Electron Beam Inspection Stage Swath Motion Control
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Solution Overview
Problem
Conventional scanning electron microscopes face significant throughput issues when inspecting numerous scattered 'hot spot' areas on manufactured substrates due to substantial overhead time from decelerating and re-accelerating the stage between inspection points, which can account for up to 30-40% of the total inspection time.
Innovation Solution
Implementing a method where the stage moves continuously along a swath path with off-axis imaging, dynamically adjusting speed based on the number of hot spots within the field of view, and using a larger field of view to cover multiple hot spots simultaneously, reducing the need to stop and re-accelerate the stage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the stage is stopped and re-accelerated between each hot spot inspection, then the imaging precision is maintained, but the inspection throughput decreases significantly
Solution Approach 1:
The stage moves continuously through the inspection area without stopping between hot spots, maintaining constant motion to eliminate deceleration and re-acceleration cycles. This continuous movement preserves imaging precision through controlled motion while dramatically improving throughput by eliminating idle time between inspections.
Solution Approach 2:
The system dynamically adjusts the stage velocity based on the density and distribution of hot spots in different regions. The stage moves faster through areas with fewer hot spots and slower through dense regions, optimizing the balance between inspection completeness and throughput while maintaining precision through controlled dynamic motion.
2Productivity
If the stage moves continuously without stopping, then the inspection throughput increases, but the imaging precision may deteriorate due to motion blur
Solution Approach 1:
The electron beam imaging and stage movement are synchronized to occur simultaneously during continuous stage motion. The beam scans and captures images while the stage moves at controlled velocity, eliminating the need to stop for imaging and thereby maintaining both throughput and precision through coordinated continuous operation.
Solution Approach 2:
The system replaces traditional mechanical stopping and positioning with electron beam scanning and synchronization. Instead of mechanically halting the stage for precise positioning, the electron beam scans and images targets during continuous motion, substituting mechanical precision requirements with beam control and timing synchronization.
3Measurement precision
If a small field of view is used for each hot spot, then the inspection precision is high, but the number of hot spots that can be inspected per hour decreases
Solution Approach 1:
The inspection area is divided into multiple fields of view that are sequentially imaged during continuous stage motion. Each field of view captures a portion of the hot spots, and the system reconstructs the complete inspection data by combining information from multiple segmented fields, maintaining precision while increasing overall throughput.
Solution Approach 2:
The system transitions from static single-field imaging to dynamic multi-field imaging along the stage motion dimension. By utilizing the temporal dimension of continuous motion to capture multiple fields of view, the system inspects more hot spots per hour while maintaining precision through coordinated beam scanning and field sequencing.
4Productivity
If the stage moves at high speed, then the inspection throughput increases, but the number of defects that can be detected decreases due to reduced scanning time
Solution Approach 1:
The electron beam continuously scans and detects defects while the stage moves at high speed, eliminating idle time between defect detection events. This continuous detection process ensures that no defects are missed even at high velocities, maintaining reliability while maximizing inspection speed through uninterrupted scanning.
Solution Approach 2:
The system uses real-time feedback from the detected hot spot distribution to dynamically adjust the stage velocity and beam scanning parameters. When defects are detected in dense regions, the system automatically slows down to ensure thorough inspection, while maintaining high speed in low-density areas, thereby preserving defect detection capability across the entire inspection process.
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 significantly reduces total inspection time by minimizing overhead time and increasing throughput, allowing for a higher number of hot spots to be inspected per hour while tolerating increased aberrations in scanned data.
Implementation Method 1
The electron source is configured to generate a primary electron beam, and the lens system is configured to focus the primary electron beam onto a surface of the substrate
Implementation Method 2
The detector is configured to detect scattered electrons emitted from the substrate
Data Source
AI summary
One embodiment relates to a method of automated inspection of scattered hot spot areas on a manufactured substrate using an electron beam apparatus. A stage holding the substrate is moved along a swath path so as to move a field of view of the electron beam apparatus such that the moving field of view covers a target area on the substrate. Off-axis imaging of the hot spot areas within the moving field of view is performed. A number of hot spot areas within the moving field of view may be determined, and the speed of the stage movement may be adjusted based on the number of hot spot areas within the moving field of view. Another embodiment relates to an electron beam apparatus for inspecting scattered areas on a manufactured substrate. Other embodiments, aspects and features are also disclosed.