Use of gas as low-k interlayer dielectric in LSI´s: Demonstration of feasibility

Reduction of the wire capacitance in LSI´s has become an issue of the utmost importance since the wire parasitic capacitance plays a significant role in determining both chip speed and power. Low dielectric constant materials such as SiOF (k=3.3) are already in use in manufacturing, while other materials with lower dielectric constants (k=2.0~3.0) are under development. Technology for further reduction of the dielectric constant, however, has not been reported so far. In this paper, we propose a gas-dielectric process that has the potential to achieve almost the minimum physically possible value for the dielectric constant: 1.0. The conceptual feasibility of the process is demonstrated, and basic process characterization data are presented. In addition, issues to be considered when integrating the proposed process into LSI manufacturing are identified, and work currently in progress addressing these issues is discussed