Flexible electronic devices rely on effective conductors integrated with elastomeric substrates. This work reports on
characterization of thin gold layers on flexible polymers as a platform for further research into their use in flexible
electronic and microsystems. This work utilizes standard microfabrication techniques and a biocompatible, silicone
polymer (polydimethylsiloxane) as the flexible substrate material. Flexible conductors defined by gold have been
realized, and the dependence of resistance on geometry has been characterized. The results follow theoretical resistance
dependence on geometry while showing an increase in the resistivity of the gold layer, a direct effect of deposition on
elastomer causing wrinkles or striations in the metal layer. This work also discusses the effect of uniaxial mechanical
deformation on thin film conductors and defines a procedure for creating and testing them in a repeatable manner. The
ability to stretch the resistors by 10%, with full recovery to original resistance value is demonstrated. This work has
implications for flexible device performance and provides a platform for integrated applications. Future work will
explore combinations with piezoelectric thin films to enable conversion of mechanical to electrical energy, as this
flexible platform will enhance the functionality of such energy generators.
Silicides have been used in CMOS technology for some years mainly to reduce sheet resistance in the source and drain
regions. This paper discusses in detail the formation of nickel silicide (NiSi) and titanium silicide (TiSi2). The
composition of silicides formed using sputtered and evaporated metals are compared. Metal films (titanium or nickel) on
silicon deposited by DC magnetron sputtering or electron beam evaporation were vacuum annealed to form
corresponding metal silicide thin films. The problem of oxygen contamination during silicidation is also discussed.
Analyses of the silicide thin films formed were carried out using Auger Electron Spectroscopy (AES) depth profiles,
Atomic Force Microscopy (AFM) surface scans, and surface profilometry for measurement of feature heights. The
average surface roughness of the silicide thin films is also compared, and it was observed that nickel silicide thin films
were much smoother than titanium silicide thin films.
Strontium-doped lead zirconate titanate (PSZT) is a piezoelectric ceramic with relatively high values of piezoelectric
coefficients. Perovskite oriented PSZT thin films are also reported to exhibit a variety of other properties including
ferroelectricity and pyroelectricity. This paper reports on a study of the surface morphology and resulting stress of PSZT
thin films, deposited under a variety of RF magnetron sputtering conditions. The study compares PSZT thin films
deposited on metal (gold and platinum) coated silicon wafers. The surface morphology of the deposited PSZT thin films
was studied using Atomic Force Microscopy (AFM). Grain size and average surface roughness measurements were
used to study the quality of the films. The thin film stress was determined using the changes in the radius of curvature of
the sample due to an added layer of thin film, and by applying Stoney's equation to relate the stress to the radius of
curvature. The variations in the level of stress for different thermodynamic conditions during RF magnetron sputter deposition are also reported.
Silicide contacts are used in semiconductor devices because of their relatively low sheet resistance as thin films and because they form contacts with relatively low values of specific contact resistivity leading overall to low values of contact resistance. Determining the true values of the specific contact resistivity of metal-to-silicide interfaces is a challenge that requires suitable test structures. The Cross Kelvin Resistor (CKR) structure is a commonly used test structure for the extraction of the specific contact resistance of ohmic contacts. Analysis using this structure has errors associated with it and the challenge is often in determining this error. This paper demonstrates a technique that uses several Cross Kelvin Resistor structures connected in a chain and determines the specific contact resistance of aluminium to nickel silicide contacts using extrapolation rather than determining the error. The formation of the nickel silicide films and the fabrication and testing results for the Cross Kelvin Resistor structures are presented.
The paper investigates conditions for depositing perovskite-oriented strontium-doped lead zirconate titanate (PSZT) thin films using RF magnetron sputtering. PSZT is a material that can exhibit high piezoelectric and ferroelectric properties. The deposition was conducted using an 8/65/35 PSZT sputtering target. The effects of sputtering conditions and the deposition rates for films sputtered onto several surfaces (including gold and platinum coated substrates) were studied. Combinations of in-situ heating during sputtering and post-deposition Rapid Thermal Annealing (RTA) were performed and resulting phases determined. RTA was carried out in argon to observe their effects. The sputtered films were analyzed by Scanning Electron Microscopy (SEM), X-ray Diffractometry (XRD), and X-Ray Photoelectron
Spectroscopy (XPS). Results show dramatic differences in the grain structure of the deposited films on the different surfaces. The stoichiometry of the sputtered films is demonstrated using XPS. In the case of gold and platinum coated substrates, sputtering was also carried out for different durations, to establish the growth rate of the film, and to observe the variation in grain size with sputtering duration. The deposited thin films were resistant to most chemical wet etchants and were Ion Beam Etched (IBE) at 19 nm/min.