Use of atomic layer epitaxy for fabrication of Si/TiN/Cu structures

The properties of titanium nitride deposited by atomic layer epitaxy (ALE) using three different deposition processes, i.e., TiI4+NH3, TiCl4+NH3 and TiCl4+Zn+NH3, as a diffusion barrier between copper and silicon were investigated. After deposition and annealing in Ar/H2, the samples were studied by means of x-ray photoelectron spectroscopy, scanning electron microscopy, x-ray diffraction, sheet resistance measurements and by defect delineating etching of the silicon substrate. ALE TiN deposited by means of the TiCl4/Zn/NH3 process showed the best barrier properties since it was stable at 700 °C, whereas TiN barriers deposited by the two alternative processes started to break down after a 75 min anneal at 650–750 °C. Even though the TiN barriers deposited by the TiI4/NH3 and TiCl4/NH3 processes were not completely comparable to the TiCl4/Zn/NH3 TiN, they were stable for a 15 min anneal at 700 °C which is comparable to or better than previously reported for chemically vapor deposited and physically vapor deposited TiN. Finally, the TiN and copper were of high purity and the deposition on patterned substrates showed good step coverage.