Chemical Vapor Deposition of Ti_xSi_1–xO₂ Films: Precursor Chemistry Impacts Films Composition

Abstract

Thin films of composition Ti x Si 1±x O 2 were grown by low-pressure (LP) CVD on silicon (100) , as the sources of SiO 2 and TiO 2 , respectively. The substrate temperature was varied between 300 C and 535 C, and the individual precursor delivery rates ranged from 5 sccm to 100 sccm. Under these conditions, growth rates ranging from 0.6 nm min ±1 to 90.0 nm min ±1 were observed. As-deposited films were amorphous to X-rays, and cross-sectional transmission electron microscopy (TEM) images showed no compositional inhomogeneity. Rutherford backscattering (RBS) spectrometry revealed that the relative concentration of TiO 2 and SiO 2 was dependent upon the choice of TiO 2 precursor. Possible multi-precursor deposition scenarios are presented and discussed in relation to the observed variation of film stoichiometry. For the TTIP±TEOS pair, the systematic variation of Ti content with deposition conditions could be accounted for by a growth scenario that limits SiO 2 growth to TiO 2 sites within the composite film. For the case of TN±TEOS the Ti content remained close to 50 % for all conditions studied. A specific chemical reaction between TN and TEOS prior to film deposition accounts for the observed composition.

CVD of Titanium Oxide Thin Films from the Reaction of Tetrakis(dimethylamido)‐ titanium with Oxygen

“…In our studies, Ti(NMe 2 ) 4 was found to be inert under 1 atm O 2 at 23 C. In the CVD reactor at 250±300 C, the reaction between Ti(NMe 2 ) 4 and O 2 was quick. The CVD reactor used was a hot-wall, horizontal apparatus [8] ( Fig.…”

“…No nitride (TiN) or oxynitrided (TiO x N y ) species were observed. The work here shows that Ti(NMe 2 ) 4 is a good precursor in the CVD of TiO 2 thin films. The dielectric constant of these films is high, and these films are potential candidates for high-k applications.…”

“…TiO 2 films have been prepared from several single-source precursors. [4,7] We studied the CVD of TiO 2 thin films from the reaction of Ti(NMe 2 ) 4 with O 2 at 250±300 C. Ti(NMe 2 ) 4 was chosen as the precursor in the current work mainly because it is a liquid at 23 C, with a boiling point of 60 C under 0.1 torr. The TiO 2 films were amorphous before annealing, but crystalline anatase after annealing at 600 C in air.…”

“…In summary, TiO 2 thin films have been deposited on Si(100) wafers via MOCVD using Ti(NMe 2 ) 4 as the volatile precursor. After annealing at 600 C, the films were crystalline anatase.…”

“…The CVD reactor used was a hot-wall, horizontal apparatus [8] ( Fig. 1) with a tank of 2 % O 2 in Ar and a bubbler containing Ti(NMe 2 ) 4 in the range 0±50 C to control the deposition rate. The two precursors were not mixed until they were in the heated zone to avoid premature reaction.…”