Native Oxide and the Residual Stress of Thin Mo and Ta Films

1996 ◽  
Vol 441 ◽  
Author(s):  
L. J. Parfitt ◽  
Z. U. Rek ◽  
S. M. Yalisove ◽  
J. C. Bilello
Keyword(s):  
Residual Stress ◽  
Film Thickness ◽  
Compressive Stress ◽  
Advanced Characterization ◽  
Grazing Incidence ◽  
Deposition Process ◽  
Native Oxide ◽  
Native Oxide Layer ◽  
Si Substrates ◽  
Transmission Electron

AbstractResidual stress changed substantially between 2.5 and 80 nm film thickness in very thin Mo and Ta coatings sputtered onto Si substrates with native oxide. For both Mo and Ta, the thinnest films had a high compressive stress on the order of 2 to 3 GPa, and the stress relaxed, or became slightly tensile, with increasing film thickness. The coatings were examined using a variety of advanced characterization techniques including Auger Electron Spectroscopy (AES), Grazing Incidence X-ray Scattering (GIXS), and High Resolution Transmission Electron Microscopy (HRTEM). AES showed the presence of 0 and C contamination at the interface between the substrate and the film; these impurities originated from the adsorbed species and the native oxide on the surface of the wafers. GIXS analysis of the Mo films showed that the lattice of the thinnest layers was considerably expanded compared to the interplanar spacing of bulk, pure Mo. This expansion was caused by incorporation of impurities from the substrate into interstitial sites, which caused the very high compressive stress. HRTEM showed that the sputter deposition process did not alter the thickness of the native oxide layer, suggesting that the Mo and Ta films interacted with only the adsorbed impurities and the top one or two layers of the SiO2. Mo films deposited onto clean W layers were tensile, which supported the hypothesis that impurities caused the high compressive stresses in the films deposited onto SiO2. Grain growth and phase transformations contributed to the relaxation in stress observed in the thicker films.

Origins of Residual Stress in Mo and Ta Films: the Role of Impurities, Microstructural Evolution, and Phase Transformations

1996 ◽  
Vol 436 ◽  
Author(s):  
L. J. Parfitt ◽  
O. P. Karpenko ◽  
Z. U. Rek ◽  
S. M. Yalisove ◽  
J. C. Bilello
Keyword(s):  
Residual Stress ◽  
Film Thickness ◽  
Phase Transformations ◽  
Compressive Stress ◽  
Native Oxide ◽  
Si Substrates ◽  
Stress Behavior ◽  
Sputter Deposited ◽  
Substrate Surfaces ◽  
20 Nm

AbstractBoth the sign and magnitude of residual stress can vary with the thickness of sputter deposited films. The origins of this behavior are not well understood. In this work, we consider the correlation between the residual stress behavior and the depth dependence of impurities in thin (2.5 nm - 150 nm) sputtered Mo and Ta films. We also consider the effects of phase transformations and microstructural changes on the stress behavior. Films were deposited onto Si substrates with native oxide. The residual stress observed in the Mo films varied from highly compressive at 2.5 nm film thickness to ∼ 0 ˜ 10 nm thickness. Ta films also exhibited a high compressive stress, which relaxed from highly compressive to tensile between 10 nm and 50 nm film thickness. Impurities in the films may originate from the sputtering targets, the background gases, and the substrate surfaces. Auger Electron Spectroscopy (AES) results showed the presence of O and C contamination near the film/Si interface; these impurities contributed to the compressive stresses in the thinner films. As anticipated, both Mo and Ta films exhibited grain growth as a function of film thickness, which may have contributed to the relaxation in the compressive stress. The Mo films were entirely bcc. The Ta films showed a transformation from the amorphous phase to the β crystalline phase between 2.5 nm and 20 nm film thickness, which contributed to the relaxation in stress observed in that thickness regime.

