Ellipsometry as a Sensitive Technique to Probe film -Substrate Interfaces: Al2O3 on Si(100) (original) (raw)
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Thin Solid Films, 2002
Al O films with thicknesses ranging from 30 to 3540 A were grown in a viscous flow reactor using atomic layer deposition 2 3( ALD) with trimethylaluminum and water as the reactants. Growth temperatures ranged from 125 to 425 8C. The Al O ALD 2 3 films were deposited successfully on a variety of substrates including Au, Co, Cr, Cu, Mo, Ni, NiFe, NiMn, Pt, PtMn, Si, stainless steel, W, and ZnO. Electrical properties were characterized by current-voltage and capacitance-voltage measurements using a mercury probe. These measurements focused mainly on Al O ALD films deposited on n-type Si(1 0 0) and on Mo-coated 2 3
Surface Science, 2000
O 3 has been deposited by evaporation and post-oxidation of Al on a flat SiO 2 substrate. The obtained films have been analysed by X-ray photoemission spectroscopy ( XPS ) and reflection electron energy loss spectroscopy (REELS ). It has been found that the modified Auger parameter of Al varies by~2.2 eV between a low coverage situation (below an equivalent monolayer) and the bulk material. This change has been attributed to variations in the coordination state of the aluminium atoms. Some minor contributions due to bonding and polarisation effects are also detected.
Bulletin of the Polish Academy of Sciences, Technical Sciences
In this work studies of barrier height local values are presented. Distribution of the gate-oxide EBG(x, y) and semiconductor-oxide E BS (x, y) barrier height local values have been determined using the photoelectric measurement methods. Two methods were used to obtain the local values of the barrier heights: modified Powell-Berglund method and modified Fowler method. Both methods were modified in such a way as to allow determination of the EBG(x, y) and EBS(x, y) distribution over the gate area using a focused UV light beam of a small diameter d = 0.3 mm. Measurements have been made on a series of Al-SiO 2 -Si(n + ) MOS structures with semitransparent (t Al = 35 nm) square aluminum gate (1 × 1 mm 2 ). It has been found that the EBG(x, y) distribution has a characteristic dome-like shape, with highest values at the center of the gate, lower at the gate edges and still lower at gate corners. On the contrary, the E BS (x, y) distribution is of a random character. Also, in this paper, both barrier height measurements have been compared with the photoelectric effective contact potential difference φ M S (x, y) measurements. These results show good agreement between distribution of the barrier heights E BG (x, y) and E BS (x, y) measurements and independently determined shape of the effective contact potential difference φ M S (x, y) distribution.
Electron Technology
In this work studies of barrier height local values are presented. Distribution of the gate-oxide EBG(x, y) and semiconductor-oxide E BS (x, y) barrier height local values have been determined using the photoelectric measurement methods. Two methods were used to obtain the local values of the barrier heights: modified Powell-Berglund method and modified Fowler method. Both methods were modified in such a way as to allow determination of the EBG(x, y) and EBS(x, y) distribution over the gate area using a focused UV light beam of a small diameter d = 0.3 mm. Measurements have been made on a series of Al-SiO 2 -Si(n + ) MOS structures with semitransparent (t Al = 35 nm) square aluminum gate (1 × 1 mm 2 ). It has been found that the EBG(x, y) distribution has a characteristic dome-like shape, with highest values at the center of the gate, lower at the gate edges and still lower at gate corners. On the contrary, the E BS (x, y) distribution is of a random character. Also, in this paper, both barrier height measurements have been compared with the photoelectric effective contact potential difference φ M S (x, y) measurements. These results show good agreement between distribution of the barrier heights E BG (x, y) and E BS (x, y) measurements and independently determined shape of the effective contact potential difference φ M S (x, y) distribution.
Electronic and optical properties of Al2O3/SiO2 thin films grown on Si substrate
Journal of Physics D: Applied Physics, 2010
The electronic and optical properties of Al2O3/SiO2 dielectric thin films grown on Si(1 0 0) by the atomic layer deposition method were studied by means of x-ray photoelectron spectroscopy and reflection electron energy loss spectroscopy (REELS). The band gaps of the Al2O3/SiO2 thin films before annealing and after annealing were 6.5 eV and 7.5 eV, respectively, and those of the γ-Al2O3 and α-Al2O3 phases were 7.1 eV and 8.4 eV, respectively. All of these were estimated from the onset values of the REELS spectra. The dielectric functions were determined by comparing the effective cross-section determined from experimental REELS with a rigorous model calculation based on dielectric response theory, using available software packages. The determined energy loss function obtained from the Al2O3/SiO2 thin films before annealing showed a broad peak at 22.7 eV, which moved to the γ-Al2O3 position at 24.3 eV after annealing. The optical properties were determined from the dielectric functio...
Journal of The Electrochemical Society, 2011
Atomic layer deposition (ALD) of Al2O3 is of interest for a wide range of micronanoelectronic applications, where the electrical properties of the deposited layers can be strongly affected by deposition conditions and post-deposition treatments. In this work, a mercury-probe capacitance-voltage characterization is carried out on Al2O3 films deposited on silicon by ALD at different temperatures and subjected to various thermal treatments in N2 ambient. Effective positive charges located at the semiconductor/dielectric interface are encountered for the films deposited at the lowest temperature (100ºC). Positive Vfb shifts are always registered after the different thermal annealing conditions studied; however, the impact of the thermal treatments is found to be different depending on the deposition temperature. A significant negative charges build-up is observed after a 30 minutes anneal at 450ºC, where improved surface passivation properties are achieved. Interestingly, the hysteresis, as well as the Vfb shifts, clearly diminish for higher deposition temperatures or after a thermal anneal. However, the highest temperature treatments (800ºC) result in significant interface states generation. Finally, exploratory experiments about the stability of the Al2O3 layers under UV-light irradiation (in the 200 nm-300 nm wavelengths range) show that this can be responsible for a significant degradation of their electrical characteristics.
Variation of the layer thickness to study the electrical property of PECVD Al2O3 / c-Si interface
Energy Procedia, 2011
This paper focusses in particular on the influence of the layer thickness on the passivation quality, the charge density and the interface defects of PECVD Al 2 O 3 passivation layers on c-Si surfaces. The surface recombination velocity and the interface defect density are observed to increase by decreasing the layer thickness. However, the density of negative charges remains almost constant with values around 3 10 12 cm -2 . An optimal passivation quality is obtained for thicknesses of 15 nm and higher. A linear relation between surface recombination velocity and D it was established, allowing the estimation of the electron capture cross section (σ n ~ 10 -13 cm -2 ). Additionally, we measured the capture cross section of holes and electrons using DLTS measurement. The results are found to be very similar to reported values for silicon dioxide. This supports the idea that the chemical passivation of crystalline silicon by Al 2 O 3 is performed by the interstitial SiO 2 layer.
Chemical deposition of Al2O3 thin films on Si substrates
Thin Solid Films, 2009
Al 2 O 3 MIS structure C-V measurements Uniform Al 2 O 3 films were deposited on silicon substrates by the sol-gel process from stable coating solutions. The technological procedure includes spin coating deposition and investigating the influence of the annealing temperature on the dielectric properties. The layers were studied by Fourier transform infrared spectroscopy and Scanning Electron Spectroscopy. The electrical measurements have been carried out on metal-insulatorsemiconductor (MIS) structures. The C-V curves show a negative fixed charge at the interface and density of the interface state, Dit, 3.7 × 10 11 eV − 1 cm − 2 for annealing temperature at 750°C.