Silicon Film Plasma Etching With HF Gas for Bowing Control
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Solution Overview
Problem
Existing etching methods for silicon-containing films using plasma processing face challenges in achieving precise control over etching shapes, particularly in maintaining the integrity of the mask and preventing issues like bowing and clogging during the etching process.
Innovation Solution
An etching method utilizing a processing gas comprising hydrogen fluoride, a first halogen-containing gas with carbon and halogen other than fluorine, and a phosphorus-containing gas, which forms plasma to etch silicon-containing films, enhancing the etching shape by promoting a balanced reaction and protecting the mask.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plasma processing is used to etch silicon-containing films, then etching efficiency is improved, but control over etching shape precision deteriorates
Solution Approach 1:
The patent applies parameter changes by carefully controlling the partial pressures of multiple gases in the plasma processing system. Specifically, it maintains hydrogen fluoride at a high partial pressure while controlling the partial pressures of oxygen-containing gas and hydrocarbon gas to specific ranges. This multi-parameter optimization enables both high etching efficiency and precise shape control by balancing the reactive species concentrations in the plasma.
Solution Approach 2:
The patent uses a composite gas mixture comprising hydrogen fluoride, oxygen-containing gas, and hydrocarbon gas. This composite processing gas creates a plasma environment that combines the benefits of different gas components: hydrogen fluoride provides efficient silicon etching, oxygen-containing gas controls plasma chemistry and prevents polymer buildup, and hydrocarbon gas forms protective polymer layers on mask surfaces. The synergistic interaction of these components resolves the contradiction between efficiency and precision.
2Productivity
If high partial pressure of hydrogen fluoride is used for efficient etching, then etching speed is improved, but mask integrity deteriorates due to bowing and clogging
Solution Approach 1:
The patent introduces oxygen-containing gas and hydrocarbon gas as intermediary substances that mediate between the hydrogen fluoride etching action and the mask surface. The oxygen-containing gas modifies the plasma chemistry to reduce excessive polymer deposition, while the hydrocarbon gas forms a protective polymer layer on the mask that prevents direct hydrogen fluoride attack and physical clogging. These intermediaries enable high etching speed while preserving mask integrity.
Solution Approach 2:
The patent converts the potentially harmful effect of hydrogen fluoride on mask materials into a beneficial process. By introducing controlled amounts of oxygen-containing and hydrocarbon gases, the system creates a protective polymer environment that actually protects the mask from hydrogen fluoride damage while allowing the hydrogen fluoride to efficiently etch the silicon-containing film underneath. The harmful direct interaction is transformed into a protected, controlled process.
3Manufacturing precision
If plasma processing parameters are optimized for shape control, then etching precision is improved, but etching efficiency deteriorates
Solution Approach 1:
The patent achieves both shape control and efficiency through a multi-parameter optimization strategy. Instead of optimizing for a single parameter, it simultaneously controls the partial pressures of three different gases: hydrogen fluoride (for etching speed), oxygen-containing gas (for plasma chemistry control and shape precision), and hydrocarbon gas (for mask protection and uniformity). This multi-dimensional parameter control resolves the efficiency-precision trade-off.
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 improves etching shape precision, suppresses bowing and clogging, and maintains a high partial pressure of hydrogen fluoride, ensuring efficient and controlled etching of silicon-containing films.
Implementation Method 1
forming plasma from a processing gas to etch the first film
Implementation Method 2
the processing gas including a hydrogen fluoride gas, a first halogen-containing gas, and a phosphorus-containing gas
Data Source
AI summary
A technique of improving an etching shape is provided.An etching method including: providing a substrate, the substrate including a first film and a second film on the first film, the first film including silicon, and the second film including at least one opening; and forming plasma from a processing gas to etch the first film, the processing gas including a hydrogen fluoride gas, a first halogen-containing gas, and a phosphorus-containing gas, and the first halogen-containing gas containing at least carbon and halogen other than fluorine.