Silicon ingots are essential to the manufacturing process for silicon wafers. Here are the basics of how these ingots are made and processed.
The process begins with heating the silicon to just above the melting point. Once liquified, a single silicon crystal is placed at the top of the melted material. To achieve doping uniformity, the seed crystal and the crucible of molten silicon rotate in opposite directions. Once the system reaches proper conditions for crystal growth, the seed crystal slowly lifts out of the melt. Growth begins with a rapid pulling of the seed crystal. This minimizes the number of crystal defects within the seed at the beginning of the growing process.
Once the ingot is fully developed, the ingot is ground to a diameter slightly larger than the desired wafer diameter. After passing numerous inspections for quality control, the ingot will proceed to the slicing stage. Because of the silicon’s hardness, a diamond edge saw carefully slices the silicon wafers, so they are slightly thicker than the target specification. The diamond edge saw also helps to minimize damage to the wafers, thickness variation, and bow and warp defects. After the wafers have been sliced, the lapping process begins. Lapping the wafer also removes saw marks and surface defects from the front and backside of the wafer. It also thins the wafer and helps to relieve stress accumulated in the wafer from the slicing process. After lapping the silicon wafers, they go through an etching and cleaning process.
Wafer World is the premier producer of silicon wafers for use in precise electronic equipment. Call today if you have any questions about our manufacturing process.