Functional Group Fluorocarbon ALE for Silicon Oxide Uniformity
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Solution Overview
Problem
Conventional atomic layer etching (ALE) methods fail to achieve satisfactory in-plane uniformity when etching silicon oxide or silicon nitride films due to physical adsorption of etchant gases, leading to suboptimal etching results.
Innovation Solution
The use of functional group-containing fluorocarbon etchant gases that chemisorb on the substrate surface through substitution reactions or hydrogen bonding, allowing for self-limiting adsorption and improved in-plane uniformity, employing a process that includes pulsing the etchant gas with a carrier gas and reactive species in a plasma-enhanced ALE process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional fluorocarbon etchant gases (e.g., C4F8) are used for etching silicon oxide or silicon nitride films by ALE, then the etching process can proceed, but in-plane uniformity of etching deteriorates due to physical adsorption causing gas-phase etching
Solution Approach 1:
The invention changes the chemical parameters of the etchant gas by introducing functional groups (hydroxyl, amino, carboxyl, etc.) to fluorocarbon molecules. This transformation converts the adsorption mechanism from physical to chemical, enabling self-limiting chemisorption that ensures uniform monolayer coverage and eliminates gas-phase etching, thereby resolving the in-plane uniformity issue
Solution Approach 2:
The invention creates composite etchant molecules by combining fluorocarbon skeletons with reactive functional groups. This composite structure provides both the etching capability of fluorocarbons and the chemisorption ability of polar groups, achieving simultaneous improvement in adsorption strength and etching performance for mineral films
2Productivity
If etchant gas flow rate or pulse duration is increased to improve etching rate, then productivity increases, but in-plane uniformity deteriorates due to excessive gas-phase etching in conventional ALE
Solution Approach 1:
The functional group-containing fluorocarbon performs self-limiting chemisorption, automatically forming a complete monolayer without requiring precise control of flow rate or pulse duration. The reactive functional groups naturally saturate the surface sites, making the process self-regulating and independent of gas supply parameters, thus maintaining uniformity across a wide range of productivity conditions
3Ease of operation
If conventional ALE uses physical adsorption of etchant gas, then the process is simple to operate, but in-plane uniformity of etching deteriorates due to non-saturating adsorption and gas-phase etching
Solution Approach 1:
The invention changes the fundamental adsorption parameter from physical to chemical interaction by incorporating polar functional groups. This transformation maintains operational simplicity while achieving self-limiting chemisorption that ensures uniform monolayer formation and eliminates the need for complex parameter optimization, resolving the contradiction between ease of operation and etching uniformity
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 approach enhances in-plane uniformity and etching rate consistency by ensuring chemisorption of the etchant gas, independent of exposure duration or flow rate, resulting in more precise and conformal etching of silicon oxide films.
Implementation Method 1
The etchant gas is chemically adsorbed on a surface of a substrate based on the principle of substitution reaction or hydrogen bonding, etc.
Implementation Method 2
The etchant gas is chemically adsorbed on a surface of a substrate based on the principle of substitution reaction or hydrogen bonding, etc.
Implementation Method 3
Atomic layer etching (ALE) is cyclic, atomic layer-level etching using an etchant gas adsorbed on a target film and reacted with excited reaction species
Implementation Method 4
The etchant gas is chemically adsorbed on a surface of a substrate based on the principle of substitution reaction or hydrogen bonding, etc.
Data Source
AI summary
A method of atomic layer etching (ALE) uses a cycle including: continuously providing a noble gas; providing a pulse of an etchant gas to the reaction space to chemisorb the etchant gas in an unexcited state in a self-limiting manner on a surface of a substrate in the reaction space; and providing a pulse of a reactive species of a noble gas in the reaction space to contact the etchant gas-chemisorbed surface of the substrate with the reactive species so that the layer on the substrate is etched. The etchant gas is a fluorocarbon gas containing a functional group with a polarity.