PIPVE Plasma Etching for High-Aspect-Ratio Oxide Patterns
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Solution Overview
Problem
Conventional plasma etching methods using perfluorocarbon gases have high global warming potential, leading to environmental concerns and inefficiencies in forming high aspect ratio structures due to fluorocarbon thin film deposition interfering with etching processes.
Innovation Solution
A plasma etching method utilizing perfluoroisopropyl vinyl ether (PIPVE) as a discharge gas, combined with argon and optional oxygen, which is vaporized and supplied to a plasma chamber with controlled flow rates and bias voltages to generate plasma for etching silicon oxide targets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If perfluorocarbon gas is used for plasma etching, then mask protection and etching selectivity are improved, but fluorocarbon thin film deposition interferes with etching and lowers etch rate
Solution Approach 1:
The patent changes the chemical parameters of the etching gas from conventional perfluorocarbon gases to perfluoroisopropyl vinyl ether (PIPVE), which has different decomposition characteristics. This parameter change reduces excessive fluorocarbon thin film deposition while maintaining mask protection, thereby resolving the contradiction between mask protection and etch rate
Solution Approach 2:
The patent uses PIPVE as a substitute gas that copies the essential function of PFC gases (mask protection through fluorocarbon deposition) but with improved characteristics (reduced excessive deposition). The PIPVE gas reproduces the beneficial effects while avoiding the harmful side effects of conventional PFC gases
2Reliability
If perfluorocarbon gas is used for plasma etching, then etching selectivity is improved, but excessive fluorocarbon deposition causes etching stop and prevents target depth achievement
Solution Approach 1:
The patent changes the gas composition parameter to PIPVE, which provides sufficient fluorocarbon deposition for mask protection and etching selectivity but prevents excessive deposition that would cause etching stop. This enables precise control of etched depth while maintaining selectivity
Solution Approach 2:
The PIPVE gas acts as an intermediary that mediates between the need for fluorocarbon deposition (for selectivity) and the need to avoid excessive deposition (for depth control). It provides the right amount of fluorocarbon thin film to maintain selectivity without causing etching stop
3Reliability
If perfluorocarbon gas is used for plasma etching, then mask protection is improved, but diameter of etched structure bottom becomes smaller than mask diameter
Solution Approach 1:
The patent changes the gas parameter to PIPVE, which reduces excessive fluorocarbon deposition on sidewalls that causes bottom narrowing. This maintains mask protection while achieving better etched structure diameter control with aspect ratio structures
4Productivity
If perfluorocarbon gas is used for plasma etching, then etching performance is improved, but global warming potential increases significantly
Solution Approach 1:
The patent adopts PIPVE gas which has low global warming potential compared to conventional PFC gases. Although PIPVE is a fluorocarbon compound, its environmental impact is significantly reduced, making it an eco-friendly alternative that maintains etching performance while reducing harmful effects
Solution Approach 2:
The patent converts the potential harm of using fluorocarbon gases (high GWP) into a benefit by selecting PIPVE, which maintains the etching performance advantages of fluorocarbon gases while having low global warming potential. This transforms an environmentally harmful practice into an environmentally friendly one
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 significantly reduces greenhouse gas emissions and enhances etching efficiency by controlling fluorocarbon thin film deposition, allowing for the formation of high aspect ratio structures with equal mask and etched diameters, while maintaining low global warming potential.
Implementation Method 1
a first container accommodating the liquid PIPVE therein may be heated to a first temperature equal to or higher than a boiling point of the PIPVE
Implementation Method 2
a third step of discharging the discharge gas to generate plasma and of performing plasma etching on the etching target using the generated plasma
Data Source
AI summary
A plasma etching method is disclosed. The plasma etching method comprises: a first step of vaporizing liquid perfluoroisopropyl vinylether (PIPVE); a second step of supplying, to a plasma chamber in which an object to be etched is arranged, the vaporized PIPVE and a discharge gas comprising argon gas; and a third step of discharging the discharge gas so as to generate plasma, and using same so as to plasma-etch the object to be etched.