Study On The Fixed Abrasive Polishing Pad For Micro-electronics Manufacturing

The materials for Integrated Circuit (IC) consist of silicon, germanium, arsenic gallium. Among them, the proportion of single crystal silicon used in IC industry is over 90 percent. As we known, silicon is a typical hard brittle material which is difficult to be machined, while the diameter of wafer trends to be larger because of the fast development of IC manufacturing technology. It is a big challenge to get a high surface quality of wafer. Based on this background, first, and the preparation mechanism of this technology was studied. Then, relevant experiment was conducted with fixed abrasive pad polishing, compared with conventional polishing.The main work and results are as follows:1. Various abrasives applied in fixed abrasive polishing pad were discussed. The modification of silicon dioxide, alumina and diamond surface was analyzed using such analysis methods as FT-IR, XPS. Abrasives were modified by ultrasonic combined with dispersant and the best dispersant was obtained through the sedimentation experiment.2. The matrix of fixed abrasive polishing pad was made by ultraviolet curing technology and ultraviolet curing parameter and kind of ultraviolet curing resin were chosen. The relation between ultraviolet pad composition and hardness, swelling rate and self conditioning of the pad was studied, which will be helpful to optimize the polishing pad. The pad hardness increases with the increasing PEGDA or TMPTA. Its swelling ratio increases with increasing EO15-TMPTA or PEG600. More EO15-TMPTA in pad body, easier the swelled pad is removed.3. The topography of fixed abrasive polishing pad was designed and relevant moulds were manufactured. Three-dimensional asperities on the pad were manufactured by silk screen printing. Three main parameters: net board, distance between net board and work-piece and scraper were chosen.4. The fixed abrasive polishing pad and the relevant slurry were prepared. The wafers polished by conventional polishing and fixed abrasives polishing under the same condition were compared by 3D Surface Profilometer. Results show that within an area of 639um×859um scan area, the average roughness Sa of wafer by fixed abrasives polishing is 0.856nm, while the one by conventional polishing is 1.70nm.