Picosun and University of Helsinki shed new light on ALD
Picosun Oy, are a supplier of advanced Atomic Layer Deposition (ALD) thin film technology, that provides equipment and solutions for commercial utilization of photo-assisted ALD. Photo-ALD enables novel ALD processes, area-selective film deposition, low deposition temperatures, savings on precursor chemical consumption and costs, and lower environmental impact of the ALD processing.
Photo-assisted ALD utilizes light to enable ALD film growth. Whereas in regular ALD film grows from two gaseous precursors which react on the coated surface one by one, in photo-ALD only one chemical is needed "“ light takes care of the rest.
"The photo-ALD method has been investigated only marginally this far, mostly because of the lack of proper equipment. Now, using Picosun's photo-ALD tools we have been able to develop this technology and related chemistry for several key ALD processes. Potential applications can be found in MEMS (MicroElectroMechanical Systems), sensors and other advanced microelectronics (for example, selective ALD to keep the chip contact areas clean), and solar cell manufacturing," comments Prof. Mikko Ritala from the University of Helsinki, Finland.
"Picosun's ambition is to take ALD where it has never gone before, to enable novel, disruptive industrial solutions and cutting-edge new products for our customers. We are very happy and proud that our photo-ALD system has enabled great results at our long-term collaboration partner, University of Helsinki. It is fascinating to introduce this technology to our industrial partners to help them find new ways to solve their manufacturing challenges," states Juhana Kostamo, Managing Director of Picosun.
In photo-assisted ALD, the coated surface is exposed to alternate pulses of precursor vapor and flashes of high intensity light. The energy of light makes the precursor molecules on the surface chemically convert into the desired coating material. Alternatively, two precursors can be used but the other becomes reactive only when illuminated. Obviously, when only one precursor is required, both costs and environmental effect of the processing are lower. In conventional ALD relying fully on gaseous precursors, area-selective film growth is particularly difficult to achieve and often requires additional processing steps for deposition and etching of passivation layers. Light, on the other hand, is easy to block from the areas that need to be left uncoated and sharply defined patterns can be created without direct contact to substrate or exposure to chemicals directing the film growth. Also, when the energy of light replaces the energy of heat, the driving force of the conventional thermal ALD, processing can be done at much lower temperatures than in regular ALD.
