In this work, characteristics of low-k methyl-silsesquiazane (MSZ) for the chemical-mechanical-planarization (CMP) process using oxygen plasma pretreatment were investigated in detail. The low-dielectric-constant (low-k) MSZ was prepared by a spin-on deposition process. The resultant wafers were followed by an oxygen (O-2) plasma treatment. After oxygen plasma treatment, the CMP process was implemented. Electrical and material analyses were utilized to explore the characteristics of post-CMP MSZ. Experimental results showed that the polish rate. of MSZ film with O-2 plasma pretreatment was increased as much as two times in magnitude, as compared to that of the MSZ without O-2 plasma pretreatment. In addition, the post-CMP MSZ exhibited superior electrical properties. These results clearly indicated that the modification surfaces that resulted from O-2-plasma treatment facilitated CMP MSZ. After CMP polishing, the MSZ film still maintained low-k quality. (C) 2004 American Vacuum Society.