Semiconductor Wafer Inspection System State Monitoring
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Solution Overview
Problem
Current surface inspection systems for semiconductor wafers lack comprehensive and sensitive monitoring capabilities, particularly in detecting defects over time, leading to inadequate detection of size stability and potential drift in defect size measurement.
Innovation Solution
A method involving a reference semiconductor wafer with defects of specific size and density, conducting reference and control inspections to measure defect positions and sizes, and assessing the system's operational state based on size differences between inspections, using a surface inspection system that includes a light source and detectors to scan the wafer surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If repeated examination of a reference semiconductor wafer is conducted to monitor operational state, then system stability can be monitored, but the sensitivity and scope of detection remains insufficient
Solution Approach 1:
The patent segments the monitoring process into multiple independent components: reference inspection for calibration, control inspection for ongoing monitoring, identification of common defects, determination of size differences, and assessment of operational state. This segmentation allows each component to serve a specific function, improving overall detection sensitivity while maintaining system stability monitoring.
Solution Approach 2:
The patent implements feedback by comparing control inspection results with reference inspection results to identify drift in defect size measurement. The system continuously monitors size differences of common defects and provides feedback on operational state, enabling early detection of measurement drift and maintaining calibration accuracy over time.
2Productivity
If measurement data is processed using size intervals to restrict processing scope, then processing efficiency is improved, but information about defects outside intervals is lost
Solution Approach 1:
The patent applies local quality by focusing the analysis on specific characteristics of common defects (size differences) rather than processing all measurement data uniformly. By identifying and analyzing only the size differences of defects that appear in both reference and control inspections, the system maintains processing efficiency while preserving critical information about defect size stability.
3Measurement precision
If defect size measurement is performed repeatedly over time to detect drift, then measurement accuracy is improved, but monitoring complexity increases
Solution Approach 1:
The patent extracts the essential monitoring function by focusing solely on size differences of common defects that appear in both reference and control inspections. This extraction simplifies the monitoring process by filtering out irrelevant information and concentrating analysis on the critical parameter (defect size) that indicates operational state changes.
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 method provides more comprehensive and sensitive monitoring of the surface inspection system's operational state, enabling early detection of changes and maintaining system stability through statistical process control and tolerance corridors, reducing the need for frequent cleaning and improving defect size measurement accuracy.
Implementation Method 1
scanning surface inspection systems may be used. These gradually illuminate the surface of the semiconductor wafer with a light spot of laser light
Implementation Method 2
detect scattered light as a function of one or different solid angles (channels)
Data Source
AI summary
The operational state of a surface inspection system for detecting defects on the surface of semiconductor wafers is monitored by:providing a reference wafer having defects of a particular number, size, and density on an examination surface;conducting a reference inspection of the reference wafer and at least one control inspection of the reference wafer by the surface inspection system, the position and size of defects on the examination surface being measured;identifying defects which, because of their position, are regarded as common defects of the reference inspection and of the control inspection;for each common defect, determining a size difference obtained from comparing its size from the reference inspection and from the control inspection; andassessing the operational state of the surface inspection system on the basis of the size differences.