Molybdenum etching solution and application thereof in nanoscale molybdenum etching

Abstract

The invention belongs to the technical field of electronic chemicals, and particularly discloses molybdenum etching liquid and application thereof in nanoscale molybdenum etching. The etching liquid comprises an alkaline solution, an oxidizing agent, a corrosion inhibitor and a metal chelating agent. The alkaline environment of the etching solution has efficient dissolving capacity, so that a stable etching rate can be maintained; meanwhile, the corrosion inhibitor and the chelating agent are added into the etching solution, the corrosion inhibitor can form a layer of thin film on the metal surface in a physical adsorption or chemical bond mode, so that the etching rate of the etching solution to the metal is stabilized and regulated, and the metal chelating agent can form a plurality of coordinate bonds with metal ions in the solution; therefore, a stable annular structure is formed, and the etching liquid is more stable. The etching solution designed by the invention is simple in component, uniform in etching effect and controllable in etching rate, can be used for nano-scale molybdenum etching, and is also suitable for etching multiple metal film layers such as molybdenum alloy.

Description

Technical Field

[0001] The invention belongs to the technical field of electronic chemicals, and in particular relates to a molybdenum etching solution and application thereof in nano-level molybdenum etching. Background Art

[0002] As a revolutionary storage technology, 3D NAND technology breaks through the physical limitations of traditional 2D NAND by vertically stacking storage cells. This technology allows more storage cells to be integrated in the same physical space, thereby significantly improving storage density. Compared with planar NAND, 3D NAND achieves higher capacity and higher performance through multi-layer stacking.

[0003] As a key metal layer in semiconductor devices, molybdenum is widely used in the production of integrated circuits due to its excellent conductivity and thermal stability. The fine processing of the molybdenum layer, especially the etching process, is crucial to ensure the performance of the components. High-precision etching liquid can achieve precise patterning of the molybdenum film, which is the prerequisite for miniaturization and high integration density circuits.

[0004] However, as the industry's requirements for component size and performance continue to increase, the molybdenum etching process is facing increasingly higher challenges. Although traditional wet chemical etching is relatively low-cost, it is difficult to cope with submicron or nanometer precision processing requirements. In addition, the etching rate is also a core parameter that directly affects production efficiency and product quality. The etching rate shown in the existing etching solution is too fast, resulting in uneven etching, making the surface of the molybdenum layer rough, and even damaging the underlying structure, affecting the final performance. Therefore, the research focus of the etching process has shifted to how to improve etching accuracy and control etching rate to achieve better etching effects. Summary of the invention

[0005] The invention provides a molybdenum etching solution and application thereof in nano-scale molybdenum etching, which can effectively control the etching rate; the etching solution has high stability and is not prone to precipitation.

[0006] The technical solution of the present invention is to provide a molybdenum etching solution, which comprises the following components by mass fraction: 5-25% of alkaline solution, 1-10% of oxidant, 0.1-3% of corrosion inhibitor and 0.05-0.3% of metal chelating agent, and the rest is water.

[0007] Furthermore, the alkaline solution is any one of ammonia water, tetramethylammonium hydroxide solution or potassium hydroxide solution.

[0008] Furthermore, the mass fraction of the alkaline solution is 10-20%, and the solvent is water.

[0009] Furthermore, the oxidant is any one of hydrogen peroxide, an aqueous solution of periodic acid, an aqueous solution of sodium hypochlorite or an aqueous solution of potassium permanganate.

[0010] Furthermore, the mass percentage of the solute in the oxidant is 10-20%.

[0011] Furthermore, the corrosion inhibitor is any one or more of glutamic acid, isoleucine, 4,4,4-trifluoro-3-(methylamino)butyric acid, pyrrolysine, cysteine, aspartic acid, and (1,1,1-trifluoro-4-oxo-4-phenylbutan-2-yl)glycine.

[0012] Furthermore, the metal chelating agent is one or more of ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, cyclohexanediaminetetraacetic acid, polyethyleneimine, and ethylene glycol bis(2-aminoethyl ether)tetraacetic acid.

[0013] Furthermore, the alkaline solution is ammonia water; and the oxidant is hydrogen peroxide.

[0014] The present invention also relates to the application of the molybdenum etching solution in nano-level molybdenum etching.

[0015] The present invention has the following beneficial effects: 1. The etching solution of the present invention is an alkaline environment (pH is 8-12), has a high dissolving ability, and is conducive to maintaining a stable etching rate. At the same time, etching is carried out in an alkaline environment, and the etching solution has high stability and is not easy to produce precipitation.

[0016] 2. Amino acid type corrosion inhibitors, due to their specific structural characteristics (polar groups, side chains, etc.), can easily form adsorption films or chemical conversion films on the metal surface through physical adsorption or in the form of chemical bonds, thereby stabilizing and regulating the etching rate of the etching solution on the metal. Metal chelating agents can form multiple coordination bonds with metal ions in the solution, thereby forming a stable ring structure, making the etching solution more stable.

