The wafer has undergone slicing, grinding, polishing and other processing processes from the drawing of the monocrystalline silicon rod. In the process, the wafer has been exposed to various chemical reagents such as polishing agent and abrasive material. At the same time, it is also polluted by particles.
When molecular impurities are adsorbed on the surface of silicon wafers, chemical cleaning first cleans these organic impurities, using carbon tetrachloride, trichloroethylene, toluene, acetone, anhydrous ethanol and other organic solvents, can also use concentrated sulfuric acid carbonization, nitric acid or alkaline hydrogen peroxide washing solution oxidation and other methods to remove.
Ionic and atomic adsorbed impurities are cleaned with hydrochloric acid, sulfuric acid, nitric acid or alkaline hydrogen peroxide washing solution to remove ionic adsorbed impurities, and then the remaining ionic and atomic impurities are cleaned with aqua king or acid hydrogen peroxide, and finally the silicon wafers are rinsed with high purity water.
In summary, the general steps of cleaning silicon wafer are as follows: molecular impurity → deionized impurity → deatomization impurity → high purity water cleaning.