Argon metastables in a high density processing plasma

Abstract

Absolute densities of metastable argon atoms (Paschen 1s5, 1s3) and the intermediate resonant state (1s4) were measured in a high density plasma etching environment. Excited species densities were measured ranging from 108 to 3×109 cm−3, depending on the particular atomic state. A straightforward reaction rate formalism consisting of only two competing electron-atom collision rates accurately predicts such densities. Because of the low densities of these long-lived excited state species, all excited argon species need to be considered only as energy loss channels in modeling high density (1011–1012 cm−3), low pressure (∼1 mTorr) plasma sources. Metastable production rates were also used to identify energy transfer mechanisms under etching conditions of Cl2/Ar mixtures and substrate biasing in the reactor.

Probe and Emission Spectrometry Diagnostics in Hollow Cathode Magnetron

“…Note that these data were obtained at a distance of 20 cm from the target. Data on metastable Ar atoms are in good agreement with the results obtained in a high-density plasma discharges [16][17][18]. We also did not account for Penning ionization of Cu and Ar atoms.…”

Determination of Ar metastable atom densities in Ar and Ar/H2inductively coupled low-temperature plasmas

“…Metastable species formation are also important electron energy-loss mechanisms and are significant for surface reactions in Ar plasmas along with H atom creation in Ar/H 2 plasmas, though they are notoriously hard to quantify through direct plasma observation techniques. Ar metastables have long lifetimes, carry significant energy that can be transferred to atoms/molecules causing Penning ionization/dissociation, and occur at high densities in lowtemperature plasmas [7][8][9]. Ar metastable atoms in Ar plasma and Ar plasma mixtures have been used for low-energy patterning of surfaces [10,11] Quantification of metastables in Ar plasmas [12][13][14] and Ar/reactive gas mixtures [15][16][17] by optical methods has been a topic of great interest.…”

Anomalous evolution of Ar metastable density with electron density in high density Ar discharge

“…[12][13][14] There have been a number of experiments and theoretical calculations especially on argon atom metastable states (1s 3 and 1s 5 in Paschen notation) density with regard to plasma power or pressure. In experiments, various techniques such as laser induced fluorescence (LIF), [15][16][17][18] laser absorption spectroscopy (LAS), 16,[19][20][21][22][23][24][25] and optical emission spectroscopy (OES) (Refs. [26][27][28][29] were used to measure 1D or 2D distribution of metastable density.…”