| Noncontact/nondestructive testing methods have always been an attractive means of material analysis. A great number of these methods can be grouped into a subset referred to as electromagnetic nondestructive testing. Whether optical (classical or lasers), ultrasonic, acoustic or microwaves, these methods exploit the interaction of electromagnetic waves with matter. Within this realm, microwave nondestructive testing methods have found uses ranging from moisture analysis to measuring the electrical and magnetic properties of semiconductors.; This thesis is primarily concerned with, although not limited to, microwave nondestructive techniques for evaluating semiconductor properties. Recently, several groups have made advances using microwave evanescent probes. Essentially these probes are variations of a thin conducting wire held perpendicular and extremely close to a semiconductor's surface. Decreasing the width of the conducting wire and its distance from the semiconductor surface has the effect of increasing the spatial resolution. While these probes are useful, we investigate the complimentary, and equally useful, eddy current probe. Instead of a thin wire tip, we use a square coil. The probe works under the fundamental principle that a coil excited by an alternating current will induce currents in a conducting sheet held close to the coil.; Even though it is usually more difficult to fabricate a small coil than a thin wire, we were able to use standard microfabrication techniques to produce a relatively easy-to-fabricate eddy current probe. More importantly, we were able to produce probes with coils significantly smaller than those previously reported. The effort to decrease the coil's size, however, is not merely an academic exercise. One of the main driving forces for decreasing coil size is the increasing miniaturization of semiconductor devices. Shrinking the sizes of these devices could lead to improving performance and/or cheaper components. Furthermore, since in a semiconductor manufacturing environment, a significant amount of time is spent characterizing and testing, noncontact and nondestructive probes like the one described in this thesis will be of extreme importance. |
