M.S. Thesis Presentation by Olivier Lauque
Monday, November 2, 1998

(Dr.Steven Danyluk, advisor)

"Effects of Abrasive Waterjet Erosion on Single Crystal Silicon"

Abstract

This thesis addresses abrasive waterjet cutting (AWJ) of single crystal silicon. The aim is to prove that AWJ can be an alternative process to current technologies (laser ablation, diamond grinding), for making curvilinear cuts.

An existing waterjet facility was modified to include a miniaturized nozzle and straight cuts of single crystal silicon were made. Preliminary trials on glass were performed to get a first-hand knowledge of brittle materials' response to waterjet erosion, to determine the range of the machining parameters, and to gain experience with the machining of inexpensive samples.

Most models of waterjet cutting use the single particle impact process. The volume removed by multiple particle impacts is then calculated by adding the volumes removed by single particles and correcting by an experimental factor. Brittle erosion is due to many solid abrasive particles striking the sample surface. It occurs as material is removed from the surface due to generation and intersection of microcracks within the material. Previous work raised three main parameters acting on the size and shape of the microcracks, then on the effectiveness of the erosion:

In this study, the kerf shape and the quality of the surface were evaluated with a SEM, an optical comparator, and a profilometer. The overall state of the kerf could then be related to the cutting parameters, which included the type of abrasive, abrasive flow, pressure, feed rate, and the cutting direction. A comparison with theoretical results and with other technologies could thus be made. Some improvements of silicon waterjet processing are proposed, like the design of a new cutting head.