Scrubber clean process induced CDM ESD-like: CSM (Charged Surface Model) event caused by dummy patterns

This paper describes a process-induced damage phenomenon on the Poly-Insulator-Poly (PIP) capacitor of mixed-mode circuit during the scrubber clean after Spin-On-Glass (SOG) layer deposition. The damage mechanism is the generated charges during the scrubber clean flow through the SOG film, metal-2 stripe, via hole and to dummy metal-1 stripe, and then charge up the parasitic capacitor (dummy metal-1 stripe / Poly-2). These stored charges can be instantly discharged to the nearby PIP capacitor and burn out the dielectric. The damage symptom is similar to but not the same as CDM ESD event, where the charges are stored in the package and flow from the substrate and through the IO pad to a pin. For this difference, this new phenomenon is named as the CSM (Chare Surface Model) event.