A thermally stable thin diffusion barrier in Cu/Si contacts was developed using a thin nano-crystalline ZrN film. The Cu/ZrN/Si contact system using a reactively sputtered ZrN barrier with 20 nm in thickness consisting of several to 10 nm grains tolerated annealing at 600 degreesC for 1 h without any Cu. penetration through the barrier. This was interpreted that the scarce structural change in the prepared nano-crystalline ZrN film due to annealing was favorite for the thermal stability of thin barrier application. (C) 2002 Elsevier Science B.V. All rights reserved.