Multi-Beam Metrology Position Feedback Alignment
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Solution Overview
Problem
Current semiconductor inspection systems face challenges in throughput due to the vast number of data points generated, especially as the demand for smaller devices increases, leading to inefficiencies in defect detection and classification.
Innovation Solution
A multi-beam metrology system that includes an illumination source to generate a beam array, an imaging subsystem to direct and image the beams at measurement locations, and a detection assembly with position detectors to adjust the imaged spots for alignment, allowing for simultaneous interrogation of multiple points on a sample.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single beam is used for inspection, then alignment is simple, but throughput is low due to sequential scanning
Solution Approach 1:
The inspection system divides a single beam into multiple parallel beams using beam splitting optics, creating an array of beams that can simultaneously inspect multiple locations on the wafer. This segmentation approach increases throughput by parallelizing the inspection process while managing complexity through systematic optical design
Solution Approach 2:
The system transitions from one-dimensional sequential scanning to two-dimensional parallel inspection by arranging beams in an array configuration. This dimensional expansion allows simultaneous inspection of multiple spatial locations, dramatically increasing throughput without proportionally increasing system complexity
2Productivity
If multiple beams are used to increase throughput, then inspection speed improves, but alignment precision deteriorates due to spot drift
Solution Approach 1:
The system incorporates feedback mechanisms that continuously monitor the positions of beam spots on the wafer and provide real-time correction signals to the beam control system. This feedback loop compensates for drift and maintains alignment precision despite the use of multiple beams operating in parallel
Solution Approach 2:
The beam positioning system transitions from static fixed positions to dynamic adjustable positions, allowing real-time modification of beam trajectories. This dynamic capability enables the system to adapt to drift conditions and maintain precise alignment across all beams throughout the inspection process
3Productivity
If beam array is used for parallel inspection, then throughput increases, but cross-talk between detection elements increases
Solution Approach 1:
The detection system assigns specialized detection elements to specific beam spots, with each detection element optimized for its local measurement task. This local specialization reduces cross-talk by ensuring that detection signals from adjacent beams are processed by dedicated elements rather than shared sensors
Solution Approach 2:
The system extracts and separates the detection functions for different beam spots into distinct detection channels, isolating the measurement processes to prevent interference. This extraction approach removes cross-talk by ensuring that signals from one beam cannot contaminate measurements from adjacent beams
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 throughput by maintaining alignment of detection elements, reducing cross-talk, and providing diagnostic information on sample variations, thereby improving the efficiency of defect detection and classification.
Implementation Method 1
one or more position detectors configured to measure positions of the imaged spots in the detection plane
Data Source
AI summary
A multi-beam metrology system includes an illumination source configured to generate a beam array, an illumination sub-system to direct the beam array to a sample at an array of measurement locations, an imaging sub-system to image the array of measurement locations as an array of imaged spots in a detection plane, and a detection assembly to generate detection signal channels associated with each of the imaged spots. The detection assembly includes an array of detection elements configured to receive the imaged spots with separate detection elements, and one or more position detectors to measure positions of the imaged spots in the detection plane. The detection assembly further generates feedback signals for the imaging sub-system based on the measured positions of the imaged spots to adjust the positions of one or more of the imaged spots in the detection plane to maintain alignment of the array of detection elements.