[0017] 3. The etching solution designed by the present invention has simple components, uniform etching effect and controllable etching rate. DETAILED DESCRIPTION

[0018] The present invention is described in detail below in conjunction with specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and a specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0019] The etching solution comprises the following components by mass fraction: 5-25% alkaline solution, 1-10% oxidant, 0.1-3% corrosion inhibitor and 0.05-0.3% metal chelating agent, and the rest is water. The alkaline solution is preferably 10-25%, more preferably 10-15%; the oxidant is preferably 5-10%; more preferably 5-7%; the corrosion inhibitor is preferably 0.1-2%; more preferably 0.2-1.5%; the metal chelating agent is preferably 0.05-0.2%. The water is deionized water. The percentages in the following examples and comparative examples are all mass percentages.

[0020] Example 1 A molybdenum etching solution has a formula of: 15% tetramethylammonium hydroxide aqueous solution (concentration is 15%), 5% sodium hypochlorite solution (concentration is 12%), 0.4% pyrrolysine and 0.05% ethylenediaminetetraacetic acid, and the rest is deionized water.

[0021] Example 2 A molybdenum etching solution has a formula of: 13% tetramethylammonium hydroxide aqueous solution (concentration is 15%), 6% periodic acid aqueous solution (concentration is 12%), 0.2% aspartic acid and 0.2% cyclohexanediaminetetraacetic acid, and the rest is deionized water.

[0022] Example 3 An etching solution has a formula of: 20% tetramethylammonium hydroxide aqueous solution (concentration is 15%), 7% hydrogen peroxide aqueous solution (concentration is 12%), 1.5% cysteine ​​and 0.08% polyethyleneimine, and the rest is deionized water.

[0023] Example 4 A molybdenum etching solution has a formula of: 18% tetramethylammonium hydroxide aqueous solution (concentration is 15%), 3% potassium permanganate aqueous solution (concentration is 12%), 0.6% glutamic acid and 0.15% ethylene glycol bis(2-aminoethyl ether) tetraacetic acid, and the rest is deionized water.

[0024] Example 5 A molybdenum etching solution has the following formula: 13% ammonia solution (concentration is 15%), 2% sodium hypochlorite solution (concentration is 15%), 0.5% aspartic acid, 0.5% isoleucine and 0.06% ethylenediaminetetraacetic acid, and the rest is deionized water.

[0025] Example 6 A molybdenum etching solution has the following formula: 8% ammonia aqueous solution (concentration is 15%), 5% periodic acid aqueous solution (concentration is 15%), 0.5% pyrrolysine and 0.2% diethylenetriaminepentaacetic acid, and the rest is deionized water.

[0026] Example 7 A molybdenum etching solution has the following formula: 12% ammonia aqueous solution (concentration is 15%), 3% potassium permanganate aqueous solution (concentration is 15%), 0.25% cysteine ​​and 0.05% polyethyleneimine, and the rest is deionized water.

[0027] Example 8 A molybdenum etching solution has a formula of: 18% ammonia solution (concentration of 15%), 6% hydrogen peroxide solution (concentration of 15%), 0.3% pyrrolysine and 0.06% ethylene glycol bis(2-aminoethyl ether) tetraacetic acid, and the rest is deionized water.

[0028] Example 9 A molybdenum etching solution has a formula of: 20% potassium hydroxide solution (concentration is 15%), 3% sodium hypochlorite aqueous solution (concentration is 15%), 0.28% pyrrolysine, 0.3% isoleucine and 0.03% diethylenetriaminepentaacetic acid, and the rest is deionized water.

[0029] Example 10 A molybdenum etching solution has a formula of: 25% potassium hydroxide solution (concentration is 15%), 6% periodic acid aqueous solution (concentration is 15%), 0.18% glutamic acid and 0.24% ethylene glycol bis (2-aminoethyl ether) tetraacetic acid, and the rest is deionized water.

[0030] Embodiment 11 A molybdenum etching solution, the formula of which is: 23% potassium hydroxide solution (concentration is 15%), 1.5% hydrogen peroxide aqueous solution (concentration is 15%), 0.3% glutamic acid, 0.2% (1,1,1-trifluoro-4-oxo-4-phenylbutan-2-yl) glycine and 0.08% cyclohexanediaminetetraacetic acid, and the rest is deionized water.

[0031] Example 12 A molybdenum etching solution has a formula of: 18% potassium hydroxide solution (concentration is 15%), 10% potassium permanganate aqueous solution (concentration is 15%), 0.27% aspartic acid, 0.16% 4,4,4-trifluoro-3-(methylamino)butyric acid and 0.08% ethylenediaminetetraacetic acid, and the rest is deionized water.

