Multilayered Film Etching Verticality via Localized Gas Supply
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Solution Overview
Problem
Existing etching methods for multilayered films in NAND type flash memory devices with three-dimensional structures often result in degraded verticality of holes in the etched regions, particularly in the diametrical direction, due to insufficient formation of protective films on sidewalls.
Innovation Solution
An etching method using a plasma processing apparatus that supplies a first processing gas containing hydrogen, hydrogen bromide, fluorine-containing, hydrocarbon, and fluorocarbon gases to the central region and a second processing gas containing hydrocarbon and fluorocarbon gases to the outer region, forming a protective fluorocarbon film on sidewalls and improving verticality by suppressing excessive film thickness and mask opening reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a processing gas containing CH2F2 and NF3 is used for etching the multilayered film, then the etching process can be performed, but the verticality of the space is degraded on partial regions of the processing target object
Solution Approach 1:
The patent applies local quality by differentiating gas supply between central and outer regions of the processing target object. The first supply unit provides processing gas toward the central region while the second supply unit provides it toward the outer region, allowing different gas compositions or flow rates to be applied to different spatial zones to maintain verticality across the entire wafer surface
Solution Approach 2:
The patent changes gas composition parameters by introducing a hydrocarbon gas component in addition to the fluorocarbon and fluorine-containing gases. This parameter change modifies the protective film formation characteristics, preventing excessive film thickness that causes mask opening reduction while maintaining adequate protection for verticality
2Manufacturing precision
If a protective film is formed on the sidewall surface of the multilayered film, then verticality is improved, but the opening size of the mask is reduced
Solution Approach 1:
The patent changes the chemical composition parameters of the processing gas by adding hydrocarbon gas to the fluorocarbon-based gas mixture. This parameter change enables formation of a protective film with controlled thickness and properties that prevents mask opening reduction while maintaining verticality enhancement
Solution Approach 2:
The patent creates a composite processing gas system combining fluorocarbon gases (for protective film formation), fluorine-containing gases (for etching), and hydrocarbon gases (for film thickness control). This composite approach produces a protective film with balanced properties that achieves both verticality improvement and mask opening preservation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method effectively maintains the verticality of etched spaces across the entire multilayered film, including partial regions, by forming a controlled protective film and reducing mask opening size, thereby enhancing the etching process's precision and consistency.
Implementation Method 1
generating plasma within the processing vessel of the plasma processing apparatus
Implementation Method 2
etching the multilayered film by generating plasma within the processing vessel
Implementation Method 3
a protective film containing fluorocarbon originated from the fluorocarbon gas is formed on a sidewall surface of the multilayered film
Implementation Method 4
hydrogen originated from the hydrocarbon gas suppresses the protective film from being formed in an excessively large thickness
Data Source
AI summary
An etching method of etching a multilayered film includes etching a multilayered film by generating plasma within a processing vessel of a plasma processing apparatus. In the etching of the multilayered film, a first processing gas containing a hydrogen gas, a hydrogen bromide gas, a fluorine-containing gas, a hydrocarbon gas, a hydrofluorocarbon gas and a fluorocarbon gas is supplied from a first supply unit configured to supply a gas toward a central region of the processing target object and a second supply unit configured to supply a gas toward outer region than the central region; a second processing gas containing a hydrocarbon gas and a fluorocarbon gas is supplied from either one of the first supply unit and the second supply unit; and the first processing gas and the second processing gas are excited.