Design and implementation of a fully automated real-time s-parameter imaging system

by Naik, Pranab Sabitru

(Uncorrected OCR) Abstract of thesis entitled DESIGN AND IMPLEMENTATION OF A FULLY AUTOMATED REAL-TIME S-PARAMETER IMAGING SYSTEM Submitted by PRANAB SABITRU NAIK for the Degree of Doctor of Philosophy at The University of Hong Kong in March 2004 This thesis reports on the design and implementation issues of the first realtime S-parameter positron imager. This is a useful tool in material science and solid-state technology for mapping the subsurface lateral defect types and concentrations. The S-parameter imager may be used on both bulk-material and thin-films samples. The system is also useful in locating top surface metallizations and structures in solid-state devices. This project consisted of three major parts, the first being a technique for scanning the sample surface with either a small positron source (22Na, 0.5 mm width) or a focused positron beam. In the latter case an electromagnetically scanning positron beam is used in a fast (2 Hz) rastering mode so as to produce an image of the sample in parallel rather than in the more conventional step-by-step sequential mode commonly used. The other two parts focused on development of the electronic instrumentation and stand-alone imaging software. In this system, the use of processing time and system resources are constantly monitored and optimized so that the system is efficient for producing a high resolution S-parameter image of the sample in real time with a general purpose personal computer. The system software possesses special features with its embedded algorithms that provide the user with adequate freedom for analyzing various aspects of the image in order to obtain a clear inference of the defect profile while at the same time keeping automatic track on the instrumentation and hardware settings. The system was successfully tested with metal and semiconductor samples for defect analysis and provisional studies on a biological specimen were encouraging. This imaging system is sample-nondestructive, reliable, interactive, user-friendly and cost effective.