PROCESS-DEVELOPMENT FOR FABRICATING LOW-VOLTAGE AND HIGH-VOLTAGE CMOSDEVICES INTO LCD DRIVERS

As Liquid Crystal Displays (LCDs) have declined in price, this has res ulted in pressure for LCD driver ICs to come down in price. This paper reviews authors' recent work to develop a low-cost CMOS process for f abricating low- and high-voltage CMOS devices into LCD driver. More sp ecifically, their effort has been to develop common CMOS process that can be applied to both low-voltage and high-voltage transistors concur rently, thus reducing the number of CMOS process steps for fabricating low- and high-voltage CMOS devices. Also, by lowering the annealing t emperature of high-voltage CMOS process, authors have succeeded in shr inking the cell size of high-voltage transistors. Compared with the co nventional process, the new process has made it possible to reduce the number of masks and process steps by 15% and 20%, respectively. In ad dition, p-channel cells and n-channel cells have been reduced in size by 64% and 45%, respectively. This makes it possible to scale down an eight gray levels LCD driver IC by 30%.