The research goals of this project are to understand the fundamental mechanics of the long wavelength waviness in wire sawed silicon wafers and to investigate the conditions for diamond pull-out from diamond coated wires. The implications of such pull-outs on surface quality and integrity of wire sawed wafers will also be investigated. A combination of analytical and numerical simulations will be pursued. A fluid-structure interaction model will be developed for long wavelength waviness generation, and a coupled thermo-mechanical analysis will be pursued for predictions of diamond pull-out conditions. Simulation results will be verified against experimental observations under laboratory conditions. Verified mechanistic models will then be utilized to develop integrated process models and control algorithms for the wire sawing process.
The current wire sawing method of wafer slicing leaves a long wavelength waviness on the wafer surface that must be corrected by an expensive lapping process. If successful, this project will improve the wire sawing process to greatly reduce the induced waviness, thereby reducing the need for lapping, and enhancing the cost effectiveness of wafer production. Abrasive pull-out affects the performance of grinding wheels, and a mechanistic model of this phenomenon will aid in grinding process design as well. These results will be of considerable value to the integrated circuit industry, particularly as the industry goes to bigger wafer diameters and finer circuit structures.
