400V MOS IC for EL display

A NUMBER of MOS developments have been attempted to provide operation at voltages higher than 200V1-5. Among these, DSA6 MOST seem to have a promising future. This paper will describe a high voltage, DSA MOS IC which operates in excess of 400V. It was designed as a driver for electroluminescent displays . Low voltage logic and thirty-two high-voltage output transistors are integrated on a single chip. The device consists of a pair of layers patterned as concentric conductive annular strips above which a layer of metal with a circular gap is deposited. This configuration and final passivation over the metal layer permit encapsulation in a plastic package. The high voltage DSA MOST was proposed earlier with a 71 substrate, a Diffusion-Self-Aligned structure, lightly doped drift region(N-), and a field plate extended from the draine lectrode1 The drift region of this device was not covered by field plates; i.e., an offset gate structure. If the field plate is extended to cover all of the drift region in these devices, the electric field at the edge of the drift region will be enhanced and the breakdown voltage reduced.