The Effects of Processing Parameters in the Chemical Vapor Deposition of Cobalt from Cobalt Tricarbonyl Nitrosyl

Abstract

This paper reports the development of a thermal chemical vapor deposition process for pure cobalt from the source precursor cobalt tricarbonyl nitrosyl for incorporation in integrated circuit silicide applications. Studies were carried out to examine the underlying mechanisms that control Co nucleation and growth kinetics, including the effects of key process parameters on film purity, texture, morphology, and electrical properties. For this purpose, systematic variations were implemented for substrate temperature, precursor flow, hydrogen reactant flow, and deposition time (thickness). Resulting films were analyzed by Rutherford backscattering spectrometry, X-ray photoelectron spectroscopy, X-ray diffraction, fourpoint resistivity probe, scanning electron microscopy, and atomic force microscopy. These investigations identified an optimized process window for the growth of pure Co with resistivity of 9 + 2 µΩ cm, smooth surface morphology, and root-mean-square surface roughness at or below 10% of film thickness.

Absolute cross sections for dissociative electron attachment and dissociative ionization of cobalt tricarbonyl nitrosyl in the energy range from 0 eV to 140 eV

“…This, can in turn cause reduced extraction efficiency for fragment ions that are formed with high kinetic energy release (KER) with respect to the thermal Ar + and SF 5 − 36 ions used for calibration. Direct information on the KER in electron induced dissociation of Co(CO) 3 NO is not available in the literature, however, Fieber-Erdmann et al 37 have studied the dissociation dynamics of positive ion formation from iron pentacarbonyl through photo-ionization in the energy range between 9.5-25 eV. In this study, they found the KER to vary between slightly above thermal to about 100 meV depending on the photon energy and the fragment formed.…”

“…The authors concluded that the remaining energy must be distributed mainly into rotational and vibrational excitations of the fragments. While no KER data are available for Co(CO) 3 NO, Sztaray and Baer 38 have modeled the internal energy distribution of the fragment ions after dissociation. Similar to what was deduced by Fieber-Erdmann et al 37 for Fe(CO) 5 , the fragment ions contain a considerable amount of internal energy after dissociation.…”

“…Its metal complexes, particularly the carbonyl derivatives cobalt octacarbonyl and cobalt tricarbonyl nitrosyl, have proven to be useful for both homogeneous 1 and heterogeneous catalyses. 2 The high volatility of Co 2 (CO) 8 and Co(CO) 3 NO make them suitable candidates for chemical vapour deposition (CVD), allowing the deposition of pure 3 or composite cobalt films for microelectronics and information technology. [4][5][6] With the advancement of nanotechnology tools and in particular focused electron beam induced deposition (FEBID) (for recent reviews on the method, see Utke et al 7 and van Dorp and Hagen 8 ), it has become possible to deposit more localized, three-dimensional structures.…”

“…13 Furthermore, commercially available cobalt carbonyl generally contains hexane as a stabilizing agent, increasing the unwanted hydrocarbon background pressure in the vacuum system. Recent research has thus focused on Co(CO) 3 NO as an alternative candidate for electron beam induced Co deposition, 13,16 as it combines high vapour pressure (100 Torr at 25…”

“…In this contribution, we present absolute DEA and DI cross sections for all available dissociation pathways upon electron impact on the FEBID precursor molecule Co(CO) 3 NO, in the energy range from 0-140 eV.…”