| Corrosion of thin metal films in electronic components has attracted much attention because it can cause catastrophic device failure. Adsorbed moisture layers, oxygen and trace amounts of contaminants are sufficient to initiate corrosion. Corrosion is also hard to eliminate because materials that are chosen for their special electrical, magnetic, or optical properties may not be corrosion resistant. In other cases, the locations that are susceptible to corrosion are hard to reach. In this thesis, corrosion sensors are discussed that can monitor both the occurrence and the rate of corrosion of metal films, in fully exposed or remote locations. Two corrosion sensors, the fiber optic micromirror and the multiple microline electrodes, are developed and applied in corrosion studies.; The fiber optic micromirror sensor is an optical fiber which has been coated with a thin metal film at the cleaved end. Incident light from the backside of the film is reflected back and reflectivity changes are related to the physical or chemical changes that occur on the front side of the micromirror. The sensors were used to monitor corrosion rate, anion adsorption, and underpotential deposition on metal surfaces. In corrosion monitoring, the fiber optic micromirror sensor was found to be best suited for uniform corrosion where corrosion products did not accumulate, and for micromirror thinner than 300A.; In anion adsorption measurements on gold, the reflectivity of the fiber optic micromirror decreased as a result of covalent bonding between the adsorbates and the micromirror. The outermost layer of gold acted as if it had lost its metallic character. In underpotential deposition of copper on gold, the reflectivity of the fiber optic micromirror increased. This was attributed to the physical addition of a metal monolayer to the micromirror.; The multiple microline electrode (MLE) was used to make electrochemical measurements in thin electrolyte layers to simulate atmospheric corrosion. The individual electrodes from the cross section of a stack of thin films served as working, counter, and reference electrodes, respectively. Although electrochemical measurements were accomplished in electrolyte layers as thin as 10{dollar}mu{dollar}m with the technique, it was difficult to reduce the electrolyte layer further. |
