High-performance thin-silicon-film transistors fabricated by double laser crystallization
Journal
Journal of Applied Physics
Journal Volume
99
Journal Issue
3
Date Issued
2006
Author(s)
Abstract
Ultralarge-grained polycrystalline-silicon films have been formed from 50-nm-thick amorphous-silicon layers using double-laser crystallization (DLC). In situ images were captured to monitor the transient melting and solidification processes. Scanning electron microscope and plan-view transmission electron microscope analyses show that lateral grain dimensions up to 10μm can be achieved by this crystallization method. Prepatterning of the amorphous-silicon film prior to DLC provides a means for modifying the lateral temperature profile (hence grain structure) via edge cooling effects. Amorphous-silicon films as thin as 20 nm can be crystallized by DLC. Atomic force microscope images showed rms surface roughness less than 3 nm. High-performance n-channel thin-film transistors (TFTs) were fabricated in 50-nm-thick DLC films, with channel regions aligned to the large-grained regions, yielding electron field-effect mobilities as high as 124cm2∕Vs, threshold voltage as low as 0.2 V, and on-off current ratio as high as 108. The DLC poly-Si TFTs show substantially better performance than control devices fabricated via excimer laser crystallization.
SDGs
Type
journal article