Wolfspeed makes premium 200 mm SiC substrates available to order
Wolfspeed has made a new Premium 200 mm n-type silicon carbide substrate commercially available, giving power device manufacturers another material option as they move production to larger wafers. The company is putting particular emphasis on crystal defects and wafer consistency, rather than diameter alone.
Its published specification is fewer than 0.01 micropipes per square centimetre, or fewer than three per wafer when measured by X-ray topography. Micropipes are defects that can render parts of a wafer unsuitable for devices. Wolfspeed also reports low threading screw dislocations and improved wafer shape and consistency between lots, although it has not published a comparative set of customer yield results.
Those measures matter because a larger wafer does not automatically produce more usable devices. A manufacturer also needs material that remains consistent through epitaxy and device fabrication, particularly as higher voltage devices and larger die increase the cost of losing an otherwise viable area of wafer.
Dr Cengiz Balkas, executive vice president of Wolfspeed’s Materials Business Unit, said the substrate gives customers “a stronger foundation for developing increasingly demanding silicon carbide devices”. Wolfspeed says the improvement in bare wafer quality can support better epitaxial results using customers’ existing processes.
The distinction between a material specification and a qualified production result is important. A device maker will still need to establish how the substrate behaves in its own epitaxy, fabrication and reliability processes. Defect maps, wafer shape, lot variation and the distribution of usable die will be more informative than a headline micropipe figure on its own.
Wolfspeed says the substrate is orderable now and that dedicated capacity is available. That gives customers a product to evaluate rather than a future development target. It does not establish how much material any particular customer has qualified or contracted.
