Wafering is an essential step in silicon wafer processing. It is a process of turning a silicon crystal into a wafer. It involves cutting and polishing the ingot into the client’s desired degree of flatness and size. Before an ingot goes through wafering, it must first undergo several steps to prepare it for slicing and polishing. In this article, we will discuss these steps and explain why they're important.
Growing highly pure silicon crystal is considered to be the first step of silicon wafer processing. But it’s not enough to just grow highly pure monocrystalline silicon crystal; you also need to do crystal shaping to achieve the accurate shape required for wafer formation. This also helps prepare the crystal for slicing.
Cropping is a technique used to cut crystals to a useful dimension to match the sawing capacity. To easily shape and manipulate the grown ingot into the client’s desired shape and flatness, it's top and bottom ends are removed using a circular diamond saw. The cutout parts are recycled back into the crystal growth operation. Parts of the ingot that fail to meet resistivity specifications are also taken out.
Grinding helps wafers achieve the precise wafer diameter specifications. Two methods can be used for crystal grinding: grinding on center and centerless grinding. This step must be done properly and carefully to prevent problems in the following operations. Improper crystal grinding may result to exit chipping and lattice slip.
After grinding the wafers into their precise wafer diameter specifications, identification flats are ground along the length of the ingot according to its orientation and dopant type.
These steps are an essential part of silicon wafer processing. They’re carried out before wafering to properly prepare the ingot for slicing and polishing. At Wafer World, we offer high-quality wafers at a reasonable price. Contact us for inquiries!