In Situ Diagnostics of Vuv Laser Cvd of Semiconductor Interfaces by Ftir Spectroscopy and Spectroscopic Ellipsometry

1995 ◽  
Vol 397 ◽  
Author(s):  
M. Barth ◽  
J. Knobloch ◽  
P. Hess
Keyword(s):  
Film Thickness ◽  
Bulk Material ◽  
Substrate Surface ◽  
Cluster Formation ◽  
Interface Layer ◽  
Native Oxide ◽  
Initial Growth ◽  
Difference Spectra ◽  
Si Substrates

ABSTRACTThe growth of high quality amorphous hydrogenated semiconductor films was explored with different in situ spectroscopic methods. Nucleation of ArF laser-induced CVD of a-Ge:H on different substrates was investigated by real time ellipsometry, whereas the F2 laser (157nm) deposition of a-Si:H was monitored by FTIR transmission spectroscopy. The ellipsometric studies reveal a significant influence of the substrate surface on the nucleation stage, which in fact determines the electronic and mechanical properties of the bulk material. Coalescence of initial clusters occurs at a thickness of 16 Å for atomically smooth hydrogen-terminated c-Si substrates, whereas on native oxide covered c-Si substrates the bulk volume void fractions are not reached until 35 Å film thickness. For the first time we present a series of IR transmission spectra with monolayer resolution of the initial growth of a-Si:H. Hereby the film thickness was measured simultaneously using a quartz crystal microbalance with corresponding sensitivity. The results give evidence for cluster formation with a coalescence radius of about 20 Å. Difference spectra calculated for layers at different depths with definite thickness reveal that the hydrogen-rich interface layer stays at the substrate surface and does not move with the surface of the growing film. The decrease of the Urbach energy switching from native oxide to H-terminated substrates suggests a strong influence of the interface morphology on the bulk material quality.

Quantitative analysis of strengthening mechanisms in thin Cu films: Effects of film thickness, grain size, and passivation

1998 ◽  
Vol 13 (5) ◽  
pp. 1307-1317 ◽  
Author(s):  
R-M. Keller ◽  
S. P. Baker ◽  
E. Arzt
Keyword(s):  
Grain Size ◽  
Film Thickness ◽  
Thermal Stresses ◽  
Native Oxide ◽  
Silicon Substrates ◽  
Native Oxide Layer ◽  
X Ray Diffraction ◽  
Cu Films ◽  
Order Of Magnitude ◽  
Constraint Model

Thermal stresses in thin Cu films on silicon substrates were examined as a function of film thickness and presence of a silicon nitride passivation layer. At room temperature, tensile stresses increased with decreasing film thickness in qualitative agreement with a dislocation constraint model. However, in order to predict the stress levels, grain-size strengthening, which is shown to follow a Hall–Petch relation, must be superimposed. An alternative explanation is strain-hardening due to the increase in dislocation density, which was measured by x-ray diffraction. At 600 °C, the passivation increases the stress by an order of magnitude; this leads to a substantially different shape of the stress-temperature curves, which now resemble those of aluminum with only a native oxide layer. The effect of passivation is shown to be very sensitive to the deposition and test conditions.

Effect of Interface Native Oxide Layer on the Properties of Annealed Ni/SiC Contacts

2013 ◽  
Vol 740-742 ◽  
pp. 485-489 ◽  
Author(s):  
Wei Huang ◽  
Shao Hui Chang ◽  
Xue Chao Liu ◽  
Zheng Zheng Li ◽  
Tian Yu Zhou ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Temperature ◽  
Oxide Layer ◽  
Native Oxide ◽  
Native Oxide Layer ◽  
High Temperature Annealing ◽  
Contact Interface ◽  
Ohmic Behavior ◽  
Transmission Electron

The near-SiC-interfaces of annealed Ni/SiC contacts were observed directly by high-resolution transmission electron microscopy (HRTEM). 1 nm native oxide layer was observed in the as-deposited contact interface. The native oxide layer cannot be removed at 650°C through rapid thermal annealing (RTA) and it was completely removed at 1000°C RTA. The residue of native oxide layer resulted in the Schottky characters. High temperature annealing (>950°C) not only removes the oxide layer in the near-SiC-interface, but also forms a well arranged flat Ni2Si/SiC interface, which contribute to the formation of ohmic behavior.

