US Patent 7776627 Flexible structures for interconnect reliability test

A method for forming an integrated circuit structure includes forming a test wafer. The step of forming the test wafer includes providing a first semiconductor substrate; and forming a first plurality of unit blocks over the first semiconductor substrate. Each of the first plurality of unit blocks includes a plurality of connection block cells arranged as an array. Each of the connection block cells includes two connection blocks, and a metal line connecting the two connection blocks. The method further includes forming a plurality of unit block boundary lines separating the first plurality of unit blocks from each other; and forming a first plurality of metal lines connecting a portion of the first plurality of unit blocks.