Abstract: In a nonvolatile memory, a floating gate (124) is covered with ONO (98), and a control gate polysilicon layer (124) is formed on the ONO. After the control gate is patterned, the control gate sidewalls are oxidized to form a protective layer (101) of silicon dioxide. This oxide protects the control gate polysilicon during a subsequent etch of the silicon nitride portion (98.2) of the ONO. Therefore, the silicon nitride can be removed with an isotropic etch. A potential damage to the substrate isolation dielectric (210) is therefore reduced. Other embodiments are also provided.

Abstract: A method for improving profile control during an etch of a nitride layer disposed above a silicon substrate is disclosed. The nitride layer 106 is disposed below a photoresist mask 108A. The method includes positioning the substrate, including the nitride layer and the photoresist mask, in a plasma processing chamber. There is also included flowing a chlorine-containing etchant source gas into the plasma processing chamber. Further, there is included igniting a plasma out of the chlorine-containing etchant source gas to form a chlorine-based plasma within the plasma processing chamber. Additionally, there is included treating, using a chlorine-based plasma, the photoresist mask in the plasma processing chamber. The treatment of the photoresist is configured to etch at least a portion of the photoresist mask and to deposit passivation polymer on vertical sidewalls of the photoresist mask without etching through the nitride layer.