Patent ID: 7582182
Filing Date: 2009-09-01
Classification: G01N,H01J,H01L

Abstract:
1. An apparatus for monitoring plasma, comprising: an insulating pipe inserted and attached into and to a chamber in or into which plasma is created or introduced; a coaxial cable provided with a probe portion formed by exposing a front core wire of the coaxial cable, and inserted into the insulating pipe from one end of the insulating pipe; an actuator for moving the coaxial cable in the insulating pipe in the axial direction thereof; a scalar reflection coefficient measuring unit for, while sweeping frequencies, transmitting electromagnetic signals of respective frequencies to the probe portion of the coaxial cable at certain power to be irradiated to a surrounding space, measuring reflection coefficients from the levels of signals reflected through the probe portion with respect to the respective frequencies, and obtaining frequency characteristics of the reflection coefficients; and a measurement operation unit for measuring a plasma absorption frequency based on a first frequency characteristic obtained by the reflection coefficient measuring unit in a state where the plasma does not exist in the chamber and a second frequency characteristic obtained by the reflection coefficient measuring unit in a state where plasma exists in the chamber, at a measurement location determined by a location of the probe portion, wherein in the state where the plasma does not exist in the chamber, the probe portion is sequentially positioned at a plurality of measurement locations by moving the coaxial cable in the axial direction thereof using the actuator, and the first frequency characteristics of the reflection coefficients is obtained at the respective measurement locations by the reflection coefficient measuring unit; and in the state where the plasma exists in the chamber, the probe portion is sequentially positioned at the plurality of measurement locations by moving the coaxial cable in the axial direction thereof using the actuator, and the second frequency characteristic of the reflection coefficients is obtained at the respective measurement locations by the reflection coefficient measuring unit.