Hard Mask Patterning Using Hydrogen-Free Etching Gas
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Solution Overview
Problem
The existing IC fabrication processes face severe polymer deposition issues when using fluorohydrocarbon etching gases for defining deep trenches, requiring frequent maintenance of the reaction chamber.
Innovation Solution
A method involving an etching gas without hydrogen, such as a perfluorocarbon compound with argon and oxygen, is used to pattern a hard mask layer, inhibiting polymer formation and reducing chamber maintenance frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fluorohydrocarbon etching gas is used to etch the hard mask layer, then the etching performance is improved, but severe polymer deposition occurs on the chamber wall
Solution Approach 1:
The patent changes the chemical composition parameters of the etching gas from fluorohydrocarbon (containing hydrogen) to perfluorocarbon (hydrogen-free), thereby eliminating polymer deposition while maintaining etching capability through adjusted gas composition and process parameters
2Productivity
If fluorohydrocarbon etching gas is used to etch the hard mask layer, then the etching performance is improved, but the chamber maintenance frequency increases
Solution Approach 1:
The patent changes the etching gas composition to perfluorocarbon-based mixtures without hydrogen, which prevents polymer deposition on chamber walls, thereby significantly reducing maintenance frequency and time loss while maintaining effective etching performance
3Ease of manufacture
If hydrogen-containing etching gas is used, then the etching process is effective, but polymer formation is severe
Solution Approach 1:
The patent eliminates hydrogen from the etching gas composition by using perfluorocarbon compounds (CF4, C4F8, C5F8) combined with oxygen and argon, fundamentally changing the chemical reactions to prevent polymer formation while preserving etching effectiveness through optimized gas ratios and process conditions
Solution Approach 2:
The patent uses composite etching gas formulations combining perfluorocarbon compounds with oxygen and argon, where each component serves a specific function: perfluorocarbon provides etching, oxygen enhances removal of etching products, and argon provides plasma stability, achieving effective etching without polymer deposition
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 effectively transfers deep-trench patterns to the hard mask layer while minimizing polymer deposition, enhancing the reliability and efficiency of the IC fabrication process.
Implementation Method 1
An etching gas not containing hydrogen is used to etch the hard mask layer with the patterned photoresist layer as a mask and thereby transfer the deep-trench opening pattern to the hard mask layer
Implementation Method 2
Since the etching gas used in the patterning method of this invention does not contain hydrogen, the polymer formation is greatly inhibited so that the frequency of the maintenance of the reaction chamber can be decreased
Data Source
AI summary
A method of patterning a hard mask layer for defining a deep trench is described. A substrate formed with an isolation structure therein is provided. A hard mask layer is formed over the substrate provided. A patterned photoresist layer is formed over the hard mask layer, having therein a deep-trench opening pattern over the isolation structure. An etching gas not containing hydrogen is used to etch the hard mask layer with the patterned photoresist layer as a mask and thereby transfer the deep-trench opening pattern to the hard mask layer.