We have performed time-resolved studies of the electromigration (EM) – induced formation, growth, migration, and spatial distribution of Al2Cu precipitates in submicron Al(0.5 wt. % Cu) runners. Of particular interest is the formation of the precipitates in relationship to the local microstructure of the runners, and the formation of voids and hillocks with respect to the location of the Al2Cu precipitates. Runners of widths 0.3, 0.5, 0.8, and 1.0 ýtm were tested at a current density of 2×106 A/cm2 and temperatures between 200 and 300°C. The evolution of the microstructure of the runners was evaluated using plan-view TEM, SEM, and EDX. The formation of voids and hillocks, and the growth of precipitates proceeds more rapidly as the width of the runners increases. However, a far greater number of precipitates nucleate in the 0.3 μm-wide line than in any of the others. As expected, voids are most likely to form near the cathode and hillocks near the anode. Large Al2Cu precipitates form near the anode long before failure occurs. Interestingly, the cathode-side bonding pad is not observed to serve as a good reservoir of Cu for the runners. Although the formation of voids near the cathode seems to be associated with the depletion of Cu in this region, hillocks and voids elsewhere are more likely to form at precipitates than in other parts of the line. Thus Al2Cu precipitates can act as sites for preferential EM-damage, reducing interconnect reliability.

The stress behavior of two structures (Ti/Al-0.5%Cu/TiN and TiN/W) has been analyzed versus temperature up to 400 °C using the Flexus measurement system. Microstructure modifications induce stress variations with temperature. Furthermore, stress relaxation after annealing has been investigated. Al-based metallization stress is essentially due to thermal issues and reaches rapidly its yield strength whereas the W film exhibits high intrinsic stress. Microstructural observations afte deposition and after annealing have been conducted using a non destructive technique, the Thermal Wave Imager.

Al and AI-1%Si 900 nanometer thin films were deposited on 100 nanometer Cu films on thermally oxidized (100 nanometer) Si wafers. The Al and Cu films were deposited using evaporation techniques, and the Al-1%Si film was sputter deposited. Different thin film samples were heated in vacuum to 175, 250, 330 and 400°C for 1 hour. The various annealed and original samples were compared using surface morphology, as well as composition versus sample depth. Differences between the Al and Al-1%Si samples are discussed.

Annealing behavior of Au, AuZn, and AuSb metallization on GaSb have been investigated by the combined use of RBS, XRD, TEM, and I-V characterization. The results give evidence that the thermally activated contact reaction strongly depends on the particular elements incorporated in the Au layer. Pure Au reacts with GaSb at 100°C. The addition of Zn to Au metallization increases the thermal stability of the metallization/semiconductor system to 200°C. Antimony, forming with gold the AuSb2 phase in metallization, provides the most stable ohmic contact system.

Among various requirements for the a-Si TFT-LCD gate electrode, low resistivity is becoming more emphasized with the increase of display size and information content as well as process feasibility. We have developed a low resistivity Mo-W alloy as a material for gate buslines.

The Mo-W film was formed by DC magnetron sputtering using Ar or Kr as the working gas. The resistivity of the fabricated film was 16 μΩ-cm when deposited with Ar, and decreased to a value as low as 13 μΩ-cm with Kr, which was less than a half that of the conventional Mo-Ta film. Inverted staggered a-Si TFTs having Mo-W gate electrodes formed with Kr were fabricated, and good transfer performance with thermal- and electrical stability was obtained. The applicability of the new alloy to LCDs with large area and high resolution was shown.

Selective deposition of copper on metal (such as TiN) versus dielectric (such as oxide) requires understanding of the mechanism of chemical-vapor-deposition copper deposition. This work studies the initial stage of CVD copper deposition with hexafluoroacetylacetonate Cu(I) trimethylvinylsilane (Cu-hfac-tmvs) precursor on tetraethylorthosilicate (TEOS) oxide using Fourier transform infrared spectroscopy (FTIR).

Diffusion barrier property of sputtered molybdenum nitride films for DRAM copper metallization was investigated as a function of annealing temperature. Molybdenum nitride thin films on silicon remained stable upon annealing 650°C-30min, but h-MoSi2 and t-MoSi2 were formed after the heat treatment at 700°C and Mo5Si3 phase was formed at 850°C. Increasing the annealing temperature decreased the stress of the γ-Mo2N/Si film down to about 0.8×1010dyne/cm2 at 800°C due to the reduction of the intrinsic stress component. Copper films on silicon substrates separated by thin layers of molybdenum nitride remained stable during the heat treatment at 600°C, but they began to fail as a diffusion barrier after the heat treatment at 650°C, when molybdenum silicides and copper silicide were thought to be formed. On heating, Cu/γ-Mo2N/Si films were affected by thermal stress as due to the thermal expansion coefficient between copper and molybdenum nitride thin films. Furthermore, interlayer interactions between copper and silicon increased with increasing the annealing temperature. The interlayer reactions were investigated by Rutherford backscattering spectrometry, X-ray photoelectron spectrscopy and Nomarski microscopy.

