ABSTRACT
A variety of organic and inorganic contaminations are often present on the surface of the silicon wafers, and these need to be removed. They may be due to the polishing chemicals or slurry components used to polish the wafers, or from some unknown sources. Sometimes, airborne dust particles, chemical residues, and other unexpected oil contamination may also be present on these surfaces. Prior to using the wafers, it is necessary to clean these contaminates from the silicon surface. Of course, the chemicals used to clean the surfaces should be highly pure and free from suspended particles. Particles in acids and solvents are typically either inherent in as-received containers, sinks, and process equipment, or they are generated during etching or cleaning processes from piping, lters, etc. The purity of the chemicals is determined by the trace materials present in them. It may become necessary to avoid certain chemicals that have trace metallic impurities, despite their high purity. Table 10.1 lists the purity of chemicals used for silicon integrated circuit fabrication, depending on the circuit complexity.
