EUV Mask Blank Ion Beam Sputtering Contamination Control
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Solution Overview
Problem
In EUV lithography, the ion beam sputtering method used for forming reflective multilayer films in mask blanks often results in contamination from target peripheral members, leading to reduced reflectance and insufficient EUV exposure, hindering high-precision patterning due to contamination in the thin films.
Innovation Solution
The method involves using an ion beam sputtering apparatus with a specific configuration, including a grid with a reduced effective area and controlled flow rate of inert gases like Ar, and an anti-adhesion shield to minimize contamination, ensuring the product of the grid area and gas flow rate is within a certain range to prevent peripheral contamination, thereby enhancing reflectance characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ion beam sputtering method is used for forming reflective multilayer films, then film formation efficiency and uniformity are improved, but contamination from target peripheral members occurs leading to reduced reflectance
Solution Approach 1:
The invention extracts and removes the harmful factor (contamination from target peripheral members) by introducing a gas flow that selectively removes sputtered particles from peripheral members before they can contaminate the reflective multilayer film. This allows the ion beam sputtering method to continue being used for efficient film formation while eliminating the contamination problem.
Solution Approach 2:
The invention changes the parameter of gas flow rate to control the removal of contamination. By optimizing the gas flow rate, the system achieves a balance between maintaining high film formation efficiency through ion beam sputtering and preventing contamination by removing sputtered particles from peripheral members.
2Manufacturing precision
If ion beam sputtering is used to form high refractive index and low refractive index layers, then uniform film thickness is achieved, but sputtered particles from peripheral members mix into the thin film causing contamination
Solution Approach 1:
The invention introduces a gas flow as an intermediary substance that acts between the target peripheral members and the reflective multilayer film. This gas flow mediates the removal of sputtered particles from peripheral members, preventing them from mixing into the thin film while allowing the ion beam sputtering process to continue forming uniform layers.
3Productivity
If extracted ion beam travels straight with constant diffusion angle, then sputtering efficiency is improved, but ion beam collides with peripheral members causing sputtering and contamination
Solution Approach 1:
The invention converts the harmful effect of ion beam collision with peripheral members into a beneficial process. By introducing a gas flow, the sputtered particles from peripheral members are immediately removed and utilized to enhance the film formation process, transforming the contamination source into a productive element that does not harm the final film quality.
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 configuration effectively reduces contamination and improves the in-plane uniformity and intensity of peak reflectance in the EUV wavelength region, ensuring high precision and efficiency in EUV lithography patterning.
Implementation Method 1
The sputtering method is a film forming method in which a surface of a sputtering target is impacted by charged particles, the sputtered particles are ejected from the target, and the sputtered particles are deposited on or above a substrate disposed opposite the target to form a thin film.
Implementation Method 2
thermoelectrons generated from a filament in the ion source collide with the introduced gas and ionize the introduced gas to generate plasma
Data Source
AI summary
A method for producing a reflective mask blank, includes: forming a reflective multilayer film on or above a substrate by using an ion beam sputtering apparatus and a process gas, the ion beam sputtering apparatus accelerating an ion generated by applying a voltage to a grid, and causing the ion to collide with a target to perform sputtering, the process gas including at least one inert gas selected from He, Ne, Ar, Kr, Xe, Rn, and N2 as an ion source, in which a product of an effective area (cm2) of the grid and a flow rate (sccm) of the process gas supplied to the ion beam sputtering apparatus during film formation is 3600 (cm2·sccm) or less.