Onto Innovation extends FAaST platform to map residual surface charge across wafers and panels in advanced packaging

Onto Innovation published a technical paper on 8 October 2026 describing how its FAaST® non-contact electrical metrology platform detects and maps residual surface charge across both full wafers and panels - a capability the company claims is invisible to conventional optical inspection and dimensional metrology.^[1]

Why electrical process control matters now

Advanced packaging process control has historically centred on defect detection: particles, voids, microbump irregularities, and bonding misalignment.^[4] A separate class of problems, however, involves subtle electrical conditions that can affect downstream yield, device reliability, and manufacturing consistency without leaving any visible signature.^[1]

Residual charge is the clearest example. As manufacturers adopt new package architectures, they introduce hygroscopic films and insulating layers that require tighter environmental control.^[1] In drier fab environments, static charge can accumulate to levels that affect subsequent process steps. Plasma-based processing, deposition, cleaning, surface preparation, and bonding operations can each generate localised charge buildup across wafers and panels.^[1]

The challenge is not simply detecting whether charge is present. Manufacturers must understand where it is accumulating, how uniformly it is distributed, and how it evolves across process steps - information that traditional inspection tools cannot provide.^[1]

What the FAaST platform measures

Onto Innovation acquired the FAaST® product line from Semilab International in a transaction valued at approximately $495 million, completed in November 2025. The platform combines corona-Kelvin and digital surface photovoltage (SPV) technologies in a non-contact configuration, requiring no sample preparation.

For advanced packaging applications, the company claims the following measurement modes:

• Full-wafer charge mapping to monitor overall process health and identify non-uniformities across the substrate
• High-resolution panel-level mapping to locate localised charge hotspots across larger format substrates
• Intra-die surface voltage measurement at micrometre resolution, demonstrated on die measuring approximately 16 × 30 mm with a zoom area of 4 × 5 mm^[1]
• Rapid full-wafer characterisation for production monitoring, with higher-resolution modes available for targeted investigation of active areas and capacitors^[1]

The FAaST platform supports both full-wafer and panel-level measurements, allowing manufacturers to apply a common methodology across evolving packaging flows.^[1] Onto Innovation states it has expanded the platform to support panel-level applications while maintaining the same non-contact approach used across its installed base.

Where charge buildup is most acute

The paper identifies hybrid bonding as a process flow where residual charge monitoring is required at several steps.^[1] Hybrid bonding surfaces must meet stringent cleanliness and flatness requirements before bonding; even small electrical non-uniformities at the CMP-prepared surface can become yield-limiting.^[4] The concern extends to heterogeneous integration more broadly: advanced packaging technologies exhibit yield sensitivities and defect mechanisms fundamentally different from front-end logic or standard packaging technology.^[2]

The broader context is that packaging innovation is now treated as a scaling lever in its own right.^[3] AI, high-performance computing, automotive electronics, and next-generation networking platforms all depend on advanced packaging to deliver bandwidth and power efficiency in shrinking footprints.^[1]

Whether the FAaST platform's claimed sensitivity translates to measurable yield improvement in production - and at what throughput cost - has not been independently verified. Onto Innovation is scheduled to appear at SEMICON Europa, where further application data may be presented.