Welcome to a New Era of Predictive Yield Process Control for Advanced Packaging
In April 2016, Fogale Nanotech Group acquired the assets of Altatech Semiconductor from Soitec in order to combine the metrology offerings of Fogale Nanotech Semicon with Altatech’s unique 2D and 3D inspection capabilities. The idea was to create a powerhouse of process control for emerging advanced packaging processes for next-generation fan-out wafer-level packaging (FOWLP), 2.5D interposer, 3D through silicon vias (3D TSVs), MEMS, and more. As I previously visited Fogale Nanotech SEMICON at the Fogale headquarters in Nimes, France, to learn about its “Swiss army knife” approach to metrology, it’s been interesting to watch the next chapter of this story unfold. It began with fanfare at SEMICON West 2016, where the newly formed company was christened UnitySC, a nod to the concept of the unified yield equation, which takes parametric data and defect density data to predict yield.
Altatech’s assets included a manufacturing facility located in Grenoble, the heart of the French Silicon Valley, and home to some of Europe’s leading-edge semiconductor research and manufacturing companies. Featuring 10,000 sq. ft. of class 10,000 cleanroom space, not to mention some pretty spectacular views of the surrounding French Alps, UnitySC decided to locate its global headquarters there.
As I was scheduled to attend the 5th annual SEMI European 3D Summit Jan. 23-25, which coincidentally also takes place in Grenoble, I decided to pay a visit to the new company. It was great to catch up with Tim Anderson, director of business development, previously of Fogale Nanotech; as well as Yann Guillou, who joined the team as director of marketing and communications. Yann and I go way back, as he was with SEMI, and launched the 3D Summit five years ago. (Not ironically, he’s the one who’s invited me to attend the summit these past five years.) Tim and Yann filled me in on Unity’s goals for the future, and Philippe Gastaldo, CTO, treated me to a tour of the cleanroom to explain the different tool capabilities.
According to Tim, what sets UnitySC apart from other players in the metrology and inspection space for advanced packaging is the combination of IR optical metrology capabilities based on microscopy, interferometry, spectrometry, and full-field profilometry, with inspection capabilities including 2D and 3D line scan confocal chromatic, phase-shift deflectometry, and Doppler velocimetry.
“UnitySC’s unique process control solutions provide key data to implement the unified yield equation, used to predict yields and allow manufacturing companies to adjust their processes, thereby creating a value-add for advanced packaging manufacturers,” explained Anderson. “One of the things that differentiate us from our competitors is this ability to measure and inspect all around and through the wafer to provide 2D and 3D inspection in one scan.”
The highlight of my visit (lunch at a local hipster hot spot called Le Garage notwithstanding) was seeing the tools in action in the cleanroom, where they can develop processes, perform demos for customers, and evaluate the results. The team works in collaboration with customers to design unique tool configurations to solve their process control problems.
Several capabilities that stand out as unique to UnitySC include:
- 3D confocal chromatic line scan, which replaces a camera with a spectrometer to analyze the full spectrum and provides height information. Every point of light is kept in focus, creating better sensitivity for surface coplanarity and micro-bump inspection.
- High-resolution edge inspection that uses five confocal chromatic sensors to look at all parts of the wafer edge (bottom, bottom bevel, apex, top bevel, and top) simultaneously. Additional programmable sensors perform the near-edge inspection.
- Phase-shift deflectometry which projects onto the reference to a high-definition camera to measure the front and backside of the wafer at the same time. It’s so sensitive, it can detect defects on 2.5nm topographies, catching more slip lines, residues, and other small defects than traditional manual approaches in a much faster time. It also provides quantitative data about what type of defect is detected.
- Nanoscale Surface Topography (NST) is a unique non-contact surface topography solution for copper chemical mechanical planarization (CMP), direct bonding, and wafer stacking applications. With a resolution of less than 0.1nm, NST provides measurements spanning all traditional contact profiling measurements and beyond, extending into the atomic force microscope (AFM) measurement space. Incorporating reflectometry in every pixel, NST provides accurate measurements unlike traditional non-contact profilometry solutions, which struggle with transparent film ensuring that you get the right measurement, all of the time.
Like all new companies, UnitySC has set out to achieve some lofty goals. They intend to be leaders in advanced process control for the emerging sector of heterogeneous integration technologies. Anderson says they aren’t interested in going after the well-served market of conventional packaging nor mainstream bumping inspection. Rather, their sweet spot is in measuring and detecting defects in the finer features processes of new and emerging markets, such as micro bumps, FOWLP, TSVs, thin wafers, advanced substrates. I’m looking forward to following this developing story over the next few years!