Ion energy distributions at rf-biased wafer surfaces

Abstract

Time evolution of ion energy distributions and optical emission in pulsed inductively coupled radio frequency plasmasTime-resolved measurements of ion energy distributions and optical emissions in pulsed radio-frequency dischargesWe report the measurement of ion energy distributions at a radio frequency ͑rf͒-biased electrode in inductively driven discharges in argon. We compare measurements made with a gridded energy analyzer and a commercial analyzer that contains a mass spectrometer and energy analyzer in tandem. The inductive drive and the rf bias in our Gaseous Electronics Conference reference cell were both at 13.56 MHz. By varying the plasma density, we were able to examine the transition region between the ''low frequency limit'' for rf bias and the intermediate frequency region where, at fixed bias frequency, the ion energy distribution width varies with the plasma density. We find that the experimental ion energy distributions become narrower as the time for ion transit through the sheath approaches the rf period, but that the ion distributions still have widths which are ϳ90% of their low frequency limit when the ion transit time is 40% of the rf period. Space-charge-induced beam broadening inside our analyzers appears to significantly affect our measurements of ion angular distributions, especially at low ion energies.

Temporally resolved ion velocity distribution measurements in a radio-frequency plasma sheath

“…[5][6][7][8] Additionally, for low to moderate values of s ion =s RF , the ion bombardment energy at the object (substrate) surface has been predicted to be strongly dependent on the RF phase, giving rise to broad, bimodal time-averaged ion energy distributions (IEDs). 2,5,[9][10][11][12][13][14] Some authors use the ratio of the RF frequency to the ion plasma frequency (x RF =x pi ) instead of s ion =s RF to classify RF sheaths; however, Kawamura et al have shown that these ratios are nearly equal for typical laboratory plasma conditions. 2 Laser-induced fluorescence (LIF) is a noninvasive optical technique for measuring the ion velocity distribution function (IVDF), f(v), in a plasma 15 with good spatial 16 and temporal 17 resolution, and has been used to probe the sheath 18,19 and presheath [20][21][22] regions.…”

2-dimensional ion velocity distributions measured by laser-induced fluorescence above a radio-frequency biased silicon wafer

“…20,21 Subsequent experiments were able to take similar measurements at an rf-powered electrode. [22][23][24][25][26][27] The time-averaged, single position energy distribution function measurements from all of these experiments tended to confirm the predicted feature of two peaks separated in energy.…”

“…The time-averaged energy distribution functions in transit through the sheath are generally not as sharply peaked as those arriving on the substrate which have been measured in several experiments [20][21][22][23][24][25][26][27] or predicted by theory. 9,14 These trends are consistent with previous measurements in this device.…”

Annealing and plasma treatment effect on structural, morphological and topographical properties of evaporated β-In2S3 films

“…Ion energy is controlled by the RF bias power P sb applied on the substrate [17]. In this case, the function of the ion energy distribution (IED) on the substrate surface for RF ICP has a double energy maxima [23,24]. Measurements of the IED and self-bias potential U sb in the RF ICP reactor showed that the U sb is positioned symmetrically between the two maxima of the IED curve.…”