EUV Pellicle Metal Filter for Pressure Equalization
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Solution Overview
Problem
In EUV exposure procedures, conventional resin filters used in pellicles for semiconductor manufacturing are prone to detachment and outgassing at high temperatures, compromising the integrity of ultra-thin silicon pellicle membranes and pattern quality due to poor heat resistance and differential pressure issues.
Innovation Solution
A pellicle with a metal or ceramic filter, integrally formed with the pellicle frame by welding or soldering, having a filtration accuracy of 0.1 to 0.3 μm, which maintains high temperature resistance and air flow efficiency while preventing dust entry and membrane breakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a resin filter is used in a pellicle for EUV exposure, then the filter can be easily manufactured and installed, but the filter detaches and outgases at high temperatures during exposure
Solution Approach 1:
The invention uses a composite structure combining a metal filter (stainless steel or ceramic) with a metal backing plate, secured by multiple fastening methods (adhesive, mechanical fasteners, and pressure). This composite approach provides both thermal stability at high temperatures and secure attachment, resolving the contradiction between ease of manufacture and reliability.
2Object-affected harmful factors
If the pellicle frame is sealed airtight, then dust is prevented from entering, but differential pressure causes membrane breakage or frame swelling during vacuum exposure
Solution Approach 1:
The invention segments the sealing system by providing multiple separate sealing locations around the pellicle frame perimeter rather than a single continuous seal. This allows pressure to be distributed and managed across multiple points, preventing excessive stress concentration that would cause membrane breakage or frame swelling during vacuum exposure, while still maintaining dust prevention.
Solution Approach 2:
The invention changes the pressure parameter by introducing a pressure equalization hole that allows internal pressure to match external atmospheric pressure during non-exposure periods. This eliminates differential pressure stress on the membrane and frame, preventing breakage or swelling, while the sealing system maintains dust prevention when needed.
3Strength
If a pressure adjustment hole is provided, then differential pressure is relieved, but dust particles can enter through the hole
Solution Approach 1:
The invention uses a metal mesh filter as an intermediary element placed over the pressure adjustment hole. This mesh filter allows pressure equalization through the hole while simultaneously blocking dust particles from entering, thus resolving the contradiction between relieving differential pressure and preventing dust contamination.
4Use of energy by moving object
If an ultra-thin silicon membrane is used for high EUV transmittance, then exposure efficiency is improved, but the membrane is more susceptible to breakage from differential pressure
Solution Approach 1:
The invention changes the pressure parameter by providing pressure equalization holes that eliminate differential pressure between the internal and external environments during non-exposure periods. This allows the use of ultra-thin silicon membranes with high EUV transmittance without the risk of breakage from pressure differential, as the membrane experiences minimal stress when not in use.
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 enables the formation of highly accurate patterns in vacuum or reduced pressure environments by preventing filter detachment and outgassing, ensuring high particle capture efficiency and rapid air pressure adjustment without compromising the pellicle membrane.
Implementation Method 1
a filter for stopping particles from entering the vent hole
Implementation Method 2
integrally formed with the pellicle frame by welding or soldering
Implementation Method 3
integrally formed with the pellicle frame by welding or soldering
Data Source
AI summary
There is provided a pellicle for EUV lithography, which has a filter attached to a vent hole made through a pellicle frame bar for air pressure adjustment, and this filter is designed to be heat-resistant by being made of either a metal or a ceramic material, and is adhered to the pellicle frame by weldering or soldering, and also the filter has a filtration accuracy of 0.1 through 0.3 μm.