Development of Voltammetry-Based Techniques for Characterization of Porous Low-k/Cu Interconnect Integration Reliability

This paper concerns the new method of detecting the integration failures in porous low-k (PLK)/Cu interconnects using simple voltammetry-based techniques. In essence, the technique takes advantage of the fact that pores in PLK allow permeation of liquid, including electrolyte, into interconnect structures. The infiltration of electrolyte allows the formation of a micro-cell, consisting of two mating Cu interconnect electrodes and the electrolyte in PLK, where simple linear voltammetry can examine various integration reliability issues pertinent to PLK/Cu interconnects. Specifically, the technique is proven to be effective in detection of 1) failure in Ta barrier, 2) cracks in the capping layer, and 3) trapped impurity in pores in PLK. The working principle of the voltammetry technique and demonstration of its effectiveness is introduced in this paper.