Semiconductor device and its fabrication

Abstract

In a semiconductor device and method for manufacturing the same, a buried insulating layer is formed on a semiconductor substrate, multiple depletion regions of a first conductivity type are formed on the buried insulating layer and separated from one another, a field oxide layer is formed among the depletion regions of the buried insulating layer, a gate oxide layer is formed on the depletion regions, a gate is formed on the gate oxide layer, impurity regions that are heavily doped with impurities of a second conductivity type is formed in the depletion regions on both sides of the gate to define a source and drain, and a counter doping layer that is lightly doped with impurities of the second conductivity type is formed under the channel defined by a portion of the depletion regions positioned between the impurity regions. The counter doping layer is formed at a predetermined or fixed distance from the upper surface of the depletion region defining the channel, overlapping the lower portion of the depletion region to achieve uniform thickness in at least a portion of the depletion region.

Dependencies are inferred from the claim text.