Photoresist stripping is frequently accomplished using solvents with multiple proprietary components as well as some water content. These are expensive chemicals which are also expensive to dispose off. As such, monitoring concentrations (especially water concentration) is important, and allows replenishing and extending the bath life. The WetSpec200 and WetSpec201 are widely use to monitor all important components to allow bath life time extension
Another common stripper is Piranha (H2SO4/H2O2) which is typically used at elevated temperatures (100-120C) resulting in a challenge to maintain H2O2 concentration within range. At these elevated temperatures, CI's NTM W was especially designed to allow accurate wafer temparature monitoring and control.
Typical Stripping applications: