US Patent 7095063 Multiple supply gate array backfill structure

A multiple supply gate array structure facilitated by the provision of a shared n-well and an isolated n-well is described. The gate array structure allows implementation of a single voltage circuit or a multiple voltage circuit. In addition, the gate array structure allows metal reprogram to provide standard logic functions, or special logic functions such as a buffer function for a signal crossing a voltage island boundary. Other special logic functions may include, for example, a level-shifter function or a fence-hold function.