In the low temperature deposition regime (T<0.3 Tm) the surface evolution of a growing film is determined by the interplay of kinetic roughening and the smoothing mechanism of surface diffusion.

In this paper we report on the surface evolution of Cu-coatings sputter deposited on Si (100)-substrates. Film thicknesses ranged from 300 Å (deposition time = 18 s) to 10 Å (deposition timeó.lO s). The ratio T/TM was 0.3. The RMS (Root Mean Square) roughness values ξ and the surface morphology of the films were determined by AFM (Atomic Force Microscopy). The dependence of the RMS roughness-values on the deposition time t was found to be non-linear according to the scaling expression ξα with =;π = 1/3. This non-linear behavior indicates a growth situation with an increasing lateral extension of surface features. Their lateral extension is quantified by a continuum approach of mass transport by surface diffusion proposed by Mullins. Calculated and experimentally observed feature extensions are in good agreement in the entire considered range of deposition times and vary from 800 Åto 10 Å.

Diamond-like carbon (DLC) films are noted for their outstanding mechanical hardness, wear resistance, chemical inertness to both acid and alkalis, and high thermal conductivity. Such properties, along with optical transparency over a wide spectral range, make DLC films good candidates for wear-resistant barriers for transparent optics. The objective of this investigation is to compare the DLC films from various commercial sources prepared using different coating technologies, i.e., radio frequency (rf) plasma, ion beam assisted, and laser ablative deposition. Characterization of the DLC films includes scanning electron, scanning Auger, and Atomic Force Microscopy, also Raman and X-ray Photoelectron Spectroscopy. The mechanical properties of these films are evaluated by Taber abrasion, nanoindentation, and ballistic impact tests. In addition, the chemical resistance and environmental stability of these films will be discussed.

Atomic force microscopy (AFM) has been used to study dissolution of the cleaved CaCO3(1014) surface in clean and impurity containing aqueous environments. In the clean solution, dissolution was found to occur by retreat of steps and creation of rhombohedral pits on a surface. Dissolution is anisotropie with two different step velocities differing by a factor of 2.3, resulting from different atomic step structures. Dissolution is partially changed after adding impurities in the solution via rounding of the fastest dissolution corner of rhombohedral pits and slowing down the step velocity in that direction. The role of impurity on dissolution is discussed in terms of preferential adsorption of impurities on kink sites.

The thermal stability of W/Si multilayers (MLs) has been simulated up to 1000°C and 8 hour anneals. The simulation has been carried out with and without the presence of Au overlayers. The results are compared with experimental results by Rutherford Backscattering spectroscopy (RBS). The RBS results also show the presence of excess Ga at the interface.

Alloys and their oxides are a very important class of materials on which modern society depends. Yet, today we do not have an adequate fundamental physical-chemical model of how oxides evolve on alloys under oxidizing conditions. This physical chemical understanding will effect our ability to design a wide range of materials from electronic devices to the improved protective oxide films on alloys. The fundamental progress, in both physics and chemistry, made on several critical questions,

•What interface(s) control alloy oxidation and how?

•What parameters provide the driving potential for oxidation?

•How does this potential respond to temperature (T), pressure (P) and compositional changes?

will be discussed. Progress on these questions have allowed models to be proposed to predict alloy oxidation behavior under any set of conditions. These models are already providing some predictive power in how the oxide overlayer and passive film structure develop. By using surface studies of the oxidation behavior of the following alloys and their thin films: Cu-Mn, Ag-Mn, Ni-Ti, Ni-Zr, Ti-Cu and Ti-Al, we have been able to delineate the factors which are most important to the oxide formation process and provide insight into the prediction of oxide layer structures. These will be illustrated with actual experimental results on selected alloys.

Planar low-temperature solid phase epitaxy of amorphous silicon in a-Si/10nmNiSi/c-Si structure was observed. The crystallization rate is well described by the arrhenius-type expression with the activation energy and preexponencial factor deduced from our measurements of 1.7 eV and 2.4×1012 nm/min, respectively. NiSi2 formation at the NiSi2/a-Si interface is believed to be the limiting stage of the transformation. The structures with thicker Ni-reached interfacial layer perform much poorer a-Si epitaxy.

The microstructure of Al/n-type GaN contact interfaces and the effects of heat treatment have been investigated. The n type GaN films (Ge doped) and A1N buffer were grown on 6H-SiC substrates by means of gas-source MBE using an ECR plasma source. The microstructure of the layers and the interfaces between layers in both as-deposited and rapid thermal annealed samples were studied by HREM and EELS. The observed results were used to analyze the growth mode of the layers and the effect of the Ge doping on the growth. On the Al/GaN interface a new phase is observed in the annealed sample. The possible structure of the new phase and its effect on electric properties is discussed.

