Patent ID: 8852384
Filing Date: 2014-10-07
Classification: G01N,H01L

Abstract:
1. A plasma processing chamber comprising: a top insulator block disposed at a top side of the plasma processing chamber; a powered substrate support disposed below the top insulator block and at a bottom side of the plasma processing chamber, wherein the top insulator block facilitates supply of an inert gas to a region between the top insulator block and the powered substrate support; a top edge electrode disposed at the top side and surrounding the top insulator block; a bottom edge electrode located opposite to the top edge electrode and surrounding the powered substrate support, the bottom edge electrode facing the top edge electrode, the bottom edge electrode located at the bottom side to form a gap between the top edge electrode and the bottom edge electrode, wherein the gap is formed to facilitate reception of a process gas, wherein the inert gas is received within the region between the top insulator block and the powered substrate support while the process gas is received in the gap, the process gas to be excited with radio frequency power to generate plasma within the gap; and a signal monitor being positioned to have a view through a window of a wall of the plasma processing chamber, the view being toward the gap to monitor intensities of the plasma, wherein the gap is annular and does not extend into the region between the top insulator block and the powered substrate support, the intensities used to determine whether the plasma is confined or unconfined within the gap, wherein the signal monitor is coupled to a system controller, wherein the system controller is configured to determine whether the plasma is confined or unconfined within the gap based on a ratio of a difference between a maximum value of the intensities and a minimum value of the intensities to an average value of the intensities.