Lithography Diffuser Aperture Control for Uniform Wafer Exposure
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Solution Overview
Problem
Existing lithographic systems face challenges in achieving precise control of light distribution and uniform intensity, leading to issues with stray light and interference, which affect the quality of circuit patterns on silicon wafers.
Innovation Solution
The introduction of a diffuser unit with a diffuser lens and opaque mask component to reduce stray light and interference, combined with a light pipe unit for homogenizing light intensity, and an exposure control unit to optimize the light beam for uniformity, ensuring efficient and precise light projection onto the wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional lithographic system uses standard light projection without additional optical components, then the system structure remains simple, but the light intensity distribution is non-uniform and contains stray light and interference
Solution Approach 1:
The optical system is divided into distinct functional modules: a diffuser unit with diffuser lens and opaque mask component for stray light reduction, and a light pipe unit for homogenization. This segmentation allows each component to perform its specific function optimally while maintaining overall system manageability and precision.
Solution Approach 2:
The diffuser unit acts as an intermediary component between the light source and the wafer, modifying the light beam by reducing stray light and interference before the light reaches the light pipe unit for final homogenization. This intermediary structure improves circuit pattern quality without requiring complete system redesign.
2Object-affected harmful factors
If the aperture of the diffuser unit is increased to reduce stray light, then stray light and interference are reduced, but the light intensity uniformity may be affected
Solution Approach 1:
The aperture size of the diffuser unit is optimized to a specific range (0.5mm to 2mm) to balance stray light reduction with light intensity uniformity. This parameter optimization ensures that the diffuser unit effectively reduces stray light and interference while the light pipe unit maintains uniform light distribution across the wafer surface.
Solution Approach 2:
The opaque mask component within the diffuser unit is strategically positioned and sized to block specific stray light paths while allowing useful light to pass through. This local modification approach reduces harmful stray light and interference without compromising the overall light intensity uniformity required for high-quality circuit patterns.
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 results in a more uniform light intensity distribution, reducing stray light and interference, thereby improving the precision and quality of circuit patterns on silicon wafers, enhancing the performance of integrated circuits.
Implementation Method 1
a diffuser unit with a diffuser lens and opaque mask component to reduce stray light and interference
Implementation Method 2
a light pipe unit for homogenizing light intensity
Data Source
AI summary
A method of using a lithographic system to perform lithography is provided. The lithographic system includes an illuminator and a projection apparatus. The illuminator is configured to output a light beam from a light source unit to a reticle through a beam shaping unit, a diffuser unit, a light pipe unit and an exposure control unit to generate a patterned light beam. The projection apparatus is configured to project the patterned light beam onto a wafer coated with a photoresist layer. The aperture of the diffuser unit is changed based on a dataset that is related a lithographic process and that includes a thickness of the photoresist layer and a numerical aperture value of a numerical aperture component of the projection apparatus. Then, the lithographic system performs the lithographic process on the wafer with the diffuser unit having the aperture thus changed.