A plasma processing system having a plasma processing chamber configured for processing a substrate is provided. The plasma processing system includes at least an upper electrode and a lower electrode for processing the substrate. The substrate is disposed on the lower electrode during plasma processing, where the upper electrode and the substrate forms a first gap. The plasma processing system also includes an upper electrode peripheral extension (UE-PE). The UE-PE is mechanically coupled to a periphery of the upper electrode, where the UE-PE is configured to be non-coplanar with the upper electrode. The plasma processing system further includes a cover ring. The cover ring is configured to concentrically surround the lower electrode, where the UE-PE and the cover ring forms a second gap.