Patent ID: 8518209

Claim:
An apparatus for determining an endpoint of a chamber cleaning process performed for a plasma processing chamber by measuring a thickness of a layer in said plasma processing chamber, said chamber cleaning process including using a plasma, said plasma processing chamber including at least one chamber wall, said at least one chamber wall including at least one surface, said layer deposited on said at least one surface of said plasma processing chamber by a prior process, the apparatus comprising: a first sensor being coplanar with said at least one surface such that a measuring surface of said first sensor and said at least one surface of said plasma processing chamber are substantially on a same plane, wherein said first sensor is configured to measure said thickness, wherein said first sensor is a coplanar ion flux probe; a second sensor configured to measure an amount of CN species in said plasma processing chamber; a third sensor configured to measure an amount of hydrogen molecules in said plasma processing chamber; means for generating said plasma in said plasma processing chamber, wherein said thickness is changed by said generating; means for pulsing an RF burst to generate a potential at a sensor head of said first sensor; and means for ascertaining said endpoint of said cleaning process by: determining a steady state condition in at least one of a voltage or a current measured using said first sensor, a start of said steady state condition representing said endpoint; determining that said endpoint has been reached when said amount of said CN species measured by said second sensor has been reduced to a predetermined level; and determining that said endpoint has been reached when said amount of hydrogen molecules measured by said third sensor has stabilized.