| 摘要 |
A test pad structure in a back-end-of-line metal interconnect structure is formed by repeated use of the same mask set, which includes a first line level mask, a first via level mask, a second line level mask, and a second via level mask. The test pad structure includes a two-dimensional array of test pads such that a first row is connected to a device macro structure in the same level, and test pads in another row are electrically connected to another device macro structure of the same design at an underlying level. The lateral shifting of electrical connection among pads located at different levels is enabled by lateral extension portions that protrude from pads and via structures that contact the lateral extension portions. This test pad structure includes more levels of testable metal interconnect structure than the number of used lithographic masks. |
| 主权项 |
1. A lithographic mask set comprising,
a first line level mask including a first opaque patterned structure located on a first transparent substrate and defining a first pattern, said first pattern including a first array of first pad shapes and first lateral extension portion shapes, wherein each of said first lateral extension portion shapes protrudes from one of said first pad shapes; a first via level mask including a second opaque patterned structure located on a second transparent substrate and defining a second pattern, said second pattern including first via shapes that, upon overlay of said second pattern with said first pattern, are located within areas of said first lateral extension portion shapes; and a second line level mask including a third opaque patterned structure located on a third transparent substrate and defining a third pattern, said third pattern including a second array of second pad shapes and second lateral extension shapes, wherein each of said second lateral extension shapes protrudes from one of said second pad shapes, and areas of second lateral extension shapes, upon overlay of said third pattern with said second pattern, include areas of said first via shapes and, upon overlay of said third pattern with said first pattern, overlap areas between said third pattern and said first pattern do not include any area of said first pad shapes or said second pad shapes. |
