Metal–organic atomic-layer deposition of titanium–silicon–nitride films

Abstract

Titanium-silicon-nitride films were grown by metal-organic atomic-layer deposition at 180°C. When silane was supplied separately in the sequence of a tetrakis͑dimethylamido͒ titanium pulse, silane pulse, and ammonia pulse, the Si content in the deposited films and the deposition thickness per cycle remained almost constant at 18 at. % and 0.22 nm/cycle, even though the silane partial pressure varied from 0.27 to 13.3 Pa. Especially, the Si content dependence is strikingly different from the conventional chemical-vapor deposition. The capacitance-voltage measurement revealed that the Ti-Si-N film prevents the diffusion of Cu up to 800°C for 60 min.Step coverage was approximately 100% even on the 0.3 m diam hole with slightly negative slope and 10:1 aspect ratio. © 1999 American Institute of Physics. ͓S0003-6951͑99͒01137-7͔As the minimum feature size of semiconductor devices shrinks, the Cu diffusion barrier must be effective even when it is as thin as 10 nm because thick diffusion barriers leave little space for Cu, and thus, nullify the advantage of Cu metallization.1,2 In this respect, more effective Cu diffusion barrier materials with a thinner thickness are required. Amorphous refractory ternary metals such as ͑Ti, Ta, W͒-Si-N, W-B-N do not have fast diffusion paths such as a grain boundary present in polycrystalline materials and are promising candidates for these applications.3,4 These diffusion barriers need to be deposited with good step coverage, especially on the sidewall, as the aspect ratio of contact/via/ trench increases.Metal-organic atomic-layer deposition ͑MOALD͒ achieves near-perfect step coverage and can control precisely the thickness and composition of grown films. 5 We have already demonstrated that TiN film could be grown with excellent conformality by MOALD using tetrakis͑ethylmethyl-amido͒titanium and NH 3 .6 However, MOALD of a ternary system may not be as easy to demonstrate as much as it is for a binary system and may not be understood straightforwardly in terms of chemical composition and growth kinetics. Therefore, in the present study, we have developed a MOALD technique for ternary Ti-Si-N films using a sequential supply of Ti͓N͑CH 3 ͒ 2 ͔ 4 ͓tetrakis͑dimethylamido͒ titanium: TDMAT͔, silane (SiH 4 ), and ammonia (NH 3 ), and evaluated the Cu diffusion barrier characteristics of a 10 nm Ti-Si-N film with high-frequency small-signal capacitance-voltage (C -V) measurements.A MOALD apparatus was used to grow Ti-Si-N films, which is schematically similar to the one described previously. 6 All the films were grown on SiO 2 ͑100 nm͒/Si wafers at the substrate temperature of 180°C and with the reactor pressure maintained at 133 Pa. TDMAT was delivered from the bubbler ͑30°C͒ to the reactor using Ar ͑70 sccm͒ as a carrier gas. Also, the flow rates of NH 3 and SiH 4 ͑forming gas with 10% SiH 4 /90% Ar͒ diluted in Ar were fixed at 70 sccm. The film thicknesses were measured by the surface profilometer. The composition of the grown film was analyzed using 9.0 MeV Cl 5ϩ elastic recoil detection...

Analysis of a transient region during the initial stage of atomic layer deposition

“…TiN is the same value as that of C NH3 SiO 2 to C NH 3 TiN , the extrapolated line intersects about 16 cycles, and thus it is possible to estimate that C TDMAT…”

“…In ALD, the film thickness, which is grown in a deposition cycle, is self-limited to a constant value at saturation conditions, which is usually less than 2 monolayers ͑MLs͒ in the case of a binary compound system and a ternary system. [1][2][3] However, the probability that a reactant will be adsorbed is dependent on the properties of the surface to which it will be adsorbed. Thus, for the case of the film deposition thickness in one deposition cycle ͑ML/cycle͒, it is inevitable that differences between the initial stage and the stabilized stage of ALD will exist.…”

Influence of the substrate hydrophilicity on the grid assisted deposition of tris-(8-hydroxyquinolinato) aluminum(III) thin films

“…Devices based on functional materials often require the growth of thin films with a thickness ranging from the nanometer to the micrometer scale. Film growth techniques can be divided into two main categories: (i) solution-based methods including spin coating [6], dip-coating [7], drop casting [8], 'layer by layer' deposition [9], electrochemical deposition [10], and (ii) dry methods including vacuum sublimation [11], laser ablation [12], and atomic layer deposition [13]. All these procedures are very robust and allow the fabrication of thin films with a precise control over thickness and morphology.…”

Deposition characteristics of Ti−Si−N films reactively sputtered from various targets in a N2/Ar gas mixture

“…[26][27][28][29][30] There have also been intensive studies on Ti-Si-N films using various deposition and annealing methods. [31][32][33][34][35] It has been shown that the diffusion capability and resistivity Deposition Characteristics of Ti-Si-N Films Reactively Sputtered from Various Targets in a N 2 /Ar Gas Mixture variation of this film are mostly influenced by the film composition. Therefore, systematic studies of the deposition characteristics of Ti-Si-N films are necessary.…”