Articles you may be interested inDifferences in erosion mechanism and selectivity between Ti and TiN in fluorocarbon plasmas for dielectric etch A model for Si, SiCH, Si O 2 , SiOCH, and porous SiOCH etch rate calculation in inductively coupled fluorocarbon plasma with a pulsed bias: Importance of the fluorocarbon layerThe authors studied the behavior of Ti hardmasks in CF 4 /Ar and C 4 F 8 /Ar discharges using conditions relevant to pattern transfer processes into organosilicate glass (OSG), a reference low-k material investigated in parallel. The authors examined various material erosion stages and determined the dependencies of etch rates (ERs) and etching selectivities (ESs) on the following plasma parameters: self-bias voltage (50-150 V), processing pressure (20-60 mTorr) and %CF 4 (10-30 %) in CF 4 /Ar discharges, and O 2 addition (0-10 %) and N 2 addition (0-20 %) to C 4 F 8 /Ar discharges. Erosion behavior and ERs were characterized by real-time ellipsometric measurements and multilayer optical modeling. These measurements were complemented by x ray photoelectron spectroscopy to study the surface composition. The impact of plasma parameter changes were investigated by comparing ERs and corresponding ESs (OSG ER/Ti ER). During the erosion of Ti, the initially oxidized film surface was transformed into a TiF x layer (x $ 3) covered by a FC film. The FC film thickness strongly depended on the FC feed gas and was significantly thicker for the C 4 F 8 -based etch (1.5 nm) than for the CF 4 -based etch (0.9 nm). Ti erosion was found to be dependent on the energy deposited on the film surface by ion bombardment and to exponentially decrease with increasing FC film thicknesses. For thin FC films (< 1 nm), erosion was ion driven, i.e., "chemical sputtering", and, for thick FC films (> 1 nm), erosion was limited by the amount of F that could diffuse through the FC layer to the Ti interface. In contrast to organic masking materials, Ti hardmasks have lower ESs for the more polymerizing C 4 F 8 -based discharges than for CF 4 -based discharges. This can be explained by the consumption of the limited supply of F at the OSG surface by C and H impurities, which form volatile CF 4 and HF etch products. For thin FC films and low ion energy deposition by ion bombardment, ESs up to 15 have been achieved.

Articles you may be interested inStudy of Ti etching and selectivity mechanism in fluorocarbon plasmas for dielectric etch J. Vac. Sci. Technol. B 30, 021804 (2012); 10.1116/1.3690643Etching characteristics of TiN used as hard mask in dielectric etch process