KR-102963872-B1 - Method for etching multi-stack of Si-containing layers and manufacturing method of semiconductor device including the same

KR102963872B1KR 102963872 B1KR102963872 B1KR 102963872B1KR-102963872-B1

Abstract

The etching method of a multilayer structure of a silicon-containing film according to the present invention is A step of introducing a substrate having a multilayer structure formed thereon, comprising a first silicon-containing film and a second silicon-containing film having a composition different from that of the first silicon-containing film, into a process chamber of an etching device, and The step of supplying etching gas to the process chamber above, and The method includes the step of activating the etching gas by plasma to etch a high aspect ratio opening of 20:1 or more in the multilayer structure, The above etching gas is characterized by comprising a first etching gas having atoms of fluorine (F), nitrogen (N), and oxygen (O) but not carbon (C) atoms, and a second etching gas having at least carbon (C) and fluorine (F) atoms.

Inventors

곽정훈
권병향
조용준

Assignees

에스케이스페셜티 주식회사

Dates

Publication Date: 20260511
Application Date: 20210226

Claims (13)

As an etching method for a multilayer structure of a silicon-containing film, A step of introducing a substrate having a multilayer structure formed thereon, comprising a first silicon-containing film and a second silicon-containing film having a composition different from that of the first silicon-containing film, into a process chamber of an etching device, and The step of supplying etching gas to the process chamber above, and The method includes the step of activating the etching gas by plasma to etch a high aspect ratio opening of 20:1 or more in the multilayer structure, The above etching gas comprises a first etching gas having atoms of fluorine (F), nitrogen (N), and oxygen (O) but not carbon (C) atoms, and a second etching gas having at least carbon (C) and fluorine (F) atoms. A method for etching a multilayer stack of silicon-containing films, characterized in that the first etching gas comprises F₃NO .
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In paragraph 1, A method for etching a multilayer stack of silicon-containing films, characterized in that the second etching gas comprises an etching gas represented by the chemical formula C x H y F z (where x is 2 to 4, y is 0 to 4, and z is 4 to 8).
In paragraph 3, A method for etching a multilayer stack of silicon-containing films, characterized in that the second etching gas has x of 2 to 4 and the ratio of C to F (x:z) is 0.5 to 1.
In paragraph 1, The silicon is characterized in that the second etching gas is one or more gases selected from the group consisting of hexafluoropropane ( C₃H₂F₆ ), hexafluorobutene ( C₄H₂F₆ ), octafluorobutane ( C₄H₂F₅ ), hexafluorobutane (C₄H₄F₆ ) , trifluoropropane ( C₃H₅F₃ ), tetrafluorobutane ( C₄H₆F₄ ) , trifluorobutane ( C₄H₇F₃ ) , difluoropropane ( C₃H₆F₂ ), difluorobutane ( C₄H₅F₆ ) , fluoropropane ( C₃H₇F₆ ), fluoromethylpropane ( C₄H₇F₆ ), octafluorocyclopentene ( C₅F₅F₆ ) , and hexafluorobenzene ( C₆F₆ ) . Etching method for a multilayer structure of a film containing a film.
In paragraph 5, A method for etching a multilayer stack of silicon- containing films, characterized in that the second etching gas comprises trifluoropropane (C₃H₅F₃ ) , tetrafluorobutane (C₄H₆F₄ ) , or hexafluorobenzene ( C₆F₆ ).
In paragraph 1, A method for etching a multilayer structure of a silicon-containing film, characterized in that, in the step of supplying the etching gas to the process chamber, a third gas containing hydrogen atoms is supplied.
In paragraph 1, A method for etching a multilayer structure of a silicon-containing film, characterized in that, in the step of supplying the etching gas to the process chamber, at least one inert gas selected from the group of inert gases consisting of helium, argon, neon, krypton, and xenon is supplied.
In paragraph 1, A method for etching a multilayer stack of silicon-containing films, characterized in that, in the supplying step, the first etching gas and the second etching gas are supplied at a flow rate ratio of 3 to 5:0.5 to 2.
In paragraph 1, A method for etching a multilayer structure of a silicon-containing film, characterized in that, in the etching step above, the etching gas is activated by direct plasma.
In paragraph 1, A method for etching a multilayer structure of a silicon-containing film, characterized in that, in the supplying step, the etching gas activated by a remote plasma is supplied.
In paragraph 1, A method for etching a multilayer stack of silicon-containing films, characterized in that the first silicon-containing film is a silicon nitride film and the second silicon-containing film is a silicon oxide film.
The step of forming a multilayer laminate of a first silicon-containing film and a second silicon-containing film having a different composition from the first silicon-containing film on a substrate, and The step of forming an etching mask on the above multilayer film, and A method for manufacturing a semiconductor device characterized by including the step of etching the multi-layered film by any one of the etching methods of claims 1, 3 and 5.

