Source/Drain Activation for Flexible Poly-Si Nanoscale pFETs with a Laser-Buffer Layer by CO₂ laser Annealing

A laser-buffer layer of SiO 2 /W/SiO 2 with a high reflectivity at 10.6 μ m enables CO 2 laser treatment for the source/drain dopant activation of poly-Si nanoscale field-effect transistor (nano-FET) (W ch /L g = 70/70 nm) on the flexible polyimide substrate. The laser-buffer layer thermally modified by CO 2 laser reduces the sheet resistance of the source/drain to 1.4 kΩ/sq. at low laser energy of 15 W and low substrate temperature of 125 °C. The flexible nano-FET (nano-fFET) exhibits a subthreshold swing (S.S) of 84 mV/dec. and a low drain-induced barrier lowering of 202 mV/V at a bending radius of 10 mm. Low degradation rate of S.S and threshold voltage (V th ) for single- and multi-channel nano-fFETs arises from oxide-trap predomination after long time hot-carrier stress as demonstrated by a ΔV th power-factor of ∼0.2.