| 摘要 |
PURPOSE:To suppress a short channel effect and to improve a punch-through breakdown strength by forming a channel impurity layer to become of a higher concentration on the periphery than that of the center of a channel region. CONSTITUTION:A first p-type layer 5 is formed as a channel impurity layer on a channel region between source and drain diffused layers 41 and 42, and second p-type layers 61, 62 are selectively formed near the layers 41, 42. Thus, even when the channel impurity layer is formed to have a relatively high concentration, the increase in the bonding capacity between a source and a drain is less than that of a conventional structure in which a channel impurity is doped in the whole element forming region. The improvement in the punch- through breakdown strength and the decrease in the short channel effect are performed at a section having high impurity concentration at the periphery of the channel region.
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