JP-7856788-B2 - Etching solution composition

Inventors

• 長尾 將
• 三井 孝雄

Assignees

• ラサ工業株式会社

Dates

Publication Date

20260511

Application Date

20230803

Priority Date

20221208

Claims (8)

1. An inorganic acid-based etching solution composition for selectively etching silicon nitride from a semiconductor containing silicon nitride and silicon oxide, An etching inhibitor that suppresses the etching of silicon dioxide, It contains a precipitation inhibitor that suppresses the deposition of silica on the surface of silicon dioxide, The etching inhibitor comprises a first etching inhibitor having three or fewer alkoxy groups, hydroxyl groups, and/or functional groups that serve as precursors to hydroxyl groups in its molecular structure, and a second etching inhibitor having four or more alkoxy groups, hydroxyl groups, and/or functional groups that serve as precursors to hydroxyl groups in its molecular structure . The first etching inhibitor is an etching solution composition which is a silane compound having an amino group .
2. An inorganic acid-based etching solution composition for selectively etching silicon nitride from a semiconductor containing silicon nitride and silicon oxide, An etching inhibitor that suppresses the etching of silicon dioxide, A precipitation inhibitor that suppresses the deposition of silica on the surface of silicon dioxide, and It contains, The etching inhibitor comprises a first etching inhibitor having three or fewer alkoxy groups, hydroxyl groups, and/or functional groups that serve as precursors to hydroxyl groups in its molecular structure, and a second etching inhibitor having four or more alkoxy groups, hydroxyl groups, and/or functional groups that serve as precursors to hydroxyl groups in its molecular structure. The aforementioned deposition inhibitor is an etching solution composition containing hydrazides.
3. An inorganic acid-based etching solution composition for selectively etching silicon nitride from a semiconductor containing silicon nitride and silicon oxide, An etching inhibitor that suppresses the etching of silicon dioxide, A precipitation inhibitor that suppresses the deposition of silica on the surface of silicon dioxide, and It contains, The etching inhibitor comprises a first etching inhibitor having three or fewer alkoxy groups, hydroxyl groups, and/or functional groups that serve as precursors to hydroxyl groups in its molecular structure, and a second etching inhibitor having four or more alkoxy groups, hydroxyl groups, and/or functional groups that serve as precursors to hydroxyl groups in its molecular structure. In its unused state, the liquid does not contain silicon nitride-derived Si. An etching solution composition that can be repeatedly used until the concentration of silicon nitride-derived Si in the solution reaches at least 3000 ppm.
4. The etching solution composition according to any one of claims 1 to 3, wherein the first etching inhibitor comprises at least one selected from the group consisting of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, and N-2-(aminoethyl)-3- aminopropylmethyldimethoxysilane, and hydrolysates thereof.
5. The etching solution composition according to any one of claims 1 to 3, wherein the second etching inhibitor is a silane compound having at least one functional group selected from the group consisting of alkyl groups, amino groups, and halogen groups.
6. The second etching inhibitor has the following chemical structure (1): The chemical structure of 1,3-dimethyltetramethoxydisiloxane shown below is (2): The siloxane compound shown below has the following chemical structure (3): The siloxane compound shown below has the following chemical structure (4): An etching solution composition according to any one of claims 1 to 3, comprising at least one selected from the group consisting of hexamethoxydisiloxane, tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, silicon tetrachloride, and hexachlorodisilane.
7. The etching solution composition according to claim 2 , wherein the hydrazides include at least one selected from the group consisting of adipic acid dihydrazide, succinic acid dihydrazide, acetohydrazide chloride, 2,2-dimethylhydrazide succinate, and azelaic acid dihydrazide.
8. The etching solution composition according to any one of claims 1 to 3, wherein the selectivity ratio [ R1 / R2 ], which is the ratio of the etching rate of silicon nitride [ R1 ] to the etching rate of silicon oxide [ R2 ], is set to 5.3 times or more compared to the selectivity ratio of the etching solution consisting only of the inorganic acid.

