Diffusion of Fluorine at High Concentration in Silicon: Experiments and Models

2004 ◽  
Vol 810 ◽  
Author(s):  
Robert R. Robison ◽  
Antonio F. Saavedra ◽  
Mark E. Law
Keyword(s):  
Time Dependence ◽  
Amorphous Silicon ◽  
Depth Profiling ◽  
Amorphous Region ◽  
High Concentration ◽  
Conventional Furnace

ABSTRACTWe have developed a model for high concentration fluorine diffusion and fluorine diffusion in amorphous silicon. In this context, we define high concentration fluorine to mean fluorine doses above the threshold of amorphization for implantation into silicon, which is approximately 1×1015/cm2 dose. We pre-amorphized with silicon to create a continuous amorphous region, and samples were subsequently implanted with the fluorine conditions of 16keV at 2×1015cm−2 dose, 30keV at 2×1014 cm−2 dose, or 16keV at 8×1015cm−2 dose. Samples were annealed by either conventional furnace or RTA with an N2 ambient for various times at temperatures of 550-750 °C. SIMS was used for depth profiling, and TEM images were also taken of the samples to check for defects and amorphous depth. We then created the model for the data by extending the fluorine model presented in our previous work, and it models the profile motion and the time dependence well. The model is also still capable of describing our previous work and fits it very well.

Dopant diffusion in amorphous silicon

2004 ◽  
Vol 810 ◽  
Author(s):  
R. Duffy ◽  
V.C. Venezia ◽  
A. Heringa ◽  
M.J.P. Hopstaken ◽  
G.C.J. Maas ◽  
...  
Keyword(s):  
Low Temperature ◽  
Ion Implantation ◽  
Amorphous Silicon ◽  
Amorphous Region ◽  
Boron Diffusion ◽  
Diffusion Characteristic ◽  
High Concentration ◽  
Isochronal Anneal ◽  
High Concentrations ◽  
Boron Diffusivity

ABSTRACTIn this work we investigate the diffusion of high-concentration ultrashallow boron, fluorine, phosphorus, and arsenic profiles in amorphous silicon. We demonstrate that boron diffuses at high concentrations in amorphous silicon during low-temperature thermal annealing. Isothermal and isochronal anneal sequences indicate that there is an initial transient enhancement of diffusion. We have observed this transient diffusion characteristic both in amorphous silicon preamorphized by germanium ion implantation and also in amorphous silicon preamorphized by silicon ion implantation. We also show that the boron diffusivity in the amorphous region is similar with and without fluorine, and that the lack of diffusion for low-concentration boron profiles indicates that boron diffusion in amorphous silicon is driven by high concentrations. Ultrashallow high-concentration fluorine profiles diffuse quite rapidly in amorphous silicon, and like boron, undergo a definite transient enhancement. In contrast, ultrashallow high- concentration phosphorus and arsenic profiles did not significantly diffuse in our experiments.

Investigation of Ge, As, and Au Diffusion in Non-Alloyed Epitaxial Au-Ge Ohmic Contacts to n-GaAs Using Secondary Ion Mass Spectroscopy Backside Sputter Depth-Profiling

1991 ◽  
Vol 240 ◽  
Author(s):  
H. S. LEE ◽  
R. T. Lareau ◽  
S. N. Schauer ◽  
R. P. Moerkirk ◽  
K. A. Jones ◽  
...  
Keyword(s):  
Ohmic Contacts ◽  
Ion Beam ◽  
Depth Profiling ◽  
Depth Resolution ◽  
High Concentration ◽  
Ohmic Behavior ◽  
Preferential Sputtering ◽  
Specific Contact ◽  
Secondary Ion ◽  
Diffusion Profiles

ABSTRACTA SIMS backside sputter depth-profile technique using marker layers is employed to characterize the diffusion profiles of the Ge, As, and Au in the Au-Ge contacts after annealing at 320 C for various times. This technique overcomes difficulties such as ion beam mixing and preferential sputtering and results in high depth resolution measurements since diffusion profiles are measured from low to high concentration. Localized reactions in the form of islands were observed across the surface of the contact after annealing and were composed of Au, Ge, and As, as determined by SIMS imaging and Auger depth profiling. Backside SIMS profiles indicate both Ge and Au diffusion into the GaAs substrate in the isalnd regions. Ohmic behavior was obtained after a 3 hour anneal with a the lowest average specific contact resistivity found to be ∼ 7 × 100−6 Ω- cm2.

