Development of a ZeptoFarad (10S-2[1] F) resolution capacitance sensor for scanning capacitance microscopy

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Tran, Thang Duc
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Here we present a technique, the Schottky Scanning Capacitance Microscopy (SSCM) developed by the University of Manitoba SPM lab, for measuring carrier profiles on semiconductor device cross-sections. SSCM utilizes a sharp conducting probe tip that is raster scanned in contact with the sample surface. As a result of the work function difference between the two materials, a space charge depletion region and therefore a capacitor is formed at the interface. By applying a small ac voltage, the voltage derivative of the contact capacitance can be measured with a capacitance sensor and a lock-in amplifier. These voltage derivative measurements are used to delineate regions of different doping levels and dopant type with high spatial resolution. In this thesis we also present experimental results obtained from imaging cross-sections of a wide variety of semiconductor devices. A newly designed capacitance sensor is presented. A conversion algorithm was written to convert the measured data to carrier concentration.(Abstract shortened by UMI.)