Characterization Of Thin Metal Films Research Articles

Fabrication and Characterization of Thin Metal Films Deposited by Electroless Plating with Organic Additives for Electrical Circuits Applications.

In our work, we studied thin nickel films deposited by electroless plating for use as a barrier and seed layer in the through-silicon vias (TSV) technology. El-Ni coatings were deposited on a copper substrate from the original electrolyte and with the use of various concentrations of organic additives in the composition of the electrolyte. The surface morphology, crystal state, and phase composition of the deposited coatings were studied by SEM, AFM, and XRD methods. The El-Ni coating deposited without the use of an organic additive has an irregular topography with rare phenocrysts of globular formations of hemispherical shape and a root mean square roughness value of 13.62 nm. The phosphorus concentration in the coating is 9.78 wt.%. According to the results of the X-ray diffraction studies of El-Ni, the coating deposited without the use of an organic additive has a nanocrystalline structure with an average nickel crystallite size of 2.76 nm. The influence of the organic additive is seen in the smoothening of the samples surface. The root mean square roughness values of the El-Ni sample coatings vary within 2.09-2.70 nm. According to microanalysis data the phosphorus concentration in the developed coatings is ~4.7-6.2 wt.%. The study of the crystalline state of the deposited coatings by X-ray diffraction made it possible to detect two arrays of nanocrystallites in their structure, with average sizes of 4.8-10.3 nm and 1.3-2.6 nm.

General approach to reliable characterization of thin metal films

Optical constants of thin metal films are strongly dependent on deposition conditions, growth mode, and thickness. We propose a universal characterization approach that allows reliable determination of thin metal film optical constants as functions of wavelength and thickness. We apply this approach to determination of refractive index dispersion of silver island films embedded between silica layers.

Characterization of thin metal films via frequency-domain thermoreflectance

Frequency-domain thermoreflectance is extended to the characterization of thin metals films on low thermal diffusivity substrates. We show how a single noncontact measurement can yield both the thickness and thermal conductivity of a thin metal film with high accuracy. Results are presented from measurements of gold and aluminum films 20–100 nm thick on fused silica substrate. The thickness measurements are verified independently with atomic force microscope cross sections, and the thermal conductivity measurements are verified through electrical conductivity measurements via the Wiedemann–Franz law. The thermoreflectance thermal conductivity values are in good agreement with the Wiedemann–Franz results for all the films at least 30 nm thick, indicating that our method can be used to estimate electrical conductivity along with thermal conductivity for sufficiently thick films.

Characterization and application of multilayer diffraction gratings as optochemical sensors

This paper is devoted to the surface characterization of phase diffraction gratings which are the key optical components of optochemical sensors. Surface plasmon resonance (SPR) in a Schottky junction with the diffraction grating at the interface is used as a basic principle underlying the device operation. With the aim of optimization of its technical parameters, the optical characterization of thin metal films is necessary. The adequate characterization tools were demonstrated: variable angle spectroscopic ellipsometry (VASE); atomic force microscopy (AFM); reflectance/transmittance spectroscopy; spectral and angular characteristics of Schottky junction photoresponse. Along with investigation technique, the most physically correct theoretical model (Bruggeman-EMA) for describing the optical and structural features of multilayer systems was employed. Potentialities of the optochemical sensor have been demonstrated as well.

Characterization of thin metal films processed at different temperatures

Thin metal of Au, Ag, and Al films were deposited onto room temperature (RT) and low temperature (LT=77 K) substrates then subjected to five types of measurement: resistivity vs film thickness, resistivity vs substrate temperature, atomic force microscopy (AFM), transmission electron microscopy (TEM), and TEM electron diffraction. In all three cases, the LT films were continuous at lower thicknesses than the RT films during resistivity vs film thickness measurements. During resistivity vs substrate temperature testing of very thin films (<100 Å), all three LT films exhibited resistivities that were orders of magnitude lower than RT films of the same thickness. In general, TEM and AFM scans of LT films exhibited better substrate coverage at lower thicknesses, and RT films showed larger grain size. Resistivity vs film thickness measurements and TEM scans were done on Pd and Ni. LT Pd films exhibited larger resistivities than the RT films at all measured thicknesses. Ni RT film started with higher resistivity and became more conductive than the LT film at larger thicknesses.

Metal Microstructures in Advanced CMOS Devices

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.

Characterization of Thin Metal Films by SIMS, AUGER, and TEM

ABSTRACTSecondary ion mass spectrometry (SIMS), Auger spectroscopy, and transmission electron microscopy (TEM) were applied to study Au, Cu, Ti, Ti-W, Cr, Al-Cu, and Al metal films deposited on both Si and ceramic substrates.SIMS analysis of as-deposited metal films was used to characterize impurity levels, both metallic and gaseous, incorporated during deposition. The results revealed that the levels varied under generally accepted deposition conditions. As-deposited and annealed films were examined with SIMS, Auger, and TEM to study interdiffusion, grain growth, and impurity segregation as a function of processing conditions. Metallic impurities were observed to modify Au/Ti interdiffusion. Large variations in residual H, C, O, and N were observed in as-deposited Al and Al-Cu films.Hydrogen, incorporated during deposition of Ti films, was observed to redistribute after thermal annealing in N2 or thermal cycling in forming gas (N2-10% H2). Samples thermally cycled in forming gas absorbed additional H into the Ti layer. SIMS/ion imaging was used to study the incorporation and segregation of H. Differences in H behavior were observed to be dependent upon metal structure, composition, and substrate material.

Preparation and characterization of thin metal films for exploding-conductor excitation

Preparation and characterization of thin metal films for exploding-conductor excitation