We report on the crystal quality and magnetotransport properties (EHE) of epitaxial (001) τ-MnA1/GaAs(100) grown by the laser ablation deposition technique. Films (10–30 nm thick) were grown by two methods: (1) ablating a τ-MnAl target, prepared in-house; (2) alternate deposition of ultra thin layers of Mn and Al (˜6 periods) followed by annealing at different temperatures. For both deposition approaches ultrathin coherent epitaxial τ-MnAl films have been grown at temperatures in the range 250–420°C that is below the ε-phase transformation temperature. Reflection high energy electron diffraction (RHEED) and high resolution transmission electron microscopy (HRTEM) were used to characterize the crystalline quality of the deposited films. The Extraordinary Hall Effect measurements (EHE) indicate that the deposited films are perpendicularly magnetized showing coercivity up to 6 kOe at room temperature. The epitaxial growth of thin film ferromagnetic materials on lattice matching semiconductor substrates offers the possibility of integrating magnetic and semiconducting devices.

Fe-O and Co-O films were prepared by DC magnetron sputtering in a mixture of Ar and O2 gases. By varying the oxygen to argon ratio, oxide films with stoichiometry FeO, Fe3O4, α-Fe2O3, CoO and Co3O4 were produced. TEM studies showed that the Fe – oxide films were polycrystalline consisting of small almost spherical grains, about 10 nm in size. Co-O films had different microstructure with grain size and shape dependent on the amount of oxygen. X-ray diffraction studies showed that the grains in Fe-O films were randomly oriented in contrast to Co-O films in which a <111> texture was observed. Pure FeO and α-Fe2O3 films were found to be superparamagnetic at room temperature but strongly ferromagnetic at low temperatures in contrast to the antiferromagnetic nature of bulk samples. A very large shift in the hysteresis loop, about 3800 Oe, was observed in field cooled Co-CoO films indicating the presence of a large unidirectional exchange anisotropy.

CoCrTa thin films with c-axis predominatly oriented perpendicular to the plane of the film were obtained by sputter deposition on thin tantalum nitride underlayers with −75 volts substrate bias applied during the deposition of the film. The relationship between the distribution of c-axes preferred crystal orientation and magnetization reversal properties of the sputtered CoCrTa films was investigated. Higher coercivities are obtained for CoCrTa films having a more random crystal orientation distribution of hcp c-axes in polycrystal films, while lower coercivity is obtained for the highly oriented films. Such behavior may be attributed to the form of the induced local energy fluctuations associated with the crystal orientation distributions.

Magnetic recording performance of cobalt-alloy perpendicular media depends upon microstructural features including preferred c-axis out-of-plane orientation, grain size and grain separation. These depend on the titanium-alloy underlayer surface structure, which in turn depends on film nucleation and growth. The Ti-alloy nucleation and growth stages are independently controlled by changing argon pressure during sputter deposition. Ti and Ti90Cr10 underlayers have qualitatively different microstructures, but in each case a two-step deposition process produces a better combination of separated magnetic layer grains and strong preferred orientation than constant argon pressure underlayer media. Correspondingly, media magnetic performance is improved over single pressure depositions. Observed microstructure and magnetic properties are consistent with simple growth models.

Giant magnetoresistance (GMR), structure, and magnetic properties of sputtered (Co90Fe10 X Å/Ag Y Å) multilayer films have been investigated. Distinct GMR behaviors including granulartype (GGMR) and ‘discontinuous’ (DGMR) are observed which are strongly dependent on the individual CoFe and Ag layer thicknesses; however, standard multilayer GMR and the associated antiferromagnetic (AFM) coupling is absent. The multilayer structure, individual layer thicknesses, and growth texture were investigated using high and low angle x-ray diffraction (HXRD & LXRD).

The surface of single-domain acicular magnetic gamma-Fe203 particles was coated with titania shell and the effect of this coating on the remanent induction and coercive force was measured.

TEM grids containing Ag65Co35 thin films were annealed under protocols corresponding to maximum giant magnetoresistance (GMR) response in thicker films. These films were examined using high resolution TEM, electron energy loss spectroscopy (EELS), and electron spectroscopic imaging (ESI), which revealed small (50 nm diameter) Ag particles and very small (approximately 2 nm diameter) clusters in a suspending matrix of Ag-Co alloy. Cobalt maps did not reveal individual cobalt clusters, indicating that if such clusters exist, they are smaller than the 1–2 nm resolution limit of the technique.

We demonstrate the detection of Magnetic X-ray Circular Dichroism (MXCD) from commercial, thin-film spin valves. Measured x-ray absorption spectra on these devices indicate magnetic polarization of the ferromagnetic constituents, Fe, Co, and Ni.

Coercivity and microstructure were investigated in Fe-based multilayers. Coercivity of the Fe layer near the film surface differs slightly from that of the layer near the substrate. The coercivity of a given Fe layer in the multilayer is related to the thickness of the given layer and to the total thickness of the layers between the given layer and the substrate. In addition, coercivity and microstructure are influenced when various metals are combined with Fe.