Chemical Vapor Deposition of Copper for Multilevel Metallization

Abstract

Since the birth of integrated circuitry about thirty five years ago, microelectronics design and manufacturing technologies have evolved toward higher integration density with smaller design rules. As the semiconductor industry moves into ultra-large-scale integration (ULSI), device geometries continue to shrink into the sub-half-micron region while circuit densities increase to optimize reliability and improve performance. The resulting demands on interconnect technologies necessitate the exploitation of all development avenues: design, materials, and manufacturing.Emerging sub-half-micron technologies require multilevel metallization (MLM) design schemes that reduce interconnection lengths and lead to lower signal transmission delays and enhanced device speeds. MLM schemes also permit increased device density, due to the ability to use the third (vertical) dimension, and easier signal routing because of higher flexibility in architectural design. These schemes, in turn, demand interconnect metals that can handle the higher current densities resulting from the decreasing size of device features, without the loss of electrical and structural integrity, and deliver the sheet resistance needed to meet performance demands. They also require reliable deposition techniques to successfully fabricate the increasingly complex architectures as lateral feature sizes are scaled down more rapidly than conductor or insulator thicknesses.