A Tem Investigation of the Effects of Tensile Stress on Thin Film Microstructure and Surface Morphology

1994 ◽  
Vol 356 ◽  
Author(s):  
Karen E. Harris ◽  
Alexander H. King
Keyword(s):  
Tensile Stress ◽  
Film Thickness ◽  
Grain Growth ◽  
Fiber Texture ◽  
Free Standing ◽  
Transmission Electron ◽  
Nominal Thickness ◽  
Columnar Grains ◽  
Crack Tips ◽  
Film Microstructure

AbstractWe have studied the microscopic effects of tensile stress on film thickness and grain growth in gold thin films of 25nm nominal thickness using transmission electron microscopy. Free-standing films were annealed at 150°C resulting in films with columnar grains and 〈111〉 fiber texture. After repeated anneals, tensile stresses caused by grain growth became large enough to cause cracks to form and propagate diffusively. While tensile stress must eventually result in an overall decrease in film thickness, local specimen thickening in front of crack tips is observed. The tensile stress also profoundly affected grain growth in these films. Grains near crack tips are larger than grains 400nm away from the tips, and elongated grains with axial ratios greater than 15 have been observed in cracked regions of the films.

Mechanisms of Grain Growth in Free-Standing Nanograined Gold Thin Films

2005 ◽  
Vol 907 ◽  
Author(s):  
J. A. Gregg ◽  
K Hattar ◽  
C H Lei ◽  
I M Robertson
Keyword(s):  
Thin Films ◽  
Grain Growth ◽  
Structural Changes ◽  
Dislocation Slip ◽  
Free Standing ◽  
Transmission Electron ◽  
Enhanced Properties ◽  
Gold Thin Films ◽  
Annealing Experiments

AbstractRetention of the enhanced properties reported for nanograined metallic systems requires that the nanostructure be insensitive to temperature and deformation. In situ transmission electron microscopy annealing experiments were employed to investigate the structural changes associated with the formation of micron-sized grains in nanograined evaporated gold thin films. This abnormal grain growth occurs randomly throughout the film. Twinning but not dislocation slip occurs in the growing grains until the grain size is in the hundreds of nanometer range. The twins appear to hinder growth and for grain growth to continue the twins must either be annihilated or be able to grow with the grain concurrently.

Grain growth in ultrathin films of CoPt and FePt

1999 ◽  
Vol 14 (8) ◽  
pp. 3263-3270 ◽  
Author(s):  
R. A. Ristau ◽  
K. Barmak ◽  
K. R. Coffey ◽  
J. K. Howard
Keyword(s):  
Electron Microscopy ◽  
Grain Growth ◽  
Ultrathin Films ◽  
Growth Stage ◽  
Fiber Texture ◽  
Digital Analysis ◽  
Bright Field ◽  
Transmission Electron ◽  
Grain Growth Kinetics ◽  
Two Stages

The microstructure of sputtered 10-nm thin films of equiatomic binary alloys of CoPt and FePt was characterized using transmission electron microscopy (TEM). Grain growth kinetics was examined using manual and digital analysis of bright-field TEM images and was seen to take two stages during annealing in these films. A rapid growth stage concurrent with the formation of a [111] fiber texture was observed to occur within the first 5–10 min of annealing, followed by a much slower growth stage after the fiber texturing was well advanced. Differences in grain growth rate and ultimate grain size were also observed to depend on heating rate.

Abnormal grain growth of sputtered CuNi(Mn) thin films

2000 ◽  
Vol 15 (5) ◽  
pp. 1062-1068 ◽  
Author(s):  
W. Brückner ◽  
V. Weihnacht ◽  
W. Pitschke ◽  
J. Thomas ◽  
S. Baunack
Keyword(s):  
Thin Films ◽  
Grain Growth ◽  
Abnormal Grain Growth ◽  
Temperature Cycle ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Columnar Grains ◽  
Maximum Temperatures ◽  
Film Substrate ◽  
20 Nm

The evolution in both stress and microstructure was investigated on sputtered Cu0.57Ni0.42Mn0.01thin films of 400 nm thickness during the first temperature cycle up to 550 °C. Samples from stress–temperature measurements up to various maximum temperatures were analyzed by x-ray diffraction, scanning and transmission electron microscopy, and Auger electron spectroscopy. The columnar grains with lateral diameters of about 20 nm in the as-deposited state coarsen to about 400 nm above 300 °C. Probably due to the impurity (Mn) drag effect, the coarsening occurs by abnormal grain growth rather than by normal grain growth, starting near the film–substrate interface. The stress development results from a combination of densification due to grain growth and plastic stress relaxation.

