Study of Singlecrystalline Pure Metal Interconnect for VLSI's

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In order to establish high performance interconnect scheme for ultra large scale,ultra high speed LSI's, a systematic study of thin film formation and characterization as well as theoretical and experimental studies of high speed signal propagation has been carried out.The DC-RF coupled mode bias sputtering technology has been developed to form high purity, high quality metal thin films on semiconductor substrates. This technology is characterized by it's unique feature of precise ion-energy control by externally applied DC biasing. As a result, high throughput of metal deposition process was established. Furthermore,the properties of deposited metal films were drastically charged by controlling the energy of Ar ions bombarding the growing metal surfaces. For instance,completely (111) oriented Al and Cu thin films with extremely smooth surface morphologies were obtained by applying a DC voltage of -40V to wafers. Very important to note is that hillock-free Al thin films were formed by optimally controlling the incoming Ar ion energy and fluence simultaneously.The theoretical and experimental analysis of signal propagation in interconnects has revealed that the conventional interconnect structure is not suitable for ultra high speed regime, thus proposing a new Metal-Oxide-Metal (MOM) structure as an candidate for ultra high speed LSI interconnects. The MOM structure using metal films prepared by newly developed bias sputtering technology will be an ideal form of interconnect for future VLSI's.