Nexwafe to open 250 MW factory for kerfless mono wafers in 2020

German start-up Nexwafe, a spin-off from the Fraunhofer Institute for Solar Energy Systems, will build a 250 MW factory for epitaxially grown, kerfless monocrystalline n-type wafers (‘epi-wafers’) in the chemical park of Bitterfeld-Wolfen in eastern Germany.

The factory will be located next to Silicon Products Bitterfeld (SPB), a former polysilicon manufacturer that is now mainly active in engineering. SPB will supply chlorosilanes from its plant to Nexwafe.

Nexwafe uses a 400 micrometer (µm) thick monocrystalline seed wafer and etches a porous layer underneath the wafer surface with an in-line machine. Silicon is deposited from the gas phase (a mixture of chlorosilanes) and epitaxially grown on the seed wafer in an in-line oven.

The seed wafer and the epi-wafer are then separated along the porous layer by two vacuum plates. The seed wafer loses 3 µm of silicon at each run and is used 50 times.

Prospective customers have demanded 150 µm thick epi-wafers. Nexwafe is currently establishing a 5 MW pilot facility at its headquarters in Freiburg. The new 250 MW factory will be built in 2019 and start ramp-up in 2020. Regarding costs, Nexwafe only says the factory will be in the black.