ALLOYING OF COPPER FOR USE IN MICROELECTRONIC METALLIZATION

Although copper offers low resistivity and high electromigration resistance, its diffusion (under electrical bias) into surrounding dielectric 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 resistivity and electromigration resistance. In this paper we present the approach taken to find such an alloying element (namely Mg or Al) and then describe 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. Methods of preparing such alloys are discussed briefly.