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 ultraviolet (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.

Investigation on characteristics of millisecond solid-phase crystallized silicon films annealed by atmospheric pressure DC arc discharge micro-thermal-plasma-jet and their application to bottom-gate thin film transistors fabrication

“…These values are a little higher than the resistivity of the poly-Si film formed by other low-temperature poly-Si processes. For instance, according to T. Noguchi, 34) the lowest resistivity of P-doped Si film formed by excimer laser annealing with a pulse energy density of 350 mJ cm −2 is 4.2 × 10 −4 Ωcm. In principle, these values are suitable for transistor fabrication.…”

Performance dependence of self-aligned dual-gate poly-Si TFTs on localized defective regions

“…The poly-Si channel layer was transformed from an a-Si layer using a laser annealing process. Therefore, multiple grain boundaries (GBs) are expected because of the grain impediment during the grain growth [40]. Multiple GBs in a poly-Si layer have been verified and are normally considered in the studies of poly-Si TFTs [37,38,41].…”