scholarly journals Modeling of simultaneous ultra filtration and diafiltration with real flux

2005 ◽  
Vol 59 (3-4) ◽  
pp. 66-72 ◽  
Author(s):  
Hela Tokos ◽  
Zoltan Zavargo ◽  
Mirjana Djuric
Keyword(s):  
Mathematical Model ◽  
Time Dependence ◽  
Solute Concentration ◽  
High Concentration ◽  
Constant Flux ◽  
Variable Volume ◽  
Rejection Coefficient ◽  
Ultra Filtration ◽  
Variable Flux

A mathematical model of diafiltration with variable volume is presented in this study. The characteristics of the process were examined, both with constant flux and variable flux. In the case of variable flux, the equations for the flux were taken from the literature, based on different theories. The time dependence of the macro solute concentration, the amount of out-wash liquid, the out-wash degree of the micro solute were studied. The results show that the accomplishment of a high concentration of macro solutes, required more time and out-wash liquid. In order to remove small amounts of micro solutes larger amounts of out-wash liquid must be used. For high degrees of out-washing, the velocity of the process increases and the amount of out-wash liquid decreases. It was observed that the rejection coefficient decreased with macro solute penetration through the membrane causing decrease of the process velocity.

Aluminum-Induced Crystallization of PECVD Amorphous Silicon

2004 ◽  
Vol 808 ◽  
Author(s):  
Kenneth Jenq ◽  
Shawn S. Chang ◽  
Yaguang Lian ◽  
Grant Z. Pan ◽  
Yahya Rahmat-Samii
Keyword(s):  
Amorphous Silicon ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Electron Beam Evaporation ◽  
Kinetics Analysis ◽  
Conventional Furnace ◽  
Through Diffusion ◽  
Induced Crystallization ◽  
Aluminum Induced Crystallization

ABSTRACTAluminum-induced crystallization (AIC) of amorphous silicon (a-Si) in a conventional furnace with N2 protection has been studied at reaction temperatures ranging from 200 to 500°C by using optical microscopy, and transmission and scanning electron microscopy. The a-Si and Al layers were deposited with plasma-enhanced chemical vapor deposition (PECVD) and electron beam evaporation, respectively. The structures in the study are Al/a-Si and a-Si/Al on Si or glass wafers coated with 3000 Å PECVD SiO2. It was found that Al induces crystallization of a-Si for both Al/a-Si and a-Si/Al structures by exchanging positions of Al and Si layer through diffusion of Si into Al and the grain size of crystallized Si (c-Si) increases with the decrease of AIC temperature. AIC for Al/a-Si structures starts at a temperature as low as 200°C, which is 100°C lower than that for a-Si/Al structures. Kinetics analysis found that the activation energies are 1.76 eV and 1.65 eV for both Al/a-Si and a-Si/Al structures, respectively. The quality of AIC c-Si depends on the order, thickness and thickness ratio of a-Si to Al. Microstructural observations indicated that the c-Si for Al/a-Si structures is better and more suitable for use in fabrication of thin film transistors (TFTs) than that for a-Si/Al structures.

Pulsed-Light-Induced Metastable Defect Creation in Hydrogenated Amorphous Silicon

1995 ◽  
Vol 377 ◽  
Author(s):  
Jong-Hwan Yoon ◽  
H. L. Kim
Keyword(s):  
Time Dependence ◽  
Amorphous Silicon ◽  
Defect Density ◽  
Hydrogenated Amorphous Silicon ◽  
Pulsed Light ◽  
Illumination Time ◽  
Defect Creation ◽  
Annealing Rate ◽  
Hydrogenated Amorphous ◽  
Metastable Defect

ABSTRACTWe report the results of a study of metastable defect creation by pulsed light soaking in undoped hydrogenated amorphous silicon (a-Si:H). An illumination time dependence of the defect density, a saturated defect density, and light-induced annealing under pulsed laser light have been studied. Measurements show approximately a t1/2 time-dependence of the defect creation, which is independent of light intensity. It is observed that the saturation value of the defect density is about one order of magnitude higher than by cw illumination in device quality films. It has been suggested that these results would be due to the difference in the light-induced defect annealing rate between cw and pulsed lights, in which it is found that the light-induced annealing rate by pulsed light is lower than by cw light.

