Wafer Inspection Screening for Targeted E-Beam Defect Detection
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Solution Overview
Problem
Optical inspection methods struggle to efficiently detect defects in small areas of semiconductor wafers due to resolution limitations and high noise levels, making electron beam inspection inefficient for comprehensive defect detection.
Innovation Solution
A wafer inspection method that involves obtaining raw data through optical inspection, generating statistical information for evaluation areas, selecting high-priority areas based on characteristics like gray level and focus maps, and performing electron beam inspection only on these selected areas to enhance defect detection efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If optical inspection is used to inspect the entire wafer, then the inspection coverage is high, but the defect detection precision is insufficient due to resolution limitations and noise
Solution Approach 1:
The wafer inspection process is segmented into two stages: optical inspection for entire wafer coverage and electron beam inspection for selected high-priority areas. This segmentation allows each method to operate in its optimal performance range, with optical providing broad coverage and electron beam providing high-precision verification where needed.
Solution Approach 2:
Different inspection methods are applied to different regions of the wafer based on defect probability. High-priority areas identified through optical inspection statistics receive electron beam inspection for high-precision defect detection, while other areas rely on optical inspection alone, optimizing both coverage and precision where needed.
2Measurement precision
If electron beam inspection is performed on the entire wafer, then the defect detection precision is high, but the inspection time is excessively long
Solution Approach 1:
Optical inspection is performed as a preliminary screening step to identify high-priority areas with higher defect probability. This preliminary action allows electron beam inspection to be focused only on these selected regions, dramatically reducing the time required for high-precision inspection while maintaining overall defect detection capability.
Solution Approach 2:
Instead of performing electron beam inspection on the entire wafer (excessive action), the method applies it only to selected high-priority areas (partial action). This partial application of the high-precision method achieves sufficient defect detection while avoiding the excessive time cost of full-wafer electron beam inspection.
3Reliability
If electron beam inspection is used for comprehensive defect detection, then the defect detection capability is high, but the inspection efficiency is low
Solution Approach 1:
Optical inspection serves as a preliminary screening tool to identify high-priority areas before electron beam inspection. This preliminary identification of defect-prone regions enables the electron beam to focus its high detection capability only where needed, maintaining high reliability while improving overall inspection efficiency.
Solution Approach 2:
The method applies electron beam inspection partially only to high-priority areas rather than comprehensively to the entire wafer. This partial application maintains high defect detection capability in critical regions while significantly improving inspection efficiency by avoiding unnecessary electron beam inspection in low-risk areas.
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 improves the efficiency of electron beam inspection by focusing on high-priority areas, reducing inspection time and enhancing defect detection capabilities in semiconductor wafers.
Implementation Method 1
the gray level represents reflectance in a first wavelength range
Implementation Method 2
performing an electron beam (e-Beam) inspection on the inspection area
Data Source
AI summary
Provided is a wafer inspection method including obtaining raw data in an optical inspection process for a wafer, identifying data in the raw data corresponding to a plurality of evaluation areas, generating statistical information for first characteristics of each evaluation area of the plurality of evaluation areas from the raw data corresponding to the plurality of evaluation areas, selecting at least some of the evaluation areas as a selection area through a comparison of the statistical information of each of the evaluation histograms, selecting an inspection area including at least a portion of the selection area, and performing an electron beam (e-Beam) inspection on the inspection area.