Destructive-Interference Radiation Filter for EUV Metrology
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Solution Overview
Problem
Existing metrology techniques struggle to accurately measure small features in modern semiconductor structures due to the use of wavelengths that are not available or usable, leading to indirect and inaccurate measurement results, and methods like scanning electron microscopy are time-consuming and limited in penetration.
Innovation Solution
A radiation filter comprising a first and second material with specific transmission and phase-changing properties, arranged in a lateral or vertical distribution, to interfere destructively and enhance the measurement of small features using short wavelength radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If visible or near-infrared radiation is used for metrology, then the pitch of the grating must be much coarser than actual product structures, but this leads to indirect and inaccurate measurement results
Solution Approach 1:
The patent changes the wavelength parameter of the radiation from visible/near-infrared to extreme ultraviolet (EUV) range (13.5 nm). This parameter change allows the grating pitch to be reduced to match actual product structures while maintaining measurement accuracy, directly resolving the contradiction between measurement precision and grating pitch size
Solution Approach 2:
Instead of using longer wavelengths (visible/near-IR) with coarser gratings to measure smaller features indirectly, the patent inverts the approach by using shorter EUV wavelengths with finer gratings that match the actual product structure dimensions, enabling direct and accurate measurement
2Measurement precision
If scanning electron microscopy is used to measure small features, then measurement capability is improved, but the process becomes time-consuming and limited in penetration
Solution Approach 1:
The patent replaces the mechanical scanning electron microscopy system with an optical/electromagnetic radiation-based scatterometry system using EUV wavelengths. This substitution enables non-contact, rapid measurement without the time-consuming scanning process while maintaining the ability to measure small features through the shorter wavelength
3Ease of manufacture
If longer wavelength radiation is used for metrology, then available radiation sources are more accessible, but penetration and sensitivity for small feature measurement are reduced
Solution Approach 1:
The patent changes the radiation wavelength parameter to EUV (13.5 nm), which provides both sufficient penetration for modern semiconductor structures and high sensitivity for small feature measurement. The use of EUV radiation from specialized sources resolves the contradiction by achieving both manufacturing feasibility and measurement reliability
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 filter enables precise measurement of small semiconductor features by enhancing the sensitivity and penetration of short wavelength radiation, improving the accuracy and efficiency of metrology processes.
Implementation Method 1
The first material and second material are arranged in a lateral distribution along a surface of the filter, and such that the first wavelength radiation transmitted through the first material and first wavelength radiation transmitted through the second material interfere destructively
Implementation Method 2
The second material has a higher transmission for a first wavelength radiation than the first material, and the second material is configured to change a phase of the first wavelength radiation
Implementation Method 3
The first material has a lower transmission for a first wavelength radiation than the second material has
Data Source
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AI summary
A radiation filter configured to filter a radiation beam comprising a plurality of wavelengths. The filter comprises a first material and a second material. The second material has a higher transmission for a first wavelength radiation than the first material. The second material is configured to change a phase of the first wavelength radiation. The first material and second material are arranged in a lateral distribution along a surface of the filter, and such that the first wavelength radiation transmitted through the first material and first wavelength radiation transmitted through the second material interfere destructively.