Surface stress model for intrinsic stresses in thin films

2000 ◽  
Vol 15 (11) ◽  
pp. 2468-2474 ◽  
Author(s):  
R. C. Cammarata ◽  
T. M. Trimble ◽  
D. J. Srolovitz
Keyword(s):  
Thin Films ◽  
Surface Stress ◽  
Sudden Change ◽  
Stress Generation ◽  
Intrinsic Stress ◽  
Stress Model ◽  
Island Growth ◽  
Stress Effects ◽  
Compressive Stresses ◽  
Island Coalescence

A simple model was presented for intrinsic stress generation in thin films resulting from surface stress effects. This mechanism can explain the origin of compressive stresses often observed during island growth prior to coalescence, as well as intrinsic compressive stresses reported for certain continuous, fully grown films. In some cases, surface stress effects may contribute to a sudden change in the intrinsic stress during island coalescence.

Surface Stress Effects on Thin Film Growth

1993 ◽  
Vol 317 ◽  
Author(s):  
R.C. Cammarata
Keyword(s):  
Thin Film ◽  
Surface Stress ◽  
Critical Thickness ◽  
Film Growth ◽  
Thin Film Growth ◽  
Stress Generation ◽  
Intrinsic Stress ◽  
Surface And Interface ◽  
Stress Effects

ABSTRACTA review of surface and interface stresses relevant to thin film growth is presented. It is shown that surface stress effects that are generally ignored in the analysis of epitaxy can have an influence on the critical thickness for epitaxy, especially at larger Misfits. A discussion of intrinsic stress generation from surface stress is also presented.

Physical Origins of Intrinsic Stresses in Volmer–Weber Thin Films

MRS Bulletin ◽  
2002 ◽  
Vol 27 (1) ◽  
pp. 19-25 ◽  
Author(s):  
Jerrold A. Floro ◽  
Eric Chason ◽  
Robert C. Cammarata ◽  
David J. Srolovitz
Keyword(s):  
Thin Films ◽  
Film Growth ◽  
Thin Film Deposition ◽  
Film Deposition ◽  
Stress Evolution ◽  
Island Nucleation ◽  
Stress Effects ◽  
Compressive Stresses ◽  
Island Coalescence ◽  
Made In

AbstractAs-deposited thin films grown by vapor deposition often exhibit large intrinsic stresses that can lead to film failure. While this is an “old” materials problem, our understanding has only recently begun to evolve in a more sophisticated fashion. Sensitive real-time measurements of stress evolution during thin-film deposition reveal a generic compressive–tensile–compressive behavior that correlates with island nucleation and growth, island coalescence, and postcoalescence film growth. In this article, we review the fundamental mechanisms that can generate stresses during the growth of Volmer–Weber thin films. Compressive stresses in both discontinuous and continuous films are generated by surface-stress effects. Tensile stresses are created during island coalescence and grain growth. Compressive stresses can also result from the flux-driven incorporation of excess atoms within grain boundaries. While significant progress has been made in this field recently, further modeling and experimentation are needed to quantitatively sort out the importance of the different mechanisms to the overall behavior.

CRACKING OF GaN FILMS

2004 ◽  
Vol 14 (01) ◽  
pp. 63-81 ◽  
Author(s):  
E. V. ETZKORN ◽  
D. R. CLARKE
Keyword(s):  
Tensile Stress ◽  
Stress Relief ◽  
Stress Generation ◽  
Island Growth ◽  
Dislocation Generation ◽  
Cracking Behavior ◽  
Brittle To Ductile Transition ◽  
Mechanics Model ◽  
Island Coalescence ◽  
Film Cracking

The cracking of GaN films and the associated cracking of substrates are described. The geometry, structure, and evolution of fracture demonstrate that GaN films crack under tensile stress during growth and are subsequently overgrown and partially healed. The film cracks channel along the (1010) GaN planes and also extend a distance of ~5 μm into the sapphire substrate. These incipient cracks in the substrate form a set of initial flaws that leads to complete fracture through the sapphire during cooling for sufficiently thick films. Each stage of this cracking behavior is well described by a fracture mechanics model that delineates a series of critical thicknesses for the onset of cracking that are functions of the film and substrate stresses, thicknesses, and elastic properties. Similar cracking behavior is found to occur independently of the choice of substrate between sapphire and SiC and is traced to a tensile stress generation mechanism early in the growth process, such as that provided by island coalescence. Cracking is the dominant stress relief mechanism, as opposed to dislocation generation or diffusion, because of the island growth mode and because of optimized growth temperatures at or below the brittle-to-ductile transition. Lateral epitaxial overgrowth (LEO) of GaN is shown to minimize substrate fracture even though film cracking remains unaffected. This effect explained in terms of the limits placed on the initial extent of insipient substrate cracks due to the LEO geometry.

