Dynamic Sensor Amplification for High-Sensitivity Defect Inspection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The miniaturization of semiconductor patterns and liquid crystal substrates makes it difficult to detect defects due to the microminimization of defect sizes and the insufficient sensitivity of existing CCD and TDI array sensors, which are overwhelmed by varying light quantities and reflected lens issues, leading to reduced sensitivity and buried weak defect scattered light.
Innovation Solution
A defect inspecting apparatus with a dynamically adjustable amplification rate sensor array and a combination of oblique and epi-illumination systems, using a laser light source and a spatial filter to enhance sensitivity by controlling the amplification rate and reducing stray light, allowing for high-sensitivity defect detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sensitivity is set to a bright section so that the sensor may not be saturated, then the sensor saturation is prevented, but the sensitivity of a dark section falls increasingly
Solution Approach 1:
The patent applies dynamic amplification rate adjustment where the sensor's amplification rate is changed during the light detection process. This allows the system to adaptively optimize sensitivity for different brightness sections, preventing saturation in bright areas while maintaining sensitivity in dark sections where defects are located.
Solution Approach 2:
The patent changes the amplification rate parameter of the sensor dynamically during detection. By adjusting this parameter based on the brightness conditions of different sections, the system achieves both saturation prevention in bright areas and maintained sensitivity in dark areas, resolving the contradiction between these two requirements.
2Measurement precision
If amplification type sensors are arranged in an array form to improve sensitivity, then sensitivity is improved, but weak defect scattered light is buried in reflected lights
Solution Approach 1:
The patent extracts and eliminates reflected light components from the detection system. By using oblique illumination and specific sensor array configurations, the system separates the weak defect scattered light from the stronger reflected light, preventing the latter from burying the former in the signal.
Solution Approach 2:
The patent performs preliminary actions to prepare the optical system for defect detection. This includes configuring the sensor array with specific amplification characteristics and positioning optical elements to preferentially detect scattered light from defects while minimizing reflected light interference before the actual defect detection occurs.
3Adaptability or versatility
If the light quantity of scattered light varies greatly depending on a portion of the inspection object, then detection coverage is maintained, but the sensitivity falls in dark sections
Solution Approach 1:
The patent uses dynamic adjustment of the sensor amplification rate to adapt to varying light quantities across different inspection areas. This allows the system to maintain appropriate sensitivity across the entire inspection object, from bright sections to dark sections where defects are located.
Solution Approach 2:
The patent changes the sensor's amplification parameter dynamically based on the detected light quantity in different areas. This parameter adjustment enables the system to compensate for variations in scattered light intensity across the inspection object, maintaining detection sensitivity in dark sections while avoiding saturation in bright sections.
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 achieves high sensitivity defect detection accuracy by dynamically adjusting the sensor amplification rate and using advanced illumination and detection systems to distinguish between bright and dark sections, preventing sensor saturation and improving detection of weak scattered light.
Implementation Method 1
an illuminating optical system having a laser light source for irradiating light onto a sample
Implementation Method 2
a detecting optical system having a sensor for detecting light generated from the sample illuminated by the illuminating optical system
Implementation Method 3
imaging a picture at a scan position on a disk plate that has a characteristic such that a center in an arrangement direction of n amplification type light receiving elements (avalanche photodiodes) in a light receiving area formed thereby takes a peak value
Data Source
AI summary
An invention being applied is a defect detecting apparatus that has: an illuminating optical system with a laser light source for irradiating a sample on whose surface a pattern is formed with light; a detecting optical system with a sensor for detecting light generated from the sample illuminated by the illuminating optical system; and a signal processing unit that extracts a defect from an image based on the light detected by the detecting optical system, in which an amplification rate of the sensor is dynamically changed during a time when the light is detected by the detecting optical system.