how is wafer made
How is wafer made ? Wafer fabrication is an extremely complex and delicate process that involves a number of key steps, as described below:
1. Silicon purification
First, silicon dioxide is extracted from sand and purified into high-purity polysilicon through a series of chemical processes.
2. Single crystal growth
Next, the polysilicon is heated to a molten state, and single-crystal growth is carried out by either the straight drawing method (CZ) or the zone melting method (FZ). During this process, seed crystals are inserted and pulled out in a slow rotation to form single crystal rods.
how is wafer made
3. Rod cutting
Subsequently, a diamond wire saw is used to cut the single crystal silicon rods into thin slices to obtain the initial form of the wafer.
4. Grinding and Polishing
The cut wafers are subjected to rough grinding and chemical-mechanical polishing (CMP) to ensure that their surfaces are smooth as a mirror and achieve the desired flatness.
5. Cleaning and Inspection
The wafers are cleaned with ultrapure water and chemical reagents to remove surface impurities, and then optically inspected to ensure that their quality meets standards.
6. Special Processing
Depending on the application requirements, annealing, epitaxial growth, or SOI (silicon on insulator) preparation may be performed to meet specific electronic performance requirements.
