Light Source Device for Surface Inspecting Apparatus Calibration
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Solution Overview
Problem
Conventional surface inspecting apparatuses are limited in detecting small defects due to the restricted particle size of polystyrene latex spheres (PSL) used for calibration, lacking settings for future semiconductor manufacturing needs.
Innovation Solution
A surface inspecting apparatus with a light source device capable of generating light with adjustable wavelength, intensity, time-dependent changes, and polarization, using a combination of direct current and pulse components, and optical fibers to simulate light conditions, allowing for the creation of a calibration curve without a calibrating wafer, enabling the detection of smaller defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a PSL of a smaller particle size is used for calibration, then the smaller defect can be inspected, but the particle size of the PSL is restricted and no settings are available for future semiconductor manufacturing needs
Solution Approach 1:
The patent changes the calibration approach from using fixed particle size PSL to using light source parameters (wavelength, intensity, temporal profile) that can be continuously adjusted. This allows the system to simulate scattering patterns from particles of any size by modifying the illumination characteristics rather than requiring physical calibration particles of specific sizes.
Solution Approach 2:
The patent creates a virtual model of particle scattering by using a light source that reproduces the scattered light characteristics without requiring actual calibration particles. The light source device copies the optical signature of scattered light from defects, enabling calibration through optical simulation rather than physical standards.
2Measurement precision
If conventional calibration methods using PSL are used, then calibration can be performed with standard particles, but the method cannot inspect defects smaller than the available PSL sizes
Solution Approach 1:
The system varies the temporal profile of the light source (using pulse widths matching the transit time of particles through the inspection spot) and wavelength to simulate scattering from smaller particles. This parameter adjustment allows the system to accurately represent the optical signature of sub-PSL defects without requiring smaller physical calibration particles.
Solution Approach 2:
The patent introduces dynamic control of the light source parameters during calibration, allowing real-time adjustment of intensity, wavelength, and temporal characteristics to match the scattering behavior of different particle sizes. This dynamic adaptation enables the system to maintain calibration accuracy across a broader range of defect sizes.
3Adaptability or versatility
If a light source device with adjustable parameters is used, then calibration without PSL is enabled, but the device complexity increases
Solution Approach 1:
The light source device is designed to perform multiple functions: it serves as both the inspection illumination source and the calibration light source. By making the light source itself adjustable in wavelength, intensity, and temporal profile, it eliminates the need for separate calibration subsystems while providing versatile calibration capabilities across different defect size ranges.
Solution Approach 2:
The system uses its own light source, with adjustable parameters, to perform self-calibration without requiring external calibration standards. The light source device calibrates the inspection system by generating reference scattering patterns through parameter adjustment, enabling the system to calibrate itself using its inherent optical components.
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
Enables the inspection of smaller defects by stabilizing light intensity and simulating light conditions, allowing for accurate particle size calculation and calibration curve formation without the need for standard particles, thus overcoming the limitations of existing technologies.
Implementation Method 1
a light source device for generating light which has simulated at least one of a wavelength, a light intensity, a time-dependent change in light intensity, and a polarization of light which was scattered, diffracted, or reflected by an inspection object
Implementation Method 2
the light source device has at least one or more optical fibers and the light is extracted from the optical fiber
Implementation Method 3
the light is inputted to a photodetector of the surface inspecting apparatus
Data Source
AI summary
A surface inspecting apparatus can inspect a smaller defect by using a PSL of a smaller particle size. However, the particle size of the PSL is restricted. In the conventional surface inspecting apparatus, therefore, no consideration has been taken as to how to inspect the defect of such a small particle size as is not set in the PSL which will be needed in the near future in an inspection of a semiconductor manufacturing step. The invention has a light source device for generating light which simulated at least one of a wavelength, a light intensity, a time-dependent change of the light intensity, and a polarization of light which was scattered, diffracted, or reflected by an inspection object, and the light is inputted to a photodetector of the surface inspecting apparatus. The smaller defect can be inspected.