1) Crystal growth, which can be divided into Czochralski method (CZ) and zone melting method (FZ). Since the molten polycrystalline material will directly contact with the quartz crucible, the impurities in the quartz crucible will contaminate the molten polycrystal. The Czochralski method straightens the single Crystalline carbon and oxygen content is relatively high, and there are many impurities and defects, but the cost is low, and it is suitable for drawing large-diameter (300mm) silicon wafers. It is currently the main semiconductor silicon wafer material. The single crystal drawn by the zone melting method has few internal defects and low carbon and oxygen content because the polycrystalline raw material is not in contact with the quartz crucible, but it is expensive and costly, and is suitable for high-power devices and some high-end products.
2) Slicing, the drawn monocrystalline silicon rod needs to cut off the head and tail material, then roll and grind it into the required diameter, cut the flat edge or V groove, and then cut into thin silicon wafers. At present, diamond wire cutting technology is usually used, which has high efficiency and relatively good warpage and curvature of silicon wafers. A small number of special-shaped pieces will be cut with an inner circle.
3) Grinding: After slicing, it is necessary to remove the damaged layer on the cut surface by grinding to ensure the quality of the silicon wafer surface, about 50um removed.
4) Corrosion: Corrosion is to further remove the damage layer caused by cutting and grinding, so as to prepare for the next polishing process. Corrosion usually includes alkali corrosion and acid corrosion. At present, due to environmental protection factors, most of them use alkali corrosion. The amount of corrosion removal will reach 30-40um, and the surface roughness can also reach the micron level.
5) Polishing: Polishing is an important process in the production of silicon wafers. Polishing is to further improve the surface quality of silicon wafers through CMP (Chemical Mechanical Polished) technology to meet the requirements for chip production. The surface roughness after polishing is usually Ra<5A.
6) Cleaning and packaging: As the line width of integrated circuits is getting smaller and smaller, the requirements for improved particle size indicators are also getting higher and higher. Cleaning and packaging is also an important process in the production of silicon wafers. Megasonic cleaning can clean and adhere to silicon Most of the particles above 0.3um on the surface of the silicon wafer are vacuum-sealed and packaged in a no-clean jam box or packed with an inert gas, so that the cleanliness of the silicon wafer surface meets the requirements of integrated circuits.