Photomask Plasma Cleaning With Optical Radical Control
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Solution Overview
Problem
Current plasma-based cleaning methods for photomasks, particularly those with ruthenium capping layers, cause damage due to uncontrolled radical species formation.
Innovation Solution
A method and system that produce a plasma with controlled radical species, monitored and adjusted based on optical emission spectra, to minimize damage and effectively remove contaminants from photomask surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plasma-based cleaning methods utilizing water vapor and/or oxygen are used to clean photomasks, then cleaning effectiveness is improved, but damage to the ruthenium capping layer occurs
Solution Approach 1:
The patent changes the chemical composition parameters of the plasma by introducing deuterium gas instead of traditional oxygen or water vapor. This parameter change transforms the plasma chemistry to produce deuterium radicals that effectively remove organic contaminants while being non-damaging to the ruthenium capping layer, thus resolving the contradiction between cleaning effectiveness and material damage
Solution Approach 2:
The patent creates an inert deuterium-based plasma environment that replaces the reactive oxygen-based atmosphere. This inert environment prevents oxidative damage to the ruthenium capping layer while maintaining effective contaminant removal capabilities through deuterium radical chemistry, thereby eliminating the harmful effects associated with traditional plasma cleaning
2Power
If uncontrolled radical species formation occurs in plasma processing, then cleaning power is increased, but selectivity and damage control are reduced
Solution Approach 1:
The patent implements real-time optical emission spectroscopy monitoring that provides feedback on plasma composition and radical species formation. This feedback mechanism allows dynamic adjustment of process parameters to maintain optimal cleaning power while preventing excessive radical formation that would cause damage, thus achieving both high cleaning power and precise damage control
Solution Approach 2:
The patent replaces traditional mechanical or chemical control methods with optical detection and spectroscopic monitoring. By using optical emission spectrum analysis, the system can non-invasively monitor radical species concentrations and plasma state, enabling precise control of cleaning power and selectivity without mechanical intervention
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 system efficiently removes organic contaminants from photomasks while minimizing damage to the ruthenium capping layer, achieving a balance in oxidation-reduction characteristics.
Implementation Method 1
producing a plasma comprising a radical species
Implementation Method 2
measuring an optical emission spectrum of the radical species
Data Source
AI summary
Methods and systems for treating a photomask are provided, which include producing a plasma comprising a radical species; measuring an optical emission spectrum of the radical species; and contacting the photomask with the radical species in a process chamber to remove a contaminant from a surface or to modify the surface of the photomask, wherein a presence of the radical species is controlled based at least in part on the measured optical emission spectrum.