Investigation of Wet Clean Induced Dielectric Surface Static Charge and Its Impact on Gate Oxide Integrity

The static electricity of wet clean was characterized by contactless surface voltage measurement on silicon oxide dielectric in this study. The paper shows surface static charge at wafer center caused by a single wafer spin cleaning tool. Deionized water (DIW) rinse was verified as the critical step of inducing static charge. It was demonstrated by metal oxide semiconductor (MOS) capacitor that such serious dielectric static charge would degrade gate oxide integrity (GOI). With dissolved CO2 to lower DIW resistance, surface static charge at wafer center is reduced and degraded GOI is restored as a result.