Wafer Inspection Synchronization Minimizing Jitter
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Solution Overview
Problem
Conventional scanning systems for inspecting semiconductor wafers face challenges in accurately detecting defects due to line jitter and optical distortion, which can lead to skewed images and reduced precision in defect detection.
Innovation Solution
The implementation of a synchronized inspection system using a pre-scanner acousto-optic deflector (AOD) and a chirp AOD, along with a synchronization system that generates timing signals for deflectors and image acquisition channels, ensures that the scanning and image acquisition processes are synchronized, minimizing line jitter and correcting optical distortion through dynamic adjustment of sampling frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional scanning systems are used to inspect semiconductor wafers, then the inspection process can be performed, but line jitter and optical distortion occur causing skewed images and reduced defect detection precision
Solution Approach 1:
The patent applies dynamics by making the sampling frequency adjustable and synchronized with the scanning rate. The system dynamically adjusts the sampling frequency based on the scanning speed to maintain proper synchronization, thereby eliminating line jitter and optical distortion while preserving image accuracy and defect detection precision
Solution Approach 2:
The patent implements feedback through a synchronization system that monitors the scanning rate and adjusts the sampling frequency accordingly. This closed-loop control ensures that the image acquisition remains synchronized with the scanning process, preventing image skew and maintaining measurement precision
2Productivity
If the scanning rate is increased to improve inspection speed, then productivity increases, but line jitter and image distortion worsen
Solution Approach 1:
The system dynamically adjusts the sampling frequency in real-time based on the scanning rate. When the scanning speed increases to improve productivity, the sampling frequency is automatically increased proportionally to maintain synchronization, thereby preventing image distortion and preserving manufacturing precision
Solution Approach 2:
The patent changes the sampling frequency parameter dynamically to match the scanning rate. By adjusting this critical parameter, the system can operate at high scanning speeds for improved productivity while maintaining proper image quality and minimizing distortion
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
This approach results in accurate and precise defect detection with minimized line jitter, enabling the production of fault-free semiconductor devices by ensuring that the image acquisition system operates in sync with the scan rate, thereby improving the overall inspection efficiency and accuracy.
Implementation Method 1
a pre-scanner acousto-optic deflector (AOD), a chirp AOD
Data Source
AI summary
An inspection system comprises a beam generator module for deflecting spots across scan portions of a specimen. The system also includes detection channels for sensing light emanating from a specimen in response to an incident beam directed towards such specimen and generating a detected image for each scan portion. The system comprises a synchronization system comprising clock generator modules for generating timing signals for deflectors of the beam generator module to scan the spots across the scan portions at a specified frequency and each of the detection channels to generate the corresponding detected image at a specified sampling rate. The timing signals are generated based on a common system clock and cause the deflectors to scan the spots and the detection channels to generate a detected image at a synchronized timing so as to minimize jitter between the scan portions in the response image.