Pattern Inspection Apparatus Using Fiber-Coupled DUV Generation
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Solution Overview
Problem
Current pattern inspection technologies face challenges in achieving high reliability and robustness against vibrations, particularly when using short-wavelength laser light sources for inspecting semiconductor and LCD patterns, due to complex and large resonator structures that require frequent maintenance and limit design flexibility and integration with inspection equipment.
Innovation Solution
A pattern inspection apparatus is designed with a built-in wavelength conversion unit and optical fibers connecting the light sources, allowing for the generation of deep ultraviolet light within the apparatus, which reduces optical path length and minimizes vibration-induced deviations, and uses a combination of laser light sources to produce DUV light through sum frequency generation, eliminating the need for resonators and enabling compact integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If resonator structures are used to generate short-wavelength laser light for high-precision inspection, then measurement precision is improved, but device complexity and reliability deteriorate due to frequent maintenance requirements
Solution Approach 1:
The patent extracts and eliminates the resonator structure from the laser generation system, using direct second-harmonic generation in a nonlinear optical crystal without requiring resonator feedback. This removes the complex resonator components that demanded frequent maintenance while preserving the ability to generate short-wavelength (266 nm or less) laser light for high-precision inspection
Solution Approach 2:
The patent changes the operational parameters by using high-power pulsed laser excitation instead of continuous wave operation with resonators. By using short-duration high-intensity pulses to drive the nonlinear optical crystal, the system achieves efficient wavelength conversion without requiring resonator structures, thereby improving reliability while maintaining measurement precision
2Measurement precision
If resonator structures are used for wavelength conversion, then measurement precision is improved, but device complexity increases due to large and complex system architecture
Solution Approach 1:
The resonator structures are completely removed from the system architecture. The patent uses direct second-harmonic generation in a nonlinear optical crystal excited by pulsed laser, eliminating the need for complex resonator cavities, mirrors, and associated alignment mechanisms, thereby dramatically simplifying the device while maintaining precision
Solution Approach 2:
The patent replaces the mechanical resonator system with a nonlinear optical process. Instead of using mechanical resonator structures to build up laser power and achieve wavelength conversion, the system uses optical field interactions in a nonlinear crystal, substituting a complex mechanical-optical system with a simpler all-optical process
3Measurement precision
If resonator structures are used for laser generation, then measurement precision is improved, but ease of operation deteriorates due to frequent maintenance requirements
Solution Approach 1:
By removing the resonator structures that require frequent maintenance, the patent dramatically improves ease of operation. The simplified system with direct second-harmonic generation has fewer components that need alignment and maintenance, making the inspection apparatus easier to operate and maintain while preserving measurement precision
4Measurement precision
If resonator structures are used for wavelength conversion, then measurement precision is improved, but adaptability deteriorates due to limited design flexibility and integration capability
Solution Approach 1:
By extracting and removing the rigid resonator structures, the patent gains significant design flexibility and adaptability. The simplified nonlinear optical wavelength conversion system can be more easily integrated with different inspection apparatus configurations and adapted to various inspection requirements, while maintaining the precision benefits of short-wavelength laser light
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 provides a high-reliability pattern inspection method with reduced vibration influence, lower power consumption, and increased design flexibility, enabling efficient inspection of ultrasmall patterns with improved maintenance efficiency and reduced production costs.
Implementation Method 1
a wavelength conversion unit operative to convert the fundamental-wave light to have a wavelength of less than or equal to 266 nanometers (nm)... uses a combination of laser light sources to produce DUV light through sum frequency generation
Data Source
AI summary
A pattern inspection apparatus is disclosed, which includes a first laser light source for emission of first laser light having a first wavelength, a second laser light source for emission of second laser light having a second wavelength, and a deep ultraviolet (DUV) light source for emission of DUV light with a wavelength of less than or equal to 266 nm based on the first laser light and the second laser light. A first optical fiber is provided for connecting between the first laser light source and the DUV light source. A second optical fiber is for connection between the second laser light source and the DUV light source. The apparatus also includes a pattern inspection unit with the DUV light source being built therein, for inspecting a workpiece pattern being tested by using the DUV light as illumination light therefor.