Effective annealing and crystallization of si film for advanced TFT system
Abstract The effect of the crystallization and activated annealing of Si films using an excimer laser and the new CW blue laser are described and compared with furnace annealing for application in advanced TFTs and for future applications. Pulsed excimer laser annealing (ELA) is currently being used extensively as a low‐temperature poly‐silicon (LTPS) process on glass substrates as its efficiency is high in the ultra‐violet (UV) region for thin Si films with thickness of 40–60 nm. ELA enables extremely low resistivity relating to high crystallinity for both the n‐ and p‐type Si films. On the other hand, CW blue laser diode annealing (BLDA) enables the smooth Si surface to have arbitral crystal grains from micro‐grains to an anisotropic huge grain structure only by controlling its power density. Both annealing techniques are expected to be applied in the future advanced TFT systems.
Effective Dopant Activation in Silicon Film Using Excimer Laser Annealing for High-Performance Thin Film Transistors
After ultraviolet (UV) pulsed excimer laser annealing (ELA) for highly phosphorus doped Si film at a dose of 2 ×1015 cm-2, the relationship between conductivity and crystallinity of the film was studied. As a result of spectroscopic ellipsometry (SE) analysis, the conductivity increased with improving the crystallinity of the annealed Si film. By optimizing laser annealing condition at 350 mJ/cm2, efficient solidified activation after melting occurs, the Si film showed extremely low sheet resistance down to 100 Ω/□, and was decreased furthermore to as low as 80 Ω/□ by increasing the shot number. The effectively activated result for the doped Si film is comparable to the result for bulk single-crystalline Si under thermal equilibrium condition. By observing the Raman shift for the effectively activated film, tensile stress was clearly confirmed similar to the case of excimer laser crystallization (ELC) for undoped Si film. ELA activation for phosphorus-doped Si film is considered to be effective for the formation of the source and drain in high-performance Si thin film transistors (TFTs) as well as for the formation of the junction of a diode sensor for system on panel (SoP).
Characterization of Aqueous Dispersions and Gels Made of Sodium Caseinate and Basil Seed Gum: Phase Behavior, Rheology, and Microstructure
The interactions between sodium caseinate (NaCas) and basil seed gum (BSG) in the presence of calcium chloride (CaCl 2 ) were investigated. The phase behavior of the mixed aqueous dispersions and their gels revealed a homogeneous mixture, obtained at the higher concentrations of both CaCl 2 and BSG. The Herschel-Bulkley model sufficiently fitted the flow behavior of the mixture solution data. Apparent viscosity increased significantly ( p  < 0.05) by increasing the concentration of BSG, where the addition of CaCl 2 had no significant effect on the viscosity of the samples ( p  > 0.05). Furthermore, there was an increase in thixotropy due to the higher concentrations of BSG and CaCl 2 . Based on the frequency sweep test, at the low frequencies, a more gel-like behavior was observed in the case of the higher concentrations of either BSG or CaCl 2 . The rheological and SEM data suggested that the stronger structure of NaCas-BSG gel in the presence of the higher concentrations of CaCl 2 was related to the induction of complex formation between the two biopolymers.