Scalability study of laser-induced vertical make-link structure

The scalability of a direct metal-to-metal connection between two different levels of metallizations has been extrapolated to be compatible with moder n semiconductor fabrication technology. A simple equation to evaluate the s calability was formulated based on focused ion beam (FIB) cross-sectional i mages of larger link structures with various sizes. With a 0.6-mum-thick me tal 1 line and a 0.5-mum-thick interlevel dielectric (ILD), a width of less than 0.5 mum is evaluated to be possible for the metal 1 line. Two limitat ions exist in the process of scaled-down link structures, which are the rat io of the thickness of ILD to the thickness of the metal 1 line, t(ILD) / t (m), and the quality of laser beam parameters including the spot size and p ositioning error. However, modern processing technologies and advanced lase r processing systems are considered to allow the scalability of a vertical make-link structure. Two layouts of two-level interconnects were designed w ith increased interconnect densities with a 1-mum pitch of a 0.5-mum-wide m etal 1 line. These results demonstrate the application of commercially viab le vertical linking technology to very large-scale integration (VLSI) appli cations.