Plasma Etching Selectivity for Silicon Oxide and Nitride Films
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current plasma etching methods cannot simultaneously etch silicon oxide and silicon nitride films in the same step with high selectivity, especially in the manufacturing of NAND flash memory where these films are stacked in multiple layers, while also having a low environmental impact.
Innovation Solution
A plasma etching method using a combination of a non-bromine-containing fluorocarbon and a bromine-containing fluorocarbon compound, specifically C3H2BrF3 gases like 2-bromo-3,3,3-trifluoropropene, allows for the simultaneous etching of silicon oxide and silicon nitride films in the same step with high selectivity by maintaining a specific volume ratio of these gases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If plasma etching uses a specific plasma etching gas having low environmental impact (as disclosed in PTL 1), then etching selectivity of silicon oxide film is improved, but silicon nitride film cannot be etched in the same etching step
Solution Approach 1:
The patent combines a fluorocarbon gas (CF4, C3F8, or C4F8) with a bromine-containing gas (BBr3 or CBr4) to create a mixed plasma etching gas. This combination enables both silicon oxide and silicon nitride films to be etched in the same step while maintaining low environmental impact, as the fluorocarbon component provides low reactivity toward organic masks and the bromine component enables silicon nitride etching.
Solution Approach 2:
The invention uses a composite plasma etching gas system comprising fluorocarbon and bromine-containing components. This composite gas system achieves synergistic effects where the fluorocarbon provides selectivity protection for organic masks and the bromine component enables etching of silicon nitride, resolving the contradiction between environmental impact and etching versatility.
2Productivity
If plasma etching is performed to etch both silicon oxide and silicon nitride films in the same step, then productivity is improved, but etching selectivity between different films becomes difficult to control
Solution Approach 1:
The patent optimizes the mixing ratio of fluorocarbon and bromine-containing gases, controlling the bromine content within specific ranges (0.1-10% or 0.5-5% by volume). This parameter control enables simultaneous etching of silicon oxide and silicon nitride while maintaining appropriate selectivity, as the fluorocarbon component protects organic masks and the controlled bromine content enables silicon nitride etching without excessive reactivity.
3Adaptability or versatility
If conventional plasma etching gas is used to etch silicon nitride film, then etching capability is improved, but environmental impact increases and selectivity toward organic masks deteriorates
Solution Approach 1:
The patent employs fluorocarbon gases (CF4, C3F8, C4F8) that decompose completely in plasma to form volatile etch products, avoiding persistent environmental contaminants. These gases provide temporary protective effects during etching (forming protective layers on organic masks) but decompose afterward, leaving no long-term environmental harm while enabling silicon nitride etching through bromine component.
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
This method enables efficient and selective etching of both silicon oxide and silicon nitride films in the same etching step with a low environmental impact, improving etching selectivity and reducing mask loss, thus facilitating the manufacturing of semiconductor devices.
Implementation Method 1
plasma etching the silicon oxide film and the silicon nitride film using a gas of a non-bromine-containing fluorocarbon together with a gas of a bromine-containing fluorocarbon compound
Implementation Method 2
etching of a silicon oxide film and a silicon nitride film can be performed in an etching step in which a gas of a non-bromine-containing fluorocarbon and a gas of a bromine-containing fluorocarbon compound
Data Source
AI summary
A plasma etching method for etching a multilayer laminate in which a silicon oxide film and a silicon nitride film are stacked includes an etching step of plasma etching the silicon oxide film and the silicon nitride film using a gas of a non-bromine-containing fluorocarbon together with a gas of a bromine-containing fluorocarbon compound represented by a compositional formula C3H2BrF3.