Lithographic Pellicle Heating to Desorb Hydrogen
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Solution Overview
Problem
The pellicle membrane in lithographic apparatuses is prone to etching by hydrogen gas, which reduces its operational lifespan and can lead to manufacturing defects.
Innovation Solution
The assembly uses various methods to desorb adsorbed hydrogen from the pellicle membrane, including heating with heated gas, radiative heating, resistive heating, inductive heating, and illuminating with light of specific wavelengths to reduce etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the pellicle membrane is made thinner to increase EUV transmissivity, then transmissivity is improved, but mechanical strength and reliability deteriorate
Solution Approach 1:
The pellicle membrane is constructed as a composite structure combining multiple materials: a thin carbon-based membrane (for high EUV transmissivity) supported by a porous substrate or framework (for mechanical strength). This composite approach allows the membrane to be sufficiently thin for high transmissivity while the supporting structure provides the necessary mechanical integrity to withstand the hostile environment.
2Productivity
If the pellicle membrane is exposed to hydrogen gas environment, then the lithographic process can proceed, but etching of carbon from the pellicle membrane occurs, reducing its lifespan
Solution Approach 1:
A protective coating layer is applied to the carbon-based pellicle membrane before exposure to the hydrogen gas environment. This coating acts as a barrier that prevents hydrogen from directly contacting and etching the carbon membrane, thereby preserving the membrane's integrity and extending its operational lifespan while allowing the lithographic process to continue.
Solution Approach 2:
The patent utilizes the hydrogen gas environment beneficially by controlling its parameters (temperature, pressure, flow rate) to minimize etching while maintaining the necessary atmosphere for the lithographic process. Additionally, the protective coating transforms the harmful etching effect into a manageable condition where the hydrogen can perform its function without causing damage.
3Duration of action of stationary object
If heating methods are applied to desorb adsorbed hydrogen, then etching is suppressed, but device complexity increases
Solution Approach 1:
The pellicle membrane structure incorporates integrated heating elements directly within or adjacent to the membrane support structure. This allows the membrane to self-regulate its temperature to desorb adsorbed hydrogen atoms, preventing etching without requiring external complex heating systems. The membrane essentially serves itself by having built-in thermal management capability.
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
By reducing the amount of adsorbed hydrogen, the assembly effectively suppresses the etching of carbon from the pellicle membrane, thereby extending its operational lifespan and maintaining imaging and overlay performance.
Implementation Method 1
heating a pellicle membrane by one of or a combination of: i) provision of heated gas, ii) radiative heating, iii) resistive heating, and iv) inductive heating
Implementation Method 2
heating a pellicle membrane by one of or a combination of: i) provision of heated gas, ii) radiative heating, iii) resistive heating, and iv) inductive heating
Implementation Method 3
heating a pellicle membrane by one of or a combination of: i) provision of heated gas, ii) radiative heating, iii) resistive heating, and iv) inductive heating
Implementation Method 4
illuminating the pellicle membrane with light having a wavelength of from around 91 nm to around 590 nm
Data Source
AI summary
An assembly for a lithographic apparatus, wherein the assembly is configured to heat a pellicle membrane by one of or a combination selected from: i) provision of heated gas, ii) radiative heating, iii) resistive heating, and/or iv) inductive heating, and/or by illuminating the pellicle membrane with light having a wavelength of from around 91 nm to around 590 nm. Also a method of extending the operative lifespan of a pellicle membrane, the method including heating at least a portion of a pellicle membrane when illuminated by EUV by one of or a combination selected from: i) providing heated gas, ii) radiative heating, iii) resistive heating, and/or iv) inductive heating to effect heating of the at least one portion of the pellicle membrane, and/or by illuminating the pellicle membrane with light having a wavelength of from around 91 nm to around 590 nm.