Effects of Oxygen Source on Film Properties of Atomic-Layer-Deposited La-Silicate Film Using La[N(SiMe3)2]3

Abstract

The effect of oxygen sources, i.e. O 3 or H 2 O, on chemical composition, dielectric constant and leakage current density of atomiclayer-deposited La-silicate films was examined. The dielectric constant of La-silicate films grown using O 3 was ∼8.0, which was lower than that of La-silicate films grown using H 2 O, ∼11.7 due to the higher Si concentrations. However, leakage current density of La-silicate films grown using O 3 was about 3 orders of magnitude lower than that of La-silicate films grown using H 2 O at an identical capacitance-equivalent-thickness (but almost half the physical thickness), due to the higher Si concentrations and less La-carbonate formation.As the next generation high-k dielectric film as well as the threshold voltage control layer, La 2 O 3 film are attracting much attention nowadays due to their high dielectric constant (∼30) 1,2 and large conduction band offset (CBO) with Si (∼2.3 eV). 1 However, atomic layer deposition (ALD) of La-containing films has several challenges such as the limited selection of precursors and inducement of unstable film growth due to its hygroscopic behavior. 3 Additionally, serious Si diffusion from the substrate into the La 2 O 3 film during deposition have been reported. 4,5 The use of Si-containing Tris[bis(trimethylsilyl)amino]lanthanum, La[N(SiMe 3 ) 2 ] 3 , as a La precursor was reported as the promising way to intentionally incorporate Si in La 2 O 3 film to prevent the diffusion of Si from Si substrates. 6 Since, significant Si diffusion during ALD of La 2 O 3 film and post-deposition annealing degrades the gate controllability by increasing permittivity of the gate oxide film, the use of Lasilicate film instead of La 2 O 3 film is more attractive. Even though the chemical properties of ALD La-silicate films using La[N(SiMe 3 ) 2 ] 3 and H 2 O were reported, 6-9 a systematic study on the influence of the type of oxygen source, H 2 O or O 3 , on the growth behavior and electrical properties of La-silicate films using La[N(SiMe 3 ) 2 ] 3 has been rarely reported. 10 In this study, the ALD behavior and electrical properties of La-silicate films according to the type of oxygen source were examined. In particular, the changes in Si concentration of the ALD La-silicate film grown using the La[N(SiMe 3 ) 2 ] 3 precursor were focused.La-silicate films were grown on a HF-cleaned p-type (100) Si substrate at a wafer temperature of 310 • C in a traveling-wave type 4-in. thermal ALD reactor with a liquid delivery system using La[N(SiMe 3 ) 2 ] 3 as the metal precursor. O 3 of 110 g/Nm 3 and H 2 O at room temperature were used as the oxygen sources for O 3 -La-silicate and H 2 O-La-silicate films, respectively. La[N(SiMe 3 ) 2 ] 3 was vaporized at 190 • C and delivered to the reactor in the Ar carrier gas of 200 sccm. The injection time of La[N(SiMe 3 ) 2 ] 3 dissolved in hexane was controlled in milliseconds to precisely deliver it to a vaporizer. The injection time for La source, H 2 O and O 3 was fixed at 0.1ms, 1s and 5s, respectively. The base pressure of th...

Magnetic behavioural change of silane exposed graphene nanoflakes

“…However, these peaks are observed in 15,19,20 In case of Si 2s XPS, the peaks observed within the range $151.1-153.0 eV are Si-Si peaks, whereas other peaks above 153.0 eV are assigned as Si-O. 22 It is very clear from these results that the changes of microstructural and bonding properties are of significance when Si is functionalized with GNFs that effect the change in electron field emission. It is also observed from the XPS decomposed peak intensity that on exposure to organo-silane (or Si-functionalization), the structures are changed from sp 2 -rich to sp 3 -rich ordered GNFs.…”