Pellicle Membrane Etching for EUV Transmission Uniformity
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Solution Overview
Problem
Pellicles in EUV lithography apparatuses degrade due to non-uniform wear, leading to transmission uniformity issues and requiring frequent replacement, which disrupts production and introduces contamination risks.
Innovation Solution
An apparatus and method for etching pellicle membranes based on predicted and/or observed wear patterns, using focused electron beams and controlled etching processes to maintain uniform transmissivity and extend operational lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a pellicle membrane is made thinner to increase EUV transmissivity, then transmissivity is improved, but mechanical strength and reliability deteriorate
Solution Approach 1:
The patent employs carbon nanotube membranes as a composite material structure that achieves both high EUV transmissivity and adequate mechanical strength. The nanotube network provides structural integrity while maintaining transparency to EUV radiation, resolving the contradiction between thinness for transmissivity and thickness for strength.
Solution Approach 2:
The invention uses an ultrathin pellicle membrane made of carbon nanotubes that functions as a flexible yet strong protective layer. This thin film structure allows maximum EUV transmission while providing sufficient mechanical protection against the harsh lithography environment.
2Illumination intensity
If a pellicle membrane is made thinner to increase EUV transmissivity, then transmissivity is improved, but operational lifespan deteriorates due to degradation
Solution Approach 1:
The carbon nanotube composite structure provides both high transmissivity and enhanced durability. The nanotube network's unique properties resist degradation from plasma exposure and thermal stress, extending operational lifespan while maintaining thinness for optimal EUV transmission.
Solution Approach 2:
The patent modifies the material parameters by using carbon nanotubes with specific structural characteristics that change the degradation behavior. The material exhibits resistance to plasma etching and thermal degradation, allowing the thin membrane to maintain its properties throughout extended operational periods.
3Illumination intensity
If a pellicle membrane is made thinner to increase EUV transmissivity, then transmissivity is improved, but resistance to harsh environment deteriorates
Solution Approach 1:
The carbon nanotube membrane forms a composite structure that inherently resists plasma attack, thermal stress, and mechanical damage. The nanoscale architecture provides both the required optical transparency and environmental hardness, allowing the thin film to survive in the harsh EUV lithography environment.
Solution Approach 2:
The patent employs a disposable pellicle membrane design where the carbon nanotube membrane is intentionally made thin and optimized for single-use or limited-life operation. This approach prioritizes maximum transmissivity while accepting that the membrane will eventually degrade and require replacement, rather than attempting to make it indefinitely durable.
4Manufacturing precision
If pellicle membrane is replaced frequently to maintain transmission uniformity, then imaging quality is improved, but productivity deteriorates due to downtime
Solution Approach 1:
The system incorporates a self-diagnosis and self-adjustment capability where the pellicle membrane's transmission uniformity is continuously monitored and automatically corrected through localized etching. This self-service approach maintains imaging quality without requiring manual intervention or membrane replacement, preserving productivity.
Solution Approach 2:
The invention applies localized etching to specific regions of the pellicle membrane where non-uniformity occurs. By modifying only the affected areas rather than replacing the entire membrane, the system maintains transmission uniformity while minimizing downtime and preserving overall productivity.
5Manufacturing precision
If pellicle membrane is etched to correct non-uniformity, then transmission uniformity is improved, but transmissivity deteriorates due to material removal
Solution Approach 1:
The etching process is applied locally only to regions where non-uniformity is detected, rather than uniformly across the entire membrane. This localized approach corrects transmission defects in specific areas while leaving the rest of the membrane intact, thereby maintaining overall high transmissivity while achieving uniformity.
Solution Approach 2:
The system applies partial etching action only where needed to achieve uniformity, using minimal material removal necessary to correct local defects. This partial action approach suffices to achieve the uniformity goal while preserving maximum overall transmissivity.
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 solution effectively maintains pellicle transmissivity within specifications, doubling its operational lifetime and reducing downtime by correcting non-uniformity without replacing the pellicle, while minimizing contamination risks.
Implementation Method 1
an etching unit configured to etch material from the pellicle membrane
Implementation Method 2
using focused electron beams and controlled etching processes
Data Source
AI summary
An apparatus for adjusting the transmissivity of a pellicle membrane, the apparatus including an etching unit configured to etch material from the pellicle membrane, and a controller configured to control the etching unit to etch the pellicle membrane based on a predicted and/or observed wear pattern of the pellicle membrane. Also a method of adjusting the transmissivity of a pellicle membrane as well as a pellicle membrane, a pellicle assembly, and the use of the same.