Laser-induced thermal desorption as anin situsurface probe during plasma processing

Cl 2 plasma etching of Si(100): Nature of the chlorinated surface layer studied by angle-resolved x-ray photoelectron spectroscopy

“…Previous work from this laboratory 4,5 indicated that the layer formed in a high-density plasma at relatively low ion energy (ϳ80 eV) consisted of a SiCl x layer with a stoichiometry and thickness that are consistent with the present study. The total Cl in the layer was found to be about twice that obtained by exposing clean Si͑100͒ to Cl 2 gas.…”

“…This finding is consistent with previous laser-induced thermal desorption measurements. 4,5 The relative Cl concentration in the layer formed under RIE ͑Ϫ75 V dc bias͒ conditions at a Cl 2 pressure of 20 mTorr was the same as that found at 4 mTorr, indicating that the steady state chlorine coverage depends on ion energy and not on the density of neutrals. Although all the measurements reported in this study were done with sample transfer under vacuum, when the chlorinated Si surface is instead exposed to air after plasma etching, the reaction with H 2 O vapors leads to formation of HCl ͑g͒ and surface SiO 2 and SiOH groups.…”

“…1 and described in more detail elsewhere, 4,5,8,10 consists of a plasma reactor, connected by a sample transfer chamber to an UHV chamber equipped with an x-ray photoelectron spectrometer ͓Surface Science Instruments model M-probe 301, monochromatized Al(K␣)͔. The plasma reactor is a 6 in.…”

Transition between two states of surface coverage and etch rate during Si etching in inductively coupled Cl2–Ar plasmas with changing mixtures

“…The surface coverage of chlorine was measured with the laser desorption ͑LD͒ surface probe ͑XeCl laser, 308 nm, 20 ns pulse length, 36 mJ/pulse, 2 pps͒, in tandem with plasma-induced emission ͑PIE͒ detection of desorbed SiCl 2 and Si and laser induced fluorescence ͑LIF͒ detection of desorbed SiCl. [7][8][9] SiCl LD-LIF was excited by the same 308 nm laser and detected at 292.4 nm, both B 2 ⌺ ϩ →X 2 ⌸ r transitions. 7,8 The SiCl 2 and Si LD-PIE signals were moni-tored at 327.0 and 288.2 nm, corresponding to the à 1 B 1 →X 1 A 1 and 4s 1 P 1 0 →3p 2 1 D 2 transitions.…”

“…[7][8][9] SiCl LD-LIF was excited by the same 308 nm laser and detected at 292.4 nm, both B 2 ⌺ ϩ →X 2 ⌸ r transitions. 7,8 The SiCl 2 and Si LD-PIE signals were moni-tored at 327.0 and 288.2 nm, corresponding to the à 1 B 1 →X 1 A 1 and 4s 1 P 1 0 →3p 2 1 D 2 transitions. 9 The first-order chlorination constants 70 ms ͑30% Cl 2 ) and 40 ms ͑75% Cl 2 ), from SiCl LD-LIF as a function of the laser repetition rate, indicate the laser desorbed regions were fully chlorinated between laser pulses at 2 pps.…”