Dynamic Stage Speed Control for Charged Particle Inspection
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Solution Overview
Problem
Conventional charged particle beam inspection systems are inefficient due to the lack of consideration for areas on a wafer that do not need inspection or have fewer features, leading to suboptimal throughput and increased inspection time.
Innovation Solution
A system and method that classify regions on a wafer by type and control the stage speed based on the type of region, allowing for faster scanning of areas without features and more detailed inspection of feature-rich areas, optimizing throughput and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If uniform scanning speed is used across the entire wafer, then inspection coverage is complete, but inspection time is excessive and throughput is low
Solution Approach 1:
The patent applies dynamic scanning speed adjustment by varying the stage velocity based on the spatial distribution of features across the wafer. The controller continuously adjusts the scanning speed parameter in real-time during inspection, using faster speeds in feature-sparse regions and slower speeds in feature-dense regions, thereby optimizing the trade-off between inspection time and detection quality without compromising coverage
Solution Approach 2:
The patent implements local quality differentiation by applying different scanning speeds to different regions of the wafer based on their feature density characteristics. Rather than using a single uniform scanning parameter, the system tailors the inspection parameters locally to match the actual inspection needs of each region, reducing time spent on low-density areas while maintaining adequate inspection of high-density areas
2Productivity
If high scanning speed is used, then throughput is improved, but inspection accuracy decreases
Solution Approach 1:
The system dynamically adjusts scanning speed based on real-time or pre-analyzed feature density information, transitioning between high-speed scanning in safe zones and low-speed scanning in critical zones. This dynamic parameter adjustment allows the system to maintain high throughput overall while ensuring adequate inspection accuracy in regions where defects are more likely to occur
Solution Approach 2:
The patent changes the scanning speed parameter as a function of spatial location and feature density. By modifying this key operational parameter based on the inspected region's characteristics, the system optimizes the balance between speed and accuracy, using faster speeds where accuracy requirements are lower and slower speeds where defect detection is critical
3Measurement precision
If low scanning speed is used, then inspection accuracy is improved, but throughput decreases
Solution Approach 1:
The system applies local quality optimization by restricting low-speed high-accuracy scanning only to regions with high feature density where defects are most likely to be found. In regions with low feature density, the system uses higher scanning speeds, thereby maintaining adequate inspection accuracy where needed while maximizing throughput in less critical 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 approach enhances inspection throughput by skipping unnecessary areas and adjusting scanning speed based on feature density, resulting in improved efficiency and accuracy of wafer inspection.
Implementation Method 1
With a SEM, electrons of a single primary electron beam, or electrons of a plurality of primary electron beams, can be focused at locations of interest of a wafer under inspection. The primary electrons interact with the wafer and may be backscattered or may cause the wafer to emit secondary electrons.
Data Source
AI summary
Apparatuses, systems, and methods for generating a beam for inspecting a wafer positioned on a stage in a charged particle beam system are disclosed. In some embodiments, a controller may include circuitry configured to classify a plurality of regions along a stripe of the wafer by type of region, the stripe being larger than a field of view of the beam, wherein the classification of the plurality of regions includes a first type of region and a second type of region; and scan the wafer by controlling a speed of the stage based on the type of region, wherein the first type of region is scanned at a first speed and the second type of region is scanned at a second speed.