Patent ID: 6584989
Filing Date: 2003-07-01
Classification: B08B,C11D,G05D,H01L,Y10S

Abstract:
An apparatus for cleaning semiconductor wafers using a dilute sulfuric peroxide hydrofluoric acid solution containing more than about 80% water by volume, the apparatus comprising:a process tank containing a cleaning solution comprising deionized water, sulfuric acid, and hydrogen peroxide; a monitoring system for performing over time a plurality of measurements of fluorine ion concentration in said cleaning solution to obtain a measured concentration level associated with each of said measurements; a source of hydrofluoric acid; a controller responsive to said measured concentration level; a pumping device responsive to said controller to add a first amount of hydrofluoric acid to said cleaning solution from said source, said first amount of hydrofluoric acid sufficient to achieve a target fluorine ion concentration level and thereafter maintaining said fluorine ion concentration substantially at said target fluorine ion concentration level; a mixing tank for blending a premixed solution comprising deionized water, sulfuric acid, and hydrogen peroxide; a tube connecting said mixing tank to said process tank through which said premixed solution is transferred to said process tank; and a valve controller for sensing a full level within said process tank and terminating the transfer of premixed solution when said full level is reached.