Photomask Repair Using Si Protection During Defect Etching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for repairing defects in extreme ultraviolet phase shift masks (EUV PSMs) cause deterioration of the absorber layer due to chemical reactions with etching gases, leading to reduced effectiveness and precision in photolithography processes.
Innovation Solution
A method involving silicon (Si) pre-treatment on the absorber layer, followed by absorber defect etching using specific etching gases and controlled e-beam radiation, with optional Si mid-treatment and post-treatment to protect the layer from further damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If absorber defect etching is performed by using etching gas, then defect removal effectiveness is improved, but absorber layer deterioration occurs due to chemical reactions
Solution Approach 1:
A silicon-based protective film is deposited on the absorber layer to serve as an intermediary barrier between the etching gas and the absorber layer. This film allows selective etching of defects while preventing harmful chemical reactions with the absorber layer material, thus resolving the contradiction between defect removal effectiveness and absorber layer preservation
Solution Approach 2:
The protective film is applied before the etching process to pre-counteract the harmful effects of etching gas. This preliminary protective action prevents the absorber layer from undergoing unwanted chemical reactions during defect etching, maintaining layer integrity while enabling effective defect removal
2Manufacturing precision
If e-beam radiation is used for absorber defect etching, then etching precision is improved, but absorber layer damage increases
Solution Approach 1:
The protective film is deposited on the absorber layer before e-beam irradiation to pre-protect the layer from damage. This preliminary protective measure enables precise e-beam etching of defects while preventing excessive energy absorption and damage to the absorber layer material
Solution Approach 2:
The protective film acts as an intermediary layer that modulates the interaction between e-beam radiation and the absorber layer. It allows sufficient energy transmission for precise defect etching while absorbing excess energy to prevent damage to the underlying absorber layer
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
Enhances the etching selectivity and precision of defect repair, minimizing damage to the absorber layer and maintaining the photomask's performance and longevity.
Implementation Method 1
injecting a precursor gas of a Si-based inorganic compound into a repair chamber and adsorbing molecules of the precursor gas of the Si-based inorganic compound onto the absorber layer
Implementation Method 2
The etching gas may cause depletion reaction with Si-based inorganic compound of a Si pre-treated surface of the absorber layer
Implementation Method 3
injecting the etching gas into the repair chamber and radiating an e-beam to the defect of the absorber layer
Data Source
AI summary
A method of repairing a photomask includes performing Si pre-treatment on an absorber layer having a defect and performing absorber defect etching by using an etching gas. The method may further include alternately performing the absorber defect etching by using an etching gas and Si mid-treatment on the absorber layer such that a total time of the absorber defect etching is 2 times to 10 times and each Si mid-treatment on the absorber layer is performed between two consecutive absorber defect etchings. The method may further include performing Si post-treatment on the absorber layer after a last time the absorber defect etching is performed.