Thermal gas-phase etching of titanium nitride (TiN) by thionyl chloride (SOCl2)

In this work, thermal based gas-phase etching of titanium nitride (TiN) is demonstrated using thionyl chloride (SOCl2) as a novel etchant. A single etchant utilised in pulsed fashion to etch TiN. This type technique may also be considered chemical or dry etching. The removed TiN amount was measured by various techniques like spectroscopic ellipsometry (SE), weighing balance and some cases X-ray reflectometry (XRR). Additionally, the post-etch surfaces were analysed with photoelectron spectroscopy (XPS) bright field transmission electron microscopy (BF-TEM). surface roughness morphology before after films atomic force (AFM). per cycle (EPC) calculated plotted function SOCl2 pulse time, purge time exposure, number cycles temperature (Tetch). An increase EPC an well observed. able starting from 270 °C about 0.03 Å almost 1.2 at 370 °C. Arrhenius plot determined activation energy (Ea) 25 kcal/mol for SOCl2. addition, selectivity between different substrates such silicon dioxide (SiO2), (Si3N4) aluminum oxide (Al2O3) investigated on blanket 3D structures. Moreover, thermodynamic calculations performed possible reactions. Titanium proposed etched form either trichloride (TiCl3) tetrachloride (TiCl4). Nitrogen volatile by-products diatomic nitrogen (N2), nitrous (N2O) (NO2).