ROLE OF THIN FILM MATERIALS ON THE TECHNOLOGY OF INTEGRATED CIRCUIT FABRICATION.

Abstract

The article reviews current technology and future trends. As VLSI circuits shrink their minimum feature size or linewidth to a micrometer or less, new demands are imposed on interconnection technology and subsequently on the techniques to deposit such materials. At the gate level, the trend is toward refractory metal interconnections to hold down interconnection resistance. It appears that polysilicon in gates will be replaced by polycides and refractory metals. In device interconnections, modified aluminum systems such as heavily doped aluminum or doped aluminum plus barrier together with noble or refractory metals will appear. Tungsten would appear to have the most advantageous properties. Regarding deposition techniques, a change from evaporation to sputtering will continue for several reasons. First, high rate magnetron sputtering (planar and S-gun) has made sputtering rates nearly comparable to evaporation rates. Second, alloys (Al-Si, Al-Cu, Ti-W, etc. ) are being increasingly used, and control of the stoichiometry of these alloy films is easier to accomplish using sputtering. Third, due largely to the requirements of VLSI circuits, new materials, especially refractory metals and refractory-metal silicides, are needed. These materials are more compatible with sputter-deposition processes.