Flexible Optical Aperture Mechanisms for Wafer Inspection
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Solution Overview
Problem
Existing optical wafer inspection systems face limitations in flexible aperture systems, including optical transmission losses, incomplete blocking, stray light, optical aberrations, limited shape flexibility, low damage threshold, and incompatibility with UV, DUV, and VUV optics, which hinder the incorporation of advanced optical features like apodization, phase plates, and spectral apertures.
Innovation Solution
A system comprising multiple optical apertures with varying shapes and properties, stacked or aligned along an optical beam path to form a combined aperture shape, allowing for high transmission, complete blocking, and minimal stray light, while enabling the inclusion of attenuation, spectral, and polarizing properties, and compatibility with diverse optical systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If liquid crystal arrays are used to provide flexible optical apertures, then aperture shape flexibility is improved, but optical transmission efficiency deteriorates due to inability to achieve full open transmission or full blocking
Solution Approach 1:
The aperture system is divided into multiple independent aperture sheets, each with specific aperture shapes and optical properties. These segmented sheets can be individually positioned and combined along the optical beam path, allowing flexible aperture configuration while maintaining high transmission efficiency through precise mechanical positioning rather than relying on liquid crystal modulation.
2Adaptability or versatility
If liquid crystal arrays are used for flexible apertures, then programming capability is improved, but stray light and optical aberrations increase
Solution Approach 1:
The invention uses mechanical aperture sheets with fixed aperture patterns instead of complex liquid crystal arrays. Each aperture sheet is a simple, robust mechanical component that can be quickly exchanged or repositioned, providing programming capability through mechanical selection rather than electrical modulation, thereby eliminating stray light and aberration issues associated with liquid crystal technology.
3Device complexity
If conventional aperture systems are used, then simplicity is maintained, but shape flexibility and ability to incorporate optical elements is limited
Solution Approach 1:
The aperture sheets are designed to be universal components that can incorporate multiple optical functions simultaneously. Each sheet can contain aperture shapes with varying attenuation, spectral, polarizing, and phase properties, allowing a single mechanical component to replace multiple specialized optical elements while maintaining system simplicity through a unified positioning mechanism.
4Device complexity
If single aperture systems are used, then device complexity is reduced, but ability to provide combined optical properties is limited
Solution Approach 1:
Multiple aperture sheets with different optical properties are merged along the optical beam path through a coordinated positioning mechanism. This combining approach allows the system to achieve complex combined optical properties (such as combined attenuation and polarization effects) while maintaining relatively simple individual components, as each sheet retains its specific function rather than requiring a single complex multi-functional element.
Data Source
AI summary
A system for providing flexible optical aperture shapes in an optical inspection system (e.g., an optical wafer inspection system) is described. The system includes one or more mechanisms for providing multiple optical aperture shapes along an optical beam path in the optical wafer inspection system. The multiple optical apertures shapes are stacked or overlapped to combine the shapes and form a single combined optical aperture shape along the optical beam path.