Seed-free fabrication of highly bi-axially oriented poly-Si thin films by continuous-wave laser crystallization with double-line beams

Highly bi-axially oriented poly-Si thin films with very long grains (100 m) were successfully fabricated on quartz substrates by continuous wave laser crystallization with parallel double-line beams, without seed crystals. The newly-developed technique restricts crystal nucleation time and enhances growth of crystal nuclei of a specific orientation selectively, which is preferentially generated. The technique achieved highly-oriented silicon grains having (110), (111) and (211) crystal orientations in the laser lateral crystallized plane, the transverse side plane and the surface plane, respectively. All the silicon grains were elongated in the laser-scanning direction and linearly arranged with a length of over 100 m and a width of 0.7 m. The laser-crystallized poly-Si films were crystallographically investigated precisely, and electrically inactive CSL 3 twin boundaries were typically observed. This technique enables simultaneous enhancement of grain size and control of crystal orientation.