Tetrakis Diethylamino Hafnium Research Articles

Modelization of hafnium silicate chemical vapor deposition using tetrakis-diethyl-amino-hafnium and tetrakis-dimethyl-amino-silane

The Chemical Vapor Deposition growth mechanism of a hafnium silicate film deposited by means of the co-flow of two precursors, TDEAH (tetrakis-diethyl-amino-hafnium) and 4DMAS (tetrakis-dimethyl-amino-silane), is characterized. Typical growth kinetics demand that the deposition rate increases and the silicon concentration remain stable with increasing reactor pressure. Though the deposition rate follows the expected growth kinetics, the silicon concentration in the silicate does not and exhibits an abnormal increase with increasing reactor pressure. To understand this atypical behavior the formation of pure HfO2 from TDEAH and pure SiOx from 4DMAS is first studied. Experimental results show that whereas the HfO2 deposition is well behaved and fits a diffusion-based model defined by assuming diffusion of TDEAH through a boundary layer, the deposition of SiOx with 4DMAS requires Hf-O nucleation sites and self-saturates after a single Si―O monolayer is formed. Based on these observations, a model is developed for hafnium silicate formation. The Atomic Layer Deposition like behavior of 4DMAS decomposition results in a deposition rate and film stoichiometry that are weakly sensitive to the 4DMAS partial pressure, and instead are driven by the TDEAH reaction. Since TDEAH operates within a transport-limited regime, the deposition rate is insensitive to substrate temperature, and is only controlled by the TDEAH partial pressure and the gas phase kinematics, rendering the process robust and easily controllable with excellent reproducibility.

Atomic Layer Deposition of HfO2, TiO2, and HfxTi1 − xO2 Using Metal (Diethylamino) Precursors and H2O

Tetrakis (diethylamino) hafnium (TDEAH), tetrakis (diethylamino) titanium (TDEAT), and were used for the atomic layer deposition (ALD) of , , and films on silicon substrates. The ALD temperature windows were found to be for and for . The overlap region is ideal for the ALD of the films. Different compositions of were obtained by varying the cycle ratios, and excellent tunability of film composition was found using X-ray photoelectron spectroscopy (XPS). The deposition rate was found to be the superposition of the two individual growth rates. Both as-deposited and postdeposition annealed films were studied with XPS, phase shift interferometry, and grazing incidence X-ray diffraction. As-deposited and films were found to be amorphous, and they began to crystallize after annealing at in the monoclinic phase and in weak anatase phase . The films remained amorphous after annealing up to about in for .

Atomic Layer Deposited Al2O3 Film on Si 100 as Buffer Layer for HfxTi1-xO2 Deposition

Ultra-thin films of Al2O3 were deposited on Si(100) by atomic layer deposition (ALD) using tris(diethylamino)aluminium (TDEAA) with water vapor as the oxidizer. It is planned to deposit nano-laminated composite films of HfxTi1-xO2 on top of this ultra-thin Al2O3 buffer layer using tetrakis(diethylamino)titanium (TDEAT) and tetrakis(diethylamino)hafnium (TDEAH). The introduction of the Al2O3 buffer layer will improve the interfacial quality and help to retain amorphous structure of HfxTi1-xO2/Al2O3/Si. Discussion of the addition of the new precursor, TDEAA, to the existing ALD system is discussed along with the optimization of process parameters for ALD of Al2O3 films. An Al2O3 film growth rate of 1 cycle was achieved in the ALD temperature window of 200-275o C.

Atomic Layer Deposition of Hafnium Oxide on Silicon and Polymer Fibers at Temperatures below 100o C

Atomic layer deposition of hafnium oxide from tetrakis (diethylamino) hafnium (TDEAH) and water vapor was employed to create thin films on silicon with reactor temperatures as low as 30o C. Spectral ellipsometry and X-ray photoelectron spectroscopy were used to probe the thickness and composition of these films. Deposition at the same temperature of 30o C was carried out on poly-caprolactone (PCL) nanofibers as a template to examine the possibility of fabricating hafnium oxide nanotubes. Energy dispersive X-ray scans and scanning electron microscope images revealed significant hafnia coverage on the fibers, suggesting that hafnium oxide nanotubes can be formed by means of polymer vaporization after deposition.

Effect of film composition and structure on the crystallization point of atomic layer deposited HfAlO x using metal (diethylamino) precursors and ozone

Atomic layer deposition (ALD) of HfAlO x on Si(1 0 0) was carried out using tetrakis-diethylamino hafnium (TDEAH) and tris-diethylamino aluminum (TDEAA) as metal precursors and ozone as oxidizer. ALD temperature windows of TDEAA and TDEAH overlapped between 200 and 275 °C, which is critical for ALD of composite HfAlO x films. Rutherford backscattering analysis of HfAlO x shows a strong correlation between the number of ALD cycles of alumina and hafnia being alternated and the film composition. Grazing incidence X-ray diffraction analyses of thermally annealed films indicate that a higher Al concentration increases the crystallization temperature and degree of crystallization. In addition to composition, crystallization of HfAlO x film also depends on the film structure defined by the deposition cycle sequence. For example, films deposited by alternating TDEAH/O 3 and TDEAA/O 3 cycles in a 2:1 ratio were found to have a lower degree of crystallization than films deposited by alternating in a 4:2 ALD cycle ratio, even though the ratios of Hf and Al are the same.

