Process Control & Metrology (Step )
Process control and metrology are essential in semiconductor manufacturing to ensure device performance, yield, and reliability. At advanced process nodes, tolerances are measured in nanometers or even angstroms, making inline monitoring and defect detection critical to successful fabrication. These activities run in parallel with every Front-End step and form the backbone of quality assurance inside the fab.
Role in Manufacturing
- Inline Monitoring: Provides real-time feedback on wafer condition after each process step.
- Defect Detection: Identifies particles, patterning errors, and line-edge roughness before wafers move to the next stage.
- Dimensional Control: Confirms linewidth, critical dimensions (CD), overlay accuracy, and film thickness uniformity.
- Yield Optimization: Enables fabs to adjust recipes, tool parameters, and consumables dynamically to maximize yield.
Key Measurements & Techniques
| Category | Techniques | Purpose | Typical Vendors |
|---|---|---|---|
| Critical Dimension (CD) Metrology | CD-SEM, Scatterometry (OCD) | Measure line widths, gate lengths, pattern fidelity | KLA, Applied Materials |
| Overlay Metrology | Optical Imaging, Scatterometry | Ensure alignment between lithography layers | ASML, Onto Innovation |
| Film Thickness / Refractive Index | Ellipsometry, Reflectometry | Verify uniformity of dielectric and metal films | KLA, Filmetrics, Nanometrics |
| Surface Defect Inspection | Brightfield/Darkfield Optical Inspection, E-beam Inspection | Detect particles, scratches, bridging defects | KLA, Hitachi High-Tech |
| 3D Metrology | CD-AFM, X-ray Metrology, TEM/FIB Cross-section | Measure 3D structures such as FinFETs and GAA transistors | Thermo Fisher, KLA |
Cleanroom Environment
- Metrology tools are typically installed inline in Class 1–100 cleanrooms.
- Strict particle control is necessary since a single particle can cause a fatal defect.
- Airborne molecular contamination (AMC) monitoring often integrated with inspection tools.
Advantages & Constraints
- Advantages: Inline defect detection saves cost by stopping defective wafers early; improves yield and tool productivity; ensures compliance with sub-5nm node requirements.
- Constraints: Metrology equipment is capital-intensive; measurements slow down throughput if not carefully optimized; 3D structures require increasingly complex measurement techniques.
Market Outlook
The process control and metrology market is forecast to grow steadily through 2030, driven by sub-3nm logic, 3D NAND, and advanced packaging. AI/ML analytics are increasingly applied to metrology data to predict yield loss and automate process tuning. Vendors are pushing e-beam and hybrid metrology platforms to meet the demands of GAA transistors and chiplet architectures.