Tri-gate polycrystalline silicon thin-film transistors fabricated by continuous-wave laser lateral crystallization with improved electron transport properties

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 (μ _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 μ _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% μ _eff enhancement and 41% reduction of μ _eff variation were achieved at the surface carrier density of 5 × 10 ¹² cm ^-2. These results are expected to be useful for the device size shrinkage of high-performance poly-Si TFT circuits.