In Situ Spectroscopic Ellipsometry Study of the Oxide Etching and Surface Damaging Processes on Silicon Under Hydrogen Plasma

1999 ◽  
Vol 591 ◽  
Author(s):  
I.M. Vargas ◽  
J.Y. Manso ◽  
J.R. Guzmán ◽  
B.R. Weiner ◽  
G. Morell
Keyword(s):  
Spectroscopic Ellipsometry ◽  
Hydrogen Plasma ◽  
Chemical Vapor ◽  
Surface Damage ◽  
Silicon Surfaces ◽  
Native Oxide ◽  
Native Oxide Layer ◽  
Si Substrates ◽  
Oxide Etching

ABSTRACTWe employed in situ ellipsometry in the monitoring of surface damage to monocrystalline silicon (Si) substrates under hydrogen plasma conditions. These measurements were complemented with spectroscopic ellipsometry and Raman spectroscopy, in order to characterize the surface conditions. It was found that heating the Si substrate to 700°C in the presence of molecular hydrogen produces etching of the native oxide layer, which is typically 10 Å thick. When the already hot and bare silicon surface is submitted to hydrogen plasma, it deteriorates very fast, becoming rough and full of voids. Modeling of the spectroscopic ellipsometry data was used to obtain a quantitative physical picture of the surface damage, in terms of roughness layer t ickness and void fraction. The results indicate that by the time a thin film starts to grow on these silicon surfaces, like in the chemical vapor deposition of diamond, the roughness produced by the hydrogen plasma has already determined to a large extent the rough nature of the film to be grown.

Rapid Thermal Annealed Undoped LPCVD Si/Single Crystal Si Substrate Structures with an Implant of Si Near Interfaces

1987 ◽  
Vol 106 ◽  
Author(s):  
S. Ogawa ◽  
S. Okuda ◽  
T. Kouzaki ◽  
T. Yoshida ◽  
Y. Yoshioka
Keyword(s):  
Single Crystal ◽  
Epitaxial Growth ◽  
Oxide Layer ◽  
Point Of View ◽  
Native Oxide ◽  
Native Oxide Layer ◽  
Si Substrate ◽  
Transmission Electron ◽  
Amorphous Si ◽  
Oxygen Atoms

ABSTRACTThe breaking up of a native oxide layer of a LPCVD amorphous Si/single crystal n+Si substrate interface by a rapid-thermal annealing was studied from the point of view of oxygen movement and morphological change. Oxygen atoms began to move at 1025 °C. After annealing at 1115 °C for 30sec, the quantity of oxygen atoms near the interface decreased dramatically and a silicon implant near the interface could enhance the decrease. More detailed observation was carried out by cross-section high-resolution transmission electron microscopy. After annealing at 940 °C for 30sec, the native oxide layer was continuous. On the qther hand, with a silicon implant near the interface, it changed into small oxide balls and an epitaxial growth occurred in the LPCVD layer with twins caused by these oxide balls. After annealing at 1115°C for 30sec, even without the silicon implant, a complete epitaxial growth occurred but it seemed that some SiOx particles dissolved into a single crystal Si layer near the interface.

Nano-Scale Native Oxide on 6H-SiC Surface and its Effect on the Ni/Native Oxide/SiC Interface Band Bending

2014 ◽  
Vol 778-780 ◽  
pp. 566-570 ◽  
Author(s):  
Wei Huang ◽  
Xi Liu ◽  
Xue Chao Liu ◽  
Tian Yu Zhou ◽  
Shi Yi Zhuo ◽  
...  
Keyword(s):  
Oxide Layer ◽  
Photoelectron Spectroscopy ◽  
Interface Energy ◽  
Native Oxide ◽  
Native Oxide Layer ◽  
Band Bending ◽  
X Ray ◽  
Vacuum Chambers ◽  
Transmission Electron ◽  
Electron Transport Properties

Native oxide layer with thickness of about 1 nm was found easy to form on 6H-SiC surface during transporting from cleaning process to vacuum chambers, which was examined by x-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HRTEM). The interface band bending was studied by synchrotron radiation photoelectron spectroscopy (SRPES). For the native-oxide/SiC surface, after Ni deposition, the binding energy of Si 2p red-shifted about 0.34 eV, which suggested the upward bending of the interface energy band. Therefore, the native oxide layer should be considered on the study of SiC devices because it may affect the electron transport properties significantly.

