Role of Trimethylaluminum in Low Temperature Atomic Layer Deposition of Silicon Nitride

Abstract

Aminosilanes are attractive precursors for atomic layer deposition of silicon oxides and nitrides because they are halide-free and more reactive than chlorosilanes. However, the deposition of silicon nitride on oxide substrates still requires relatively high temperatures. We show here that for a process involving disec-butylaminosilane and hydrazine, the insertion of Al from trimethyl aluminum allows the deposition of silicon nitride films at relatively low temperatures (250 °C). Firstprinciples calculations reveal that the presence of Al increases the binding of molecular hydrazine, thereby effectively enhancing the reactivity of hydrazine with the silicon precursor during the atomic layer deposition process, which leads to nitrogen incorporation into silicon. However, the range of this enhancement is limited to ∼1 nm, requiring additional trimethylaluminum exposures to continue the Si 3 N 4 deposition.

Atomic Layer Modulation of Multicomponent Thin Films through Combination of Experimental and Theoretical Approaches

“…As a result, Carish can more favorably adsorb on the TMA-exposed surface than on the bare oxide surface. It is well-known from previous studies that treatment of the surface with TMA can facilitate successive adsorption of other precursors. , From DFT calculations, it is confirmed that each TMA and Carish precursor can adsorb at the unoccupied surface site in both the [C-T] and [T-C] sequences.…”

“…It is well-known from previous studies that treatment of the surface with TMA can facilitate successive adsorption of other precursors. 37,38 From DFT calculations, it is confirmed that each TMA and Carish precursor can adsorb at the unoccupied surface site in both the S2b in the Supporting Information). As observed in Figure 3a, the already adsorbed Carish molecules still showed two larger diketonato ligands (shown in cyan), which sterically hindered further Carish molecular adsorption.…”

“…On the pure metallic Ru substrate, adsorption of the Carish precursor was found to occur dissociatively even without presence of H or OH on the surface, as shown in the chemical equation below: On the other hand, on oxide subrates with OH groups as in the current study, the precursor can be expected to partially lose its ligands. , The heteroleptic Carish precursor is expected to adsorb via losing CO ligands as the byproduct, retaining the diketonate ligands and forming dative bonds with OH groups ( E ads = +1.24 eV, chemical equation , Figure a). While it is also possible to form another adsorption structure, via protonation of the diketonate ligands, retention of CO, and formation of direct Ru–O bonds, such a structure is highly endothermic ( E ads = +2.39 eV, chemical equation , not shown) and, thus, ignored. For adsorption of TMA, the Al atom of TMA was adsorbed on the O atom of the surface hydroxyl (−OH). , While TMA is known to produce a mixture of −Al­(CH 3 ) and −Al­(CH 3 ) 2 upon adsorption onto the substrate surface, ,− in the interest of clarity in the discussion, we have assumed −Al­(CH 3 ) to be the only surface product of TMA ( E ads = −3.11 eV, chemical equation , Figure b). Then, coadsorption of Carish and TMA as in the C-T and T-C sequences is considered. When Carish adsorbs on a TMA-exposed surface, E ads is decreased to −0.57 eV as shown in Figure c, indicating that Carish adsorbs more favorably on a TMA-covered surface than a TMA-free surface.…”

Thermal Atomic Layer Etching of Silica and Alumina Thin Films Using Trimethylaluminum with Hydrogen Fluoride or Fluoroform

“…Precursor exposure parameters were: HF (1 s pulse, Δ P = 800 mTorr), CHF 3 (5 s pulse, Δ P = 9.35 Torr), TMA (2 s pulse, Δ P = 800 mTorr), D 2 O (1 s pulse, Δ P = 300 mTorr). The TMA exposure parameters used herein are sufficient for saturation, since saturation of the hydroxyl-terminated Si(111) surface was previously demonstrated on the same home-build reactor using a 1 s TMA exposure (390 mTorr) at 250 °C …”

“…% D, Sigma-Aldrich) was used for the fluorine removal experiment to distinguish between species associated with the cleaning process and potential changes in water vapor adsorption on the spectrometer 111) surface was previously demonstrated on the same home-build reactor using a 1 s TMA exposure (390 mTorr) at 250 °C. 43 A Thermo Nicolet 6700 infrared interferometer (400−4000 cm −1 range) was connected to the reactor chamber to perform in situ FTIR measurements. All spectra were recorded in transmission mode at 4 cm −1 spectral resolution.…”