Effects of Small Amount of Copper on Si{110} Etching in KOH Aqueous Solution

Etching on Si{110} in KOH aqueous solutions containing a small amount of Cu has been studied. It is found that 100ppb-level Cu in KOH aqueous solution forms pyramidal shaped hillocks of Si and roughes the etched surface. It is understood that the hillocks are caused by masking effect of Cu particles deposited on Si. The results also show that 100ppb-level Cu reduces the etching rate since the hillocks consist of slowly etched {311} planes