Method for cleaning a silicon substrate

摘要

A silicon substrate is cleaned using a liquid mixture primarily containing ammonia and hydrogen peroxide. A liquid containing ammonia is added to the liquid mixture to maintain the concentration of ammonia in the liquid mixture applied to the silicon substrate in the range between 2.5 wt. % and 3.5 wt. %. The liquid containing ammonia is added to the liquid mixture at a constant time interval. The constant time interval is set to be equal to a time period which is necessary for the concentration of ammonia in the liquid mixture to change from a first concentration level of no more than 3.5 wt. % to a second concentration level of no less than 2.5 wt. %, the second concentration level being lower than the first concentration level. The concentration of ammonia in the liquid containing ammonia and the amount thereof to be added to the liquid mixture are adjusted so as to increase the concentration of ammonia in the liquid mixture to the first concentration level by addition thereof.