Wafer Stage Particle Capture Routing for Immersion Lithography
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Solution Overview
Problem
In immersion lithography systems, particles conveyed by the immersion fluid can accumulate on the wafer, leading to improper patterning and increased risk of manufacturing errors due to changes in surface properties between the wafer stage and the wafer.
Innovation Solution
A particle capture area with surface properties similar to the wafer is integrated onto the wafer stage, allowing particles to be collected before they reach the wafer. The lens system is routed to overlap this area before patterning, reducing the number of particles conveyed onto the wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If immersion fluid is used to pattern the wafer, then patterning precision is improved, but particles are conveyed onto the wafer causing manufacturing errors
Solution Approach 1:
The immersion hood is calibrated by moving it over sensors and a particle capture area before actual wafer patterning. This preliminary action positions the immersion hood correctly and allows particles to be captured on the particle capture area before they can contaminate the wafer during production patterning operations.
Solution Approach 2:
A particle capture area with surface properties similar to the wafer is introduced as an intermediary between the immersion hood and the wafer. This intermediate area captures particles conveyed by the immersion fluid, preventing them from reaching and contaminating the actual wafer being patterned.
2Productivity
If the lens system is positioned directly over the wafer for patterning, then patterning efficiency is improved, but particles accumulate on the wafer surface
Solution Approach 1:
The system performs a preliminary routing of the immersion hood over the particle capture area before positioning it over the wafer for actual patterning. This preliminary action allows particles to be captured in advance, ensuring that when the hood is positioned directly over the wafer for efficient patterning, fewer particles are conveyed onto the wafer surface.
3Productivity
If immersion fluid flow is increased to improve patterning speed, then productivity is improved, but particle conveyance to the wafer increases
Solution Approach 1:
The particle capture area serves as an intermediary that intercepts particles conveyed by the immersion fluid. Even when immersion fluid flow is increased to improve patterning speed, the particle capture area captures the particles before they reach the wafer, allowing high-speed patterning without proportional increase in particle contamination.
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 implementation of a particle capture area significantly reduces the number of particles on the wafer during patterning, enhancing production yield and reducing the risk of manufacturing errors in immersion lithography systems.
Implementation Method 1
Immersion lithography uses an immersion fluid between a lens system and the wafer in order to reduce magnitudes of changes in refractive index between the lens system and the wafer. Reducing the magnitude of changes in the refractive index helps to avoid refraction or bending of the light used to pattern the wafer.
Data Source
AI summary
A method of controlling a wafer stage includes moving the wafer stage to position an immersion hood over a first sensor in the wafer stage. The method further includes moving the wafer stage to position the immersion hood over a first particle capture area on the wafer stage after moving the wafer stage to position the immersion hood over the first sensor. The method further includes moving the wafer stage to define a first routing track over the first particle capture area. The method further includes moving the wafer stage to position the immersion hood over an area for receiving a wafer on the wafer stage after defining the first routing track.