US-12628591-B2 - Etching method and method for producing semiconductor element

Abstract

Provided is an etching method capable of selectively etching an etching object containing silicon nitride as compared with a non-etching object while the generation of particles and a variation in etching rate are suppressed. The etching method includes an etching step of bringing an etching gas containing more than 20% by volume of nitrosyl fluoride into contact with a member to be etched ( 12 ) having an etching object that is to be etched by the etching gas and having a non-etching object that is not to be etched by the etching gas, to selectively etch the etching object as compared with the non-etching object without plasma. The etching object contains silicon nitride.

Inventors

• Kazuma Matsui

Assignees

• RESONAC CORPORATION

Dates

Publication Date

20260512

Application Date

20220330

Priority Date

20210520

Claims (11)

1. 1 . An etching method comprising: an etching step of bringing an etching gas containing 30% or more by volume of nitrosyl fluoride into contact with a member to be etched having an etching object that is to be etched by the etching gas and having a non-etching object that is not to be etched by the etching gas, to selectively etch the etching object as compared with the non-etching object without plasma, wherein, the etching object contains silicon nitride, and the etching gas is a gas exclusively containing nitrosyl fluoride or a mixed gas containing nitrosyl fluoride and a dilution gas.
2. 2 . The etching method according to claim 1 , wherein the non-etching object is at least one of silicon oxide and amorphous carbon.
3. 3 . The etching method according to claim 2 , wherein in the etching step, a temperature condition is 50° C. or more and 250° C. or less.
4. 4 . The etching method according to claim 1 , wherein an etching selectivity that is a ratio of an etching rate of the etching object to an etching rate of the non-etching object is 10 or more.
5. 5 . A method for producing a semiconductor element, the method using the etching method according to claim 1 to produce a semiconductor element, wherein, the member to be etched is a semiconductor substrate having the etching object and the non-etching object, and the method comprises a processing step of removing at least a part of the etching object from the semiconductor substrate by the etching.
6. 6 . The etching method according to claim 2 , wherein an etching selectivity that is a ratio of an etching rate of the etching object to an etching rate of the non-etching object is 10 or more.
7. 7 . The etching method according to claim 3 , wherein an etching selectivity that is a ratio of an etching rate of the etching object to an etching rate of the non-etching object is 10 or more.
8. 8 . A method for producing a semiconductor element, the method using the etching method according to claim 2 to produce a semiconductor element, wherein, the member to be etched is a semiconductor substrate having the etching object and the non-etching object, and the method comprises a processing step of removing at least a part of the etching object from the semiconductor substrate by the etching.
9. 9 . A method for producing a semiconductor element, the method using the etching method according to claim 3 to produce a semiconductor element, wherein, the member to be etched is a semiconductor substrate having the etching object and the non-etching object, and the method comprises a processing step of removing at least a part of the etching object from the semiconductor substrate by the etching.
10. 10 . A method for producing a semiconductor element, the method using the etching method according to claim 4 to produce a semiconductor element, wherein, the member to be etched is a semiconductor substrate having the etching object and the non-etching object, and the method comprises a processing step of removing at least a part of the etching object from the semiconductor substrate by the etching.
11. 11 . The etching method according to claim 1 , wherein the etching gas contains nitrosyl fluoride at 33.3% by volume or more.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application is a National Stage of International Application No. PCT/JP2022/016207 filed Mar. 30, 2022, claiming priority based on Japanese Patent Application No. 2021-085388 filed May 20, 2021. TECHNICAL FIELD The present invention relates to an etching method and a method for producing a semiconductor element. BACKGROUND ART Nitrosyl fluoride (NOF) is usable as an etching gas for etching a silicon material in a semiconductor production process. For example, PTL 1 discloses a method of selectively etching silicon nitride as compared with silicon oxide by using an etching gas containing nitrosyl fluoride at a concentration of 0.1 to 20% by volume. In the method, silicon nitride is an etching object that is to be etched by the etching gas, whereas silicon oxide is a non-etching object that is not to be etched by the etching gas. CITATION LIST Patent Literature PTL 1: U.S. Ser. No. 10/529,581 B SUMMARY OF INVENTION Technical Problem When an etching gas containing nitrosyl fluoride at a low concentration is used to perform etching, the etching is required to be performed at a high temperature in order to increase the ratio of the etching rate of silicon nitride to the etching rate of silicon oxide or the etching selectivity. At a higher etching temperature, however, it becomes difficult to uniformly maintain the temperature of a member to be etched having an etching object and a non-etching object or the temperature of an etching gas during etching, and this may vary the etching rate of an etching object. In addition, at a high etching temperature, members included in an etching system may be worn or a member to be etched may be excessively etched, and this may generate particles. When the generated particles adhere to a member to be etched, structural collapse or short-circuit of the member to be etched may be caused, and this may reduce the production yield of semiconductor elements. The present invention is intended to provide an etching method capable of selectively etching an etching object containing silicon nitride as compared with a non-etching object while the generation of particles and a variation in etching rate are suppressed and to provide a method for producing a semiconductor element. Solution to Problem To solve the problems, aspects of the present invention are the following [1] to [7]. [1] An etching method including an etching step of bringing an etching gas containing more than 20% by volume of nitrosyl fluoride into contact with a member to be etched having an etching object that is to be etched by the etching gas and having a non-etching object that is not to be etched by the etching gas, to selectively etch the etching object as compared with the non-etching object without plasma, in which the etching object contains silicon nitride. [2] The etching method according to the aspect [1], in which the etching gas contains nitrosyl fluoride at 30% by volume or more. [3] The etching method according to the aspect [1] or [2], in which the etching gas is a gas exclusively containing nitrosyl fluoride or a mixed gas containing nitrosyl fluoride and a dilution gas. [4] The etching method according to any one of the aspects [1] to [3], in which the non-etching object is at least one of silicon oxide and amorphous carbon. [5] The etching method according to the aspect [4], in which in the etching step, the temperature condition is 50° C. or more and 250° C. or less. [6] The etching method according to any one of the aspects [1] to [5], in which the etching selectivity that is the ratio of the etching rate of the etching object to the etching rate of the non-etching object is 10 or more. [7] A method for producing a semiconductor element, the method using the etching method according to any one of the aspects [1] to [6] to produce a semiconductor element, the member to be etched being a semiconductor substrate having the etching object and the non-etching object,the method including a processing step of removing at least a part of the etching object from the semiconductor substrate by the etching. Advantageous Effects of Invention According to the present invention, an etching object containing silicon nitride can be selectively etched as compared with a non-etching object while the generation of particles and a variation in etching rate are suppressed. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a schematic view of an example etching system illustrating an embodiment of an etching method pertaining to the present invention; and FIG. 2 is a view illustrating a member to be etched used in Examples and Comparative Examples. DESCRIPTION OF EMBODIMENTS Embodiments of the present invention will now be described. The embodiments are merely examples of the present invention, and the present invention is not limited to the embodiments. Various modifications or improvements can be made in the embodiments, and such modifications and improvements can be encompassed by t