Yuka Hayami

Characterization of cleaning technology for silicon surfaces by hot pure water containing little dissolved oxygen

We introduce new cleaning technology using pure water containing little dissolved oxygen (LDO water). To maintain the concentration of dissolved oxygen in water, we performed experiments in a glove box, controlling the ambient between the water and the ambient gas so as to satisfy Henrys law. In the experiment using intentionally contaminated wafers and LDO water containing 1 ppb of dissolved oxygen at room temperature, the amount of residual metallic contaminants, except copper, on a Silicon surface decreased from 1014 atom/cm2 to 1011 atom/cm2 after hot LDO water treatment for 30 min at the boiling point. The cleaning ability depends on the dissolved oxygen concentration, temperature of LDO, and treatment time. The ability to eliminate aluminum during the 30 min hot LDO water treatment was lower than for the other metals. Moreover, the adsorption velocity of aluminum from hot LDO water on the wafer surface was much larger than that of the other metals. Since this hot LDO water treatment simultaneously etched silicon and silicon dioxide with the removal of metal, we also investigated the morphology and chemical structure of the wafer surface after this cleaning process.