An amorphized tungsten nitride diffusion barrier is compared with that of polycrystalline tungsten nitride preventing the diffusion of copper into Si during post annealing processes at 600 – 800 °C for 30 min. Experimental evidence such as RBS, TEM, XRD measurements shows that the amorphized tungsten nitride layer perfectly blocks the expeditious diffusion of the Cu film due to the amorphous grain boundaries stuffed with N impurities.

Sputtered A1N films developed for piezoelectric resonators are extremely chemically reactive. As-sputtered films react with boiling water resulting in a complete loss of the AIN bond structure. Experiments to determine the effect on chemical stability of annealing the sputtered films at 1000 °C, indicate annealing in an oxidizing gas leads to partial oxidation of AlN. Annealing in an inert gas prevents oxidation but does not protect the films from attack by boiling water. Annealing in a reducing gas followed by annealing in an inert gas renders A1N films stable in boiling water. A1N film structure and composition have been studied via Refractive Index, XRD, SIMS, SEM, AES, XPS and FTIR evaluations.

The formation mechanism of facets occurring during epitaxial growth of CoSi2 are described using a Co/Ta bilayer. At the early stage of annealing, the diffusion of Co atom occurs across the interlayed Ta layer, first forming a CoSi layer on the Si substrate. CoSi2 grains nucleate at the CoSi/silicon interface and grows laterally parallel to the surface. Due to the difference of dominant moving species in CoS2 and CoSi, the CoSi2 grain at the interface impedes the interface movement, thereby, leading to the facet formation. Epitaxial CoSi2 grains nucleated at the non-epitaxial CoSi2/silicon interface and the faceted corner and grow laterally along the Si surface. With increasing annealing temperature, the epitaxial quality of the CoSi2 improves because of increased lateral growth rate of the CoSi2.

We have investigated the physical properties of Ti-Si-N films for future Cu metallization on ULSIs. Our Ti-Si-N films were found to be amorphous by X-ray diffraction measurements. Thermal stability of the amorphous structure was confirmed, even after annealing at 600°C for 30 minutes in an Ar ambient. The atomic composition of the film was identified as Ti:Si:N=1:0.6:1.6 by chemical analysis. The film stress was found to be tensile and 0.3GPa. The electrical resistivity was about 0.5m Ωcm at room temperature.

The effectiveness of the film as a diffusion barrier was evaluated by n+/p and p+/n junction leakage measurements. The junction depth was 0.2Ω m and the contact area was 300×80μ2. No degradation of leakage characteristics was observed for these diodes, even after annealing at 600°C for 30 minutes in an N2/H2 ambient.

These results demonstrate that amorphous Ti-Si-N barrier metal is a promising candidate for application in deep-submicron ULSIs.

In this paper, we present the microstructural evolution of silicide phase with TiNxSi structure. The nitrogen atoms in the TiNx film limites the available Ti atoms that react with Si substrate to form silicide. Hence, the thickness of Ti-Si amorphous interlayer (a-interlayer) was much thinner in comparison with that from pure Ti film after annealing (RTA) at 500°C. Upon RTA at above 600°C, at first thin epitaxial C49-TiSi2 was formed with an extremely uniform thickness on Si(100) substrate. Also the stable character of the epitaxial C49-TiSi2 supress the structure transformation of TiSi2 from C49 to C54.

Ruthenium oxide (RuO2) / tantalum nitride (Ta2N) precision thin film resistors were fabricated by dc magnetron reactive sputtering. Proper thermal treatment was utilized to tune the temperature coefficient of resistance (TCR) to near zero. The TCR of these samples could be easily tuned to ±10 ppm/°C. Accelerated life time (ALT) tests at 150 °C for up to 1000 hours demonstrated very good stability both in p□(Δp/p≤0.5%)and TCR (ΔTCR ≤ ±2 ppm/°C). Auger electron spectroscopy (AES) showed that the RuO2 cap layer became deficient in oxygen after annealing, with Ru-Ta-O and Ta2O5 sublayers as the interfacial reaction products. The upper layer of Ta2N was oxidized. Transmission electron microscopy (TEM) revealed that the sample underwent a (re)crystallization. The as-deposited Ta2N was a uniform amorphous phase, and the as-deposited RuO2 possessed fine microcrystals embedded in an amorphous matrix. Crystallization and oxidation occurred in the Ta2N film during annealing, with recrystallization and oxygen redistribution in the RuO2 film.

