Over recent years, advancements in semiconductor technology have grown exponentially, bringing innovations that support Moore’s Law and satisfy the increasing demands for efficiency, miniaturization, and precision. At the heart of these advancements is the evolution of defect inspection, specifically targeted at identifying systemic issues embedded within the manufacturing processes.
One such breakthrough is PDF Solutions new high-throughput point scan system, which revolutionizes e-beam inspection for detecting systematic voltage contrast (VC) defects. This post explores the fundamentals of point scan technology, its unique advantages, and its role in accelerating defect detection accuracy and resolution in semiconductor development.
What is Point Scan Technology?
Point scan is a next-generation e-beam inspection system designed to address limitations of traditional vector scan methods. Instead of capturing detailed images around a defect site, point scan collects a single, highly precise pixel per defect hotspot. This enables incredibly high throughput, allowing the system to detect systematic defects with significantly less delay.
The key advancements of the point scan system include two primary innovations:
- Continuous Stage Scanning – The wafer stage moves continuously under the electron beam, eliminating the need for field-of-view (FOV) leaps and reducing settling time associated with leap-and-scan systems.
- Single Pixel Inspection – The system uses extremely precise alignment to collect just one pixel directly from each defect’s hotspot, eliminating the need for buffer regions or multiple-pixel patches.
By combining these advancements, point scan technology achieves throughput rates of over 1 billion hotspots per hour, significantly boosting defect detection speed while maintaining high purity for systematic defect data.
Key Advantages of Point Scan Technology
Implementing the point scan system introduces several advantages over traditional e-beam inspection approaches, providing unmatched throughput and enhancing yield optimization efforts across manufacturing pipelines.
- Improved Inspection Throughput
Traditional leap-and-scan tools slow down inspection processes due to their FOV movements and pixel collection times. Point scan, utilizing continuous stage motion, eliminates this bottleneck. The result? Two to three orders of magnitude faster inspections, equating to the inspection of billions of hotspots per hour.
- Enhanced Precision Using Local Alignment
E-beam systems face inherent challenges with coordinate accuracy, often introducing minor errors during inspection. Point scan systems address this limitation through precise local alignments near defect hotspots. This ensures each inspection pixel lands directly on the signal pad with minimal drift, reducing false positives and enhancing output reliability.
- Seamless Scalability for Dense and Sparse Areas
The system intelligently optimizes scanning speed based on hotspot density across the wafer. By dynamically filtering out redundant hotspots and prioritizing critical defect areas, it handles both sparse and dense regions without unnecessary slowdowns.
- High-Purity Defect Signal Capture
While traditional patch-based images aggregate multiple pixel signals, point scan focuses only on the single-pixel signal generated at the defect site. This method increases signal strength, enabling defect detection even in the most challenging scenarios with minimal noise interference.
Methodology for Maximizing Defect Inspection
Effective adoption of point scan technology depends on employing an optimized methodology tailored for systematic defect identification. Below are key steps that make this system invaluable for defect mitigation efforts.
Systematic Hotspot Selection
- Localized Signal Capability: Selection begins by identifying electrical nodes, vias, or metal pads whose VC signals accurately reflect relevant defect mechanisms.
- Geometry-Centric Filtering: Narrow hotspots are prioritized for defects involving metal islands or voids.
- Redundancy Elimination: Ensure inspected nodes lack alternative redundancy paths to isolate true defect contributors.
Two-Pass Inspection
The point scan system performs inspections in two critical phases to ensure accuracy:
- Pass 1 collects single-pixel data for all hotspots, flagging outliers through VC patterns.
- Pass 2 captures review images of flagged outliers, allowing deep analysis of defect morphology to finalize defect assessments.
Binning for Root Cause Analysis
Hotspot defect data are binned based on redundancy paths, metal feature dimensions, and geometric properties. Programmable binning workflows enable detailed defect characterization to statistically isolate root causes and resolve recurring manufacturing challenges more efficiently.
Case Study: Resolving Metal 2 Missing Metal Fill Defects
One noteworthy application of the point scan system involved resolving a challenging Metal 2 missing metal fill (MMF) issue (also called buried void). This defect mechanism, initially affecting numerous wafers across production batches, was successfully mitigated using targeted point scan inspections. This was discussed by Intel at the 2025 ASMC conference.
Initial Stages
Wide-scale inspections revealed that MMF primarily impacted smaller and narrower metal islands. Targeted scans were then implemented to validate defect localization, achieving scan rates of 1 billion vias per hour with high consistency. Transmission electron microscopy (TEM) further confirmed defect signals across key hotspots, correlating well against end-of-line (EOL) data trends.
Process Refinements
A series of controlled split experiments was conducted to identify root causes. Modifications to the seed layer and barrier material thicknesses were tested, dramatically reducing defect rates by 6 orders of magnitude. The system’s high throughput allowed rapid iteration, ensuring process fixes were validated under progressively stressful conditions.
The Role of Point Scan in Future Semiconductor Manufacturing
Advanced e-beam inspection tools like point scan represent a paradigm shift in how semiconductor manufacturers approach defect detection and resolution. By incorporating innovations in continuous scanning and single-point detection, these systems deliver unmatched performance for both development-phase wafers and high-volume manufacturing.
With accelerating scaling requirements for sub-10nm devices and increasing defect detection complexity, staying ahead of evolving challenges requires precise, high-throughput systems. Point scan technology ensures semiconductor production remains efficient, scalable, and ready to meet the demands of future nodes.
Through Intel’s implementation of point scan systems, the industry witnesses how foundational technologies enable faster yield ramp, higher precision defect mitigation, and robust manufacturing readiness across cutting-edge nodes.