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Silicon has a diamond cubic crystal structure and a lattice parameter of 5.43Å. Silicon wafers are sliced from the single-crystal silicon ingots that are grown with a certain orientation after melting highly pure polycrystalline silicon. Orientations are described using Miller Indices, such as [100], [111], and [110].

The crystalline orientation of a wafer determines its mechanical, physical and chemical properties, the deposition, ion implantation, diffusion, etching, and CMP processes, as well as the properties of resulting devices.

For silicon crystals grown as single, the impurities that have been added to achieve electrical conductivity (B, P, As, and Sb) must be removed as much as possible.

Wafers can be then divided into n- and p-types according to the properties of the aforementioned impurities, and achieve levels of electrical conductivity between conductors and insulators.

Semiconductors are usually classified as having an electrical resistivity at room temperature, which ranges from 10-2 to 109ohm-cm, very sensitive to temperature.

If an insulator is defined as having a resistivity at or above 1014ohm-cm, then most intrinsic, completely crystalline semiconductors become insulators at an absolute temperature of 0K.

The surface of a silicon wafer must not contain any damage or small amount of chemicals, which may have a critical impact on circuit manufacturing, and requires a high level of flatness in order to achieve smoothness in the device process and high-quality circuits.