Effect of substrate roughness on microstructure, uniaxial anisotropy, and coercivity of Co/Pt multilayer thin films

Chung‐Hee Chang; Mark H. Kryder

doi:10.1063/1.356810

Stress in Giant Magnetoresistive Ni66Fe16Co18/Ag Multilayer thin Films

MRS Proceedings ◽

10.1557/proc-356-403 ◽

1994 ◽

Vol 356 ◽

Cited By ~ 1

Author(s):

J.D. Jarratt ◽

J.A. Barnard

Keyword(s):

Thin Films ◽

Compressive Stress ◽

Giant Magnetoresistance ◽

Uniaxial Anisotropy ◽

Structural Evolution ◽

Film Plane ◽

Film Stress ◽

Bilayer Film ◽

Multilayer Thin Films ◽

Thin Film Stress

AbstractThin film stress has been measured in (Ni66Fe16Co18 25 Å/Ag 50 Å) multilayer thin films that exhibit annealing-induced giant magnetoresistance (GMR) known as ‘discontinuous’ GMR1. This GMR results when NiFeCo layers are broken up into discontinuous ferromagnetic islands or platelets by immiscible Ag atom grain boundary diffusion normal to the film plane. As-deposited films display no GMR and are in compression. An MR value of 5 % with a relatively sharp profile can be induced in a ten bilayer sample annealed at 400°C for 15 min. Annealing generally results in a decrease in the as-deposited compressive stress and can result in tensile stress at high enough temperatures. Interestingly, at the annealing temperatures corresponding to the maximum induced GMR, there is a plateau in the otherwise monotonic decrease in compressive stress with increasing temperature.Stress-temperature plots reveal a plateau in the stress value during the heating of a ten bilayer sample due to plastic deformation in the film via densification. Isothermal stress-time plots done on a single sample show increasing compressive stress relief after each successively higher temperature anneal. The stress was also measured in a single bilayer film with the same volume of film as in a ten bilayer sample but far fewer interfaces. High and low angle x-ray diffraction (HXRD, LXRD) was used to reveal the structural evolution with annealing. Magnetic (M-H) hysteresis measurements revealed increasing coercivity and decreasing induced as-deposited in-plane magnetic uniaxial anisotropy with annealing temperature.

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Characterization of reactive phase formation in sputter-deposited Ni/Al multilayer thin films using TEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100167469 ◽

1996 ◽

Vol 54 ◽

pp. 1000-1001

Author(s):

G. Lucadamo ◽

K. Barmak ◽

C. Michaelsen

Keyword(s):

Thin Films ◽

Phase Formation ◽

Dark Field ◽

Nickel Layer ◽

Multilayer Thin Films ◽

Cross Sectional ◽

Dark Field Imaging ◽

Transmission Electron ◽

Sputter Deposited ◽

Constant Heating

The subject of reactive phase formation in multilayer thin films of varying periodicity has stimulated much research over the past few years. Recent studies have sought to understand the reactions that occur during the annealing of Ni/Al multilayers. Dark field imaging from transmission electron microscopy (TEM) studies in conjunction with in situ x-ray diffraction measurements, and calorimetry experiments (isothermal and constant heating rate), have yielded new insights into the sequence of phases that occur during annealing and the evolution of their microstructure.In this paper we report on reactive phase formation in sputter-deposited lNi:3Al multilayer thin films with a periodicity A (the combined thickness of an aluminum and nickel layer) from 2.5 to 320 nm. A cross-sectional TEM micrograph of an as-deposited film with a periodicity of 10 nm is shown in figure 1. This image shows diffraction contrast from the Ni grains and occasionally from the Al grains in their respective layers.

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The use of transmission and analytical electron microscopy in studying reactions and phase transformations in thin film

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100150046 ◽

1993 ◽

Vol 51 ◽

pp. 842-843

Author(s):

K. Barmak

Keyword(s):

Thin Film ◽

Thin Films ◽

Phase Transformations ◽

Analytical Electron Microscopy ◽

Ex Situ ◽

Multilayer Thin Films ◽

Absolute Concentration ◽

Analytical Electron ◽

Deposition Step

Generally, processing of thin films involves several annealing steps in addition to the deposition step. During the annealing steps, diffusion, transformations and reactions take place. In this paper, examples of the use of TEM and AEM for ex situ and in situ studies of reactions and phase transformations in thin films will be presented.The ex situ studies were carried out on Nb/Al multilayer thin films annealed to different stages of reaction. Figure 1 shows a multilayer with dNb = 383 and dAl = 117 nm annealed at 750°C for 4 hours. As can be seen in the micrograph, there are four phases, Nb/Nb3-xAl/Nb2-xAl/NbAl3, present in the film at this stage of the reaction. The composition of each of the four regions marked 1-4 was obtained by EDX analysis. The absolute concentration in each region could not be determined due to the lack of thickness and geometry parameters that were required to make the necessary absorption and fluorescence corrections.

