Multiwavelength Mask Inspection with Tunable Spectrum Feedback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing semiconductor mask inspection technologies using single wavelength light sources struggle with resolution limitations and non-uniform sensitivity, particularly in inspecting complex mask pattern designs, leading to potential defects and false detections.
Innovation Solution
Implementing a tunable wavelength light source system with an acousto-optical modulator (AOM) and spectrometers for real-time spectrum monitoring and feedback control, along with an optical path stabilizer and imaging device calibration to enhance resolution and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single wavelength light source is used for mask inspection, then the device complexity is reduced, but the measurement precision and sensitivity are insufficient for complex mask patterns
Solution Approach 1:
The patent implements a multiwavelength light source system that can operate at multiple discrete wavelengths (e.g., 405nm, 488nm, 532nm, 633nm) using a single integrated apparatus. This allows the inspection system to handle various mask pattern complexities and defect types with one universal device, improving measurement precision while avoiding the need for multiple separate single-wavelength systems.
Solution Approach 2:
The system employs an acousto-optical modulator (AOM) that dynamically switches between different wavelengths in real-time during inspection. The controller can adjust the wavelength based on the specific inspection requirements, allowing the system to adapt its characteristics dynamically rather than being fixed to a single wavelength, thereby improving sensitivity for different pattern types.
2Manufacturing precision
If a single wavelength light source is used, then the device complexity is minimized, but the resolution is insufficient for detecting small defects in complex circuits
Solution Approach 1:
The patent changes the wavelength parameter of the light source to optimize resolution for different defect sizes and pattern densities. By selecting appropriate wavelengths from the available discrete set (shorter wavelengths for higher resolution, longer wavelengths for better penetration), the system achieves high manufacturing precision without requiring multiple specialized optical systems.
Solution Approach 2:
The system incorporates spectrometers for real-time spectrum monitoring and feedback control of the light source wavelength. This feedback mechanism ensures that the correct wavelength is selected and maintained during inspection, enabling high-resolution defect detection while keeping the control system manageable through automated wavelength selection based on inspection requirements.
3Reliability
If multiwavelength light source is implemented, then the inspection sensitivity and resolution are improved, but the device complexity increases
Solution Approach 1:
The multiwavelength light source is segmented into distinct wavelength components, each generated by separate laser sources (e.g., violet 405nm, blue 488nm, green 532nm, red 633nm lasers). The AOM selectively activates only the required wavelength segments based on inspection needs, reducing the operational complexity despite having multiple potential wavelengths available. This segmentation allows reliable defect detection while maintaining manageable system control.
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 system improves resolution, spectrum monitoring, and sensitivity by allowing multiwavelength inspection, reducing the risk of defect miss or false detection, and enhancing defect signal response.
Implementation Method 1
a tunable wavelength light source function may be implemented using a multiwavelength nonlinear light source, a wavelength selector, an acousto-optical modulator (AOM),
Implementation Method 2
one or more spectrometers may be included that perform real-time spectrum variation monitoring
Data Source
AI summary
A method includes positioning a substrate in an optical path of a multiwavelength light source; generating a first detection result by exposing a first region of the substrate to a first light having a first wavelength band selected by the light source; and generating a second detection result by exposing a second region of the substrate to a second light having a second wavelength band selected by the multiwavelength light source. A system includes a multiwavelength light source including a light source and a wavelength selector in an optical path of light generated by the light source. The system further includes a spectrometer operable to measure a spectrum of a first light selected by the wavelength selector; a mask stage operable to position a mask in the optical path; and a controller operable to adjust a parameter of the multiwavelength light source responsive to the spectrum of the first light.