Abstract
Development of the “System-on-glass” display with low temperature Poly-Si (LTPS) TFT has rapidly advanced recently. The display incorporated with nonvolatile memories becomes an attractive topic. In this study, nonvolatile memories using low temperature poly-Si process with oxide-nitride-oxide (ONO) stack structure on glass was studied and fabricated. The memory window should be lager than 1V to meet the logic memory circuit. The operation of nonvolatile memory is giving differential bias combination on gate, source and drain, in order to program and erase. The traps of grain boundary in poly-Si, however, maybe degrade the performance in some operational mode. There could be some reliability issue in low temperature poly-Si nonvolatile memory. We therefore investigate various operational modes in N-channel and P-channel so as to search which operational mode is reliable. Using Fowler-Nordheim tunneling to program and hot hole injection to erase, the threshold voltage memory has 1.5V at P/E time of 100ms. After 104 P/E cycles, the devices maintain a 1.5v threshold voltage memory.