Stress and Microstructure Evolution in Compositionally Graded Al1-xGaxN Buffer Layers for GaN Growth on Si

2005 ◽  
Vol 892 ◽  
Author(s):  
Xiaojun Weng ◽  
Srinivasan Raghavan ◽  
Elizabeth C Dickey ◽  
Joan M Redwing
Keyword(s):  
Buffer Layer ◽  
Compressive Stress ◽  
Microstructure Evolution ◽  
Buffer Layers ◽  
Threading Dislocation ◽  
Cross Sectional ◽  
Si Substrates ◽  
Transmission Electron ◽  
Dislocation Annihilation

AbstractWe have studied the evolution of stress and microstructure of compositionally graded Al1-xGaxN (0 ≤ x ≤1) buffer layers on (111) Si substrates with varying thicknesses. In-situ stress measurements reveal a tensile-to-compressive stress transition that occurs near the half-thickness in each buffer layer. Cross-sectional transmission electron microscopy (TEM) shows a significant reduction in threading dislocation (TD) density in the top half of the buffer layer, suggesting that the compressive stress enhances the threading dislocation annihilation. The composition of the buffer layers varies linearly with thickness, as determined by X-ray energy dispersive spectrometry (XEDS). The composition grading-induced compressive stress offsets the tensile stress introduced by microstructure evolution, thus yielding a tensile-to-compressive stress transition at x ≈ 0.5.

Sputter Deposition of CuInSe2 and CuGaSe2 from Composite Targets on (100) Si

2009 ◽  
Vol 1210 ◽  
Author(s):  
Okechukwu N. Akpa ◽  
Shaik Shoieb ◽  
Trenton R. Thompson ◽  
Tamara F. Isaacs-Smith ◽  
Philip Anderson ◽  
...  
Keyword(s):  
Hall Mobility ◽  
Rf Magnetron Sputtering ◽  
Film Structure ◽  
Rutherford Backscattering ◽  
Film Deposition ◽  
Native Oxide ◽  
Cross Sectional ◽  
Si Substrates ◽  
Transmission Electron ◽  
Contamination Levels

AbstractThin films of CuInSe2 (CIS) and CuGaSe2 (CGS) were deposited on (100) Si substrates by RF magnetron sputtering using stoichiometric targets, at various substrate temperatures. Prior to film deposition, the Si substrates were cleaned using the RCA cleaning procedure and treated in a buffered oxide etch (BOE) solution. Deposited films were characterized using Rutherford backscattering spectroscopy (RBS), transmission electron microscopy (TEM) of cross-sectional samples and Hall measurements. Rutherford backscattering analysis indicated that the CIS films had a composition of Cu0.8In1.1Se1.9, whereas CGS films were Cu-poor and Ga-rich with a composition of Cu0.3Ga1.5Se1.5. Clean Cu-chalcopyrite/Si interfaces were obtained using BOE treated Si substrates. Transmission electron micrographs of cross-sectional samples indicated a polycrystalline film structure and that the native oxide on the Si substrate was eliminated. Energy dispersive X-ray spectroscopy (EDS) conducted in the TEM showed that contamination levels in the films were low. The Hall-mobility experiments performed the CIS film indicated that the material was of p-type conductivity with a carrier concentration of 9.6 x 1020/cm3 and a Hall mobility of 390 cm2V-1s-1.

Study of Germanium Epitaxial Recrystallization on Bulk-Si Substrates

2010 ◽  
Vol 1252 ◽  
Author(s):  
Byron Ho ◽  
Reinaldo Vega ◽  
Tsu-Jae King-Liu
Keyword(s):  
Electron Microscopy ◽  
Diffusion Theory ◽  
Grazing Incidence ◽  
Quasi Equilibrium ◽  
X Ray Diffraction ◽  
Rapid Thermal Anneal ◽  
Simple Diffusion ◽  
X Ray ◽  
Si Substrates ◽  
Transmission Electron

AbstractLPCVD Ge films are deposited onto bulk Si substrates and subjected to either a rapid thermal anneal (RTA) or furnace anneal (FA) at a temperature that is higher than the melting point of Ge in an attempt to induce epitaxial recrystallization. Spiking into the Si and voids in the Ge film are observed after the anneal. This is attributed to defect-assisted Ge diffusion into the Si substrate caused by strain at the Ge-Si interface. Simple diffusion theory using published diffusivity values predicts diffusion depths similar to the spiking depths observed by scanning electron microscopy and transmission electron microscopy. Approaches to reduce the strain at the interface are explored. It is found that the quasi-equilibrium nature of FA reduces spiking and that there is an area dependence. Grazing-incidence x-ray diffraction analysis suggests that this technique for epitaxial recrystallization does not result in single-crystalline Ge.

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