Quantitative investigation of titanium/amorphous-silicon multilayer thin film reactions

1990 ◽  
Vol 5 (3) ◽  
pp. 593-600 ◽  
Author(s):  
R. R. De Avillez ◽  
L. A. Clevenger ◽  
C. V. Thompson ◽  
K. N. Tu
Keyword(s):  
Thin Film ◽  
Activation Energy ◽  
Amorphous Silicon ◽  
Depth Profiling ◽  
Multilayer Films ◽  
Heat Of Formation ◽  
Titanium Silicide ◽  
Scanning Calorimetry ◽  
Cross Sectional ◽  
Silicide Layer

Growth of amorphous-titanium-silicidc and crystalline C49 TiSi2 in titanium/amorphous-silicon multilayer films was investigated using a combination of differential scanning calorimetry (DSC), thin film x-ray diffraction, Auger depth profiling, and cross-sectional transmission electron microscopy. The multilayer films had an atomic concentration ratio of 1Ti to 2Si and a modulation period of 30 nm. In the as-deposited condition, a thin amorphous-titanium-silicide layer was found to exist between the titanium and silicon layers. Heating the multilayer film from room temperature to 700 K caused the release of an exothermic heat over a broad temperature range and an endothermic heat over a narrow range. The exothermic hump was attributed to thickening of the amorphous-titanium silicide layer, and the endothermic step was attributed to the homogenization and/or densification of the amorphous-silicon and amorphous-titanium-silicide layers. An interpretation of previously reported data for growth of amorphous-titanium-silicide indicates an activation energy of 1.0 ± 0.1 eV and a pre-exponential coefficient of 1.9 × 10−7 cm2/s. Annealing at high temperatures caused formation of C49 TiSi2 at the amorphous-titanium-silicide/amorphous-silicon interfaces with an activation energy of 3.1 ± 0.1 eV. This activation energy was attributed to both the nucleation and the early stages of growth of C49 TiSi2. The heat of formation of C49 TiSi2 from a reaction of amorphous-titanium-silicide and crystalline titanium was found to be –25.8 ± 8.8 kJ/mol and the heat of formation of amorphous-titanium-silicide was estimated to be –130.6 kJ/mol.

High Temperature Post-deposition Annealing Studies of Layer-by-layer (LBL) Deposited Hydrogenated Amorphous Silicon Films

2009 ◽  
Vol 1153 ◽  
Author(s):  
Goh Boon Tong ◽  
Siti Meriam Ab. Gani ◽  
Muhamad Rasat Muhamad ◽  
Saadah Abdul Rahman
Keyword(s):  
High Temperature ◽  
Amorphous Silicon ◽  
Hydrogenated Amorphous Silicon ◽  
Chemical Vapour ◽  
Film Surface ◽  
Layer By Layer ◽  
High Concentration ◽  
Post Deposition Annealing ◽  
Hydrogenated Amorphous ◽  
Post Deposition

AbstractHigh temperature post-deposition annealing studies were done on hydrogenated amorphous silicon thin films deposited by plasma-enhanced chemical vapour deposition (PECVD) using the layer-by-layer (LBL) deposition technique. The films were annealed at temperatures of 400 °C, 600 °C, 800 °C and 1000 °C in ambient nitrogen for one hour. Auger electron spectroscopy (AES) depth profiling results showed that high concentration of O atoms were present at the substrate/film interface and at film surface. Very low concentration of O atoms was present separating silicon layers at regular intervals from the film surface and the substrate due to the nature of the LBL deposition and these silicon oxide layers were stable to high annealing temperature. Reflectance spectroscopy measurements showed that the onset of transformation from amorphous to crystalline phase in the LBL a-Si:H film structure started when annealed at temperature of 600 °C but the X-ray diffraction (XRD) and Raman scattering spectroscopy showed that this transition only started at 800 °C. The films were polycrystalline with very small grains when annealed at 800 °C and 1000 °C. Fourier transform infrared spectroscopy (FTIR), measurements showed that hydrogen was completely evolved from the film at the on-set of crystallization when annealed at 800 °C. The edge of the reflectance fringes shifted to longer wavelength decrease in hydrogen content but shifted to shorter wavelength with increase in crystallinity.

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