Peter W. Green

Low Temperature Poly-Si on Flexible Polymer Substrates for Active Matrix Displays and Other Applications

A variety of polymer materials including polyimide (PI), polyarylate (PAR), polynorbonene (PNB) and polyethersulphone (PES) have been studied for use as substrates in the formation of active matrix displays based upon polycrystalline silicon (poly-Si) thin film transistors (TFTs). A process used to fabricate transflective mobile phone displays at 250°C on such substrates is described in detail. The NMOS TFTs show a mobility of 100cm 2 /Vs, and a threshold voltage of 3.9V; the PMOS devices have a mobility of 52cm 2 /Vs, and a threshold voltage of -6V. Issues relating to performance of these devices, yield of the arrays, and manufacturability are discussed.