Defect Inspection Apparatus with Dual Detection Optical Systems
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Solution Overview
Problem
Existing defect inspection apparatuses require excessive time for precise position adjustment due to the need for repeated adjustments of detection systems, which hampers high-accuracy and efficient defect inspection processes.
Innovation Solution
A defect inspection apparatus with a stage that moves a sample and pattern substrate, featuring an illumination optical system emitting light at an inclined angle, and multiple detection optical systems that adjust focal positions and detector orientations using scattered light signals, allowing for rapid and precise alignment through advanced signal processing and control units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If repeated position adjustment of detection systems is performed to achieve high accuracy, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent applies preliminary action by pre-forming multiple repeating patterns on the pattern substrate before the actual measurement process. These pre-formed patterns serve as reference markers that enable rapid position adjustment of the detection system without requiring repeated iterative adjustments during measurement. The patterns are prepared in advance at specific positions corresponding to where scattered light needs to be detected, allowing the detection system to be quickly aligned to the correct positions.
Solution Approach 2:
The patent implements feedback by using the scattered light signals from the pre-formed repeating patterns to provide positional information back to the detection system. The detection system detects the scattered light from these reference patterns and uses this feedback information to automatically adjust its position and orientation, eliminating the need for manual repeated adjustments. This closed-loop feedback mechanism ensures high positioning accuracy while minimizing adjustment time.
2Measurement precision
If multiple detection optical systems are used to detect scattered light from different directions, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by designing the pattern substrate with multiple repeating patterns that serve multiple functions simultaneously. The same set of pre-formed patterns is used for both position adjustment of the detection system and for the actual defect inspection process. This multi-functional design eliminates the need for separate adjustment patterns and inspection patterns, reducing overall system complexity while maintaining the capability for high-precision multi-directional scattered light detection.
Solution Approach 2:
The patent merges the position adjustment function and the defect inspection function into a single integrated process. The pre-formed repeating patterns serve dual purposes: they act as reference markers for detecting system alignment and also as the actual inspection targets for identifying defects. By combining these two functions and using the same optical paths and detection mechanisms for both, the system reduces complexity while achieving high measurement precision through multiple detection angles.
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 rapid and accurate position adjustment of detection systems, significantly reducing inspection time and improving processing efficiency by utilizing scattered light signals for real-time adjustments.
Implementation Method 1
a first detection optical system that forms an image on a first detector and detects scattered light generated in the normal direction by irradiation of the illumination light
Data Source
AI summary
As a technique to improve processing efficiency of defect inspection by quickly adjusting a position of a detection system, provided is a defect inspection apparatus including: a stage that moves with a sample and a pattern substrate placed thereon; an illumination optical system that irradiates an object on the stage from a direction inclined from the normal direction of the pattern substrate; a first detection optical system that detects scattered light in the normal direction; a second detection optical system that detects scattered light in a direction different from the scattered light detected by the first detection optical system; a signal processing unit that processes both scattered light signals; and a control unit. The control unit implements first adjustment processing of adjusting a focal position of the first or the second detection optical system and a three-dimensional position of each detector with respect to an illumination region by using a scattered light signal and second adjustment processing of adjusting a focal point by changing a position in an optical axis direction of a detector of the first or the second detection optical system and a position in a height direction of the stage, and implements the second adjustment processing at a higher frequency than the first adjustment processing.