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 lat-eral 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 R3 twin boundaries were typically observed. This technique enables simultaneous enhancement of grain size and control of crystal orientation. VC 2011 The Electrochemical Society. [DOI: 10.1149/1.3610410] All rights reserved. Manuscript submitted February 3, 2011; revised manuscript received April 25, 2011. Published July 18, 2011. The laser annealing technique for silicon thin films is widely used to fabricate low-temperature poly-Si thin-film transistors (LTPS TFTs). In particular, excimer-laser annealing (ELA) has been developed for practical applications.1 In this method, a poly-Si film with submicron silicon crystal grains is formed uniformly on

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Tri-gate channel structures were applied to polycrystalline silicon (poly-Si) thin-film transistors (TFTs) fabricated by continuous-wave (CW) laser lateral crystallization (CLC). We had two objectives in using tri-gate structures in CLC poly-Si TFTs. One was the enhancement of effective electron mobility ( eff ) by using the tensile strain induced by the CLC process and the lateral-strain-relaxation effect in tri-gate structures. The other was the reduction of eff variation caused by increasing the number of surfaces with different crystal orientations by up to a factor of three. By applying tri-gate structures to CLC poly-Si TFTs, both 8% eff enhancement and 41% reduction of eff variation were achieved at the surface carrier density of 5 Â 10 12 cm À2 . These results are expected to be useful for the device size shrinkage of high-performance poly-Si TFT circuits.