Plasma Etching RF Cycling for Residue-Free Mask Removal
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Solution Overview
Problem
In etching processes involving substrates with insulating films and metal layers, residues from metal-containing reaction products often adhere to the substrate due to low selectivity between the insulating film and the metal-containing layer.
Innovation Solution
A plasma processing method involving a substrate with a first mask layer and a metal-containing layer, where a process gas containing fluorocarbon and hydrofluorocarbon gases is used, and radio-frequency power is supplied in a specific pattern, including a first power for plasma formation and a second power with a lower frequency applied after a predetermined time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the flow rate of N2 gas is increased to sputter reaction products, then residue adhesion is prevented, but etching selectivity between insulating film and metal layer deteriorates
Solution Approach 1:
The patent applies periodic action by alternating between a first radio-frequency power (high frequency) that forms plasma for etching and a second radio-frequency power (low frequency) that sputters reaction products. This periodic switching between different power frequencies enables both etching and residue removal without continuously increasing N2 gas flow, thereby maintaining etching selectivity while preventing residue adhesion.
Solution Approach 2:
The patent changes parameters by switching between different radio-frequency power frequencies and adjusting the timing of power application. By controlling the frequency and timing of radio-frequency power application rather than relying solely on gas flow rate adjustments, the method achieves both effective residue removal and maintained etching selectivity.
2Object-generated harmful factors
If N2 gas flow rate is increased to remove residues, then cleaning effect improves, but process time and energy consumption increase
Solution Approach 1:
The periodic switching between high-frequency plasma formation and low-frequency sputtering enables efficient residue removal during the etching process itself, rather than requiring separate prolonged cleaning steps. This integrated approach reduces overall process time while maintaining effective residue removal.
Solution Approach 2:
The method maintains continuous useful action by performing both etching and residue removal in an integrated process rather than as separate sequential steps. The low-frequency radio-frequency power continues to sputter reaction products during and between high-frequency etching cycles, ensuring continuous residue removal without extending total process time.
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 improves the selectivity between the Si-containing anti-reflection film and the metal-containing film, reducing residue formation and enhancing etching efficiency.
Implementation Method 1
supplying a first radio-frequency power that forms a plasma from the process gas into the processing container
Implementation Method 2
supplying a second radio-frequency power having a frequency lower than a frequency of the first radio-frequency power to the stage
Data Source
AI summary
A plasma processing method includes: (a) mounting a substrate including a first mask layer, which is a removal target, formed on a first layer with a metal-containing layer that is included therein to be partially exposed, on a stage disposed inside a processing container of the plasma processing apparatus; (b) supplying a process gas containing one or more of fluorocarbon gas and hydrofluorocarbon gas into the processing container; (c) supplying a first radio-frequency power that forms a plasma from the process gas into the processing container; (d) supplying a second radio-frequency power having a frequency lower than a frequency of the first radio-frequency power to the stage after a predetermined time is elapsed from stop of the first radio-frequency power; and (e) repeating (c) and (d).