Silicon wafer processing involves using highly pure silicon substrates made from single-crystal silicon. Single-crystal silicon is known to possess zero defects that can reduce the lifetimes of minority carriers; that is why they are highly desirable for wafer production. These silicon substrates must have a high degree of chemical purity, high structural uniformity, and a high degree of crystalline perfection. To achieve this level of perfection, it is essential to refine the raw materials and grow the single-crystal silicon using the CZ or FZ method.
What are the Two Ways to Grow Single Crystal for Wafer Processing?
CZ Method or Czochralski Crystal Growth
The CZ method involves the crystalline solidification of atoms from a liquid phase at a junction. CZ growing during silicon wafer processing include the following steps:
A container fused with silica is supplied with a charge of undoped EGS together with an exact amount of reduced silicon alloy.
The gases inside the growth room are then cleared out.
The growth room is then back-filled with inert gas to prevent atmospheric gases from entering the melt during crystal growing.
The silicon charge located inside the chamber is then tempered to the melting point.
A small seed of crystal silicon with accurate orientation resistance is added to the molten silicon.
The seed crystal is then removed.
FZ Method or Float Zone Crystal Growth
The FZ method involves passing a molten zone through a polysilicon rod. This polysilicon rod has the same measurement as the final ingot. FZ method produces crystals that are highly pure compared to the crystals produced by the CZ method.The FZ process involves the following steps:
A polysilicon rod is firmly fixed vertically inside a room filled with an inert gas.
Then, a needle-eye coil that can go through the rod is mobilized. It will supply the rod's RF power, which will melt a 2 cm long zone. This molten zone should be maintained in a stable liquid form.
The coil, together with the molten zone, is then moved through the rod. It purifies the rod, creating a near-perfect single crystal.
Looking for a Reliable Silicon Wafer Processing?
Silicon wafer processing involves several steps that are carried out meticulously to produce high-quality wafers. At Wafer World, we offer a wide range of high-quality wafers at a reasonable price. Contact us for a quote!
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