Interlayer Mediated Epitaxy of Cobalt Silicide on Silicon (100) from Low Temperature Chemical Vapor Deposition of Cobalt Formation Mechanisms and Associated Properties

Abstract

This paper reports the development of a methodology for the growth of epitaxial CoSi2 that uses Co films deposited by low temperature (390°C) chemical vapor deposition (CVD) from cobalt tricarbonyl nitrosyl [Co(CO)3NO] as source precursor. This CVD process exploits the reaction kinetics associated with the adsorption and decomposition of CoCO)3NO on Si surfaces to ensure the in situ, sequential growth of an ultrathin interfacial oxide layer followed by a Co thin film in a single deposition step. It is demonstrated that this interlayer, consisting of a Si-O or a Co-Si-O phase, inhibits silicidation for uncapped CVD Co regardless of annealing times and temperatures. Instead, Co agglomeration is observed, with the degree of agglomeration being proportional to the annealing temperature. The agglomeration is due to a reduction in the overall energy of the system through decrease of the Co/substrate interfacial area. Alternatively, for Ti/TiN capped CVD Co samples, the interfacial layer appears to play a role similar to that observed for similar layers in interlayer mediated epitaxy (IME). This assessment is supported by the observation of epitaxial CoSi2 for capped CVD Co samples after a single-step anneal at 725°C for 30 s. In contrast, Ti/TiN capped PVD Co samples annealed under identical processing conditions exhibited a polycrystalline CoSi2 phase with a strong (200) texture. As such, the methodology presented herein represents a modified IME technique for the growth of high quality, epitaxial CoSi2 films for applications in emerging microelectronics device technologies.

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

“…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. Based on this and the fact that the bonding and dissociation mechanisms in Co(CO) 3 NO and Fe(CO) 5 are similar, we adopt the values reported by FieberErdmann et al 37 as a reasonable estimate of the KER in DI of the cobalt complex under study.…”

“…The cross section for the SF 5 − formation from SF 6 has its maximum at about 0.55 eV, 35 hence falls within this range. Thus, above 0.2 eV, intensity changes in the electron beam should not influence the DEA cross section values significantly.…”

“…Absolute cross sections for positive ion formation were calibrated relative to the cross section for Ar + given by Rejoub and co-workers with a stated accuracy of ±5%, 34 and absolute cross sections for the negative ion formation were calibrated relative to the cross section of SF 5 − from SF 6 at 300 K. 35 Explicit error margins are not given for the SF 5 − cross section, 35 but judging from error bars shown and their discussion these should be accurate within ±10%.…”

“…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. Cobalt octacarbonyl and cobalt tricarbonyl nitrosyl have thus been used in FEBID to deposit catalysts for carbon nanotube growth, 9 and to fabricate magnetic force microscopy (MFM) tips, 10,11 crossbar Hall nanosensors, 12 electrode contacts, 10 and cobalt nanowires.…”

High-resolution characterization of the forbidden Si 200 and Si 222 reflections

“…If this is true, then the question arises, how do we distinguish between substrate-related and real layer peaks? In the case of CoSi 2 on Si(100) (Londergan et al, 2001) the detection of a clear CoSi 2 400 reflection confirms the existence of a (100)-oriented CoSi 2 layer, while the identification of a peak at about 2Â = 33…”