Evolution of tensile residual stress in thin metal films during energetic particle deposition

Physical-vapor-deposited thin metal films often exhibit tensile residual stresses. We studied the stress evolution in thin Cr films and found that increasing bombardment with energetic particles (atoms or ions) at low energies leads to an increase of tensile stress to a maximum followed by a rapid decrease. Microstructural characterization by transmission electron microscopy revealed that two different microstructures are observed for the same level of tensile stress: films processed at low bombardment had columnar porosity while no porosity was observed in films processed at higher bombardment. The observed stress evolution is interpreted by considering how the mean interatomic distance (and hence the force) in the intercolumnar regions is modified by energetic particle bombardment.

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Fundamental aspects of residual stress evolution in thin metal films during energetic particle deposition A . Misra and M. Nastasi

Adhesion Aspects of Thin Films, Volume 1 ◽

10.1201/b11971-8 ◽

2014 ◽

pp. 25-35

Keyword(s):

Residual Stress ◽

Energetic Particle ◽

Particle Deposition ◽

Metal Films ◽

Thin Metal ◽

Thin Metal Films ◽

Stress Evolution

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Metal Microstructures in Advanced CMOS Devices

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100164258 ◽

1996 ◽

Vol 54 ◽

pp. 358-359

Author(s):

L. M. Gignac ◽

K. P. Rodbell

Keyword(s):

Grain Boundaries ◽

Semiconductor Device ◽

Chemical Vapor ◽

Microstructural Characterization ◽

Metal Films ◽

Thin Metal ◽

Electrical Performance ◽

Thin Metal Films ◽

Chemical Vapor Deposited ◽

Boundary Properties

As advanced semiconductor device features shrink, grain boundaries and interfaces become increasingly more important to the properties of thin metal films. With film thicknesses decreasing to the range of 10 nm and the corresponding features also decreasing to sub-micrometer sizes, interface and grain boundary properties become dominant. In this regime the details of the surfaces and grain boundaries dictate the interactions between film layers and the subsequent electrical properties. Therefore it is necessary to accurately characterize these materials on the proper length scale in order to first understand and then to improve the device effectiveness. In this talk we will examine the importance of microstructural characterization of thin metal films used in semiconductor devices and show how microstructure can influence the electrical performance. Specifically, we will review Co and Ti silicides for silicon contact and gate conductor applications, Ti/TiN liner films used for adhesion and diffusion barriers in chemical vapor deposited (CVD) tungsten vertical wiring (vias) and Ti/AlCu/Ti-TiN films used as planar interconnect metal lines.

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Epitaxial Al and Cu films grown on CaF2/Si(111)

MRS Proceedings ◽

10.1557/proc-648-p11.38 ◽

2000 ◽

Vol 648 ◽

Author(s):

Yuriy V. Shusterman ◽

Nikolai L. Yakovlev ◽

Katharine Dovidenko ◽

Leo J. Schowalter

Keyword(s):

Size Effect ◽

High Energy ◽

Metal Films ◽

Thin Metal ◽

Room Temperature Resistivity ◽

Thin Metal Films ◽

Cu Films ◽

Transmission Electron ◽

Materials Research ◽

Magneto Resistance

AbstractThe ability to grow single-crystalline Al and Cu films is of significance for several areas of materials research, such as the resistivity size effect in thin metal films, electromigration failure of interconnects, and magneto-resistance studies. Here, we explore the microstructure and resistivity of thin Al and Cu films grown on CaF2/Si(111). A three-step technique of CaF2 growth is described that permits deposition under imperfect vacuum conditions and promotes smoothness of subsequent thin metal films. Reflection high-energy electron diffraction shows that epitaxial Al(111) is obtained directly on CaF2, while epitaxial Cu(111) is obtained only by growing on a 1 nm thick Al seed layer pre-deposited on CaF2. Transmission electron microscopy reveals that 75 nm thick Al films have 150 nm wide sub-grains misoriented by less than 1 degree. For 75 nm thick Cu, the grains are only 30 nm wide and are misoriented by as much as 10 degrees. Room temperature resistivity measurements of the 10-300 nm thick Al films agree with the Fuchs-Sondheimer model in which conduction electrons scatter totally diffusely at the film interfaces. For 50-1000 nm thick Cu films, the resistivity size effect is substantially greater than the prediction of this model, which may be explained in terms of grain boundary scattering.

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Internal Stress Evolution in Multicomponent Thin Metal Films under Electric Current

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.129-130.215 ◽

1996 ◽

Vol 129-130 ◽

pp. 215-224

Author(s):

Leonid Klinger ◽

A. Katsman ◽

L. Levin

Keyword(s):

Internal Stress ◽

Electric Current ◽

Metal Films ◽

Thin Metal ◽

Thin Metal Films ◽

Stress Evolution

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Structural and Electrical Properties of Thin Metal Films Deposited at Low Temperature

MRS Proceedings ◽

10.1557/proc-382-455 ◽

1995 ◽

Vol 382 ◽

Author(s):

L. He ◽

E. Li ◽

E. Morrison ◽

D. Sirur ◽

Z. Q. Shi

Keyword(s):

Low Temperature ◽

Room Temperature ◽

Resistivity Measurement ◽

Electrical Measurement ◽

Metal Films ◽

Thin Metal ◽

Thin Metal Films ◽

Transmission Electron ◽

Structural And Electrical Properties ◽

Measurement Results

ABSTRACTThin metal layers play an important role in the development of electronic devices. The thin metal films deposited at low temperature (LT=77K) showed some unique properties which enhanced device performance. The micro-structural properties of thin metal films formed at room temperature (RT) and LT were investigated. An insulating substrate was used for Au, Pd Al and Ag metal deposition. The metal films were deposited by vacuum evaporation with thickness ranged from 100 Å to 100 Å. The surface morphology of the metal films was determined by transmission electron spectroscopy (TEM). The resistance of the films was insitu measured as a function of film thickness and temperature. Electrical measurement found that these films shown several orders lower resistance compared to the film obtained at room temperature at very thin thickness, which, implies potential application of these films on electronic and optoelectronic devices. It is found that the LT films showed much lower densities of grain boundaries than the RT samples. This is consistent with the resistivity measurement results.

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Electromigration in Thin Metal Films in the Presence of Two Stress-Relaxation Mechanisms

MRS Proceedings ◽

10.1557/proc-428-167 ◽

1996 ◽

Vol 428 ◽

Cited By ~ 1

Author(s):

A. Katsman ◽

L. Levin

Keyword(s):

Stress Relaxation ◽

Current Density ◽

Threshold Stress ◽

Metal Films ◽

Thin Metal ◽

Diffusional Creep ◽

Thin Metal Films ◽

Stress Evolution ◽

Threshold Length ◽

Kinetics Of

AbstractKinetics of mass transfer in thin metal films during electromigration was analyzed as a function of the generated internal stress. Stress evolution was considered for the case when two different stress relaxation mechanisms can operate simultaneously near the anode end of the strip: thresholdless diffusional creep through a fixed aperture, and diffusional creep with a threshold stress, σt, through the same aperture. Stress distribution and electromigration rate were found as explicit functions of the film length, the aperture size, and the current density. The apparent threshold length was analyzed. It was shown that an apparent threshold product can grow with the current density, in agreement with the experimental results.

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