Focused Ion Beam (Fib)
Focused Ion Beam (FIB) is a precision micro/nano-machining and imaging instrument that uses a focused beam of ions (typically gallium) to mill, deposit, and image materials at nanometer scale — the essential semiconductor failure analysis tool for site-specific cross-sectioning, TEM sample preparation, and circuit edit that enables direct examination of device structures at exact locations of interest.
What Is a FIB?
- Definition: An instrument that focuses a beam of ions (Ga⁺, Xe⁺, or other species) to a spot size of 5-10 nm, enabling controlled material removal (sputtering/milling), material deposition, and ion-beam imaging at nanometer resolution.
- Primary Ion Source: Gallium Liquid Metal Ion Source (LMIS) — the standard for semiconductor FIB work. Newer systems use xenon plasma for faster bulk milling.
- Modes: Milling (material removal), deposition (metal or insulator), imaging (secondary electrons/ions), and implantation.
Why FIB Matters
- Site-Specific Cross-Sectioning: Navigate to an exact defect location on a chip and cut a cross-section through it — revealing internal structure invisible from the surface.
- TEM Sample Preparation: The standard method for preparing TEM lamellae (thin slices) from specific locations in semiconductor devices — essential for atomic-resolution analysis.
- Circuit Edit: Modify integrated circuits by cutting metal lines or depositing new conductors — enabling rapid debug of prototype chips without mask revisions.
- Failure Analysis: Expose buried defects, voids, delamination, and contamination at the precise failure site identified by electrical testing or optical inspection.
FIB Capabilities
- Milling: Remove material layer by layer with nm precision — create cross-sections, thin lamellae, trenches, and 3D tomography slices.
- Deposition: Deposit metal (Pt, W, C) or insulator (SiO₂) to protect surfaces, create electrical connections, or repair circuitry.
- Imaging: Ion-beam-induced secondary electron images provide voltage contrast, channeling contrast, and topographic information.
- 3D Tomography: Automated serial sectioning (slice and image) creates full 3D reconstructions of device structures.
FIB Applications in Semiconductor Manufacturing
| Application | Purpose | Typical Time |
|---|---|---|
| Cross-section | Examine internal structure | 30-60 min |
| TEM lamella prep | Prepare site-specific TEM sample | 2-4 hours |
| Circuit edit | Modify prototype IC | 4-8 hours |
| 3D tomography | Full volume reconstruction | 8-48 hours |
| Defect de-processing | Expose buried defects | 30-90 min |
Leading FIB Manufacturers
- Thermo Fisher Scientific (FEI): Helios, Scios — industry-standard dual-beam FIB-SEM systems for semiconductor FA and sample prep.
- ZEISS: Crossbeam series — high-performance FIB-SEM for advanced materials analysis.
- Hitachi: NB5000, Ethos — FIB-SEM with advanced automation for semiconductor applications.
- Tescan: SOLARIS — FIB-SEM with unique detector configurations.
FIB is the Swiss Army knife of semiconductor failure analysis — providing the unique ability to navigate to any location on a chip and precisely excavate, modify, or prepare that exact spot for detailed analysis, making it the indispensable first step in most semiconductor defect investigations.