Depositing Pd on InP at cryogenic substrate temperatures has previously been found to significantly increase the barrier height of the resulting Schottky diode. In this work, bulk samples of Pd/n-InP were fabricated using substrate temperatures of 300K (RT) and 77K (LT). The structural differences between the RT and LT samples were then studied using Cross-Sectional Transmission Electron Microscopy (XTEM), Atomic Force Microscopy (AFM), X-Ray Diffraction (XRD), Auger Electron Spectroscopy (AES), and Secondary Ion Mass Spectroscopy (SIMS). The XTEM and depth profiling results indicated that the RT samples had an amorphous interaction layer approximately 150Å thick, while the LT samples had an interfacial layer less than 30Å thick. Therefore, depositing Pd at low temperatures greatly reduced the interaction between Pd and InP. XRD lines corresponding to (111) and (200) Pd were obtained as well. The lines in the RT case had a greater integrated intensity than in the LT case, indicating that the RT Pd had a higher degree of crystallinity. AFM was used to compare the morphology of the LT and RT Pd surfaces as a function of metal thickness.

Thermal stability, microstructure and electrical property of molybdenum nitride film were studied for application of ULSI's DRAM capacitor electrode and copper diffusion barrier. Phase transformation from Mo to γ-Mo2N was observed at 20% N2/(Ar+N2) flow ratio and γ-Mo2N and Δ-MoN phases coexisted at 50% N2 flow ratio. γ-Mo2N film was found to crystallize at 400°C. Amorphous γ-Mo2N deposited at 300 °C remained stable upon 750 °C heat treatment. Breakdown strengths of Y -Mo2N/Ta2O&/Si MOS capacitor before and after 850 °C annealing were 2.4 MV/cm and 1.85 MV/cm at 1×10-6 A/cm2, respectively. After 850 °C annealing, dielectric constant of Ta2Os film decreased to 19.

Microstructure changes, after annealing, of tungsten suicide (WSiϰ) films formed on the polysilicon films by CVD (chemical vapor deposition) and by sputtering were compared. For both CVD and sputtered WSiϰ films, microstructural evolutions during annealing were caused by three mechanisms; crystallization from amorphous phase, stoichiometrical change, and grain growth. The microstructures and the electrical resistances of WSiϰ films after annealing were depended on the deposition method. The movement of excess Si in WSiϰ film to poly-silicon during annealing was faster in case of sputtering than in case of CVD. At annealing temperature below 850°C, CVD films showed higher resistivity and smaller grain size than sputtered films. On the other hand, at anneal temperature above 850°C, the grain growth rate of the CVD film was higher than that of the sputtered film, and the CVD film resulted in lower resistivity than the sputtered film. The retardation of grain growth for the sputter-WSiϰ film is thought to be caused by impurity contamination such as argon added into the film during sputtering.

In this article the analysis of IR reflection-absorption spectra of InP own oxides, formed by anodic, thermal and chemical oxidation was made. The influence of oxidation methods, heat treatment and presence of metal covering at the outside surface of own oxides on their structural-chemical properties were determined. On the basis of received results, the explanations of the causes of the change in electrophysical properties of InP own oxides were obtained.

In this article the analysis of Auger-profiles of anodic oxide-semiconductor structures, which were formed on the base of InP, InGaAs and InGaAsP was made. It was determined that anodic oxide-InP interface has minimum thickness of intermediate layer between oxide and semiconductor. It got the thermodynamic substantiation of the effects observed.

CdS thin films with different compositions were deposited by the electrospray pyrolysis of CdCl2 and (NH2)2 CS solutions mixed in different proportions. The diverse morphology of the films was analyzed using AFM/SEM observations. The relative atomic concentrations of Cd and S species in the bulk, and at the surface of the films were estimated using EDS and XPS quantification routines, respectively. It was found that the surfaces of all types of investigated films were enriched by metallic species and the atomic surface ratio of Cd/S was between 1.6 and 3.2. Chemisorption of oxygen and carbon monoxide on the film surfaces at low temperatures between 290 K and 500 K has been studied in order to get information about Cd surface sites on the chemisorption. Metallic surface species are considered as basic centres for the chemisorption of CO and O2 gases. Three different oxygen species with different binding energies for Ols electrons were found on the film surfaces. The electronic structure of the surface complex CO, together with its influence on the charge transfer reactions during excitation are discussed in terms of a model based on the correlation between collective electronic characteristics of the crystal and local quantum-mechanical parameters of the chemisorbed complex.

Epitaxial and textured ceria (CeO2) films have been prepared by electron beam evaporation on (001) LaAlO3, (11 02) sapphire, (001) Au, and (001) Pd substrates using either ceria or metallic cerium as sources. Both the deposition temperature and the deposition rate were varied to determine their effects on the microstructure of CeO2 films. It was found that CeO2 films grew epitaxially on sapphire within the deposition rate of 0.5A/s, starting at a temperature of 650°C, while for epitaxial CeO2 on LaAlO3, the deposition temperature could be as low as 600°C with a deposition rate as high as 1.0Å/s. On (001) Au substrate, only (001) textured film can be fabricated between 580°C and 700°C at a deposition rate from 0.3 to 1.0A/s. On (001) Pd substrates, mixtures of textured and epitaxial films were achieved at a deposition rate of 0.2–0.5Å/S in the 700°C to 750°C temperature range.