Characterization Of Lpcvd Aluminum For Vlsi Processing

Aluminum and aluminum alloys are widely used for metallizing devices in VLSI processing. Such films can be deposited by a variety of techniques, which all presently suffer from inadequate step coverage. In this paper, we discuss the properties of aluminum films deposited by a low pressure chemical vapor deposition process using tri-isobutyl aluminum as a source. Results of this work demonstrate that this process provides conformal step coverage, introduces no surface states, and promises to yield high wafer throughput. Films deposited on oxidized silicon monitors exhibit excellent properties in terms of chemical purity, adhesion, and electrical resistivity. Films deposited on device wafers prove to be compatible with current VLSI processing in terms of patterning, dry etching, and bondability and appear to have no effect on overall device performance. However, drawbacks of LPCVD aluminum appear to be in its structure-related properties: namely, electromigration resistance and Al-Si interdiffusion. These problems and potential solutions are addressed.