SiOx structural modifications by ion bombardment and their influence on electrical properties (original) (raw)
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Ion beam effects in SiOx (x<2) subjected to low energy Ar+, He+ and N2+ bombardment
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2002
The effect of low kinetic energy (0:5 < E k < 5 keV) Ar þ , He þ and N þ 2 ion bombardment on non-stoichiometric silicon oxide SiO x ðx ¼ 1:3Þ thin films has been studied by X-ray photoemission spectroscopy, reflection electron energy loss spectroscopy and, for the case of the N þ 2 bombarded samples, also by X-ray absorption spectroscopy at the O K and N K absorption edges. Thus, the composition of the altered layer of the bombarded material, as well as the chemical states of the elements in the samples have been determined. It has been found that preferential removal of oxygen takes place in SiO 1:3 after Ar þ bombardment with ions of E k > 2 keV. A detailed analysis of the Si 2p and Si KLL spectral shapes reveal that new Si þ and, to a lesser extend, Si 4þ species are formed in detriment of the initial Si 3þ and Si þ species present in the original SiO 1:3 sample. Bombardment with Ar þ ions of lower kinetic energy (E k < 2 keV) produces the disproportionation of the SiO 1:3 material, mainly with formation of Si 4þ and Si þ species, while the relative amount of Si 3þ decreases. By contrast with this behaviour, He þ bombardment does not produce any significant reduction or disproportionation of the SiO 1:3 samples. These results reveal that both the kinetic energy of the impinging ions and the ability for transferring this energy to the target atoms are critical parameters for an effective control of the modifications induced in the bombarded samples. On the other hand, the ''as-deposited'' SiO 1:3 and the Ar þ bombarded SiO 1:3 are characterised by bulk plasmon energies of 18.6 and 18.0 eV, and therefore, according to the free-electron theory, the density of these materials are 1.7 and 1.6 g/cm 3 , respectively. In the case of the N þ 2 bombardment, reactive implantation of nitrogen within the altered layer takes place with the formation of a new silicon oxynitride compound with the stoichiometry SiO 0:9 N 0:6 . The amount of incorporated nitrogen in this case is higher than that required to compensate the non-stoichiometry in the original SiO 1:3 material. This result indicates that preferential removal of oxygen also occurs under N þ 2 bombardment. The formed silicon oxynitride is characterised by an Auger parameter of 1713.4 eV, with a band gap of 2-3 eV and a bulk plasmon energy of 21.9 eV. Ó 2002 Published by Elsevier Science B.V.
Silicon Suboxides: The “Co-Deposition” of a-Si:H and SiO2
MRS Proceedings, 1988
ABSTRACTThe deposition mechanism of silicon suboxides (SiOx, x<2) prepared by remote plasma enhanced chemical vapor deposition (Remote PECVD) is investigated. These films were deposited in a Deposition/Analysis chamber designed to investigate the gas phase chemistry. In this technique, an O2/He mixture is plasma excited, and the silane reactant is injected into the deposition chamber down-stream from the plasma tube. We show that if the plasma after-glow is prevented from extending into the deposition region by an electrical grid placed between the plasma tube and the deposition region, silicon dioxide is then deposited for all O2/He mixtures investigated (0.1 to 1.0 %). In contrast, hydrogenated suboxides of silicon are deposited when the plasma after-glow is allowed to extend past the grid into the deposition region.
The effects of ion implantation through very thin silicon oxide films
1994
The ion implantation of heavy dopant species through very thin silicon oxide gate insulators d?grades the insulating properties of the oxide inducing an enhanced leakage current in MOS siructures as well as a decrease of the dielectric breakdown voltage. In the present work we study quantitatively the possible physico-chemical causes of these degradation phenomena a l d of their recovery by thermal annealing using isotopic tracing techniques. Films of with thicknesses ranging from 4 to 10 nm thermally grown on (100) silicon wafers were irnplanted with As and Sb to fluences between 1014 and 1016 Using nuclear reaction aialyses, secondary ions mass spectrometry, nuclear resonance profiling and channeling of a-particles with detection a t grazing angles we measured the amount of oxygen lost from the silicon dioxide films due to sputtering a t the oxide-vacuum interface, the amounts of oxygen r6 coil-implanted into silicon from the oxide film and into the silicon oxide from the residual...
Characterization of electron beam induced modification of thermally grown SiO2
Applied Physics Letters, 1995
We used local probe techniques to characterize electron beam ͑e-beam͒ induced changes in thin oxides on silicon. Primary effects of the 1 nm wide, 300 keV e beam included the formation of positive charges trapped in the SiO 2 , physical restructuring in the oxide, and deposition of carbonaceous compounds. Charges remained stable in thicker oxides ͑460 nm͒ and appeared as changes in the contact potential or microwave response with widths down to 100 nm. In thinner oxides ͑20 nm͒ the amount of charge was smaller and less stable; below 7 nm no charge was detected. Physical changes in the oxide, evident as a swelling of irradiated areas, accounted for the etching selectivity of these regions. © 1995 American Institute of Physics.
