Thermal Decomposition of Ti(O–iPr)₂(dpm)₂ in the Gas Phase

Abstract

Scaling of metal-oxide-semiconductor (MOS) transistors to smaller dimensions has been a key driving force in the IC industry. As we approach the sub-quarter micron regime, a whole new set of problems regarding the device performance arises. One of the major concerns is the high gate leakage current. To address this problem, a lot of effort has been concentrated on the use of the so-called "high-K dielectrics" as gate insulators. However, the implications of using these materials on the electrical performance of MOS devices need to be studied. This work is an effort towards the same. There has also been a lot of discussion about the trade-offs related to the use of retrograde channel profiles in deep sub-micron transistors. It is also shown in this work that a retrograde profile can be optimized to have an advantage over uniform doping.

Thermal Decomposition of Ti(O-iPr)[sub 2](dpm)[sub 2] on Pt Foil

“…These may be produced by the decomposition of a t-butyl group on Pt. The t-butyl group is easily dissociated from the dpm ligand in either the solid or gas phase at temperatures of near 370 K. 18,19 Accordingly, it is likely that the t-butyl group, which had already dissociated from Ti͑O-iPr͒ 2 ͑dpm͒ 2 during vaporization at 420 K, was introduced into the UHV chamber together with the Ti precursor in the dosing step. The t-butyl group adsorbed to the Pt surface is decomposed at relatively low temperatures, as previously reported.…”

“…28,29 The desorption of propylene and propanal, which occurs at temperatures above 470 K, indicates that the dpm ligand in Ti͑O-iPr͒ 2 ͑dpm͒ 2 is dissociated under this condition. Table III, which lists the activation energies for the dissociation of chemical bonds in gaseous Ti͑O-iPr͒ 2 ͑dpm͒ 2 , indicates that bonds in the dpm ligand have higher activation energies than those in the isopropoxy ligand 19 and, consequently, the dpm ligand is dissociated at higher temperatures than the isopropoxy ligand.…”

“…Activation energies for the dissociation of bonds in isopropoxy and dpm ligands. 19 C199 Journal of The Electrochemical Society, 153 ͑3͒ C195-C201 ͑2006͒ C199 500 K according to XPS͒, i.e., to acetone and isopropanol by disproportionation at 400 K and to acetone and hydrocarbons with lower carbon numbers at 470 K. The dpm ligand is dissociated to propylene and propanal in two steps at 470 and 650 K. Eventually, TiO x and carbon remain on the Pt surface after decomposition at higher temperatures.…”

“…18 Heo et al reported on the activation energy for the dissociation of individual bonds in dpm and isopropoxy ligands. 19 In addition to the above results obtained in the solid and gas phases, information concerning the decomposition of the Ti precursor on the surface of a substrate is also required for controlling film properties because the latter are directly related to the surface reactions of the Ti precursor. 20,21 Several studies of reactions of Ti precursors on different substrates have been reported, but they were mainly focused on precursors with simple molecular structures such as TiCl 4 and TTiP.…”

Smooth and Conformal TiO2Thin-Film Formation Using Supercritical Fluid Deposition

“…Therefore, these three titanium precursors with tmhd or acac ligands were chosen as potential precursors for TiO 2 -SCFD at low process temperatures. The thermal decomposition temperatures of the precursors were reported to be around 400 • C under vacuum conditions; [28][29][30] thus, a decomposition temperature below 400 • C in SCFD would prevent thermal damage on integrated logic circuits. Table I shows the solubilities of these precursors in scCO 2 and the corresponding properties of the deposited films.…”