Low-temperature poly-Si TFTs of metal source and drain using blue-laser-diode annealing (BLDA)

Abstract

Blue-laser-diode annealing (BLDA) in the continuous wave mode was performed for sputtered silicon (Si) films. Polycrystalline silicon (poly-Si) thin-film transistors (TFTs) were fabricated on a glass substrate. For the source and drain formation, titanium (Ti) was evaporated to make the metal directly contact the channel Si film without adopting n + doping. The improvement of the drain current was confirmed after hydrogen annealing at 400°C, and the typical poly-Si TFT characteristic with 50 cm 2 /Vs deduced effective carrier mobility was successfully observed. As the low-cost TFT fabrication without ion implantation becomes feasible, the low-temperature fabrication of poly-Si TFTs using BLDA is expected. ARTICLE HISTORY

Low-temperature poly Si TFTs via BLDA for a Ne-sputtered Si film using sputtered gate SiO2

“…In these two TFTs, a gate SiO 2 was formed via RF sputtering using SiO 2 as the target [19]. As an a-Si film deposited by a PE CVD film at below 300°C has a high hydrogen atom content, the Si film was subjected to de-hydrogenated annealing at 500°C for 1 h in N 2 ambient before BLDA to obtain a high-crystal structure for the Si film.…”

“…Based on the result, the Si film obtained after BLDA had apparently been crystallized. Figure 4 shows the transmission electron microscopy (TEM) image of the poly-Si films sputtered via BLDA at 5 W [19]. The grain size is less than 300 nm, and the film has slightly small defects.…”

“…is considerably reduced by terminating with hydrogen atoms. The device structure with a metal S/D is shown in Figure 2 [19].…”

“…Top-gate-structured poly-Si TFTs with a metal source and drain (S/D) poly-crystallized using BLDA were fabricated based on a low-temperature process on glass [19]. For the TFT fabrication, a 50-nm-thick Si film was deposited via RF sputtering.…”

Appearance of the p-channel performance of poly-Si TFTs with a metal S/D electrode using BLDA aiming for low-cost CMOS

“…On the other hand, blue laser diode annealing (BLDA) for the a-Si film has been reported as a candidate for the next-generation LTPS process [6][7][8] because the blue diode laser beam can heat up the thin a-Si film uniformly due to its slightly higher penetration depth compared to the ultraviolet (UV) light beam, and is expected to realize a uniform grain size and to be effectively activated with reduced surface roughness [6][7][8][9][10]. The n-channel poly-Si TFT with a Ti metal source/drain (S/D) electrode deposited onto the sputtered poly-Si film after BLDA without using ion implantation has been proposed, and the n-channel transistor characteristic has been reported [11]. The typical transfer curve for a same-structured TFT based on an Si film that underwent plasma-enhanced chemical vapor deposition (PECVD) is shown in Figure 1 [12].…”