Stability of Ruthenium-Silica Bilayer Structures

1994 ◽  
Vol 343 ◽  
Author(s):  
Zara Weng-Sieh ◽  
Tai. D. Nguyen ◽  
Ronald Gronsky
Keyword(s):  
Grain Size ◽  
Film Thickness ◽  
Silicon Dioxide ◽  
Grain Growth ◽  
Original Film ◽  
Grain Sizes ◽  
Transmission Electron ◽  
20 Nm ◽  
Spherical Grains ◽  
Deposited Films

ABSTRACTThe microstructural evolution of ruthenium-silicon dioxide bilayer structures upon annealing is studied using transmission electron microscopy. SiO2/Ru/SiO2 structures, with thicknesses of 2/1/2 nm, 4/2/4 nm, 8/4/8 nm, and 20/10/20 nm, are formed by magnetron sputtering and annealed at 300 or 600°C. As-deposited films have grain sizes on the order of the Ru film thickness. After annealing at 600°C, significant grain growth is observed for all thicknesses, such that the final grain sizes are approximately 3 to 20x greater than the original film thickness. The largest increase in the average Ru grain size is observed for the 2 nm thick ruthenium film possibly due to the coalescence of Ru grains. The coalescence of the Ru particles in the 1 and 2 nm thick films results in the formation of lamellar Ru grains, which disrupts the contiguity of the Ru film. In all other cases, the increase in grain size is attributed to normal grain growth, but the formation of anomalous spherical grains is also observed.

The Geometry of Grain Disappearance in Thin Polycrystalline Films

1994 ◽  
Vol 343 ◽  
Author(s):  
S. J. Townsend ◽  
C. S. Nichols
Keyword(s):  
Thin Film ◽  
Film Thickness ◽  
Grain Boundaries ◽  
Grain Growth ◽  
Polycrystalline Films ◽  
Surface Drag ◽  
Columnar Grains ◽  
Simulation Results ◽  
Thin Polycrystalline

ABSTRACTDuring grain growth, shrinking columnar grains in thin-film polycrystalline microstructures eventually reach sizes comparable to the film thickness. Due to surface drag, the sides of such grains may bow inward rather than remaining fiat through the bulk of the film. The grain boundaries delimiting such small shrinking grains may become unstable long before the surface of the shrinking grain reaches zero area. We report simulation results demonstrating such an instability in the limit of infinite surface drag. This may lead to extremely rapid disappearance of 4- or 5- sided grains, such as have been recently observed in in situ hot-stage TEM experiments on aluminum thin film polycrystals.

Hillock Formation in Tensile Loaded Films

1995 ◽  
Vol 391 ◽  
Author(s):  
Karen E. Harris ◽  
Alexander H. King
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Room Temperature ◽  
Large Single Crystal ◽  
Free Standing ◽  
Boundary Area ◽  
Compressive Stresses ◽  
Transmission Electron ◽  
Nominal Thickness ◽  
Hillock Formation

AbstractWhile hillocks usually form to relieve compressive stresses in thin films resulting from electromigration or a difference in thermal expansion in the film and substrate, we have observed hillock formation in tensile-loaded films. We have used transmission electron microscopy to study hillocks which formed in free-standing gold thin films of 25nm nominal thickness. Grain growth during 150°C anneals reduced the grain boundary area and associated free volume, placing the films under tensile stress. While hillock formation could only increase this stress, large single crystal or polycrystalline hillocks with thicknesses up to three times the film thickness are observed after 400°C annealing, after long room temperature anneals, and during TEM observation. These observations suggest the operation of a hillock formation mechanism not explained by any existing hillock formation theories.

Stress and texture in sputter deposited Cr films

2003 ◽  
Vol 795 ◽  
Author(s):  
S. Yu. Grachev ◽  
J.-D. Kamminga ◽  
G. C. A. M. Janssen
Keyword(s):  
Tensile Stress ◽  
Film Thickness ◽  
Grain Growth ◽  
Power Law ◽  
Fiber Type ◽  
Intrinsic Stress ◽  
Stress Evolution ◽  
Power Law Exponent ◽  
Sputter Deposited ◽  
Chromium Films

ABSTRACTIntrinsic stress in coatings is often responsible for its performance. We studied tensile stress in sputter deposited chromium films as a function of film thickness and Ar pressure during deposition. We correlate the stress evolution to the grain growth in the polycrystalline films. Both grain growth and stress evolution obey the same power law dependence on thickness. We conclude that the tensile stress is generated at the grain boundaries. The power law exponent did not depend on pressure of Ar and remained 0.36. However, texture and microstructure in the layers changed when pressure was increased from 2×10-2 to 6×10-2 mbar. Texture switched from 110 to 111 fiber type. Grooves and sharp star-like grains were observed at higher pressure. We explain changes in terms of suppressed shadowing and less surface diffusion.

