Manufacturing reliable unlanded vias without CVD barrier layers

As device dimensions shrink in semiconductor technology, new tools and techniques are needed to solve reliability issues due to small overlap tolerances. For the 0.25 μm technology and beyond, Titanium Nitride (TiN) Chemical Vapor Deposition (CVD) tools and processes were developed to improve the reliability of unlanded vias with small overlap tolerances in these processes. These tools are expensive and thus cost prohibitive to implement for smaller companies. In this paper, a financially preferable solution using more conventional Physical Vapor Deposition (PVD) equipment that is already in use is presented. Depositing and anisotropically etching PVD TiN can create a protective sidewall on the underlying metal prior to the deposition of the Inter-Metal Dielectric (IMD). The resulting quality of via strings in extreme misaligned (unlanded) conditions with and without this sidewall is examined.