Atomic layer deposited alumina (Al2O3) thin films on a high-Qmechanical silicon oscillator

Hahtela, Ossi; Sievilä, Päivi; Chekurov, Nikolai; Tittonen, Ilkka

doi:10.1088/0960-1317/17/4/010

Cited by 19 publications

(8 citation statements)

References 27 publications

(52 reference statements)

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“…This reduction indicates that the trap levels originating from the imperfections of the oxide-silicon interfaces such as dangling bonds and defects are healed out upon annealing. 11 This shows that the plasma-assisted ALD films have a much better interface and oxide properties compared to the thermal ALD films. Because the Al 2 O 3 /Si conduction band-offset is 2.8 eV, the effect of Schottky emission of electrons can be ignored.…”

Section: Resultsmentioning

confidence: 91%

Dielectric Properties of Thermal and Plasma-Assisted Atomic Layer Deposited Al[sub 2]O[sub 3] Thin Films

Jinesh

Hemmen

Sanden

et al. 2011

J. Electrochem. Soc.

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A comparative electrical characterization study of aluminum oxide ͑Al 2 O 3 ͒ deposited by thermal and plasma-assisted atomic layer depositions ͑ALDs͒ in a single reactor is presented. Capacitance and leakage current measurements show that the Al 2 O 3 deposited by the plasma-assisted ALD shows excellent dielectric properties, such as better interfaces with silicon, lower oxide trap charges, higher tunnel barrier with aluminum electrode, and better dielectric permittivity ͑k = 8.8͒, than the thermal ALD Al 2 O 3 . Remarkably, the plasma-assisted ALD Al 2 O 3 films exhibit more negative fixed oxide charge density than the thermal ALD Al 2 O 3 layers. In addition, it is shown that plasma-assisted ALD Al 2 O 3 exhibits negligible trap-assisted ͑Poole-Frenkel͒ conduction unlike the thermal ALD Al 2 O 3 films, resulting in higher breakdown electric fields than the thermal ALD prepared films.Among various metal oxides with medium dielectric permittivity, Al 2 O 3 has been proposed as a promising and reliable candidate as an initial replacement for the conventional silicon oxide ͑SiO 2 ͒ as a gate oxide material in metal-oxide-semiconductor transistors because of its higher dielectric permittivity of ϳ8-9, low leakage current level, and high breakdown electric fields due to its large bandgap ͑8.8 eV͒. 1-3 Al 2 O 3 is known for its large band-offset with silicon, which is crucial for achieving low leakage currents through the devices. 4 Moreover, Al 2 O 3 has an excellent thermal and chemical stabilities, for instance, it remains amorphous until temperatures above 800°C. 5 Upon using atomic layer deposition ͑ALD͒, reactive chemistries can be used which ensure very good chemisorption and growth behavior on various substrates at low deposition temperatures. 3 It has been reported that Al 2 O 3 can be deposited on silicon with very small interfacial oxide layer thickness compared to other high-k oxides, 6 which makes it useful as an oxidation-barrier for the ALD processing of other high-k layers as well. 7 More than as a gate oxide, Al 2 O 3 is an important material for numerous application domains, for instance, to enhance the quantum efficiency of silicon in metal-insulator-semiconductor devices, 8,9 to encapsulate materials and devices that are sensitive to environments such as humidity, to enhance the Q-factor of silicon cantilevers, 10,11 to enable functionalization on hydrophobic graphene and carbon nanotube surfaces for the applications in nanoelectronics, 12,13 and to passivate surfaces of silicon solar cells. 14 Remarkable about ALD processed Al 2 O 3 is that the oxide can contain intrinsic negative fixed oxide charges 14 that are beneficial for the applications in charge-trap flash memory devices 15 and, in particular, high-efficiency silicon solar cells. 16,17 With the added value of ALD achieving good conformality in the high aspect-ratio features, high capacitance density metal-insulator-metal ͑MIM͒ capacitors have been realized for the integration of passive elements. 18,19 In this paper, we compare the dielec...

