Atomic chlorine concentration measurements in a plasma etching reactor. I. A comparison of infrared absorption and optical emission actinometry

Abstract

Articles you may be interested inHBr concentration and temperature measurements in a plasma etch reactor using diode laser absorption spectroscopy J.Oxygen atom actinometry reinvestigated: Comparison with absolute measurements by resonance absorption at 130 nm Atomic chlorine concentrations in C1 2 and CF 3 Cl plasmas have been measured using both infrared absorption spectroscopy and optical emission actinometry. These measurements were made over a range of plasma conditions including plasma excitation frequencies of 72 kHz-13.5 MHz, power inputs of 10-100 W, and pressures of 200-800 mTorr. In C1 2 plasmas, the technique of optical emission actinometry misrepresents atomic chlorine concentration changes by nearly an order of magnitude. The errors in the actinometry technique are believed to result from excited state Cl production by electron impact dissociation of C1 2 • A simple model for Cl emission is in good agreement with the experimental observations. In CF 3 CI discharges, the technique of optical emission actinometry is shown to accurately represent variations in atomic chlorine concentration with changing process conditions. 792

Radical and Molecular Product Concentration Measurements in CH4 RF Plasmas by Infrared Tunable Diode Laser Absorption

“…They form an off-axis resonator, 2 2 in which the laser beam enters and exits through the same central hole in the downstream mirror, and forms a spot pattern on both mirrors which can be circular or which can be flattened into an ellipse (as we now use it) whose major axis is still almost the full 15 cm but with a minor axis of a little over 1 cm. For CH 4 studies, mirrors with a nominal 224 cm radius of curvature were used with a spacing resulting in 48 passes.…”

Experimental investigation of SF6–O2 plasma for advancement of the anisotropic Si etch process

“…where Ix is the measured intensity of species x, ne is the electron density and nx is the concentration of species x. Here, kx is the electron impact excitation rate constant, which is given by [40] X = ∫  X ( ) ( )√…”

“…where ε denotes the electron energy, me stands for the electron mass, σ x (ε) is the electron impact excitation cross section and f(ε) is the electron energy distribution function normalised to 1 [40].…”

In-situ quantification of deposition amount in a poly-Si etch chamber using optical emission spectroscopy of etching plasmas

“…When excitation cross sections of the two species are similar, the excitation efficiencies ki and k. are similar. As a result, the ratio (kjl k,) become constant [4].…”

“…The actinometry requires assumptions that chemical species in plasmas are excited by electron impact of ground-state, then must be relaxed by photoemission. Under these assumptions [3], [4], emission intensity ratio of a chemical species of interest (Ii) to of an inert atom (1,) can be reduced to the density ratio of the species (Oi) to of the inert atom (4) as the formula (I).…”