It is no secret that manufacturing success in Europe lies not in attempting mass production on the scale seen in Asia, but in creating the technical and process solutions that are needed to serve this mass production. These are the dedicated and highly-technical companies making new and clever equipment needed by vital and growing global industries. With its ALD passivation system, Levitech is filling this niche for solar photovoltaic panels.
Levitech began as a business unit of Dutch semiconductor equipment manufacturer ASM International, centred on the Levitor Rapid Thermal Processing (RTP) system. In 2009, this unit was split off as ASM moved to concentrate on its core products. Levitech, as it was named, became an independent company with ASM as one of its shareholders.
The core technology of the Levitor system provided the basis for Levitech to focus on its primary intention: to develop a system for the PV market based on the potential uses of aluminium oxide as a passivation layer in solar cell concepts.
Heavy investment in that project over the past few years has resulted in the Levitrack Atomic Layer Deposition (ALD) system. The Levitrack system is based on the innovative concept of precursor separation in space, rather than time, in combination with the floating wafer and conductive heating technology developed for the Levitor RTP products.
In the Levitrack system, substrates float in a linear gas track and are heated to the required process temperature within a matter of seconds. Once the substrates reach the process temperature, they float through a series of ALD deposition cells. Each of these cells consists of two precursors, which are separated in space by a nitrogen purge (acting as inert gas curtains).
The number of ALD deposition cells determines the final layer thickness. The combination of a relatively large purge gas flow and the narrow gap between the substrate and the gas divider block ensures a very effective separation of the precursors.
The unique design of ALD deposition cells technology allows for single-side ALD growth, as one side of the gas track runs only with nitrogen. As the Levitrack is optimised for a fast linear motion of the substrates, the system guarantees a high throughput at over 2400 wafers an hour, while targeting well over 3000 wafers an hour in the coming year. These throughputs are difficult to reach in production with batch-like systems.
“The solar industry is slowly but surely embracing Atomic Layer Deposition as a mass production solution for maximizing solar cell efficiencies,” Levitech CEO Jaap Beijersbergen said. “We know that aluminium oxide (Al2O3) film provides excellent cell passivation and increased cell efficiencies, especially when deposited in uniform, pinhole-free and dense layers. This is a particular feature of the ALD technique and in the Levitrack these qualities are combined with an efficient and effective platform for mass production.”