Abstract
In slurry based wafering of silicon bricks using multi wire saws, the slurry is subject to significant evolution with time as the grits are worn and silicon kerf accumulates. A good understanding of this evolution would allow wafer producers to make better informed decisions on when and how to replenish slurry during wafering.
This publication summarises certain important slurry properties and presents some experimental results regarding their evolution. Sampling the slurry at the front of and at the rear of silicon bricks during wafering has allowed the effect of a single pass through the sawing channel to be studied. The wear on the slurry grit is interpreted from the point of view of identifying what portion of the particle size distribution plays the most critical role in wafering, and how this critical region changes as the slurry ages.
It is found that in a relatively fresh slurry, the particles around the median size and slightly larger are the most active, while particles more than a few µm below the median play little part. As the slurry ages, the active region of the particle size distribution narrows, and shifts towards larger particles even though there are fewer such particles available. This leads to less slurry-brick interaction and poorer material removal properties.
This publication summarises certain important slurry properties and presents some experimental results regarding their evolution. Sampling the slurry at the front of and at the rear of silicon bricks during wafering has allowed the effect of a single pass through the sawing channel to be studied. The wear on the slurry grit is interpreted from the point of view of identifying what portion of the particle size distribution plays the most critical role in wafering, and how this critical region changes as the slurry ages.
It is found that in a relatively fresh slurry, the particles around the median size and slightly larger are the most active, while particles more than a few µm below the median play little part. As the slurry ages, the active region of the particle size distribution narrows, and shifts towards larger particles even though there are fewer such particles available. This leads to less slurry-brick interaction and poorer material removal properties.