Effects of Water Desorption from SiO₂ Substrates on the Thickness of Manganese Oxide Diffusion Barrier Layer Formed by Chemical Vapor Deposition

Abstract

Hysteresis in the field effect of bilayer graphene is observed at a low temperature. We attribute this effect to charge traps in the substrate. When the sweep rate of the back-gate voltage is increased to higher values, the hysteresis becomes more pronounced. By measuring the hysteresis in the field effect, the lifetime of the charge traps is estimated as 16.9 min. It is shown that the influence of charge traps on graphene is strongly affected by a magnetic field. Above 5 T the hysteresis remains constant.Since the discovery of free-standing atomically thin graphite-the so-called graphene-such monolayers of carbon have been intensively studied [1]-[3]. This system is especially interesting because graphene exhibits a field effect, i.e. by applying a gate voltage it is possible to change the majority charge carriers from holes to electrons [1]. In some samples, hysteresis effects were observed by measuring the field effect of graphene at room temperature [4]. The observed shift in the charge neutrality point depends on the sweep direction of the back-gate voltage and is attributed to dipolar adsorbates, e.g. water that act as charge traps [5]. To suppress such hysteresis under ambient conditions the substrate can be coated with a thin layer of a hydrophobic substance [6]. Using microsoldered graphene, it was shown that polymethylmethacrylate (PMMA) has a doping effect on graphene but does not change the voltage-induced hysteresis [7]. At low temperatures, Yoo et al [8] observed a hysteresis effect in graphene nanorings, which they attribute to available trap states in the rough edges of the graphene nanoring structure. Furthermore, hysteresis effects were observed on some systems similar to graphene, e.g. carbon nanotubes. Lee et al [9] argue that their observed hysteresis in carbon nanotubes at T = 56 K is due to silanol groups (SiOH) at the surface of the substrate.

Structural and Electronic Properties of a Mn Oxide Diffusion Barrier Layer Formed by Chemical Vapor Deposition

“…Based on these considerations, Neishi et al [12] and Matsumoto et al [14], [15] reported the deposition behavior and diffusion barrier property, as mentioned already. However, the diffusion barrier property was examined only with an EDS, which is not capable of detecting the small amount of elements of less than 0.1 at%.…”

“…The deposited layer was tentatively indicated as MnO x . The thickness of the amorphous layer could be controlled by changing deposition temperature [12] and by absorbed moisture in tetraethyl orthosilicate (TEOS)-SiO 2 substrates [14]. A conformal deposition of the thin MnO x layer was also possible in high-aspect-ratio contact holes [15].…”

Study of Chemical Vapor Deposition of Manganese on Porous SiCOH Low-k Dielectrics Using Bis(ethylcyclopentadienyl)manganese

“…The as-deposited films (referred to as pristine) have different pore size and porosity as described in the Table I. As reported in the litterature, 4 to form a thin MnO x layer, moisture desorbing from the substrate is needed to participate in the hydrolysis reaction of the Mn precursor during the CVD process. For this purpose, to increase the amount of adsorbed water by a controllable way, the films were subjected to O 2 plasma during 200 sec (inductively coupled plasma chamber -ICP) * Electrochemical Society Active Member.…”

“…For further technology scaling, Chemical Vapor Deposition (CVD) of Mn has been investigated using Mn-amidinate and more predominately using Bisethylcyclopentadienyl manganese, (EtCp) 2 Mn precursors. [1][2][3][4] For both precursors, the barrier properties of CVD-Mn-based layers were also studied and proven on dense SiO 2 substrates. 1,2 However, if CVD-Mn-based barriers must be used in advanced technologies, it has to be formed on porous SiCOH low dielectric constant (low-k) materials in order to satisfy signal transmission speed needs within the chip.…”

Deposition behavior and substrate dependency of ALD MnO<inf>x</inf> diffusion barrier layer

“…However, we reported previously that the presence of absorbed water in dielectrics has notable effects on the structure, composition, and thickness of the CVD-grown MnO x layer [8][9][10]. Since the amount of the absorbed water is difficult to control, a new MnO x forming process should be developed so as not to be influenced by the absorbed water in the dielectric substrates.…”