SINGLE-CRYSTAL SILICON MICROBLOCKS PRODUCED BY A SELECTIVE RECRYSTALLIZATION TECHNIQUE

A Previously reported ac magnetic-field technique has here been applie d to selective recrystallization on quartz substrates of polysilicon t hin films which had been patterned into specific microblock designs. W ith the recrystallization it has been possible to produce single-cryst al silicon microblocks of a maximum size of approximately 60 X 40 X 2 mum,3 large enough for the fabrication of high-performance thin-film t ransistors. Microblocks used in the experiments were of two types: ''n etwork'' rectangles, connected on the wafer two dimensionally with pol ysilicon paths, and ''isolated'' rectangles adjacent to the network re ctangles. The surface morphology of the recrystallized silicon films w as observed with scanning electron microscopy. While no grain boundari es were found on the surfaces of the recrystallized network rectangles , many grain boundaries were observed to remain on the recrystallized isolated rectangles. X-ray diffractions for the recrystallized network rectangles were measured with a microfocused x-ray beam, and the recr ystallized network rectangles were confirmed to be single-crystal sili con' microblocks of good crystal quality. It had been expected that ne twork rectangles would be more greatly heated, as compared to isolated rectangles, by the eddy currents induced by the ac magnetic fields, a nd the observed higher quality of network-rectangle recrystallization has verified that anticipated eddy-current contribution.