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JP-7856918-B2 - Dry etching method, semiconductor device manufacturing method, and dry etching gas composition

JP7856918B2JP 7856918 B2JP7856918 B2JP 7856918B2JP-7856918-B2

Inventors

  • 澤村 涼介
  • 鈴木 聖唯
  • 大森 啓之
  • 八尾 章史

Assignees

  • セントラル硝子株式会社

Dates

Publication Date
20260512
Application Date
20241210
Priority Date
20200313

Claims (20)

  1. A step of reacting silicon oxide with gaseous hydrogen fluoride and a gaseous organic amine compound, a hydrogen fluoride salt of a gaseous organic amine compound, or gaseous hydrogen fluoride, a gaseous organic amine compound, and a hydrogen fluoride salt of a gaseous organic amine compound, The process includes a step of sublimating the reaction product generated by the above reaction without supplying gaseous hydrogen fluoride, gaseous organic amine compounds, or a hydrogen fluoride salt of a gaseous organic amine compound, A dry etching method characterized in that the organic amine compound is an organic amine mixture containing at least two compounds represented by the following general formula (1). (In general formula (1), N is a nitrogen atom. R1 is a hydrocarbon group having 1 to 10 carbon atoms, which may have a ring, heteroatom, or halogen atom. R2 and R3 are hydrogen atoms or hydrocarbon groups having 1 to 10 carbon atoms, which may have a ring, heteroatom, or halogen atom. However, if the hydrocarbon group has 3 or more carbon atoms, it may have a branched chain structure or a cyclic structure. The heteroatom of the hydrocarbon group is a nitrogen atom, oxygen atom, sulfur atom, or phosphorus atom. Furthermore, if both R1 and R2 are hydrocarbon groups having 1 or more carbon atoms, R1 and R2 may be directly bonded to form a cyclic structure. Furthermore, if R1 or R2 is directly bonded by a double bond to form a cyclic structure, R3 may be absent and form an aromatic ring. Also, R1 , R2 , and R3 may be the same hydrocarbon group or different hydrocarbon groups.)
  2. The dry etching method according to claim 1, wherein the organic amine mixture comprises at least a secondary amine and a tertiary amine.
  3. The dry etching method according to claim 2, wherein the composition ratio of the organic amine mixture is such that the secondary amine is contained in an amount of 10 volume ppm to 10 volume percent relative to the total amount of the tertiary amine and the secondary amine.
  4. The dry etching method according to claim 3, wherein the composition ratio of the organic amine mixture is such that the secondary amine is present in an amount of 100 volume ppm to 5000 volume ppm relative to the total amount of the tertiary amine and the secondary amine.
  5. The dry etching method according to any one of claims 2 to 4, wherein the secondary amine is one of dimethylamine, diethylamine, ethylisopropylamine, and ethylpropylamine, and the tertiary amine is one of trimethylamine, triethylamine, and dimethylethylamine.
  6. The dry etching method according to claim 5, wherein the secondary amine is dimethylamine and the tertiary amine is trimethylamine.
  7. A dry etching method according to any one of claims 1 to 6, wherein the reaction of silicon oxide with gaseous hydrogen fluoride and a gaseous organic amine mixture, a hydrogen fluoride salt of the gaseous organic amine mixture, or gaseous hydrogen fluoride, a gaseous organic amine mixture, and a hydrogen fluoride salt of the gaseous organic amine mixture is carried out without the formation of a plasma state.
  8. The dry etching method according to any one of claims 1 to 7, characterized in that the temperature of the silicon oxide during the reaction is 200°C or lower.
  9. The above reaction is A dry etching method according to any one of claims 1 to 8, characterized by comprising the step of contacting the silicon oxide with a processing gas containing the hydrogen fluoride and the organic amine mixture, a processing gas containing a hydrogen fluoride salt of the organic amine mixture, or a processing gas containing the hydrogen fluoride, the organic amine mixture, and a hydrogen fluoride salt of the organic amine mixture.
  10. The dry etching method according to claim 9, characterized in that the ratio of hydrogen fluoride contained in the processing gas to the organic amine mixture is 0.001 or more and 100 or less, obtained by dividing the total number of moles of organic amine compounds contained in the organic amine mixture by the number of moles of hydrogen fluoride.
  11. The above reaction is A dry etching method according to any one of claims 1 to 8, characterized by comprising the steps of contacting a silicon oxide with a processing gas containing the organic amine mixture and contacting the silicon oxide with a processing gas containing hydrogen fluoride.
  12. A dry etching method according to any one of claims 1 to 11, for selectively etching a silicon oxide film on a substrate in which both a silicon oxide film and a silicon nitride film are exposed.
  13. The dry etching method according to claim 12, characterized in that the selectivity ratio of the silicon oxide film to the silicon nitride film is 2.5 or higher.
  14. A dry etching method according to any one of claims 1 to 11, for selectively etching a silicon oxide film on a substrate in which both a silicon oxide film and a polycrystalline silicon film are exposed.
  15. The dry etching method according to any one of claims 1 to 14, characterized in that heating is performed in the sublimation step.
  16. The dry etching method according to claim 15, characterized in that the sublimation step is heated to 200°C or below.
  17. The dry etching method according to any one of claims 1 to 16, wherein the organic amine mixture further comprises ammonia.
  18. A method for manufacturing a semiconductor device, characterized by including a step of etching a silicon oxide film on a semiconductor substrate having a silicon oxide film by applying the dry etching method described in any one of claims 1 to 17.
  19. An organic amine mixture for use in the dry etching method described in claim 1 , characterized in that it comprises at least two compounds represented by the following general formula (1). (In general formula (1), N is a nitrogen atom. R1 is a hydrocarbon group having 1 to 10 carbon atoms, which may have a ring, heteroatom, or halogen atom. R2 and R3 are hydrogen atoms or hydrocarbon groups having 1 to 10 carbon atoms, which may have a ring, heteroatom, or halogen atom. However, if the hydrocarbon group has 3 or more carbon atoms, it may have a branched chain structure or a cyclic structure. The heteroatom of the hydrocarbon group is a nitrogen atom, oxygen atom, sulfur atom, or phosphorus atom. Furthermore, if both R1 and R2 are hydrocarbon groups having 1 or more carbon atoms, R1 and R2 may be directly bonded to form a cyclic structure. Furthermore, if R1 or R2 is directly bonded by a double bond to form a cyclic structure, R3 may be absent and form an aromatic ring. Also, R1 , R2 , and R3 may be the same hydrocarbon group or different hydrocarbon groups.)
  20. The organic amine mixture according to claim 19, wherein the organic amine mixture comprises at least a secondary amine and a tertiary amine.

