Surface loss rates of H and Cl radicals in an inductively coupled plasma etcher derived from time-resolved electron density and optical emission measurements

Abstract

A study is undertaken of the loss kinetics of H and Cl atoms in an inductively coupled plasma (ICP) reactor used for the etching of III-V semiconductor materials. A time-resolved optical emission spectroscopy technique, also referred to as pulsed induced fluorescence (PIF), has been combined with time-resolved microwave hairpin probe measurements of the electron density in a pulsed Cl2/H2-based discharge for this purpose. The surface loss rate of H, kwH, was measured in H2 plasma and was found to lie in the 125–500 s−1 range (γH surface recombination coefficient of ∼0.006–0.023), depending on the reactor walls conditioning. The PIF technique was then evaluated for the derivation of kwCl, and γCl in Cl2-based plasmas. In contrast to H2 plasma, significant variations in the electron density may occur over the millisecond time scale corresponding to Cl2 dissociation at the rising edge of the plasma pulse. By comparing the temporal evolution of the electron density and the Ar-line intensity curves with 10% of Ar added in the discharge, the authors show that a time-resolved actinometry procedure using Ar as an actinometer is valid at low to moderate ICP powers to estimate the Cl loss rate. They measured a Cl loss rate of ∼125–200 s−1 (0.03≤γCl≤0.06) at 150 W ICP power for a reactor state close to etching conditions. The Cl surface loss rate was also estimated for high ICP power (800 W) following the same procedure, giving a value of ∼130–150 s−1 (γCl∼0.04), which is close to that measured at 150 W ICP power.

A Comparative Study of HBr-Ar and HBr-Cl2 Plasma Chemistries for Dry Etch Applications

“…This is quite close to c Cl values derived in Refs. [29] and [30] from both Cl 2 plasma modeling and diagnostics, but by about 3 times higher than ones measured by Kota et al [31] (*0.015 at 350 K). The last disagreement is probably due to the fact that the data of Ref.…”

Dynamical Monte Carlo methods for plasma-surface reactions

“…Note that the sites with the three highest reactivities correspond only to 1%, 2% and 3% of the total number surface sites [cf. expression(12)], so that when [S] = 500 there are only 5, 10 and 15 sites of these types in the simulation. The calculation made with 7500 sites provides results barely distinguishable from the expected ones.The qualitative indications from figure 3 can be quantified, for instance, by introducing an absolute error defined as the average of…”

Electron density modulation in a pulsed dual-frequency (2/13.56 MHz) dual-antenna inductively coupled plasma discharge

“…The technique for measuring time resolved electron density using a resonance hairpin probe is described previously and applied in several pulse plasma systems. 35,[37][38][39] Briefly, to obtain the resonance signal in the time resolved mode, a single frequency output from the microwave generator is generated and applied to the hairpin structure. The reflected signal is recorded as a function of time within the pulse.…”