Wet Cleaning by Using Amphoteric Electrolyzed Water for Mask Cleaning

Abstract

This study proposes a novel technology that satisfies the technical requirements of the cleaning extreme ultraviolet (EUV) semiconductor devices. A special electrolysis was applied to ultrapure water, generating water with amphoteric characteristics (pH of 6.5–6.7 and an oxidation reduction potential (ORP) of −540 to −560 mV). The feasibility of the prepared amphoteric water as a non-chemical agent for performing EUV wet cleaning was evaluated on 4×-nm masks. Some excellent results were obtained, confirming that water cleaning can satisfy the EUV requirements. Amphoteric water eliminated the adsorbed remnants of previous chemical treatments with minimal surface modifications, reducing the probability of haze formation. The high particle removal efficiency suggests that the double-layer repulsion of colloids is supplemented by other mechanisms. Thus, amphoteric water heralds a new cleaning concept in the EUV device era.