Sau khi vỗ, wafer được rất phẳng, bề mặt thô. Hơn nữa trên đầu trang của các xốp, có một lớp định hướng thường được các nguyên tử các bị tác động. Những lớp này bị hư hỏng loại bỏ trong một khắc hóa chất thủ tục. | Chip - Fabrication Gerhard Maderbacher Hannes Reinisch Everything starts with sand. SiO2 quartz sand 2C carbon 2000 C Si silicon purity 97 2 CO carbon monoxide but we need 3 Overview Hyper pure polysilicon production 1. Hydrochlorination of Silicon Si 3 HCL SiHCLg H2 2. Distillation of Trichlorsilane impurities such as Fe Al and B are removed impurities 1 ppm cm1 2 3 3. Reduction back to Silicon SiHClg H2 Si 3 HCI After this chemical process the polycrystalline silicon must be transformed into ingots with a singular crystal orientation. cross section of a Si - chunk4 1 Czochralski-Process Poly-Si chunks are loaded into the crucible For p-type wafers we put Boron into the crucible for n-type wafers Phosphorus If the poly-Si is melt a seed of single crystal silicon is putted into the melt. - The ingot grows with the same crystal orientation monocrystalline ingot Ingot Czochralski-Process 6 Round Grinding Process Plunge-Cut grinding Cupwheel grinding Crystal Ingots coming from crystal growing are slightly oversized in diameter and typically not round - with a grinding wheel the ingot is shaped to a precision needed for wafer Grinding wheel 2 Lapping Wire sawing does not produce perfectly flat wafers - lapping is necessary Lapping remove variations of thickness Edge Contour Grinding edges of as-cut wafers are sharp and need to be shaped - make the wafer robust against further handling and mechanical stress Lapping
