Jong-Sik Kim, Gon-Ho Kim, Tae-Hun Chung, Geun-Young Yeom and Kwang-Ho Kwon, Characterization of Oxygen Plasma by Using the Langmuir Probe in an Inductively Coupled Plasma, Journal of the Korean Physical Society, Vol. 38, No. 3, 259-263, 2001.

Oxygen plasmas were investigated by using a Langmuir probe for an inductively coupled plasmawith various rf powers, 100~400 W, and operating pressures, 0.1 ~100 mTorr. The probe current ratio of the positive and negative currents (I+=[Ie + I-]) increased with the generationof negative ions and had its maximum value in the pressure region of 40~70 mTorr. Also, the operating pressure to achieve the maximum shifted from the low-pressure region to the high pressure region with increasing input power because enhanced ion loss through positive-negative ion recombination.