Low-GWP Plasma Etching Gas Composition for High-Aspect-Ratio Patterns
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Solution Overview
Problem
The semiconductor industry faces challenges in reducing the high global warming potential (GWP) of perfluoro compounds (PFCs) used in plasma etching processes, which are essential for manufacturing high aspect ratio structures in semiconductor devices.
Innovation Solution
A plasma etching method using a mixture of HFE-347mcc3 and PFP as discharge gases, which have a low GWP and excellent etching characteristics, is employed. The method involves vaporizing these gases and supplying them, along with argon, to a plasma chamber where the etching target is located.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If PFC gas is used for plasma etching to achieve high aspect ratio structures, then etching performance is improved, but global warming potential increases significantly
Solution Approach 1:
The patent changes the chemical composition parameters of the etching gas from traditional PFC gases (CF4, C2F6, C4F6, C4F8) to a mixed gas system containing HFE-347mcc3, PFP, and O2. This parameter change maintains etching performance while reducing GWP from 6500+ to significantly lower values, directly resolving the contradiction between etching performance and environmental impact
Solution Approach 2:
The patent employs a composite gas system combining HFE-347mcc3, PFP, and O2 in specific ratios. This composite approach leverages the complementary properties of each component: HFE-347mcc3 and PFP provide etching capability with low GWP, while O2 controls fluorocarbon film formation. The composite gas mixture achieves both low environmental impact and high etching performance, resolving the technical contradiction
2Manufacturing precision
If fluorocarbon thin film is formed during PFC plasma etching to protect wall surface, then etch profile shape is controlled, but etch stop phenomenon occurs in hole pattern structures
Solution Approach 1:
The patent applies partial action by adding O2 to the etching gas mixture in controlled amounts (5-50 sccm). This partial addition of oxygen is sufficient to control fluorocarbon film formation and prevent etch stop, while avoiding excessive oxygen that would reduce etching rate. The balanced approach maintains both profile control and etching continuity
Solution Approach 2:
The patent changes the gas composition parameters by introducing O2 alongside HFE-347mcc3 and PFP. This parameter change dynamically controls the fluorocarbon film thickness during etching, preventing excessive film formation that causes etch stop while maintaining enough film for profile protection. The modified gas parameters resolve the contradiction between profile control and etching continuity
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 allows for the formation of high aspect ratio etched structures with minimal change in hole pattern diameter and small pattern deformation, while significantly reducing greenhouse gas emissions compared to traditional PFC-based methods.
Implementation Method 1
a third step of discharging the discharge gas to generate plasma and of plasma-etching the etching target using the generated plasma
Implementation Method 2
a first step of vaporizing liquid heptafluoropropyl methyl ether (HFE-347mcc3) and liquid pentafluoropropanol (PFP)
Data Source
AI summary
Disclosed is a plasma etching method. The method includes a first step of vaporizing liquid heptafluoropropyl methyl ether (HFE-347mcc3) and liquid pentafluoropropanol (PFP); a second step of supplying a discharge gas containing the vaporized HFE-347mcc3, the vaporized PFP, and argon gas to a plasma chamber in which an etching target is disposed; and a third step of discharging the discharge gas to generate plasma and of plasma-etching the etching target using the generated plasma.