Silicon wafer manufacturing processes are roughly divided into crystal growth processes and wafer processing processes.

  • Polycrystalline silicon (nugget)

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  • Single crystal pulling (CZ method)

    In the CZ method, a black heater graphite crucible, a quartz crucible, and polycrystalline silicon are set in a pulling device, heated and melted under reduced pressure in an inert atmosphere, and then gradually pulled up with a seed crystal to grow a single crystal.

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  • monocrystalline silicon ingot

    A grown monocrystalline silicon ingot has such a shape. In the case of crystals for phi 200mm wafers, the weight of one ingot is 60-100kg.

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  • Peripheral grinding

    Cut to specified length and grind outer circumference to specified diameter. A plane (orientation flat) or groove (notch) that indicates the crystal orientation is added to a part of the outer circumference.

    An ingot that has completed peripheral processing will have the shape shown in the left figure. (This drawing is for the notched version).

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  • Slicing

    The ingot is cut into wafer shape by wire saw method or inner diameter blade method.

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  • Bevel processing (peripheral chamfering)

    The outer periphery of the wafer is ground to the product diameter with a diamond grindstone, and the end face is ground and chamfered into an arc shape.

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  • Lapping (double-sided mechanical polishing)

    Between the rotating upper and lower lapping machines, the carrier on which the wafer is set rotates, supplying abrasive grains to polish both sides.

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  • Etching (double-sided chemical polishing)

    Etching is performed while rotating the jig on which the wafer is set in an acid-mixed etchant to completely remove the damaged layer from the previous machining process.

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  • Donor erasure heat treatment

    Heat treatment is performed in a diffusion furnace to decompose unstable donors (n-type impurities) caused by oxygen generated during crystal growth and restore the original resistivity.

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  • Polishing (single side mirror polishing)

    A plate with a wafer attached is pressed against a rotating surface plate on which a polishing cloth is pasted, and while polishing materials are supplied, polishing is continued by a combination of mechanical and chemical actions until a mirror surface is obtained.

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  • Washing

    Clean the wafers chemically and physically with chemicals and ultrapure water.

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  • Inspection

    A high-intensity spotlight is placed on the wafer surface to perform an appearance inspection, as well as an inspection of flatness, resistivity, and the number of microscopic particles adhering to the surface.

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  • Packing

    Wafers are packed in clean shipping cases and sealed in special bags that are impermeable to moisture.

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  • Shipping

    Wafers are shipped in shock-absorbing shipping boxes to prevent damage from minor impacts.

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