ALLOYING OF COPPER FOR USE IN MICROELECTRONIC METALLIZATION

Although copper offers low resistivity and high electromigration resis tance, its diffusion (under electrical bias) into surrounding dielectr ic layers, poor adhesion to such layers, and poor corrosion resistance has necessitated the search for an alloying element that can provide a solution to all these problems without affecting copper's resistivit y and electromigration resistance. In this paper we present the approa ch taken to find such an alloying element (namely Mg or Al) and then d escribe and discuss the results obtained from the use of Cu(Mg) and Cu (Al) alloys. It is shown that although both systems will work well, Cu (Mg) offers better properties, especially its low alloy resistivity. M ethods of preparing such alloys are discussed briefly.