SIZE-FILTERED MULTIMETAL STRUCTURES

摘要

A size-filtered metal interconnect structure allows formation of metal structures having different compositions. Trenches having different widths are formed in a dielectric material layer. A blocking material layer is conformally deposited to completely fill trenches having a width less than a threshold width. An isotropic etch is performed to remove the blocking material layer in wide trenches, i.e., trenches having a width greater than the threshold width, while narrow trenches, i.e., trenches having a width less than the threshold width, remain plugged with remaining portions of the blocking material layer. The wide trenches are filled and planarized with a first metal to form first metal structures having a width greater than the critical width. The remaining portions of the blocking material layer are removed to form cavities, which are filled with a second metal to form second metal structures having a width less than the critical width.