Test structure with TDDB test pattern

摘要

A test structure includes a time dependent dielectric breakdown (TDDB) test pattern formed in a dielectric material on a wafer. The test pattern includes first and second conductive lines formed in the dielectric material. The second conductive line is adjacent to the first conductive line. The first conductive line and the second conductive line are separated by a first minimum distance at a first portion of the TDDB test pattern. The first conductive line and the second conductive line are separated by a second minimum distance at a second portion of the TDDB test pattern. The second minimum distance is greater than the first minimum distance. The second portion is different than the first portion. It also may have a third different portion with a third larger minimum distance between the first and second conductive lines. The TDDB test pattern may have a comb-comb or a comb-serpent structure, for example.