Surface Plasma Treatment of Polyimide Film for Cu Metallization

Surface modification of polyimide films by oxygen/argon atmospheric pressure plasma (APP) was studied for copper metallization under several conditions, including plasma treatment time, gas ratio, and power of radio frequency (RF; 13.56MHz) plasma. The effects of APP treatments on the surface properties of polyimide (PI) films were investigated in terms of Fourier-transform infrared (FT-IR) spectroscopy, atomic force microscopy (AFM), and contact angle measurements. The results showed that the root-mean-squared (RMS) roughness of untreated PI films was 1.48nm, increasing to 2.08, 2.17, and 2.57nm after plasma treatment at 200, 400, and 600W, respectively. At the same time, the contact angle of untreated PI film was 73.0 � and reduced to 25.9, 20.3, and 17.3 � after plasma treatment at 200, 400, and 600W, respectively. The lowest contact angle and the maximum RMS roughness were 13 � and 8.50nm, respectively. Those values were achieved by oxygen/argon APP at an RF plasma power of 600W and with 50 repetitions. Also, X-ray diffraction (XRD) was used to examine the Cu surface structure in the Cu/PI system to indicate the quality of Cu foil. The highest Ið111Þ=Ið200Þ ratio was 1.89 at an RF power of 600W by oxygen/argon APP treatment. # 2011 The Japan Society of Applied Physics