NON-DESTRUCTIVE TESTING OF PASSIVE ELECTRONIC COMPONENTS

habilitation thesis

English

My focus up to now was oriented to the experimental methods serving for the evaluation of quality and reliability of the passive electronic components. Most of the work was done on the cermet and polymers based thick film resistors and tantalum and niobium oxide capacitors. My inaugural dissertation consists of two parts: the first one summarizes the measuring methods and their possible utilization for resistors and capacitors evaluation; in the second one my most important papers dealing with this subject are enclosed. The overview on my work done during last ten years on the Physics Department of Faculty of Electrical Engineering and Communication of Brno University of Technology is given. Reliability of electronic devices is caused predominantly by failures which result from the latent defects created during the manufacture processes or during the operating life of the devices. A search for non-destructive methods to characterize quality and predict reliability of vast ensembles became a trend in the last four decades. The most promising methods to provide a non-destructive evaluation are the analysis of electron transport parameters. Experiments are based on the measurements of device VA characteristics, its non-linearity using the non-linearity index (NLI), electronic noise spectroscopy, and electro-ultrasonic spectroscopy. Other method used for the structure quality evaluation is based on the potential distribution measurements on the sample surface. Leakage current value for the fixed temperature and applied voltage are frequently used as the reliability indicator for tantalum and niobium capacitors. Leakage current provides information on the insulating layer thickness, its homogeneity and the number of defects in tested sample. In the insulating layer there are defects, which are responsible for the value and time evolution of the leakage current. The leakage current is a result of the random process of charge carrier transport and a DC component gives then information about the first statistical moment of this process. The additional information on the process related to the electric charge carrier transport is obtained form the second moment of random process, which is the noise spectral density. The sensitivity of excess electrical noise to defects in the device structure is the main reason to use the noise spectral density as a noise reliability indicator. The noise spectral density depends on stress and damage and varies among nominally identical devices. This component is called excess noise spectral density and it is not of the fundamental origin. The sensitivity of the noise spectral density, NLI, and electro-ultrasonic spectroscopy (EUS) to the structure defects and other irregularities is typical feature of these methods. It is due to microphysical origin of fluctuation cased by quantum transitions of charge carriers and non linear electron transport near defects. Measuring apparatus DISPOT designed in our laboratory enables to provide the measurement of the surface potential distribution. Sheet resistance of the thick film layer and interface resistance formed between two layers can be determined from these measurements. These experiments were performed to optimize the thick film resistor/conductor system and the interface and sheet resistances of cathode layers during the optimization of the technology for tantalum and niobium oxide capacitors production.

Passive Components, Noise, Non-linearity, Electro-ultrasonic spectroscopy, Potential Distribution Measurement

SEDLÁKOVÁ, V.

1. 4. 2010

Vědecké spisy vysokého učení technického v Brně

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