Effects of wafer spin speed during dry etch post-wet cleaning on a metal line

Abstract

The effects of wafer spin speed during a wet cleaning process after dry etching of a metal line patterning was investigated in detail. In this experiment, a conventional single wafer spin tool was used to clean 200mm wafers with a dilute acid mixture (sulfuric acid; H2SO4 5.5wt% and hydrofluoric acid; HF 0.01wt%) in de-ionized water (DIW). We confirmed that the polymer removability, the pitting, and the electrical resistance of a metal line were dependent on the wafer spin speed. Moreover, very different results were obtained from the center and edges of the wafer. When the dilute acid mixture is supplied onto the wafer center, the chemical is consumed with a chemical reaction toward the wafer edge. When large size wafers are used, or the wafer spin speed is lower, more degraded chemical could be transported to the wafer edge. A higher spin speed is useful for wafers of large size (300–450mm) as an effective parameter in the cleaning process based on this experiment result.