Modification of organosilicate glasses low-k films under extreme and vacuum ultraviolet radiation

Abstract

Degradation of chemical composition of porous low-k films under extreme and various vacuum ultraviolet emissions is studied using specially developed sources. It is shown that the most significant damage is induced by Xe line emission (147 nm) in comparison with Ar (106 nm), He (58 nm), and Sn (13.5 nm) emissions. No direct damage was detected for 193 nm emission. Photoabsorption cross-sections and photodissociation quantum yields were derived for four films under study. 147 nm photons penetrate deeply into low-k films due to smaller photoabsorption cross-section and still have sufficient energy to excite Si-O-Si matrix and break Si-CH3 bonds.

DBD‐based plasma polymerization from monomer‐argon mixtures: Analytical model of monomer reactions with excited argon species

“…At g = 1 · 10 18 cm −3 s −1 a photon flux at the walls of 1 · 10 16 cm −2 s −1 is estimated (0.2 · g · h /2). This light should be absorbed within a depth of a few 10 nm and should result in a high number of Si–CH 3 bond scissions per volume and time; the corresponding quantum yield is about 0.3 . Therefore, a steady state of the surface with a high areal density of radical centers, able to recombine with incoming silyl or siloxy radicals, should be possible…”

Photoabsorption and damage of OSG low‐k films by VUV emission at 140–160 nm

“…Since the decomposition of surface methyl groups SiCH 3 under the VUV radiation is the primary reason of the OSG damage, the focus in FTIR analysis was made on changes (namely depletion) of these groups as a function of photon fluence . The relative depletion of SiCH 3 groups, namely [SiCH 3 ]/[SiCH 3 ] 0 (here [SiCH 3 ] 0 is the initial column density of SiCH 3 groups, that is, the number of SiCH 3 bonds per unit area integrated along a path, [SiCH 3 ] is the current column density) was estimated by measuring the decrease of the infrared absorbance peak at 1274 cm −1 .…”

“…Damage during plasma processing is one of the most serious. The main damage is caused by radicals and VUV photons . While several technological approaches were developed to decrease radical‐induced damage, VUV photons penetrating deeply into low‐k films lead to the irreversible damage …”

“…The photon‐induced damage of OSG films by VUV radiation depends on the absorption coefficient . It was shown that the wavelength dependence of OSG absorption coefficient reduced to Si atom density (in fact, it can be considered as absorption cross section per Si atom) is similar to that of SiO 2 for the wavelengths below ∼130–140 nm with its absolute value being only slightly lower (factor ∼2) than that of SiO 2 .…”

“…Since OSG damage under exposure to VUV photons is observed as a depletion of SiCH 3 bonds with the following moisture uptake after the sample is exposed to the atmosphere (producing SiOH bonds instead SiCH 3 ), this damage mechanism is usually considered to be the direct absorption of VUV photons by SiCH 3 groups . Another approach is assuming the excitation of “O 3 SiCH 3 ” cluster electronic states and the subsequent transition of the excitation energy into SiCH 3 bond break . The wavelength dependency of SiCH 3 dissociation probability near the threshold can be influenced by various factors: exact absorption mechanism including different excitation energy conversion channels, porosity effects, and even pore structure.…”