Fracture of Thin Tantalum Nitride Films on Ain Substrates

1996 ◽  
Vol 436 ◽  
Author(s):  
N. R. Moody ◽  
D. Medlin ◽  
D. P. Norwood
Keyword(s):  
Tantalum Nitride ◽  
High Porosity ◽  
Structure Property ◽  
Structure Property Relationships ◽  
Production Run ◽  
Transmission Electron ◽  
Nominal Thickness ◽  
Columnar Grains ◽  
Sputter Deposited ◽  
Film Substrate

AbstractNanoindentation, continuous nanoscratch testing, and transmission electron microscopy were used in this study to determine the structure-property relationships of thin tantalum nitride resistor films on aluminum nitride substrates. The films were sputter-deposited to a nominal thickness of 200 nm during one production run and then tested at room temperature. Most films were uniform in structure and thickness, consisting of fine equiaxed crystallites along the film-substrate interfaces and long columnar grains further away from the interface. However, one film varied greatly in thickness across the substrate. It had large crystallites along the film-substrate interface and clusters of columnar grains. Most importantly, it contained a far greater amount of porosity than the other films. The high porosity content led to significantly lower elastic moduli and hardness values than the low porosity films and a much greater susceptibility to fracture.

Secondary Grain Growth in Thin Films

1985 ◽  
Vol 57 ◽  
Author(s):  
C. V. Thompson ◽  
Henry I. Smith
Keyword(s):  
Thin Films ◽  
Surface Energy ◽  
Film Thickness ◽  
Grain Growth ◽  
Growth Surface ◽  
Rate Theory ◽  
Semiconductor Films ◽  
Crystal Films ◽  
Columnar Grains ◽  
A Minor

AbstractNormal grain growth in thin films leads to columnar grains with sizes roughly equal to the film thickness. In subsequent grain growth, a minor fraction of the grains continue to grow at appreciable rates, leading initially to a bimodal grain size distribution and ultimately to a monomodal distribution of grains with sizes much larger than the film thickness. Those grains which continue to grow, secondary grains, often have uniform or restricted texture, suggesting that in such cases surface energy minimization plays an important role in driving their preferential growth. Surface-energy-driven secondary grain growth can, in principle, lead to single crystal films. Turnbull and co-workers were among the first to apply rate theory to the analysis of grain boundary motion, grain growth, and recrystallization. These models have been adapted to describe surface-energy-driven secondary grain growth in thin films. Recent experiments on secondary grain growth in thin metallic and semiconductor films are reviewed. It has been shown that film thickness, film composition and surface topography have pronounced effects on growth rates, final grain sizes and orientations.

Effect of Annealing on Microstructural Development and Grain Orientation in Electrodeposited Ni

2010 ◽  
Vol 160 ◽  
pp. 235-240 ◽  
Author(s):  
Uta Klement ◽  
L. Hollang ◽  
S.R. Dey ◽  
M. Battabyal ◽  
O.V. Mishin ◽  
...  
Keyword(s):  
Grain Growth ◽  
Cross Sections ◽  
Electron Backscatter Diffraction ◽  
Microstructural Development ◽  
Growth Behaviour ◽  
Coalescence Model ◽  
Transmission Electron ◽  
Columnar Grains ◽  
Backscatter Diffraction

Thick (up to 5 mm) Ni electrodeposits were produced by the pulsed electrodeposition (PED) technique. The PED-Ni was investigated in planar and cross-sections using high resolution scanning electron microscopy. Grain size and local texture were studied by electron backscatter diffraction. Thermal stability and grain growth behaviour were investigated using in-situ annealing in the transmission electron microscope. It is observed that columnar grains are present in the material and that the orientation of grains is not uniform. Textures and in-situ annealing behaviour are compared to previous data on nanocrystalline PED-Ni and Ni-Fe, where a subgrain coalescence model adopted from recrystallization is used to describe the occurrence of abnormal grain growth upon annealing and where twinning was found to be responsible for the texture development.

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