃ for 30 minutes> Each aluminum dish containing a mask composition prepared according to Examples 1-4 and Comparative Examples 1 and 2 and dried at 120°C for 3 hours was placed in an electric furnace set to 500°C and heated for 30 minutes. After removing the aluminum dishes, the mass of each dish was measured. Based on these measurements and those taken after heating at 120°C for 3 hours, the rate of change in mass after heating at 500°C for 30 minutes was calculated.

[0053] <Evaluation of Coating Properties> The coatability of each mask composition was evaluated. Specifically, each mask composition was spin-coated (1500 rpm, 30 seconds) onto an excimer-treated Si substrate using a spin coater (Mikasa MS-B100) to create a coating film. The surface of the coating film immediately after coating was observed. Furthermore, the coatability was evaluated based on the following criteria.

[0054] ◎: No streaks or unevenness were produced, and there were no missing coating films.

[0055] ○: Unevenness was produced, but no streaks or missing coating film were produced.

[0056] △: Stripes and unevenness were produced, but there were no missing coating films.

[0057] ×: This indicates that streaks and / or unevenness have occurred, and part of the coating film is missing.

[0058] <Evaluation of drying film-forming properties> The drying film-forming properties of each mask composition were evaluated. Specifically, the coating surface of the test samples was observed. Furthermore, the evaluation of drying film-forming properties was determined based on the following criteria.

[0059] ◎: No streaks or unevenness were produced, and there were no missing coating films.

[0060] ○: Unevenness was produced, but no streaks or missing coating film were produced.

[0061] △: Stripes and unevenness were produced, but there were no missing coating films.

[0062] ×: This indicates that streaks and / or unevenness have occurred, and part of the coating film is missing.

[0063] <Evaluation of film thickness adaptability> The film thickness adaptability of each mask composition was evaluated. Specifically, the cross-section of the test specimens was observed using an electron microscope (Hitachi High Technology Co., Ltd. SU5000), and the film thickness at any 10 points was measured. The film thickness was calculated based on the average value. Furthermore, the film thickness adaptability was evaluated using the following criteria.

[0064] ◎: Above 1.0μm ○: 0.5μm or larger and less than 1.0μm △: Above 0.3μm and below 0.5μm ×: less than 0.3μm Industrial availability The dry etching mask composition disclosed herein can be used to form masks that achieve thick film formation and improve etching resistance.

[0065] Cross-references of related applications This application claims priority based on Japan Patent Application No. 2024-054045 filed with the Japan Patent Office on March 28, 2024, all of the disclosure of which is incorporated herein by reference in its entirety.

[0066] Explanation of reference numerals in the attached figures 10: Etched material 20: Photoresist, 30: Masking compositions 32: Masks for etching processes.

Claims

1. A composition for use in masking, wherein, have: Metal hydroxides, and Solvent; The metal hydroxide is dispersed or dissolved in the solvent.

2. The mask composition according to claim 1, wherein, The mass of the mask composition heated at 120°C for 3 hours is 0.1% to 50.0% of the total mass of the mask composition.

3. The mask composition according to claim 1, wherein, The ratio of the mass of the mask composition heated at 120°C for 3 hours to the mass of the mask composition heated at 120°C for 3 hours and then further heated at 500°C for 30 minutes is 60 to 100 by mass.

4. The mask composition according to claim 1, wherein, The content of the metal element constituting the metal hydroxide is 25-70% by mass relative to the mask composition when the mask composition is heated at 120°C for 3 hours.

5. The mask composition according to claim 1, wherein, The pH value is 10-14.

6. The mask composition according to claim 1, wherein, The viscosity at 20 rpm is 1 to 15 times that at 200 rpm.

7. The mask composition according to claim 1, wherein, The viscosity at 20 rpm is 1~100 mPa·s.

8. A mask for etching, wherein, Contains scaly metal hydroxides, The flaky metal hydroxides are stacked.

9. The etching mask according to claim 8, wherein, The film thickness is 1 μm or more.

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