Behavior of atomic radicals and their effects on organic low dielectric constant film etching in high density N2/H2 and N2/NH3 plasmas

Abstract

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.

Measurement and modeling of neutral, radical, and ion densities in H2-N2-Ar plasmas

“…For example, thin films of silicon nitride which are fabricated by plasma-enhanced chemical vapor deposition (PECVD) in the semiconductor industry are used as passivation layers 4 and in the photovoltaic industry 3,5 . For the etching of organic low-k layers hydrofluorocarbons are replaced by H 2 -N 2 due to economic and ecological reasons 6,7 . Other applications of H 2 -N 2 plasmas are nitriding 8,9 , the plasma-enhanced atomic layer deposition of TaN and TiN thin films 8,10 , the etching of organic low dielectric constant (low-k) films 6,8,11 and the chemical synthesis of ammonia 8,12,13 .…”

“…For the etching of organic low-k layers hydrofluorocarbons are replaced by H 2 -N 2 due to economic and ecological reasons 6,7 . Other applications of H 2 -N 2 plasmas are nitriding 8,9 , the plasma-enhanced atomic layer deposition of TaN and TiN thin films 8,10 , the etching of organic low dielectric constant (low-k) films 6,8,11 and the chemical synthesis of ammonia 8,12,13 . The latter is also of interest in nuclear fusion research where N 2 is puffed into the plasma edge of the hydrogen plasma to reduce the local heat load of the so-called divertor region [14][15][16][17][18][19] .…”

Integration of Low‐ k Dielectric Films in Damascene Processes

“…On the other hand, inert gases, such as nitrogen, densify the surface completely. The formation of a top layer rich in carbon and nitrogen has been reported for polymer surface treated with nitrogen [163]. Unfortunately, these sealed polymer fi lms seem to loose their sealing property when exposed to elevated temperature (>300°C) [27].…”

Optical emission diagnostics of etching of low-k dielectrics in a two frequency inductively coupled plasma

“…Nevertheless optimization of the procedure is still an open issue [4]. On the other hand it turned out that one of the options for etching such organic materials is to use a mixture of oxygen, nitrogen and hydrogen [5]. This is an additional benefit as there is a lot of pressure on microelectronic industry to replace fluorocarbons from the technological exhaust gases due to their high global warming potential.…”