The post etch residual polymer removal process cleans polymers from the surface of wafers. This is done in the spray solvent tool, where a commonly used post-etchant chemical, EKC, is fed to.
It is very important to keep the EKC solution in tight specification as too much water in the solution risks corroding the system, and too little water in solution does not efficiently remove the polymers. Vaisala K-PATENTS® semicon refractometer offers 2 different control strategies either to automate chemical refilling or automate spiking after each wafer run, and warrant safe wafer production.
Semicon refractometer can also alert the potential EKC traces in IPA before IPA gets contaminated with EKC in the following IPA/dry process.
Fabs can achieve clear benefits using a semicon refractometer:
Vaisala’s application note explains how a semicon refractometer can improve process with recommended installation points for best performance.
Download the application note for full details.