Effect of dynamic corrosion on dishing behavior in copper chemical mechanical planarization
|關鍵字:||銅化學機械研磨;研磨液;陷碟;動態腐蝕;Copper CMP;Slurry;Dishing;Dynamic corrosion|
|摘要:||由於銅本身具有良好的導電性和優越的抗電子遷移能力，半導體產業為降低導線間RC Delay的效應，使得銅成為半導體製程中取代鋁的新一代導電材料，因為銅金屬無法進行蝕刻製程，使得化學機械研磨製程的應用更加廣泛。在未來先進製程（20/14nm）甚至到3D IC製程，化學機械研磨仍是表面平坦化不可或缺的一段製程。
According to copper is with nice electrical conductivity and better ability to reduce electron migration, it has been utilized to replace aluminum as a new generation of conductive material in the semiconductor manufacturing process by reducing the effects of RC Delay which cause between conducted wires in the semiconductor industry. In the future, semiconductor manufacturing advanced process (20/14nm) and even to the 3D IC manufacturing process, chemical mechanical polishing is an integral process of the surface planarization . The process of chemical mechanical polishing are generally divided into two polishing process. The first process is the removal of copper, and the second is the barrier layer removed and the dishing repair. It means the second polishing process can repair the surface with some slightly defects such as scratches on the copper wire and the particle residues on the surface, which caused by the first process. Consequently, the depth of dishing which made by the first process will greatly affect the repair capacity made by the second polishing. In addition to this , the dishing control on the depth of dishing is a major issue in the chemical mechanical polishing process. The dishing is mainly produced and impacted by two major factors in the polishing process; one of the factors is the mechanical force and the other is the chemical interaction. For the mechanical force, the major impact of mechanical force is from the polishing machine, polishing pad and abrasive particles, and therefore the impact could be adjusted by machine parameters to control the influence of mechanical force. In terms of the factor of the chemical interaction, this study investigated the correlation between the chemical interaction and the dishing performing in the chemical mechanical polishing process. In the microscopic world, it is difficult to define specifically various corrosion (8 kinds of corrosion patterns) are occurred by the reaction between the wafer, the polishing solution or the polishing pad during the chemical mechanical polishing process. Accordingly, this study simplified the definition of all the corrosion types as two categories which are static corrosion and dynamic corrosion. Moreover, the experiments of the static corrosion and dynamic corrosion are completed by experimental design and data measurements which are applying the polishing machine parameter setting and measuring instruments. Experimental slurry are designed to process with the different pH and adjusting various corrosion inhibitors in the fixed pH, which are considered to process the polishing and gain the data to be analyzed by using the analysis instrument. To research and discuss the relation between the dishing behavior and four indexes : removal rate, electrochemical - corrosion current, static corrosion and dynamic corrosion. In this study, it is also discussed if any one of these indexes could be the key to anticipate the dishing behavior and usefully select corrosion inhibitor excluding the effect of mechanical force.