Post-CMP cleaning

One of the major defects of CMP is the residual particles. These submicron and smaller particles cause catastrophic failure for memory disks and for ever-smaller IC chips. Any particles left behind can have a significant effect on the outcomes of downstream process steps. These include creating imperfections ranging from bumps or pits to regions of excessive electrical resistance. Post-CMP cleaning is an important process in removing these particles. This process is usually accomplished with a deionized-water or dilute cleaning agent rinse. This process involves mechanical action by contacting one or more rotating roller brushes, while the wafer or disk itself is rotated and sprayed. In order to develop effective cleaning processes to meet the stringent requirements of the fabrication of advanced integrated circuits (ICs) and information storage diskettes, it is essential to understand the mechanisms of particle removal. Figure 8.1 shows the schematic diagram of a post-CMP cleaning setup. The brush is generally made of polyvinyl alcohol (PVA). This material is open pore.