Method and apparatus for measuring electron density of plasma

An apparatus for measuring electron density of a plasma in a plasma reaction chamber comprises:

• a capacitive coupled plasma generation means for generating the plasma in the plasma reaction chamber, said capacitive coupled plasma generation means having a pair of coupled electrodes wherebetween the plasma is generated,
• an electron injecting means for injecting electrons in the plasma so that plasma oscillation is generated, said electron injecting means having an electron emission electrode which is capable of emitting electrons by applying a high frequency electromagnetic field,
• an antenna for detecting an amplitude of said plasma oscillation, and
• a frequency measuring means for measuring a plasma frequency which gives a maximum amplitude of the plasma oscillation.

An apparatus for measuring electron density of a plasma in a plasma reaction chamber comprising:

• a plasma generating means for generating the plasma in a plasma generation chamber neighboring to the plasma reaction chamber,
• an electron injecting means for injecting electrons into the plasma of the plasma reaction chamber, said electron injecting means having a pair of electrodes to which an alternating electromagnetic field is applied so that electrons in a space charge layer formed in a vicinity of each of a pair of the electrodes are accelerated to be injected into the plasma which eventually, generate plasma oscillation,
• an antenna for detecting an amplitude of said plasma oscillation, and
• a frequency measuring means for measuring a plasma oscillation frequency which gives a maximum amplitude of said plasma oscillation.