| The fast-growing integrated-circuit (IC) industry brings great challenges into chipdetection. Electrooptical detection is now being considered as a powerful andattractive option for high precision local electric field measurement, primarily due toits unique merits like large intrinsic bandwidths (DC to THz), noninvasiveness andhigh spatial resolution. The core component of an electrooptical probe is a tiny pieceof electrooptical film consisting either of polymers or semiconductor crystals, affixedto the tip of a tapered waveguide or a fiber. If the optical performance of the film, e.g.,refractive index or birefringence, is affected by external electric field, the probe isfeasibly implemented as a proximity electric field sensor, functioning when it isbrought to the immediate surface of an integrated circuit (IC). Waveform of theelectric signal at a particular site of the IC is thus attainable by measuring the phasemodulation of a laser beam traveling through the film on the probe. This makes theelectrooptical detection a promising tool for IC fault diagnosis and designimprovement.Nevertheless, a drawback of electro-optical detection that is hindering itspractical use is the inherent difficulty in calibrating the voltage magnitude. Althoughsome proposals try to overcome the complexity, they are not applicable to theelectrooptical detection using an external probe. It is difficult to correctly determinethe value of the applied voltage because of the emanating field divergence from an ICcircuit line and the uncertainty of the physical contact between the probe tip and thecircuit. The former, associated with the IC layout, local routing, line width andspacing, is caused by interruption of neighbored nodes or lines. The latter is inevitablein different runs of each voltage measurement process since no appropriate and finedistance monitoring or feedback mechanism has been found for such system. Atip-grounded waveguide micro-sensor was proposed to overcome the difficulty of quantitative voltage calibration in electrooptical detection for integrated circuits test.On this basis, we optimized the thickness of the electrooptical material of the sensorto eliminate the influence of the circuit layout on the measured signals by fringe fieldsimulation. The improved sensor in return made it possible to calibrate the voltagewith known reference electric signals quantitatively. This method circumvented theuncertainty of the probe conditions of each measurement point. Finally, a calibrationaccuracy of better than6%was obtained, which satisfied broad applications inintegrated circuit industry.Another essential drawback of electro-optical detection is low voltage sensitivity,primarily due to (i) the electrooptical coefficients γijof crystals are generally small, atthe order of several pm/V;(ii) the emanating field from circuits are subject tosignificant decay by the air gap between the electrooptical probe and the circuit undertest because of the nature of the non-contact detection mode and the existence of thepassivation layer of the circuit surface. In this dissertation,we has made threeproposals to increasing voltage sensitivity:(i) acoustic resonant effect of inorganiccrystals;(ii) molecular orientation effect of polar liquids;(iii) the large Kerr effect ofpolymer-stable liquid crystals.First, we solve the voltage sensitivity problem with the help of the acoustic (e.g.,piezoelectric and electrostrictive) effect, a common property of almost all dielectrics.In contrast to the general electro-optic effect, the light phase modulation induced bythe acoustic effect is two orders of magnitude stronger at its resonant frequency, as weobserved in a GaAs thin film probe. Furthermore, this novel method shows a highlyreproducible linearity between the detected signals and the input voltages, whichfacilitates the voltage calibration. Beside, we introduced ZnO films of highpiezoelectricity to the electro-optical detection. ZnO thin films were epitaxiallydeposited on the tip of a tapered waveguide using a radio frequency magnetronsputtering method. Although the electro-optical coefficient was evaluated as only0.2pm/V, ZnO films exhibits high sensitivity in electro-optical detection due to thepizeo-rensonance. Second, efforts have therefore been devoted to exploration of novel electroopticalmaterials. Electrooptical polymer, due to the γijas high as of the order of hundreds ofpm/V has shown a promising prospect to enhance the sensitivity. However, problemsassociated with the polymer film are low abrasive resistance and weak adhesion to theglass cone, so that the probe is difficult to endure high-speed, multi-point, large areadetection as an atomic force microscopic tip does. In addition, the air gap between theelectrooptical probe and the measurement point still can't be eliminated. In thisdissertation, we propose a novel electro-optical probe mechanism, which useliquid-state polar molecules as the sensing film, which is coated onto the circuitsurface, instead of being affixed to the scanning tip end. An electro-optical probeconfiguration with polar molecule liquids as the sensing film was designed forelectro-optical detetion. This scheme has not only eliminated the air gap, but also usedmolecular orientation as a response to the electric field excitation, leading to asensitivity of0.1mV/√Hz. This method exhibited voltage sensitivity enhancement oftwo orders of magnitude larger than the normal method using a GaAs probe in thesame measurement system. Based on the mechanism of orientation polarization, theelectro-optic coefficient was measured to be250pm/V by Teng-Man method atmodulation field of100Hz. This technology will be promising in applications oflow-frequency field detection. We present an anomalous electro-optic effect in polarliquid films: liquids, usually considered to be isotropic, possess the linearelectro-optic effect that occurs only in materials lacking inversion symmetry. Due tothe observed large effect in the low-frequency range and slow response speed, thisstrange effect was thought to come from the field-induced orientation of large mass.Therefore, we brought forward a physical model that contributed to the interpretationof this phenomenon: field-induced pre-oriented, short-range orderly dipole clusters inliquid films break the macroscopic symmetry and results in this asymmetric effect.Finally, combined with spectral analysis, the formation of clusters induced by anelectric pulse was proved.Third, polymer-stabilized liquid crystals (PSLC) with experimentally observed large electro-optic effect are introduced to the electro-optical detection to improve thevoltage sensitivity. The Kerr constant of materials prepared in this study reached ashigh as7.2×10-9 m/V2, increasing the sensitivity by1000times than the conventionalelectro-optical materials. The noncontact detection configuration, using the laser beamas a probe, enables quick2-demension scanning measurements. This detection meansoffers several advantages including the following:(1) it uses the focused laser beamas a probe, which overcomes the complexity of the precision positioning ofconventional external probes;(2) due to the fluidity of PSLC materials before curing,field sensing materials could closely contact with the circuit surface,(3) an ITO layeris introduced to screen all the fringing electric field of the given circuit in the PSLCmaterial so as to further enhance the voltage sensitivity.
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