A mass-spectroscopical study of the decomposition of Ti(NMe2)4 in a mixed Ar–H2–N2 pulsed d.c. plasma

Driessen, J. P. A. M.; Kuypers, A. D.; Schoonman, J.

doi:10.1016/s0257-8972(98)00696-3

Cited by 12 publications

(6 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Alternatively, plasma activation of hydrogen as well as a pulsed plasma-enhanced activation of TDMAT could be considered as a means for removal of carbon-containing ligands. 27 …”

Section: Discussionmentioning

confidence: 99%

“…[22][23][24] Plasma-enhanced chemical vapor deposition ͑PECVD͒ of TiN 25,26 has received increasing attention as a means to further decrease the deposition temperature and to establish dense coatings with low levels of contamination. Neutral free radicals and transamination reactions are believed to participate in the cleavage of carbon-containing ligands [25][26][27] and nonuniform coatings are again observed. Use of ammonia results in powdery nonadherent coatings due to the enhanced gas-phase reactivity, specifically homogeneous nucleation processes.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Infrared Spectroscopic Study of Decomposition of Ti ( N ( CH ₃ ) ₂ ) ₄

Driessen

Schoonman

Jensen

2001

J. Electrochem. Soc.

View full text Add to dashboard Cite

The decomposition of Ti͑N͑CH 3 ͒ 2 ͒ 4 ͑TDMAT͒ has been studied in N 2 and H 2 environments and surface temperatures between 473 and 623 K by using Fourier transform infrared spectroscopy. The pressure in the system was 5 Torr, with a TDMAT partial pressure of 0.3 Torr. The evolution of gas-phase species was monitored by characteristic infrared absorption. For temperatures less than 478 K, an average number of more than three ligands per TDMAT molecule is observed. Approximately one ligand per two TDMAT molecules decomposes into methane-and carbon-containing species in the coating. This slow decomposition pathway implies intermolecular hydrogen transfer between multiple TDMAT molecules. A decomposition mechanism consistent with the experimental observations is proposed. For temperatures greater than 478 K, the conversion rate of TDMAT into products increases drastically. Less gaseous species are observed, Auger electron spectroscopy measurements show more carbon contamination in the coating, and additional absorption peaks appear in the IR spectra. Nuclear magnetic resonance spectroscopy indicates that these peaks can be assigned to a mixture of oligomers of TDMAT reaction fragments that desorb from the hot surface. The increased carbon content at elevated temperatures is attributed to incomplete desorption of ligands or metallacycle formation.There has been extensive interest in chemical vapor deposition ͑CVD͒ of TiN coatings because of their useful materials properties and wide range of applications. The dense structure and the low resistivity of TiN make it a suitable diffusion barrier layer in semiconductor devices. 1-5 The high hardness of TiN makes it useful for wear resistant applications. 6,7 These characteristics, combined with its corrosion resistance, also make it a good biocompatible coating for implantable human body parts. 7 Thin coatings of TiN also find use as transparent conducting layers in liquid crystal displays. 8 Finally, the gold color of TiN is desirable for many decorative applications.TiN has traditionally been deposited using TiCl 4 and N 2 or NH 3 as precursors, 1,9 but growth temperatures are typically too high, and below ϳ900 K chlorine incorporation degrades the useful properties of TiN films. Metallorganic precursors, specifically tetrakisamidotitanium compounds ͓Ti͑NR 2 ͒ 4 ͑R ϭ CH 3 or C 2 H 5 ͔, have been explored as alternative precursors for deposition at lower temperatures. Thermal decomposition of tetrakis͑dimethylamido͒titanium ͑TDMAT͒ for the deposition of TiN for diffusion barriers resulted in very uniform films at temperatures between 653 and 743 K, but the coatings contained as much as 30 atom % carbon, which increased the electrical resistivity. 2 For wear resistant applications, incorporation of hydrocarbon fragments of TDMAT in the coating causes an unwelcome softening. The high carbon content in the deposit has been attributed to the formation of stable gas-phase intermediates. 10-13 The formation of metallacycles followed by the cleavage of the highly reactive meth...

