ABSTRACT
This chapter discusses the metallic materials commonly used to form the conducting layers in integrated circuitry. It shows how a lithographic process can be used to pattern the conduction tracks on the chip surface. The chapter focuses on the metallisation systems used on silicon integrated circuits, and describes the metals used in circuits on GaAs wafers and high-temperature devices. There are two obvious requirements for a conductor material: that the resistivity of the thin films be as low as possible; and that the films should adhere strongly to both oxide and silicon surfaces. The chapter considers the development of aluminium alloy metallisation schemes, and presents a few of the advantages and problems associated with the use of gold conductors. The most theory of high-angle grain boundary structure is based on the so-called structural unit model. The chapter provides the diffusion through very large arrays of grain boundaries in a polycrystalline thin film.
