High-Mobility Poly-Si Thin Film Transistors Fabricated on Stainless-Steel Foils by Low-Temperature Processes Using Sputter-Depositions

Abstract

High mobility n-and p-channel polycrystalline Si thin film transistors (poly-Si TFTs) are successfully fabricated on flexible stainless-steel foils through low-temperature processes ( 200 • C). In the low-temperature process, all films in the poly-Si TFT including active Si and gate SiO 2 films are deposited by glow-discharge sputtering and the Si films are crystallized by KrF excimer laser irradiation. Resulting n-and p-channel poly-Si TFTs show excellent characteristics of mobility of 106 cm 2 /V·s and 66 cm 2 /V·s, respectively. Moreover, they show low off-currents of 1 × 10 −10 A and on/off current ratios as high as 1 × 10 6 . Thus, these poly-Si TFTs are very promising for driver circuits and switching devices in novel flat panel displays of lightweight and mechanically strong liquid crystal displays and light emitting displays.

A New Approach of Polycrystalline Silicon Film on Plastic Substrate Prepared by Ion Beam Deposition Followed by Excimer Laser Crystallization at Room Temperature

“…4) The low content of hydrogen in the a-Si film is easily controlled using the sputtering technique (hydrogen content < 1%). 5,6) However, the sputtered a-Si film also has the problem of film delamination during ELA. Some reports explain that this delamination is due to film ablation by explosive evolution of captured Ar gas.…”

Large-grain polycrystalline silicon film by sequential lateral solidification on a plastic substrate

“…However, the majority of transparent plastic substrates are temperature-resistant only up to 200 -C, necessitating low-temperature procedures for the crystallization of amorphous silicon (a-Si) films [1][2][3][4][5][6][7]. Similar to conventional process of the Si industry, SiO 2 and a-Si films are deposited successively.…”

“…To prevent the abrupt effusion of hydrogen during laser crystallization from damaging the Si films, researchers tested a multiple-step crystallization process [1,2]. When a-Si films are deposited by radio frequency (RF) magnetron sputtering [3][4][5] or by DC sputtering [6,7], they contain a residual working gas, such as Ar or He, which imposes difficulty in practicing a-Si laser annealing.…”

Amorphous oxide TFT and their applications in electrophoretic displays

“…Degradation of a-Si by electrical bias stress also causes a serious problem [62]. LTPS has been extensively studied as an alternative for a-Si, due to high mobility of more than 100 cm 2 /V s [63,64]. However, LTPS TFT suffers from its poor homogeneity owing to the grain boundaries.…”