Description

The present invention relates to an inorganic acid-based etching solution composition for selectively etching silicon nitride from a semiconductor containing silicon nitride and silicon oxide. With the increasing integration and capacity of semiconductor circuits in recent years, there is a growing demand for more precise etching technologies. For example, in the manufacturing of NAND flash memory with a three-dimensional structure (3D NAND), silicon nitride films and silicon oxide films are alternately stacked and then immersed in an etching solution. In this process, it is necessary to precisely remove only the silicon nitride film. Therefore, various etching solutions (compositions) have been developed to achieve high etching selectivity in the etching process. For example, the etching solution composition described in Patent Document 1 is used in the manufacturing process of three-dimensional semiconductors and is a composition comprising a solution containing silica and alkali, phosphoric acid, and water. According to Patent Document 1, using such an etching solution composition suppresses the etching of silicon oxide films and improves the etching selectivity of silicon nitride films (see paragraph 0013 of the specification of Patent Document 1). Furthermore, as another technology, there is an etching solution composition containing water, phosphoric acid, and a hydroxyl group-containing solvent, as described in Patent Document 2. According to Patent Document 2, polyols, glycols, monohydric alcohols, etc., are exemplified as hydroxyl group-containing solvents, and it is stated that these components function to protect the silicon oxide film, so that the silicon nitride film is etched preferentially and selectively (see paragraph 0025 of the specification of Patent Document 2). Japanese Patent Publication No. 2020-96160Japanese Patent Publication No. 2018-207108 Embodiments of the etching solution composition according to the present invention will now be described. However, the present invention is not intended to be limited to the following embodiments. [Etching solution composition] The etching solution composition according to the present invention is used to selectively etch silicon nitride from a semiconductor containing silicon nitride and silicon oxide. The components included in the etching solution composition are described below. <Inorganic acid> The etching solution composition according to the present invention is based on an inorganic acid. Examples of inorganic acids include phosphoric acid, sulfuric acid, nitric acid, hydrochloric acid, and mixed acids of these inorganic acids. Of these inorganic acids, phosphoric acid is preferred. When used diluted, phosphoric acid is in the form of an aqueous solution, and its concentration is preferably 50 to 100% by weight (wt%), more preferably 70 to 95% by weight, and even more preferably 85 to 95% by weight. Note that the phosphoric acid only needs to be adjusted to the above concentration when using the etching solution composition. For example, the appropriate concentration can be achieved by concentrating a stock solution containing a low-concentration aqueous phosphoric acid solution at or before use, diluting a stock solution containing phosphoric acid with a concentration exceeding 100% by weight (strong phosphoric acid) with water at or before use, or by dissolving anhydrous phosphoric acid ( P2O5 ) in water at or before use. <Etching Inhibitor> The etching solution composition according to the present invention contains an etching inhibitor that suppresses the etching of silicon dioxide. The etching inhibitor comprises a plurality of etching inhibitors with different chemical structures. In this embodiment, the etching inhibitor includes a first etching inhibitor and a second etching inhibitor. The first etching inhibitor is a compound having three or fewer alkoxy groups, hydroxyl groups, and/or functional groups that are precursors to hydroxyl groups in its molecular structure, and is preferably a silane compound having an amino group. The second etching inhibitor is a compound having four or more alkoxy groups, hydroxyl groups, and/or functional groups that are precursors to hydroxyl groups in its molecular structure, and is preferably a silane compound having at least one functional group selected from the group consisting of alkyl groups, amino groups, and halogen groups. For compounds having hydroxyl groups, any compound that can ultimately change to have hydroxyl groups in the solution is acceptable. [First etching inhibitor] The first etching inhibitors include methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, dimethoxydiphenylsilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, octyltriethoxysilane, 1,6-bis(trimethoxysilyl)hexane, vinyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysil