Abstract
films co‐sputtered from boron and 
targets were used as diffusion barriers between Cu thin films and Si substrates. Material characteristics of 
films and metallurgical reactions of 
system annealed in the temperature range 400–800°C for 30 min were investigated by glancing angle X‐ray diffraction, Auger electron spectroscopy, X‐ray photoelectron spectroscopy, scanning electron microscopy, and sheet resistance measurements. The chemical composition and resistivity of the co‐sputtered TiB films are sensitive to the bias applied on the substrate. A nanocrystalline 
film with a resistivity of 300 μΩ cm was obtained when a negative bias of 200 V was applied to the substrate during sputtering. After depositing a copper overlayer, we observed that the sheet resistance of the 
system stayed at a constant value after annealing up to 600°C for 30 min; however, the sheet resistance increased by almost five orders of magnitude after annealing at 700 and 800°C. At that point, the surface morphology was seriously deteriorated and formation of 
was also observed. The co‐sputtered 
diffusion barrier accordingly breaks down after annealing at 700°C for 30 min. © 2000 The Electrochemical Society. All rights reserved.