An organic film, FLARE™, is one of the most prospective candidates for interlayer insulating films with low dielectric constants (low k). This organic low k film was etched in inductively coupled high-density plasmas employing N2/H2 and N2/NH3 gases. By changing the mixing ratio of these gases, the anisotropic etching profile was obtained. The etching plasmas were evaluated by quadruple mass spectroscopy and the vacuum ultraviolet absorption spectroscopy employing microplasma as a light source. N and H radical densities were estimated on the order of 1011–1012 cm−3 and 1012–1013 cm−3, respectively. The behavior of etch rate corresponded well to that of H radical density. H radicals were found to be important species for organic low k film etching, while N radicals could not etch without ion bombardments. On the other hand, N radicals were found to be effective for the formation of protection layer on the sidewall against the etching by the H radicals. The ratio of H and N radical densities would be important for the etching of organic low k film employing N–H plasmas.

We have developed a measurement technique for absolute H-atom densities in process plasmas using vacuum ultraviolet absorption spectroscopy employing a high-pressure microdischarge hollow-cathode lamp (MHCL) as a Lyman α (Lα, 121.6 nm) emission light source. Characterization of the Lα emission-line profile could be simplified by using a high-pressure discharge at about 1 atm. The effect of self-absorption in the MHCL was reduced to an insignificant level by decreasing the H2 partial pressure. The contribution of the collisional broadening to the Lα emission profile was estimated from the saturation characteristics of the absorption intensity when the optical thickness of the plasma was varied. The technique was applied to the measurement of the absolute H-atom density in an inductively coupled H2 plasma.

Absolute fluorine atom concentrations in fluorocarbon plasmas determined from CF 2 loss kinetics

We have developed a vacuum ultraviolet absorption spectroscopy (VUVAS) technique employing a high-pressure nitrogen molecule (N2) microdischarge hollow cathode lamp (N2 MHCL) as a light source of the atomic nitrogen (N) resonance lines for measuring absolute N densities in process plasmas. The estimations of self-absorption and the emission line profiles of the N2 MHCL, which are necessary for absolute N density determination, were carried out. The measurement of absolute N densities have been demonstrated for an inductively coupled N2 plasma using the VUVAS system employing the N2 MHCL.