| 摘要 |
PURPOSE: A fabrication method of high voltage horizontal diffusion MOS transistors is provided to reduce a manufacturing cost by simplifying processes using same buffer oxide layers. CONSTITUTION: The method comprises the steps of: an upper region forming step to grow an epi-layer(2) on a substrate(1) and to form a deep well(3); a lower region forming step to a channel region and drift regions(5,7) to deposit a field oxide layer(8) on the drift regions, the deep well and the epi-layer; an ion implanting step for controlling a threshold voltage on the channel region, wherein same buffer oxide layers(9,11) are used for an ion-implantation buffer; a gate oxide forming step to deposit a thick first gate oxide layer(10) on the channel and drift regions formed on the well and to deposit a thin second gate oxide layer(12) formed on the epi-layer; and a device region forming step to form a gate on the field oxide, a source(13) and channel stop regions(14,17) in the channel region by ion-implanting, and a drain(18) in the drift region.
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