Remote Plasma Fluorine Etch for Silicon Oxide Selectivity
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Solution Overview
Problem
Existing etching processes struggle to selectively remove silicon oxide from patterned substrates without deforming delicate structures, as they either fail to penetrate constrained trenches or produce solid by-products that deform remaining materials.
Innovation Solution
A remote plasma etch process using a fluorine-containing precursor combined with water vapor is employed, which flows into the substrate processing region to etch silicon oxide selectively, avoiding the production of solid by-products and minimizing deformation of delicate structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If wet HF etch is used to selectively remove silicon oxide, then selectivity towards silicon oxide is improved, but the process cannot penetrate constrained trenches and deforms remaining material
Solution Approach 1:
The patent replaces wet chemical etching with a plasma-based etching process that uses fluorine radicals generated remotely. This substitution allows the etch process to penetrate constrained trenches effectively while maintaining selectivity towards silicon oxide through controlled chemical reactions rather than bulk wet etching.
Solution Approach 2:
The patent introduces water vapor as an intermediary substance that reacts with fluorine radicals to enhance silicon oxide etching. This intermediary mechanism enables selective removal of silicon oxide while avoiding direct contact that would cause deformation of remaining structures.
2Ease of operation
If local plasma is used to penetrate constrained trenches, then penetration ability is improved, but substrate damage occurs through electric arcs
Solution Approach 1:
The patent extracts the plasma generation from the substrate processing region by using a remote plasma source. The fluorine-containing precursor is excited to form fluorine radicals in a remote chamber, which then flow into the substrate region without carrying ionizing energy that would cause electric arcs and substrate damage.
Solution Approach 2:
The patent replaces local plasma discharge with remote plasma chemistry. Instead of using ionized plasma that causes electric arcs, the system uses neutral fluorine radicals generated remotely, eliminating the harmful electrical effects while maintaining the chemical etching capability.
3Manufacturing precision
If Siconi etch is used to achieve conformal etching and silicon oxide selectivity, then selectivity towards silicon oxide is improved, but solid by-products deform delicate structures
Solution Approach 1:
The patent changes the process parameters by using a fluorine-containing precursor with water vapor instead of the traditional Siconi gas mixture. This parameter change modifies the reaction chemistry to produce volatile etch products rather than solid by-products, eliminating the deformation issue while maintaining silicon oxide selectivity.
Solution Approach 2:
The patent converts the potential harm of solid by-product formation into a benefit by selecting reaction conditions and precursors that produce volatile products. The chemical reactions are designed to create gaseous etch products that can be easily removed, transforming the problem of by-product accumulation into an advantage of clean, deformation-free etching.
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 effectively trims silicon oxide while preserving the shape of thin residual structures, such as cylindrical conducting columns, with high selectivity over silicon and silicon nitride, reducing deformation and maintaining the integrity of patterned substrates.
Implementation Method 1
A remote plasma etch process using a fluorine-containing precursor combined with water vapor is employed
Implementation Method 2
The chemical reaction resulting from the combination produces reactants which etch the patterned heterogeneous structures
Implementation Method 3
plasma effluents from the remote plasma are flowed into a substrate processing region where the plasma effluents combine with water vapor
Data Source
AI summary
A method of etching exposed silicon oxide on patterned heterogeneous structures is described and includes a remote plasma etch formed from a fluorine-containing precursor. Plasma effluents from the remote plasma are flowed into a substrate processing region where the plasma effluents combine with water vapor. The chemical reaction resulting from the combination produces reactants which etch the patterned heterogeneous structures to produce, in embodiments, a thin residual structure exhibiting little deformation. The methods may be used to conformally trim silicon oxide while removing little or no silicon, polysilicon, silicon nitride, titanium or titanium nitride. In an exemplary embodiment, the etch processes described herein have been found to remove mold oxide around a thin cylindrical conducting structure without causing the cylindrical structure to significantly deform.