Textured Substrate Holder for Low-Noise Optical Metrology
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Solution Overview
Problem
Existing substrate measurement systems face challenges in minimizing unwanted background noise signals from optical beam reflection on substrate holders, which complicates the precision and efficiency of metrology processes.
Innovation Solution
The substrate holder is designed with a textured surface that scatters optical beams away from the optical detector, reducing noise signal reflection and incorporating a chuck to secure the substrate, along with a reflectometry system that uses MIR wavelengths to penetrate through absorbing hardmask layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a smooth substrate holder surface is used, then the optical beam reflects directly toward the optical detector causing noise signals, but the measurement precision deteriorates due to unwanted background noise
Solution Approach 1:
The substrate holder surface is given a specific localized texture (such as pyramidal structures or gratings) only in the regions where optical beams interact with it, while other regions may remain smooth. This localized texturing散射s optical beams away from the detector without requiring the entire holder to be textured, thus reducing noise signals while maintaining manufacturing feasibility
Solution Approach 2:
Instead of trying to eliminate all reflections from the substrate holder, the invention converts the harmful direct reflection into beneficial scattered reflections by texturing the surface. The scattered light, which would otherwise be a noise source, is redirected away from the detector path, transforming the reflection problem into a solution that actively reduces noise signals
2Measurement precision
If the substrate holder surface is textured to scatter optical beams, then noise signal reflection is reduced, but the device complexity increases due to additional surface processing
Solution Approach 1:
The surface texture parameters (such as grating period, depth, and orientation) are optimized to achieve effective light scattering at specific wavelengths while maintaining compatibility with standard manufacturing processes. By carefully selecting these parameters, the invention achieves noise reduction without requiring overly complex or specialized device structures
Solution Approach 2:
Instead of using complex mechanical structures or additional optical components to manage reflections, the invention substitutes a relatively simple surface texturing approach. This replaces what would otherwise require complex mechanical adjustment mechanisms with a passive optical solution that achieves the same noise reduction effect
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
This design reduces substrate holder reflection, enhancing the accuracy and throughput of substrate measurement systems by minimizing noise signals and allowing real-time monitoring of film thickness and uniformity across substrates.
Implementation Method 1
The surface has a texture that causes an optical beam incident on the surface to scatter in a direction away from an optical detector to be located above the substrate holder
Implementation Method 2
a reflectometry system that uses MIR wavelengths to penetrate through absorbing hardmask layers
Data Source
AI summary
An apparatus includes a substrate holder having a surface to receive a substrate. The surface has a texture that causes an optical beam incident on the surface to scatter in at least one direction away from an optical detector to be located above the substrate holder.