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TEM studies of solid-state reactions in sputter-deposited Nb/Al multilayer thin films

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100167561 ◽

1996 ◽

Vol 54 ◽

pp. 1020-1021

Author(s):

F. Ma ◽

S. Vivekanand ◽

K. Barmak ◽

C. Michaelsen

Keyword(s):

Thin Films ◽

Solid State ◽

Stoichiometric Composition ◽

Analytical Electron Microscopy ◽

Grain Structure ◽

Solid State Reactions ◽

Multilayer Thin Films ◽

X Ray Diffraction ◽

X Ray ◽

Sputter Deposited

Solid state reactions in sputter-deposited Nb/Al multilayer thin films have been studied by transmission and analytical electron microscopy (TEM/AEM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The Nb/Al multilayer thin films for TEM studies were sputter-deposited on (1102)sapphire substrates. The periodicity of the films is in the range 10-500 nm. The overall composition of the films are 1/3, 2/1, and 3/1 Nb/Al, corresponding to the stoichiometric composition of the three intermetallic phases in this system.Figure 1 is a TEM micrograph of an as-deposited film with periodicity A = dA1 + dNb = 72 nm, where d's are layer thicknesses. The polycrystalline nature of the Al and Nb layers with their columnar grain structure is evident in the figure. Both Nb and Al layers exhibit crystallographic texture, with the electron diffraction pattern for this film showing stronger diffraction spots in the direction normal to the multilayer. The X-ray diffraction patterns of all films are dominated by the Al(l 11) and Nb(l 10) peaks and show a merging of these two peaks with decreasing periodicity.

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Electrical Anisotropy of Thin Metal Films Growing on Dielectric Substrates

Nonlinear Analysis Modelling and Control ◽

10.15388/na.2002.7.2.15193 ◽

2002 ◽

Vol 7 (2) ◽

pp. 45-52

Author(s):

L. Jakučionis ◽

V. Kleiza

Keyword(s):

Magnetic Field ◽

Thin Films ◽

Uniaxial Anisotropy ◽

Metal Films ◽

Thin Layers ◽

Electrical Anisotropy ◽

Electrical Field ◽

Dielectric Substrates ◽

Unequal Probability ◽

Conductive Thin Films

Electrical properties of conductive thin films, that are produced by vacuum evaporation on the dielectric substrates, and which properties depend on their thickness, usually are anisotropic i.e. they have uniaxial anisotropy. If the condensate grow on dielectric substrates on which plane electrical field E is created the transverse voltage U⊥ appears on the boundary of the film in the direction perpendicular to E. Transverse voltage U⊥ depends on the angle γ between the applied magnetic field H and axis of light magnetisation. When electric field E is applied to continuous or grid layers, U⊥ and resistance R of layers are changed by changing γ. It means that value of U⊥ is the measure of anisotropy magnitude. Increasing voltage U0 , which is created by E, U⊥ increases to certain magnitude and later decreases. The anisotropy of continuous thin layers is excited by inequality of conductivity tensor components σ0 ≠ σ⊥. The reason of anisotropy is explained by the model which shows that properties of grain boundaries are defined by unequal probability of transient of charge carrier.

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Progressive Debonding of Multilayer Interconnect Structures

MRS Proceedings ◽

10.1557/proc-473-21 ◽

1997 ◽

Vol 473 ◽

Cited By ~ 9

Author(s):

Michael Lane ◽

Robert Ware ◽

Steven Voss ◽

Qing Ma ◽

Harry Fujimoto ◽

...

Keyword(s):

Thin Films ◽

Crack Growth ◽

Driving Force ◽

Adhesion Energy ◽

Time Dependent ◽

Multilayer Thin Films ◽

Processing Conditions ◽

Interface Morphology ◽

Entire Sample ◽

Crack Growth Velocity

ABSTRACTProgressive (or time dependent) debonding of interfaces poses serious problems in interconnect structures involving multilayer thin films stacks. The existence of such subcriticai debonding associated with environmentally assisted crack-growth processes is examined for a TiN/SiO2 interface commonly encountered in interconnect structures. The rate of debond extension is found to be sensitive to the mechanical driving force as well as the interface morphology, chemistry, and yielding of adjacent ductile layers. In order to investigate the effect of interconnect structure, particularly the effect of an adjacent ductile Al-Cu layer, on subcriticai debonding along the TiN/SiO2 interface, a set of samples was prepared with Al-Cu layer thicknesses varying from 0.2–4.0 μm. All other processing conditions remained the same over the entire sample run. Results showed that for a given crack growth velocity, the debond driving force scaled with Al-Cu layer thickness. Normalizing the data by the critical adhesion energy allowed a universal subcriticai debond rate curve to be derived.

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