Description

Method for etching multi-stack of Si-containing layers and manufacturing method of semiconductor device including the same The present invention relates to a method for etching a silicon-containing film and a method for manufacturing a semiconductor device including the same. More specifically, the invention relates to a method for performing high aspect ratio etching on a multilayer stack of silicon-containing films of different compositions and a method for manufacturing a semiconductor device including the etching method. Generally, a series of processes such as deposition, photolithography, and etching are performed to manufacture semiconductor devices on a substrate. These processes are carried out in deposition equipment (e.g., CVD equipment), photolithography equipment, etching equipment, etc. Among these, the etching process is a process that forms ultrafine structures of a desired pattern by selectively removing a thin film deposited on a substrate by the deposition process along a pattern formed by the photolithography process. Recently, in the field of semiconductor memory, a technology for vertically stacking semiconductor memory cells is being applied to achieve high integration or high capacity while suppressing the increase in the planar size of semiconductor memory chips. For example, in the field of NAND flash memory, memory cells, which serve as units for storing data, are stacked in 128 layers or more (such NAND flash memory is also called 3D NAND flash memory), and the number of stacked memory cells is expected to increase further as the high integration or high capacity of NAND flash memory progresses. In this 3D NAND flash memory, to stack memory cells, a multilayer stack of silicon-containing films is formed by alternately stacking silicon-containing films of different components (e.g., silicon nitride film (Si x N y ) and silicon oxide film (SiO 2 )), and then, to form vertical channels, holes with a high aspect ratio are formed in the multilayer stack of silicon-containing films by an etching process. As the number of layers of silicon-containing multilayers formed in 3D NAND flash memory continues to increase, the aspect ratio of holes that must be formed in silicon-containing multilayers is becoming larger. To form high aspect ratio holes in a multilayer structure of silicon-containing films, it is required that the silicon-containing film exhibits a high etch selectivity with respect to an etching mask (e.g., photoresist or hard mask), while the silicon-containing films of different components forming the multilayer structure possess similar etch rates (i.e., similar etch selectivity with respect to each other) and an overall high etch rate. Furthermore, the high aspect ratio holes must not be clogged by etching byproducts, nor should bowing occur. Fluorinated hydrocarbon-based (C x H y F z ) etching gas is known as an etching gas used to form holes with a high aspect ratio in a multilayer structure of silicon-containing films (Patent Document 1, WO2014/104290). Patent Document 1 discloses a method for etching a multilayer film composed of a silicon oxide film and a silicon nitride film using an etching gas containing a chain-type saturated fluorinated hydrocarbon compound. When using the chain-type saturated fluorinated hydrocarbon disclosed in Patent Document 1, the multilayer film of silicon nitride and silicon oxide can be etched with a high selectivity ratio with respect to the etching mask, but there is a difference in etching rate between the silicon nitride and silicon oxide films constituting the multilayer film, making it difficult to form holes with a high aspect ratio well, and there is also a problem of reduced productivity due to the overall low etching rate. These problems are becoming a major obstacle hindering the continuous high integration of 3D NAND flash memory. FIGS. 1a and 1b are schematic diagrams of an etching apparatus for performing an etching method according to one embodiment of the present invention. FIG. 2 is a flowchart of an etching method according to one embodiment of the present invention. FIG. 3 is a flowchart of a method for manufacturing a semiconductor device according to one embodiment of the present invention. Embodiments of the present invention will be described in detail below with reference to the attached drawings. Identical components in the drawings are denoted by the same reference numerals, and redundant descriptions thereof are omitted. FIGS. 1a and 1b illustrate an etching apparatus (1) for carrying out an etching method according to one embodiment of the present invention. The etching device (1) is a capacitively coupled plasma (CCP) device capable of generating direct plasma, and plasma (P) is generated directly within the process chamber (10) of the etching device (1) through plasma discharge. However, the present invention is not limited to a capacitively coupled plasma device and may be any other type of device as long as