[0032] Comparative Example 1 A molybdenum etching solution, having the same formula as that of Example 8, except that the ammonia aqueous solution is not added.

[0033] Comparative Example 2 A molybdenum etching solution, whose formula is the same as that of Example 8, except that the hydrogen peroxide aqueous solution is not added.

[0034] Comparative Example 3 A molybdenum etching solution, having the same formula as that of Example 8, except that pyrrolysine is not added.

[0035] Comparative Example 4 A platinum etching solution, having the same formula as that of Example 8, except that ethylene glycol bis(2-aminoethyl ether)tetraacetic acid is not added.

[0036] Comparative Example 5 A molybdenum etching solution, having the same formula as that of Example 8, wherein pyrrolysine is replaced by N,N-dimethylacetamide.

[0037] Comparative Example 6 A platinum etching solution, having the same formula as that of Example 8, wherein ethylene glycol bis(2-aminoethyl ether)tetraacetic acid is replaced by dithiopropanol.

[0038] Etching experiment The molybdenum etching solution in the above-mentioned embodiment and comparative example was used for etching experiments, specifically, 30g of etching solution was taken in a 100ml beaker, and a stirrer was placed in the beaker, the heating jacket temperature was set to 25°C, the stirring speed was 100 rpm / min, and the 3D NAND structure piece was etched when the solution temperature reached and stabilized at 25±0.5°C. Before etching, the structure piece was cut into a size of 2*1cm, and the etching method was immersion etching, that is, the structure piece was split and placed in the etching solution, the etching time was recorded, and the etching rate was calculated according to the ratio of the thickness of the etched metal film layer to the etching time. The etching solution of the present invention adjusts the etching rate of metal molybdenum by regulating the content of the chelating agent and the corrosion inhibitor in the etching solution. After etching, the structure piece was cleaned with deionized water and dried with nitrogen, and observed by magnification under a scanning electron microscope to verify the etching effect of the etching solution and observe whether there was any residue. The experimental results of all embodiments and comparative examples are shown in Table 1.

[0039] Table 1

[0040] There is a significant difference in the etching rate between the etching solution prepared in Example 1 and the etching solution prepared in Comparative Example 1, indicating that the alkaline environment is conducive to the etching of metal molybdenum. The presence of the oxidant can increase the activity of the surface of the metal molybdenum by oxidation, making it easier to be dissolved by the components in the etching solution. There is a significant difference in the etching rate between the etching solution prepared in Example 2 and the etching solution prepared in Comparative Example 2, further proving that the presence of the oxidant is more conducive to the etching of metal molybdenum.

[0041] The etching rates of the etching solution prepared in Example 1 and the etching solution prepared in Comparative Example 4 are compared, which proves that the addition of the corrosion inhibitor can form a thin film on the metal surface by physical adsorption or in the form of chemical bonds, thereby stabilizing and regulating the etching rate of the etching solution on the metal.

[0042] The above embodiments describe the preferred implementation of the present invention, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A molybdenum etching solution, characterized in that The etching solution comprises the following components by mass fraction: 5-25% of alkaline solution, 1-10% of oxidant, 0.1-3% of corrosion inhibitor and 0.05-0.3% of metal chelating agent, and the rest is water.

2. platinum etching solution according to claim 1, characterized in that: The alkaline solution is one of ammonia water, tetramethylammonium hydroxide solution or potassium hydroxide solution.

3. platinum etching solution according to claim 2, characterized in that: The mass fraction of the alkaline solution is 10-20%, and the solvent is water.

4. platinum etching solution according to claim 1, characterized in that: The oxidant is any one of hydrogen peroxide, an aqueous solution of periodic acid, an aqueous solution of sodium hypochlorite or an aqueous solution of potassium permanganate.

5. platinum etching solution according to claim 1, characterized in that: The mass percentage of the solute in the oxidant is 10-20%.

6. platinum etching solution according to claim 1, characterized in that: The corrosion inhibitor is any one or more of glutamic acid, isoleucine, 4,4,4-trifluoro-3-(methylamino)butyric acid, pyrrolysine, cysteine, aspartic acid, and (1,1,1-trifluoro-4-oxo-4-phenylbutan-2-yl)glycine.

7. The platinum etching solution according to claim 1, wherein: The metal chelating agent is one or more of ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, cyclohexanediaminetetraacetic acid, polyethyleneimine, and ethylene glycol bis(2-aminoethyl ether)tetraacetic acid.

8. The platinum etching solution according to any one of claims 1 to 7, characterized in that: The alkaline solution is ammonia water; the oxidant is hydrogen peroxide.

9. Application of the platinum etching solution described in any one of claims 1 to 8 in nanoscale platinum etching.

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