Metal-induced laterally crystallized polycrystalline silicon: technology, material, and devices

Abstract

Polycrystalline silicon (poly-Si) has been obtained by low- temperature (< 500 degree(s)C), nickel-based, metal-induced crystallization (MIC) of amorphous silicon. Because crystallization outside of the nickel-covered regions is not only possible but also commonly utilized, the technique is more often called metal-induced lateral crystallization (MILC). Based on studies on the crystallization kinetics and material characteristics, a unified mechanism is proposed for MIC both under and outside of the nickel coverage. Conduction in MILC poly-Si is found to be anisotropic with respect to the MILC direction. While the material quality of MILC poly-Si is significantly better than that of solid- phase crystallized poly-Si, the performance of MILC poly-Si thin-film transistors (TFTs) is quite sensitive to and degraded by the inclusion of MIC/MILC interfaces in the device channel regions. When such interfaces are eliminated, excellent TFTs are obtained that can be used to realize high performance systems-on-panels, including sophisticated displays based on liquid crystals or organic light-emitting diodes. The application of MILC poly-Si is not limited to low-temperature electronics, it is found that high- temperature recrystallization results in MILC poly-Si with material quality approaching that of single-crystal Si. Re- crystallized MILC poly-Si has been used to realize high performance piezo-resistors and TFTs for integrated sensor applications.