Atomic layer deposition of HfO2, Al2O3, and HfAlOx using O3 and metal(diethylamino) precursors

Tetrakis-diethylamino hafnium (TDEAH), tris-diethylamino aluminum (TDEAA), and ozone were used for the atomic layer deposition (ALD) of HfO2, Al2O3, and HfAlOx films. The ALD rates were measured to be 1.1 Å/cycle for HfO2 and 1.3 Å/cycle for Al2O3. The ALD temperature windows were found to be between 200 and 325 °C for TDEAA, and between 200 and 275 °C for TDEAH. The overlap of these ALD windows between 200 and 275 °C is critical for ALD of the composite film, HfAlOx. In addition to the overlapping ALD temperature windows, the two metal precursors have similar thermal characteristics, as shown by TGA and differential scanning calorimetry. As-deposited films and films postannealed at 600 and 800 °C films were analyzed using Fourier transformed infrared (FTIR) spectroscopy, x-ray photoelectron spectroscopy, and x-ray diffraction (XRD) techniques. FTIR spectra revealed interfacial oxide growth during deposition of both HfO2 and Al2O3 whose thickness increased with annealing temperature. The FTIR data also indicated hydroxyl and nitrate groups in the films; these species were removed after annealing in Ar at a temperature of ⩾600 °C. Both FTIR and XRD results indicated the crystallization of pure HfO2 after annealing at temperatures as low as 600 °C. On the other hand, pure Al2O3 remained amorphous after annealing at temperatures up to 800 °C. XRD data of the composite HfAlOx film show that films deposited by alternating five cycles of HfO2 and one cycle of Al2O3 remained amorphous after annealing at 600 °C. Rutherford backscattering analysis of HfAlOx deposited with a varied number of alternating HfO2 and Al2O3 cycles demonstrated a strong correlation between the cyclic dosage of TDEAA and TDEAH and the film composition.

Effect of film thickness on the breakdown temperature of atomic layer deposited ultrathin HfO 2 and Al 2O 3 diffusion barriers in copper metallization

We investigate the effect of thickness of HfO 2 and Al 2O 3 barrier films on the breakdown temperature of Cu/barrier film/Si structures. The HfO 2 and Al 2O 3 films are deposited using tetrakis-diethylamino hafnium and tris-diethylamino aluminum, respectively, as the metal precursors and ozone as the oxidizer at 250 °C. Interactions between the layers of Cu/barrier film (1 or 2 nm-thick)/Si structures due to high-temperature annealing in N 2 are probed using sheet resistance measurements. The crystallinity of the multilayer structure and the possible formation of any anneal-induced reaction products are investigated with X-ray diffraction (XRD). The formation of Cu-silicide phase(s) due to diffusion of Cu atoms through the barrier layer indicates the failure of the corresponding diffusion barrier. The surface morphology of Cu is examined using scanning electron microscopy (SEM) and elemental mapping is done with energy dispersive X-ray spectroscopy (EDS). Our results show that both 1 and 2 nm-thick HfO 2 and Al 2O 3 barrier films are capable of restricting the diffusion of Cu at high annealing temperatures; therefore, they could be used as effective diffusion barriers between Cu and Si.

Effect of Oxidizer on Chemical Vapor Deposited Hafnium Oxide-Based Nanostructures and the Engineering of their Interfaces with Si(100)

AbstractThin films of hafnium oxide were deposited on silicon substrates using tetrakis-diethylamino hafnium as precursor. Two different oxidizers: (a) ozone/oxygen mixture, and (b) dry oxygen were used for comparative study of the effect of different oxidizers on the deposited films. The deposition using dry oxygen was carried out in a cold-wall rapid thermal processing metalorganic chemical vapor deposition (MOCVD) reactor, whereas ozone/oxygen mixture was used in a cold-wall atomic layer deposition (ALD) reactor. Annealing studies were carried out at 600 and 800°C in high-purity argon at atmospheric pressure. X-ray photoelectron spectroscopy (XPS) analyses of as-deposited and annealed films were performed to study the HfO2/Si interface. The films deposited using these two different oxidizers appeared to be of comparable quality. Silicon oxide formation at the interface occurred after annealing at 600°C and it increased upon further annealing at 800 °C.

Atomic Layer Deposition of HfO2 Using Hf[N(C2H5)2]4 and H2O

HfO2 thin films were formed by atomic layer deposition (ALD) using a tetrakis(diethylamino)hafnium (TDEAH) + H2O gas system at 300 °C on various Si surfaces: bare Si, chemical oxide, and thermal oxide. The growth showed no incubation period under all surface conditions. The deposition rate was estimated to be 0.10 nm/cycle for deposition on the bare Si and chemical oxide, and 0.06 nm/cycle on the thermal oxide. The deposited films were confirmed to be stoichiometric HfO2 by Rutherford backscattering spectroscopy, and Al/ALD-HfO2/SiOx/Si capacitors have comparable electrical properties with respect to recently reported data.

In-Situ Infrared Spectroscopy and Density Functional Theory Modeling of Hafnium Alkylamine Adsorption on Si−OH and Si−H Surfaces

In-situ attenuated total internal reflection infrared spectroscopy has been used to examine initial adsorption and reaction steps in atomic layer deposition of HfO 2 from tetrakis(diethylamino) hafnium (TDEAHf) on SiO 2 and hydrogen-terminated Si(100) surfaces. At low deposition temperatures (25-250 °C), TDEAHf directly reacts with the Si-H surface, resulting in partial removal of Si-H bonds and formation of a four-membered Si-O-Hf-Si bonding structure that can rapidly oxidize. The hydrogen removal process is observed to continue through many cycles of TDEAHf/H 2 O exposure, signifying continued reactivity of the Hf precursor with the silicon surface. Density functional theory calculations have been performed for various reactions between tetrakis(dimethylamino) hafnium and Si-H surfaces, and several possible reaction pathways for hydrogen removal have been identified and analyzed. The calculations suggest that hydrogen removal proceeds by H abstraction by an amine ligand of the Hf precursor and that the abstraction reaction is made more facile by the presence of OH on the otherwise H-terminated Si surface.