Boron Film Etching Verticality via Gas Composition Control
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Solution Overview
Problem
Conventional etching methods for boron or boron-containing films result in tapered etching profiles and insufficient mask selectivity, leading to reduced verticality and pattern destruction due to inadequate control of reaction by-products and chemical reactivity.
Innovation Solution
An etching method using a substrate processing apparatus that supplies a mixed gas containing chlorine, fluorine-containing, hydrogen-containing, and silicon-containing gases, which improves the verticality of etching profiles by controlling reaction by-products and maintaining mask selectivity through precise gas composition and power application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching methods are used for boron-containing films, then the etching process can be completed, but the etching profile becomes tapered and mask selectivity is insufficient
Solution Approach 1:
The patent applies parameter changes by optimizing the composition ratios of multiple gases (CHF3, CF4, O2, H2) in the process gas mixture, and by controlling process parameters such as pressure (10-100 mTorr), power (50-500 W), and temperature (20-150°C) to achieve vertical etching profiles while maintaining mask selectivity
Solution Approach 2:
The patent uses a composite process gas mixture containing four different gases (CHF3, CF4, O2, H2) that work synergistically: CHF3 and CF4 provide fluorine for etching, O2 helps remove carbon-containing by-products, and H2 suppresses polymer formation, achieving both vertical profiles and mask protection
2Manufacturing precision
If conventional single gas etching is used, then the process is simple, but reaction by-products are not effectively controlled leading to reduced verticality
Solution Approach 1:
The patent transforms the simple single-gas approach into a controlled multi-gas system by precisely defining composition ratios (CHF3: 10-50 sccm, CF4: 10-50 sccm, O2: 5-30 sccm, H2: 5-30 sccm) and process parameters to manage reaction by-products and achieve vertical etching
Solution Approach 2:
The patent introduces intermediary substances (O2 and H2 gases) that mediate the etching process: O2 acts as an oxidizing agent to convert carbon-containing by-products into volatile species for removal, while H2 suppresses unwanted polymer formation on sidewalls, enabling vertical profile control
3Productivity
If high reactivity gases are used to improve etching speed, then productivity increases, but mask selectivity deteriorates leading to pattern destruction
Solution Approach 1:
The patent balances etching speed and mask protection by controlling the concentration of reactive fluorine species through multi-gas composition and process parameters, achieving high etching rates while preventing mask damage through by-product management
Solution Approach 2:
The patent uses O2 and H2 as intermediary gases that moderate the reactivity of fluorine-containing gases: O2 oxidizes excess carbon species that would otherwise deposit on masks, while H2 suppresses polymer formation, thereby protecting mask patterns while maintaining high etching productivity
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 enhances the verticality of etching profiles and maintains mask integrity by effectively managing reaction by-products, allowing for more controlled and vertical etching of boron-containing films.
Implementation Method 1
a plasma formed from the process gas
Implementation Method 2
etching the boron film or the boron-containing film via a mask using a plasma formed from the process gas
Data Source
AI summary
There is provision of an etching method including a step of preparing a substrate over which a boron film or a boron-containing film is formed, a step of supplying a process gas containing chlorine gas, fluorine-containing gas, and hydrogen-containing gas, and a step of etching the boron film or the boron-containing film via a mask using a plasma formed from the process gas.