Controllable varactor within dummy substrate pattern

摘要

A dummy region varactor for improving a CMP process and improving electrical isolation from active areas and a method for forming the same, the varactor including a semiconductor substrate having a dummy region said dummy region including a first well region having a first polarity; shallow trench isolation (STI) structures disposed in the dummy region defining adjacent mesa regions comprising first, second, and third mesa regions; a second well region having a second polarity underlying the first mesa region having the second polarity to form a PN junction interface; wherein said second and third mesa regions having the first polarity are formed adjacent either side of said first mesa region.