EUV Inspection Optics With Variable Mirror for Multi-Mode Metrology
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Solution Overview
Problem
Existing semiconductor inspection apparatuses lack flexibility and capability to perform multiple processes efficiently, particularly in high-resolution imaging, inspection, and measurement of semiconductor devices using extreme ultraviolet light.
Innovation Solution
A semiconductor inspection apparatus is designed with a light source portion that includes a laser source, a second-harmonic generation crystal, and a gas cell to generate extreme-ultraviolet light, combined with a variable mirror module and detector apparatus to enable multiple inspection modes, including ptychography, scatterometry, and reflectometry, using beams with different wavelength bands and pulse durations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single-wavelength light source is used for semiconductor inspection, then the inspection process is simple, but the versatility and capability to perform multiple inspection modes are limited
Solution Approach 1:
The light source system is designed to perform multiple functions by generating both fundamental wavelength light and second-harmonic wavelength light using the same laser source and gas cell. The system can switch between different inspection modes (ptychography, scatterometry, reflectometry) by selecting different wavelength bands, making a single apparatus capable of performing what previously required multiple separate systems.
Solution Approach 2:
The system changes the wavelength parameter of the light source by utilizing nonlinear optical conversion in the gas cell. By adjusting the laser source output and using second-harmonic generation in the gas cell, the system can produce different wavelength bands (fundamental and harmonic) from the same physical components, enabling versatile inspection capabilities without adding multiple independent light sources.
2Adaptability or versatility
If multiple light sources with different wavelength bands are used, then various inspection modes can be performed, but the device complexity and cost increase
Solution Approach 1:
The system merges the functions of multiple light sources into a single integrated light source system. The laser source, gas cell, and optical components work together to generate both fundamental and second-harmonic wavelength light, eliminating the need for separate light sources and reducing overall system complexity while maintaining multi-mode inspection capability.
Solution Approach 2:
The gas cell acts as an intermediary that performs second-harmonic generation to convert fundamental wavelength light into second-harmonic wavelength light. This intermediary component enables wavelength conversion within the same optical path, allowing the system to access different wavelength bands without requiring separate light source systems.
3Measurement precision
If extreme ultraviolet light is used for high-resolution imaging, then measurement precision improves, but the complexity of generating and controlling the light increases
Solution Approach 1:
The system replaces complex mechanical extreme ultraviolet light generation methods (such as synchrotrons or complex plasma sources) with a more compact nonlinear optical conversion approach using a gas cell and laser source. This substitution achieves extreme ultraviolet wavelengths through optical frequency doubling while maintaining simpler system architecture and better controllability.
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 apparatus provides enhanced flexibility and capability to perform various inspection processes, improving measurement accuracy and versatility in characterizing semiconductor structures with high resolution and precision.
Implementation Method 1
a second-harmonic generation crystal disposed in a path of the first beam and configured to separate, from the first beam, a second beam having a different wavelength band from the first beam
Implementation Method 2
a gas cell disposed in the path of the first beam and a path of the second beam and configured to supply a gas in the path of the first beam and the path of the second beam to generate the extreme-ultraviolet light
Implementation Method 3
an extreme-ultraviolet filter disposed in a path of the first beam output from the light source portion and configured to separate extreme-ultraviolet light from the first beam
Implementation Method 4
a condensing mirror configured to concentrate, on an upper surface of a substrate, the extreme-ultraviolet light incident from the variable mirror module
Implementation Method 5
an inspection portion including a detector apparatus configured detect scattered light
Data Source
AI summary
A semiconductor inspection apparatus includes a light source portion configured to output a first beam, an extreme-ultraviolet filter disposed in a path of the first beam output from the light source portion and configured to separate extreme-ultraviolet light from the first beam, and an inspection portion including a detector apparatus configured detect scattered light, wherein the inspection portion further includes an inspection portion optical system comprising a variable mirror module disposed in a path of the extreme-ultraviolet light.