Patent ID: 7722778

Claim:
A method for detecting a plasma unconfinement condition in a plasma processing chamber, said plasma unconfinement condition being characterized by the presence of plasma in excess of a pre-defined specification outside of a designed plasma confinement volume within said plasma processing chamber, the method comprising: defining said designed plasma confinement volume; selecting a plasma processing chamber component, said plasma processing chamber component conducting no return RF current during plasma processing if said plasma is confined within said pre-defined specification within said designed plasma confinement volume, said plasma being confined within said pre-defined specification within said designed confinement volume if plasma density in one or more locations outside said designed confinement volume does not exceed a threshold, said plasma processing chamber component conducting a detectable return RF current during said plasma processing if said plasma is in excess of said pre-defined specification outside said designed plasma confinement volume during said plasma processing, said plasma being in excess of said pre-defined specification outside said designed confinement volume if said plasma density in said one or more locations outside said designed confinement volume exceeds said threshold; providing a sensor for performing current detection related to said plasma processing chamber component by disposing said sensor in a selected position such that said sensor does not contact said plasma processing chamber component, wherein said sensor and said selected position are configured to provide an electrical parameter having discriminable variation between a first state and a second state, said first state being characteristic of absence of said detectable return RF current in said plasma processing chamber component, said second state being characteristic of presence of said detectable return RF current conducted through said plasma processing chamber component; and providing a sensor data processing arrangement that is coupled to said sensor, said sensor data processing arrangement being configured to provide, responsive to said electrical parameter, a data signal signifying whether said plasma processing chamber is experiencing said plasma unconfinement condition.