Control of material is key to GaN success says Exagan boss

Control of material is key to GaN success says Exagan boss

Interviews |
By Nick Flaherty

DuPont believes that the time is right for a new player to enter the market if it can deliver products with right cost/performance benefits. Users will switch to wide-bandgap materials such as GaN if there is a two to three times benefit in a key parameter or parameters – and if the price is right, DuPont says. With 200-mm production in prospect, Exagan will be able to ramp up volume on demand, addressing the price side of the equation he said at this week’s PCIM show.

An important aspect of the production process, DuPont continues, is that Exagan has full control over the epitaxy of placing the thin layer of GaN on the silicon substrate wafer. The involves control of both electrical and mechanical (relieving stresses in the transition from the silicon to the III-V crystal lattice). Exagan, which is a spinout from Leti and Soitec, has its own facility in Grenoble where the epi steps of the process are carried out; diffusion of the actual devices takes place at X-Fab. In GaN [devices], DuPont says, “Part of the design is being able to change both the epitaxy and the process.”

Exagan will enter the market with 650V devices, which it is calling “G-FETs”, that will be “regular” – that is, normally-off – FETs, and is actively targeting applications in power supplies, server power and automotive sectors – especially the on-board EV charger function. Exagan says it is sampling lead customers now and and expects to be in volume production later in 2017. A 1200V product is in R&D.

In their earlier statement, X-Fab Silicon Foundries and Exagan, announced that they had demonstrated the mass-production capability to manufacture highly efficient high-voltage power devices on 200-mm GaN-on-silicon wafers using X-FAB’s standard CMOS production facility in Dresden, Germany. This accomplishment is the result of a joint development agreement launched in 2015, enabling cost/performance advantages that could not be achieved with smaller wafers.

Exagan and X-FAB have successfully resolved many of the challenges related to material stress, defectivity and process integration while using standard fabrication equipment and process recipes. Combined with the use of 200-mm wafers, this will significantly lower the cost of mass producing GaN-on-silicon devices.

Previous work with GaN had been limited to 100-mm and 150-mm wafers due to the challenges of layering GaN films on silicon substrates. Exagan’s G-Stack technology enables GaN-on-silicon devices to be manufactured more cost effectively on 200-mm substrates by depositing a unique stack of GaN and strain-management layers that relieves the stress between GaN and silicon layers. The resulting devices have been shown to exhibit high breakdown voltage, low vertical leakage and high-temperature operation.




If you enjoyed this article, you will like the following ones: don't miss them by subscribing to :    eeNews on Google News


Linked Articles