Polycrystalline boron carbon nitride (BCN) films are synthesized by plasma-assisted chemical vapor deposition using BCl3, CH4 and N-2 as source gases. In order to investigate the influence of the annealing process on properties of Cu/BCN/p-Si samples, capacitance-voltage, current-voltage, X-ray photoelectron spectroscopy and Auger electron spectroscopy measurements are carried out. The dielectric constant of the as-grown BCN film decreases after annealing at 400 degreesC for 15 min. A dielectric constant as low as 2.1 is achieved. Cu diffusion is examined by AES measurements for samples annealed in the temperature range from 350 to 450 degreesC. The diffusion depth of Cu is estimated to be from 76 to 88 nm. No variation in the leakage current occurs after annealing at 375 degreesC (C) 2002 Elsevier Science B.V. All rights reserved.