Thermal stability study of TiN/TiSi2 diffusion barrier between Cu and n+Si

Publisher Website
Google Scholar
Abstract
The failure mechanism of the TiN/TiSi2 bilayers as diffusion barriers between Cu and n +Si was investigated. The TiN/TiSi2 bilayers were formed by either annealing Ti (50 nm)/n +Si via various rapid thermal processes or reactively sputtering TiN (50 nm) on TiSi2. The degradation study of the Cu/TiN/TiSi2/n +Si contact system was undertaken by scanning electron microscopy, cross‐section transmission electron microscopy (XTEM), secondary‐ion‐mass spectrometry (SIMS), and diode leakage current and contact resistancemeasurements.Leakage currentmeasurements indicated no deterioration of n +‐p diode junctions up to 475 °C for 30 min in a N2 ambient. For the sintering temperature at 500 °C, the leakage current increased abruptly and SIMS profiles revealed a large amount of Cu atoms diffusing into the junctions of n +‐p diodes. XTEM showed that the small pyramidal‐shaped Cu3Si crystallite (with a size 0.25 μm) precipitated in the n +Si substrate. The formation of Cu3Si increased the occupied volume, then generated the gap between TiSi2 and n +Si, and gradually increased the specific contact resistance. The diffusion resistance, depending on the thickness of TiN film, was also observed.

This publication has 23 references indexed in Scilit: