A semiconductor processing apparatus includes a supporting platform configured to support a wafer stack structure comprising a first wafer bonded over a second wafer, and an injection device movably disposed above the supporting platform. The injection device includes an edge detector configured to locate a beveled edge between the first wafer and the second wafer, and a plasma injector coupled to the edge detector and configured to perform a plasma treatment over the beveled edge between the first wafer and the second wafer.

A splash prevention system includes one or more devices that are configured to reduce the likelihood of errant sealant particles landing on a top and/or a bottom surface of a wafer stack during an edge sealing operation. An injector nozzle may dispense sealant into the groove around the wafer stack as a chuck is used to rotate the wafer stack. A vacuum device of the splash prevention system may provide a negative-pressure gas flow at the edge of the wafer stack, and the negative-pressure gas flow is used to collect errant sealant particles. Additionally and/or alternatively, an air curtain device may provide a positive-pressure gas flow at the edge of the wafer stack, and the positive-pressure gas flow may be used to dispel errant sealant particles away from the edge of the wafer stack.