F.R. Brotzen

Thermal conductivity of thin SiO2 films

Abstract On the basis of a mathematical model developed here, thermal conductivities were determined in silicon oxide films of four thicknesses. The films were deposited by plasma-enhanced chemical vapor deposition on monocrystalline silicon substrates. Heat losses by convection and radiation were minimized. The conductivities of the films are significantly lower than those of bulk SiO 2 . As the film thickness decreases, the thermal conductivity is lowered considerably.

Effect of thickness on the transverse thermal conductivity of thin dielectric films

The transverse thermal conductivities of SiO2 thin films are determined as a function of film thickness. The results indicate that the apparent thermal conductivities of SiO2 thin films are much lower than the thermal conductivity of bulk SiO2. In addition, a slight decrease in the thermal conductivity is observed as the average temperature within the dielectric film increases. The average transverse thermal conductivity decreases drastically as the film thickness is reduced. This strong thickness dependence is explained in terms of an interfacial thermal resistance that develops at the SiO2/Si interface. The experimentally determined value for the interfacial thermal resistance, Rint, is 2.05 mm2 °C W−1.

The effective transverse thermal conductivity of amorphous Si3N4 thin films

The effective transverse thermal conductivity of Si3N4 thin films is determined as a function of film thickness. Results indicate that the effective thermal conductivity behavior of Si3N4 thin films is similar to that exhibited by amorphous SiO2 films; that is, there is no significant difference between the thermal conductivity of amorphous Si3N4 and amorphous SiO2 thin films as a function of thickness or temperature. The average effective transverse thermal conductivity decreases drastically as the film thickness is reduced. This strong thickness dependence is ascribed to a thermal resistance that is localized at the amorphous film/Si‐substrate interface. Within the narrow temperature range studied, the interfacial thermal resistance and the intrinsic conductivity of amorphous films increase with temperature; however, the interfacial resistance dominates as the film thickness is reduced. In light of the observed similarities between the Si3N4 results and those previously obtained on SiO2, the reduction i...

Mechanical properties and microstructures of Al-1%Si thin film metallizations

Abstract The microstructures and mechanical properties of Al-1%Si thin film metallizations annealed at temperatures ranging from 250 to 500 °C and then chemically removed from their substrates were evaluated at room temperature. Transmission electron microscopy revealed significant grain growth throughout the temperature range studied. The calculated activation energy for grain growth agrees well with previously reported values for the activation energy for aluminum self-diffusion along grain boundaries. The mechanical properties were evaluated under biaxial stress conditions using a testing device that provided reproducible stress-strain diagrams. Increasing grain size leads to an overall decrease in the tensile strength and plastic flow stress at a given strain. Details of the sample preparation, testing equipment and experimental procedure are presented, and the results are discussed in terms of microstructure-property relationships.

Mechanical testing of thin metallic films

Mechanical properties of thin-film metallizations used as interconnects in VLSI devices can be studied by different techniques. The present investigation centers about mechanical testing of aluminum films of submicron dimensions. Free-standing films were subjected to bulge and uniaxial testing, while films adherent to the silicon substrate were tested in an apparatus that employed cantilever specimens. It measured the deflection as a function of a variable load. The results of these in situ tests can be compared with stress-strain curves of free-standing films of identical composition. Because of the very high sensitivity required of the equipment, various experimental problems tend to arise, which are discussed in detail.

Impedance‐Spectroscopy Response of Aluminum‐Copper‐Silicon Alloys

The effects of Cu and Si additions as well as heat-treatment on the ac impedance-spectroscopy response and anodic dc polarization of Al-Cu-Si alloys were evaluated. The observed corrosion behavior was correlated with the changes in microstructure and age-hardening response induced through artificial aging of Al-Cu and Al-Cu-Si alloys. In the solution-treated condition, Si additions were found to lead to a very slight increase in corrosion resistance, while Cu additions were found to lower the overall corrosion resistance significantly. Cu and Si additions also led to an increase in the open-circuit potentials of Al-Cu-Si alloys

A Galvanic Series for Thin‐Film Metallizations and Barrier Layers Commonly Used in the Microelectronics Industry

A galvanic series was developed for a variety of thin-film metallizations and barrier layers deposited on oxidized Si substrates. The series was determined by listing the stable open-circuit potentials of thin-film metallizations, barrier layers, and metal/barrier-layer couples that were evaluated using a 2000 ppm NH 4 Cl electrolyte. The findings are particularly meaningful for the manufacture of microelectronic devices, because the relative corrosion tendencies of microelectronic materials have been determined traditionally from galvanic tables based on their bulk counterparts in seawater

Creep of thin metallic films

Abstract Free-standing films of Al, AlSi (1%) and Cu, 1 μm thick, were prepared by chemical ablation from commercially produced metallizations deposited on Si/SiO 2 substrates. The films were tested at various temperatures and stresses in a specially designed creep apparatus. By varying temperatures and loads, the activation energies and stress dependences for secondary creep were determined. In addition, primary creep curves were generated by adding small load increments during the tests. By evaluating these curves, the activation volumes and dislocation densities were obtained.

Mechanical behavior of aluminum and Al-Cu(2%) thin films☆

Abstract Stress-strain and creep curves were obtained for aluminum and Al-Cu(2%) metallizations 1 μm thick deposited on silicon substrates. The biaxial stress-strain curves were generated by bulge testing, while creep was measured in uniaxial tension. Annealing treatment of aluminum films revealed only small changes in grain size and had only little influence on the film strength. The activation energy for creep of aluminum films rose with annealing temperatures. The stress-strain curves for Al-Cu(2%) films evinced the effects of heterogeneous precipitation hardening followed by homogeneous precipitation hardening at 250°C. Steady state creep of aluminum films had activation energies that were lower than those of Al-Cu(2%) metallizations.

The effect of hydrogen on mechanical properties of oxygen-strengthened titanium

The effect of oxygen on the hydrogen embrittlement in titanium was investigated in two Ti-based alloys containing different amounts of oxygen: 0.064 and 0.154, in wt pct. Tensile, impact, and hardness tests were performed with and without prior hydrogenation of the specimens. Results show that, while the presence of hydrogen, even in relatively small amounts, will not affect the hardness or room-temperature tensile properties determined at relatively slow strain rates, hydrogen will reduce significantly the impact resistance, as determined by the Charpy V-notch test. This deleterious effect on the impact resistance was found to be exacerbated by an increase of oxygen in the alloy.