AVS 47th International Symposium
    Plasma Science and Technology Thursday Sessions
       Session PS2-ThM

Paper PS2-ThM1
Advanced Actinometry of Inductively Coupled Cl@sub 2@-Ar Plasmas For Plasma Etching

Thursday, October 5, 2000, 8:20 am, Room 311

Session: Plasma Diagnostics II
Presenter: N.C.M. Fuller, Columbia University
Authors: N.C.M. Fuller, Columbia University
I.P. Herman, Columbia University
V.M. Donnelly, Bell Laboratories, Lucent Technologies
Correspondent: Click to Email
The exact composition of Cl@sub 2@-Ar plasmas can influence the overall mechanism and rates of adlayer formation and removal (ion-induced sputtering) during the etching of various materials; therefore, the mixture composition can be altered to improve the overall plasma chemical etching process. To this end, optical emission spectroscopy (OES) and Langmuir probe analysis have been used to measure the electron temperature, T@sub e@ and the absolute species densities in a high-density inductively coupled (ICP) chlorine-argon plasma at 18 mTorr as function of the 13.56 MHz radio frequency (rf) power and argon fraction. In the H (bright) mode, the electron temperature, T@sub e@, measured by trace rare gases optical emission spectroscopy (TRG-OES), increases from 3 eV at 350 W to ~ 6 eV at 770 W for a chlorine plasma (1% Ar). At 600 W (10.6 Wcm@super -2@), T@sub e@ increases from 5.0 eV to ~ 6.5 eV as the argon fraction increases from 0.01 to 0.73. In the E mode at 200 W, the fraction of Cl@sub 2@ that dissociates to form Cl increases from ~10% to ~ 40% as the argon fraction increases from 0.01 to 0.73. In the H mode at 600 W, this dissociation fraction increases from 82% to 96% over the same range. In the H mode and for all argon fractions, the electron density, calculated by a global model, increases by at least an order of magnitude from 300 W to ~ 750 W, and at 600 W it decreases from 1.0 x 10@super 12@ cm@super -3@ to 5.5 x 10@super 10@ cm@super -3@ as the argon fraction increases from 0.01 to 0.73. OES is also used to estimate the peak value of the electron impact excitation cross section for the dissociative excitation of Cl@sub 2@ to the Cl (4p@super 2@ D@super 0@ J@super '@ = 3/2, 5/2) excited state with subsequent emission at 822.2 nm. This peak value is 1.7±0.3 x 10@super -19@ cm@super 2@. The changes in the surface adlayer when the mixture composition is varied will also be discussed.