Description

This disclosure relates to a dry etching method for dry etching silicon oxide, a method for manufacturing a semiconductor device using the dry etching method, and a dry etching gas composition. In the manufacturing process of semiconductor devices, there is a step to etch the silicon oxide film present on the surface of the semiconductor wafer, whether it be a CVD-based oxide film, a thermal oxide film, or a native oxide film. Methods for etching such silicon oxide films include wet etching using chemical solutions and plasma etching using reactive gas plasma. However, wet etching had the problem of easily causing adverse effects from the chemical solution on components not being etched. Furthermore, plasma etching had the problem of causing electrical damage to the wafer due to the plasma. To address these problems, methods for dry etching without using plasma have been attempted. For example, Patent Document 1 discloses a method for dry etching SiO2 without using plasma by adding gaseous water, Patent Document 2 discloses gaseous methanol, Patent Document 3 discloses gaseous acetic acid, and Patent Document 4 discloses gaseous isopropyl alcohol to hydrogen fluoride gas. Furthermore, a method using a mixed gas containing hydrogen fluoride gas and ammonia gas has been investigated for high-speed etching of SiO₂ . For example, Patent Document 5 discloses a two-step etching method comprising: an AFS layer formation step (Chemical Oxide Removal; COR treatment) in which a mixed gas containing HF gas and NH₃ gas is supplied to the surface of a silicon oxide film on a substrate, causing a chemical reaction between the silicon oxide film and the mixed gas to transform the silicon oxide film into ammonium silicon fluoride (AFS), and generating this reaction product layer on the silicon layer of the substrate; and a heating step (Post Heat Treatment; PHT treatment) in which the AFS layer is heated without supplying the mixed gas to sublimate or thermally decompose. Japanese Patent Application Publication No. 6-181188Japanese Patent Application Publication No. 8-81788Special Publication No. 9-509531Special Publication No. 2001-503571Japanese Patent Publication No. 2007-180418 (Japanese Patent Publication No. 4890025) Figure 1 is a schematic diagram of a reaction apparatus, which is an example of an etching apparatus used in the dry etching method according to the embodiment of this disclosure.Figure 2 is a graph showing the relationship between the concentration of amine 2 (amine 2 / (amine 1 + amine 2) (volume ppm)) and the amount of etching when dimethylamine was used as amine 2 in Examples 1 to 3 and Comparative Examples 1 and 2. The following is a detailed description of this disclosure. However, the following explanation of the constituent elements is merely an example of an embodiment of this disclosure and is not limited to these specific details. It can be implemented in various modified forms within the scope of its essence. The dry etching method of the present disclosure is a method for dry etching silicon oxide by reacting silicon oxide with gaseous hydrogen fluoride and a gaseous organic amine compound, a hydrogen fluoride salt of a gaseous organic amine compound, or gaseous hydrogen fluoride, a gaseous organic amine compound and a hydrogen fluoride salt of a gaseous organic amine compound, The above organic amine compound is characterized by being an organic amine mixture containing at least two compounds represented by the following general formula (1). (In general formula (1), N is a nitrogen atom. R1 is a hydrocarbon group having 1 to 10 carbon atoms, which may have a ring, heteroatom, or halogen atom. R2 and R3 are hydrogen atoms or hydrocarbon groups having 1 to 10 carbon atoms, which may have a ring, heteroatom, or halogen atom. However, if the hydrocarbon group has 3 or more carbon atoms, it may have a branched chain structure or a cyclic structure. The heteroatom of the hydrocarbon group is a nitrogen atom, oxygen atom, sulfur atom, or phosphorus atom. Furthermore, if both R1 and R2 are hydrocarbon groups having 1 or more carbon atoms, R1 and R2 may be directly bonded to form a cyclic structure. Furthermore, if R1 or R2 is directly bonded by a double bond to form a cyclic structure, R3 may be absent and form an aromatic ring. Also, R1 , R2 , and R3 may be the same hydrocarbon group or different hydrocarbon groups.) [First Embodiment] In the first embodiment, a mixture of gaseous hydrogen fluoride and at least two compounds represented by the general formula (1) is supplied to an etching apparatus and brought into contact with silicon oxide to dry etch the silicon oxide. That is, a process gas containing the hydrogen fluoride and the organic amine mixture, a process gas containing the hydrogen fluoride salt of the organic amine mixture, or a process gas containing the hydrogen fluoride, the organic amine mixture, and the hydrogen fluoride salt of the organic amine mixture is brought into contact