Laser slicing to slash SiC wafer production costs, increases yield

August 22, 2016 // By Julien Happich
Japanese ingot processing equipment manufacturer DISCO Corporation has unveiled a new laser-based technique to slice wafers out of a SiC ingot, producing 50% more wafers through reduced material losses while slashing production times by a factor of six.

Dubbed KABRA (for Key Amorphous-Black Repetitive Absorption), the patent-pending process uses a focused laser to form an amorphous layer of SiC decomposed into its constituents silicon (Si) and carbon (C), which becomes the base point for separating the wafer through cleavage.

While today's wafer production typically involves the use of multiple diamond wire saws, taking several days to slice through an ingot and producing considerable material waste (about 200µm of material loss per wafer), the KABRA process is not only much faster but also requires less wafer processing steps because it doesn’t leave micro-undulations on the surface, as do wire saws.


Diamond wire saw process.

Making practical comparisons, the company says that while competing processes typically require about two hours to slice a wafer from a 4-inch diametre SiC ingot (between 2 to 3 days for a full ingot), the new process only requires 25 minutes to slice a wafer (30mns when working with 6-inch diametre SiC ingots).


KABRA process flow: KABRA formation inside
the ingot by laser irradiation; wafer separation,
grinding to the specified thickness and
upper surface grinding of the ingot for the next
laser irradiation.

Because wire processing leaves some undulations (about 50µm high) on the surface of wafers, a lapping process is further required. DISCO Corporation claims its KABRA process eliminates this extra step, further reducing costs.

The company is now offering to perform test cuts in its head office and R&D centre in Tokyo.

Visit DISCO Corporation at www.disco.co.jp