show abstract

“…Alternatively, plasma activation of hydrogen as well as a pulsed plasma-enhanced activation of TDMAT could be considered as a means for removal of carbon-containing ligands. 27 …”

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Infrared Spectroscopic Study of Decomposition of Ti ( N ( CH ₃ ) ₂ ) ₄

Driessen

Schoonman

Jensen

2001

J. Electrochem. Soc.

View full text Add to dashboard Cite

show abstract

“…2 Due to the importance of TDMAT, the reaction of organotitanium compounds in the gas phase has been studied both theoretically 5,22,34,35 and experimentally. 20,24,28,[36][37][38][39][40] Another important focus of applied research involved has been on the reaction of TDMAT with different substrates such as metals, nitrides, and silica. 20,21,[23][24][25][26][27]29,38,[41][42][43] However, in spite of the importance of the interaction of TDMAT with the technologically relevant Si(100) surface, studies of the system TDMATSi(100) are very scarce.…”

Section: Introductionmentioning

confidence: 99%

“…Due to the importance of TDMAT, the reaction of organotitanium compounds in the gas phase has been studied both theoretically ,,, and experimentally. ,,,− Another important focus of applied research involved has been on the reaction of TDMAT with different substrates such as metals, nitrides, and silica. ,,− ,,,− However, in spite of the importance of the interaction of TDMAT with the technologically relevant Si(100) surface, studies of the system TDMAT−Si(100) are very scarce. ,, As opposed to the transamination reaction, where the small NH 3 molecule interacts readily with Ti atom in TDMAT, the direct interaction of Ti with a flat surface might be sterically hindered. Our mechanistic approach considers the TDMAT molecule as an amine, since the initial interaction with the surface is likely to involve the lone pair of nitrogen and the highly reactive silicon surface atoms.…”

Section: Introductionmentioning

confidence: 99%

Chemistry of Diffusion Barrier Film Formation: Adsorption and Dissociation of Tetrakis(dimethylamino)titanium on Si(100)-2 × 1

Rodríguez‐Reyes

Teplyakov

2007

J. Phys. Chem. C

View full text Add to dashboard Cite

Tetrakis(dimethylamino)titanium (TDMAT) is one of the most prominent precursors for deposition of thin diffusion barrier films onto semiconductor substrates for microelectronic applications. Adsorption and dissociation of this compound on a Si(100)-2 × 1 surface is studied by a combination of density functional calculations and infrared spectroscopy. Our computational investigation suggests that initial interaction occurs through the nucleophilic attack of a surface silicon atom by the lone pair of nitrogen. This molecularly adsorbed state (where the N atom attached to the surface is tetra-coordinated) is found to be a local minimum, and further transformation leads to the dissociation through scission of either the N-Ti or the N-C bond. Dissociation of TDMAT is permitted kinetically if it occurs through the scission of the N-Ti bond, while scission of an N-C bond is kinetically hindered despite the thermodynamic stability of the structure produced. In view of its amine-like behavior upon adsorption, TDMAT was expected to be molecularly adsorbed at cryogenic temperatures but dissociated at room temperature. These two facts are confirmed by infrared spectroscopy. Dissociation pathways involving two neighboring Si-Si dimers of the Si(100)-2 × 1 surface were considered as well, and the formation of an interdimer N-Ti bridge is found to be energetically possible. The elucidation of the mechanism of TDMAT adsorption holds the promise of a better understanding of the initial steps of thin film growth.

show abstract

“…Another observation from our work that corroborates previous observations is the fact that DMA generation is enhanced by NH 3 addition to the gas mixture. This may perhaps be explained by a transamination reaction, but the mechanistic details of how that may happen have not been determined, or even discussed much, in the literature. ,,,− Regardless, a couple of interesting observations from the data in Figure add to our knowledge on the kinetics of this step. First, the effect of ammonia starts to be noticeable only at surface temperatures of 550 K or above.…”

Section: Discussionmentioning

confidence: 99%