Process of Silicon Wafer Fabrication

More than 90% of the earth's crust is composed of Silica. It is the principle platform for semiconductor devices. The most advanced semiconductor technologies of today require monocrystalline Silicon wafers applications. There is a complete series of steps and processes that have to be followed to transform raw silicon into a single-crystal wafer products.

Reduction of raw silicon with Carbon is done in an electric furnace. MG-Si reacts with HCl to form trichlorosilane (TCS). This process is done in a fluidized-bed reactor. Impurities such as Fe, Al and B are removed while converting MG-Si to TCS. This ultra-pure TCS is subsequently vaporized and flowed into a deposition reactor. Here it is transformed into elemental silicon.

A process known as Crystal Growing transforms the polycrystalline silicon into ingots. With a series of fabrication steps these ingots are converted into final product of Thermal Oxide Silicon Wafers. The Polysilicon is mechanically broken and undergoes surface etching and cleaning process. These ingot pieces are then packed into quartz crucibles in a CZ furnace.

A monocrystalline Silicon seed is installed into a seed shaft and slowly, the seed convert into the Silicon melt. Both the crucible and seed are rotated in opposite directions to allow crystal formation. When the required crystal diameter is attained, the seed lift is increased

During the growth process, the crucible slowly dissolves Oxygen into the melt. Intentional additions of dopants control the resistivity of the final material. Their doping should be intensively controlled along with the oxygen content. Heat dissipation during crystal cooling determines the microscopic defect in the final crystal. When the growth process is complete, the wafer crystals are cooled down within the furnace. This gradual cooling of Thermal Oxide Silicon Wafers allows the crystal lattice to stabilize.

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