By Ed Korczynski
Veeco Instruments (Veeco) recently announced that Veeco CNT—formerly known as Ultratech/Cambridge Nanotech—shipped its 500th Atomic Layer Deposition (ALD) system to the North Carolina State University. The Veeco CNT Fiji G2 ALD system will enable the University to perform research for next-generation electronic devices including wearables and sensors. Veeco announced the overall acquisition of Ultratech on May 26 of this year. Executive technologists from Veeco discussed the evolution of ALD technology with Solid State Technology in an exclusive interview just prior to SEMICON West 2017.
Professor Roy Gordon from Harvard University been famous for decades as an innovator in the science of thin-film depositions, and people from his group were part of the founding of Cambridge Nanotech in 2003. Continuity from the original team has been maintained throughout the acquisitions, such that Veeco inherited a lot of process know-how along with the hardware technologies. “Cambridge Nanotech has had a broad history of working with ALD technology,” said Ganesh Sandaren, VP of Veeco CNT Applied Technology, “and that’s been a big advantage for us in working with some major researchers who really appreciate what we’re providing.”
The Figure shows that the company’s ALD chambers have evolved over time from simple single-wafer thermal ALD, to single-wafer plasma-enhance ALD (PEALD), to a large chamber targeting batch processing of up to ten 370 mm x 470 mm (Gen2.5) flat-panels for display applications, and a “large area” chamber capable of 1m x 1.2m substrates for photovoltaic and FPD applications. The large area chamber allows customers to do things like put down an encapsulating layer or an active layer such as buffer materials on CIGS-based solar cells.
Evolution of Atomic-Layer Deposition (ALD) technology starts with single-wafer thermal chambers, adds plasma energy, and then goes to batch processing for manufacturing. (Source: Veeco CNT).
“There a tendency to think that ALD only belongs in the high-k dielectric application for semiconductor devices, but there are many ongoing applications outside of IC fabs,” reminded Gerry Blumenstock, VP and GM of MBE business unit and Veeco CNT. “Customers who want to do heterogeneous materials develop can now have MBE and ALD in a single tool connected by a vacuum cluster configuration. We have customers today that do not want to break vacuum between processes.” Veeco’s MBE tools are mostly used for R&D, but are also reportedly used for HVM of laser chips.
To date, Cambridge Nanotech tools are generally used by R&D labs, but Veeco is open to the possibility of creating tools for High-Volume Manufacturing (HVM) if customers call for them. “Now that this is part of Veeco, we have the service infrastructure to be able to support end-users in high-volume manufacturing like any of the major OEMs,” said Blumenstock. “It’s an interesting future possibility, but in the next six months to a year we’re focusing on improving our offering to the R&D community. Still, we’re staying close to HVM because if a real opportunity arose there’s no reason we couldn’t get into it.”
In IC fab R&D today, some of the most challenging depositions are of Self-Assembled Monolayers (SAM) that are needed as part of the process-flow to enable Direct Self-Assembly (DSA) of patterns to extend optical lithography to the finest possible device features. SAM are typically created using ALD-type processes, and can also be used to enable selective ALD of more than a monolayer. Veeco-CNT is actively working on SAM in R&D with multiple customers now, and claim that major IC device manufacturers have purchased tools.
At the leading edge of materials R&D, researchers are always experimenting with new chemical precursors. “Having a precursor that has good vapor-pressure, and is reactive yet somewhat stable is what is needed,” reminded Sundaram. “People will generally chose a liquid over a solid precursor because of higher vapor pressure. There are many classes of precursors, and many are halogens but they have disadvantages in some reactions. So we see continue to move to metal-organic precursors, which tend to provide good vapor-pressures and not form undesirable byproducts.”