The Chemical Vapor Deposition of Al-Cu Films Utilizing Independent Aluminum and Copper Organometallic Sources in a Simultaneous Deposition

The chemical vapor deposition (CVD) of aluminum is now gaining accceptance as a viable metallization technology for the fabrication of sub-0.5 micron interconnects. The incorporation of 0.5% copper into these aluminum films to enhance their electromogration resistance has been achieved by a number of different approaches. These techniques include the sequential CVD of the individual metals and the consecutive growth of CVD Al / PVD Cu followed by an interdiffusing thermal anneal. The potentially more elegant and streamlined solution explored in this paper is the simultaneous deposition of Al and Cu by CVD. A key requirement of this approach is the selection of copper precursors which are stable, volatile and free from oxygen and fluorine. The absence of the latter two elements is essential due to the high probablity of their extraction from the copper precursor by aluminum to form involatile aluminum oxyfluoride species. In our investigation of simultaneous Al/Cu we have utilized two well known aluminum hydride based precursors (DMAH and DMEAA) with two different copper precursors and we herein report the successful deposition of Al-Cu alloys using this approach. A discussion is presented of the dependence of the resulting Al-Cu film quality upon the choice of Al and Cu precursors used in addition to the CVD process parameters utilized for film growth.