Damage induced by high energy multiply charged oxygen ions in oxide coated silicon
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2006
P-type oxide coated silicon samples of resistivity 120 X cm were irradiated with 60 MeV oxygen ions of fixed charge states 4 + , 5 + , 6 + and 7 + at an equal fluence of, /, $10 13 ions/cm 2. The induced damage was estimated by Hall voltage, Hall coefficient, carrier concentration and lifetime of minority carriers. The results indicate that Hall voltage (V H) and Hall coefficient (R H) increases, while carrier concentration (n) decreases with the charge state of impinging oxygen ions. The V H increases from 22 mV to 76.5 mV at typical current of 0.5 mA, R H from 0.42 • 10 5 cm 3 /C to 2.16 • 10 5 cm 3 /C and n decreases from 9 • 10 13 cm À3 to 2.88 • 10 13 cm À3 for the different charge states. This fact is an evidence that the oxygen ions with an individual fixed charge state passing through very thin 40 Å layer of silicon dioxide, induces significant damage at the SiO 2-Si interface through the mechanism of electronic stopping power. The lifetime of minority charge carriers, s (bulk property), remains constant at around 6 ls for all the charge states of the 60 MeV energy oxygen ion irradiated samples at a constant fluence of, /, 10 13 ions/cm 2 .
Comparison of secondary ion emission induced in silicon oxide by MeV and keV ion bombardment
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1994
The surface and near-surface composition of SiO, layers have been investigated by negative secondary ion emission mass spectrometry (SIMS) using MeV and keV ion bombardment in combination with time-of-flight (TOF) mass analysis. The spectra recorded in the mass range O-100 u are dominated by surface impurities, notably hydrocarbons and silicon polyanions incorporating H and OH entities. The characteristic (fragmentation) patterns are quite different for low-and high-velocity ion impact. In high-velocity TOF-SIMS analysis of P-doped layers, prepared by chemical vapour deposition (CVD), the mass lines at 63 and 79 u are very prominent and appear to correlate with the phosphorus concentration (PO, and PO,, respectively). It is shown, however, that for unambiguous P analysis one has to use dynamic SIMS or high mass resolution.
Open Physics, 2007
In this paper we present the results of research into a relation(s) between the bias voltage of an oxide/a-Si:H/c-Si sample during formation of very-thin and thin oxides and the resulting distribution of oxide/semiconductor interface states in the a-Si:H band gap. Two oxygen plasma sources were used for the first time in our laboratories for formation of oxide layers on a-Si:H: i) inductively coupled plasma in connection with its application at plasma anodic oxidation; ii) rf plasma as the source of positive oxygen ions for the plasma immersion ion implantation process. The oxide growth on a-Si:H during plasma anodization is also simply described theoretically. Properties of plasmatic structures are compared to ones treated by chemical oxidation that uses 68 wt% nitric acid aqueous solutions. We have confirmed that three parameters of the oxide growth process — kinetic energy of interacting particles, UV-VIS-NIR light emitted by plasma sources, and bias of the samples — determine th...
High energy electron-beam irradiation effects in Si-SiOxstructures
Journal of Physics: Conference Series, 2016
Homogeneous SiO x films (x=1.3, 200 nm and 1000 nm thick) and composite a-Si-SiO y films (y ~ 1.80) containing amorphous Si nanoparticles have been prepared on crystalline (c-Si) substrate. A part of the films was irradiated at temperature below 50 o C by 20 MeV electrons with two different fluences (7.2×10 14 and 1.44×10 15 el.cm-2). Atomic force microscopy (AFM), Raman spectroscopy and capacitance (conductance)-voltage (C(G)-V) measurements on Al/c-Si/SiO x /Al or Al/c-Si/(a-Si-SiO y)/Al structures were used to get information about the irradiation induced changes in the surface morphology, the phase composition in the film bulk and at the Si-SiO x interface. The AFM results show that the electron irradiation decreases the film surface roughness of the films annealed at 250 o C. The Raman scattering data imply appearance of amorphous silicon phase and some structural changes in the oxide matrix of the homogeneous SiO x films. In the composite films electron beam stimulated decrease of the defects at the a-Si/SiO y interface has been assumed. The initial C(G)-V results speak about electron induced formation of electrically active defects in the SiO y matrix of the composite films.
Reconstruction of the SiO2 structure damaged by low-energy Ar-implanted ions
Journal of Applied Physics, 1997
The damage created in SiO 2 layers by low-energy Ar ions ͑130 keV͒ and the reconstruction of the structure after various annealing steps have been characterized as a function of the implantation dose. Quantitative determinations of the damage produced have been performed from infrared spectroscopy. We show that two dose thresholds for damage are encountered: At 10 14 cm Ϫ2 damage saturates and for doses above 10 17 cm Ϫ2 sputtering effects dominate. Annealing at high temperatures ͑1100°C͒ restores the structure of the initial nonimplanted oxide only for doses below the second threshold, although some disorder remains. Electroluminescence measurements show that annealing is able to eliminate electrically active defects. For implantation doses greater than 10 17 cm Ϫ2 , annealing is unable to restore the structure completely as sputtering effects create a depleted oxygen layer at the surface and substoichiometric defects appear. The presence of microcavities created by the Ar atoms at such high doses may affect the annealing behavior.