Scalability study of laser-induced vertical make-link structure

Abstract

The scalability of a direct metal-to-metal connection between two different levels of metallizations has been extrapolated to be compatible with modern semiconductor fabrication technology. A simple equation to evaluate the scalability was formulated based on focused ion beam (FIR) cross-sectional images of larger link structures with various sizes. With a 0.6-/spl mu/m-thick metal 1 line and a 0.5-/spl mu/m-thick interlevel dielectric (ILD), a width of less than 0.5 /spl mu/m is evaluated to be possible for the metal 1 line. Two limitations exist in the process of scaled-down link structures, which are the ratio of the thickness of ILD to the thickness of the metal 1 line, t/sub ILD//t/sub m/, and the quality of laser beam parameters including the spot size and positioning error. However, modern processing technologies and advanced laser processing systems are considered to allow the scalability of a vertical make-link structure. Two layouts of two-level interconnects were designed with increased interconnect densities with a 1-/spl mu/m pitch of a 0.5-/spl mu/m-wide metal 1 line. These results demonstrate the application of commercially viable vertical linking technology to very large-scale integration (VLSI) applications.