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Section: Resultsmentioning

confidence: 91%

Dielectric Properties of Thermal and Plasma-Assisted Atomic Layer Deposited Al[sub 2]O[sub 3] Thin Films

Jinesh

Hemmen

Sanden

et al. 2011

J. Electrochem. Soc.

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“…Moreover, for the ALD Al2O3 films, the cohesive film strength and interfacial shear strength were obtained by multiplying the corresponding strain values in Table 2 by the elastic modulus. The elastic modulus values for the ALD Al2O3 thin films are available from the literature [30,32,46,[48][49][50][51][52] and the value of 150 GPa was used for the sample deposited at 135 °C, while 170 GPa was used for the samples deposited at 155 °C and 220 °C (Table 3). Interfacial shear strains versus the saturated critical crack density (sCD) times total film thickness (h) for all films on polyimide.…”

Section: Critical Fracture Onset Strain For Different Thicknesses Of mentioning

confidence: 99%

Thin-Film Engineering of Mechanical Fragmentation Properties of Atomic-Layer-Deposited Metal Oxides

et al. 2020

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Mechanical fracture properties were studied for the common atomic-layer-deposited Al2O3, ZnO, TiO2, ZrO2, and Y2O3 thin films, and selected multilayer combinations via uniaxial tensile testing and Weibull statistics. The crack onset strains and interfacial shear strains were studied, and for crack onset strain, TiO2/Al2O3 and ZrO2/Al2O3 bilayer films exhibited the highest values. The films adhered well to the polyimide carrier substrates, as delamination of the films was not observed. For Al2O3 films, higher deposition temperatures resulted in higher crack onset strain and cohesive strain values, which was explained by the temperature dependence of the residual strain. Doping Y2O3 with Al or nanolaminating it with Al2O3 enabled control over the crystal size of Y2O3, and provided us with means for improving the mechanical properties of the Y2O3 films. Tensile fracture toughness and fracture energy are reported for Al2O3 films grown at 135 °C, 155 °C, and 220 °C. We present thin-film engineering via multilayering and residual-strain control in order to tailor the mechanical properties of thin-film systems for applications requiring mechanical stretchability and flexibility.

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“…Al 2 O 3 thin films have been deposited by different techniques including sol–gel , solvothermal , physical vapor deposition (PVD) , atomic layer deposition (ALD) , and chemical vapor deposition (CVD) techniques . Only amorphous Al 2 O 3 has been produced for deposition temperatures below 700 °C.…”

Section: Introductionmentioning

confidence: 99%

Study of precursor chemistry and solvent systems in pp-MOCVD processing with alumina case study

Gunby

Krumdieck

Murthy

et al. 2015

Phys. Status Solidi A

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Alumina synthesis presents an opportunity to study the processing science of direct liquid injection pulsed‐pressure MOCVD. The current study uses three alumina precursors and two solvent systems to study the physical chemistry of the flash evaporation processes that can occur in the pulsed‐pressure approach from fundamental considerations and experimental observation. Three precursors were studied, aluminum tri‐isopropoxide, aluminum tri‐secbutoxide, and aluminum tri‐tertbutoxide, with hexane and toluene solvents. Scoping studies identified the deposition temperature range for each precursor using silicon substrates. All deposited materials were amorphous alumina with the characteristic spheroidal microstructure. The morphology of the surfaces was used to provide the evidence to study the degree of flash evaporation, and the possible arrival of liquid droplets or solid aerosol particles. The morphological evidence consists of SEM images showing uniform coatings deposited from vapor arrival, and clusters about the size of the expected aerosols formed when droplets freeze or precursor is concentrated and dried out after flash evaporation of the solvent. The volatility of the solvent and precursor is less important for determining what degree of flash evaporation or aerosol deposition occurs than the relative diffusivity of the precursor compared to the solvent.

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Atomic layer deposited alumina (Al₂O₃) thin films on a high-Qmechanical silicon oscillator

Cited by 19 publications

References 27 publications

Dielectric Properties of Thermal and Plasma-Assisted Atomic Layer Deposited Al[sub 2]O[sub 3] Thin Films

Dielectric Properties of Thermal and Plasma-Assisted Atomic Layer Deposited Al[sub 2]O[sub 3] Thin Films

Thin-Film Engineering of Mechanical Fragmentation Properties of Atomic-Layer-Deposited Metal Oxides

Study of precursor chemistry and solvent systems in pp-MOCVD processing with alumina case study

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