Stress and Microstructural Evolution of Lpcvd Polysilicon Thin Films During High Temperature Annealing

1996 ◽  
Vol 441 ◽  
Author(s):  
Chia-Liang Yu ◽  
Paul A. Flinn ◽  
Seok-Hee Lee ◽  
John C. Bravman
Keyword(s):  
Thin Films ◽  
High Temperature ◽  
Stress Relaxation ◽  
Deposition Temperature ◽  
Stress Generation ◽  
Deformation Model ◽  
Silicon Thin Films ◽  
Compressive Stresses ◽  
Polysilicon Films ◽  
Curvature Measurements

AbstractThe mechanisms of stress generation and stress relaxation of LPCVD silicon thin films were studied using high temperature wafer curvature measurements. The stresses generated during depositions are measured as functions of deposition temperature and microstructure. Amorphous silicon deposited with a compressive stress shows a large stress change toward tensile during crystallization. The stress relaxation of polysilicon films deposited with tensile stresses can be described by a deformation model from Ashby and Frost [1]. The polysilicon films deposited with compressive stresses have hydrogen incorporated during deposition and shows hydrogen evolution during thermal cycles.

Intrinsic stress effects on the growth of planar SiO2 films

1999 ◽  
Vol 14 (12) ◽  
pp. 4508-4513 ◽  
Author(s):  
T. J. Delph ◽  
M-T. Lin
Keyword(s):  
Thin Films ◽  
Diffusion Equation ◽  
Layer Thickness ◽  
Diffusion Coefficients ◽  
Diffusion Rate ◽  
Numerical Study ◽  
Stress Gradient ◽  
Additional Term ◽  
Intrinsic Stress ◽  
Stress Effects

We report here on the results of a numerical study on the effects of intrinsic stress on the growth of SiO2 thin films. In accordance with a widely accepted model of stress effects upon silicon oxidation, we assume that the intrinsic stress affects only the oxidant diffusion rate. We examine several different models of stress-assisted diffusion. In the first of these models, the diffusivity is taken to be an exponential function of the stress, whereas in the second, the stress gradient appears as an additional term in the standard diffusion equation. Intrinsic stress effects result in deviations of up to 18% in expected layer thickness, depending upon the mode of oxidation and the diffusion model adopted. The implications of these results for the measurement of diffusion coefficients in SiO2 films are discussed.

Electron Microscopy Studies of The Chemistry And Microstructure of BaF2 / YBa2Cu3O7-x Thin Films

1994 ◽  
Vol 52 ◽  
pp. 796-797
Author(s):  
J. L. Lee ◽  
C. A. Weiss ◽  
R. A. Buhrman ◽  
J. Silcox
Keyword(s):  
Thin Film ◽  
Electron Microscopy ◽  
Thin Films ◽  
Scanning Transmission Electron Microscope ◽  
Atomic Scale ◽  
Island Growth ◽  
Multilayer Systems ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Mgo Substrate

BaF2 thin films are being investigated as candidates for use in YBa2Cu3O7-x (YBCO) / BaF2 thin film multilayer systems, given the favorable dielectric properties of BaF2. In this study, the microstructural and chemical compatibility of BaF2 thin films with YBCO thin films is examined using transmission electron microscopy and microanalysis. The specimen was prepared by using laser ablation to first deposit an approximately 2500 Å thick (0 0 1) YBCO thin film onto a (0 0 1) MgO substrate. An approximately 7500 Å thick (0 0 1) BaF2 thin film was subsequendy thermally evaporated onto the YBCO film.Images from a VG HB501A UHV scanning transmission electron microscope (STEM) operating at 100 kV show that the thickness of the BaF2 film is rather uniform, with the BaF2/YBCO interface being quite flat. Relatively few intrinsic defects, such as hillocks and depressions, were evident in the BaF2 film. Moreover, the hillocks and depressions appear to be faceted along {111} planes, suggesting that the surface is smooth and well-ordered on an atomic scale and that an island growth mechanism is involved in the evolution of the BaF2 film.

X-ray diffraction and Raman investigations of thickness dependent stress effects on Pb(ZrxTi1−x)O3 thin films

2006 ◽  
Vol 88 (25) ◽  
pp. 252901 ◽  
Author(s):  
Jyrki Lappalainen ◽  
Vilho Lantto ◽  
Johannes Frantti ◽  
Jussi Hiltunen
Keyword(s):  
Thin Films ◽  
X Ray Diffraction ◽  
X Ray ◽  
Stress Effects
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