Production Processes

Silicon wafers are produced in a highly advanced environment

Silicon wafer production takes place in three steps. SUMCO carries out each of these steps in clean rooms boasting the highest level of cleanliness. Applying the strictest quality control, we produce silicon wafers of exceptionally high purity and quality.

Overview diagram showing the flow, from the manufacturing of silicon wafers to the assembly of final electronic products.

Monocrystalline pulling process

Manufacturing of monocrystalline ingots used as the material of silicon wafers

The monocrystalline ingots that make up the silicon wafer are manufactured using high-quality polysilicon as the raw material.

  • Flow of CZ process for making monocrystalline ingot

    The monocrystalline silicon ingots from which silicon wafers are created are manufactured by a technique called the CZ (Czochralski) crystal growth process.
    Polysilicon purified until the metal impurities are no more than a few parts per billion (ppb) is put into a quartz crucible along with boron (B) and phosphorous (P), and melted at a temperature of around 1420℃. The boron and phosphorous impurities are added in minute amounts to adjust the electrical resistance of the final semiconductors, determining their properties.
    A seed crystal silicon rod is placed on the surface of the molten silicon in the crucible, and is pulled up while rotating it, to form a monocrystalline ingot having the same orientation of atoms as the seed crystal.

  • Flow of CZ process for making monocrystalline ingot

Other processes can be used on request

In response to customer needs, we also make use of the MCZ (Magnetic field applied Czochralski) technique, applying a strong magnetic field, or the FZ (Float-Zone) technique whereby monocrystalline ingots are made at low oxygen levels without using a quartz crucible. SUMCO is able to meet customer requests at the monocrystalline ingot manufacturing stage.

Diagram illustrating the single crystal silicon manufacturing process and equipment structure using CZ (Czochralski) and MCZ (Magnetic Czochralski) methods.

Wafer forming process

Achieving ultra-flat wafers with exceptional surface cleanliness

The monocrystalline ingots manufactured by the CZ process go through five carefully controlled steps to become polished wafers.

The five steps of wafer forming

  • 01

    Slicing

    The circumference of the monocrystalline ingot is ground down to a uniform diameter. Based on the resistivity desired by the customer, the ingot is then cut into slices of around 1mm thickness, using an inner-diameter saw or wire saw, to form the wafers.

    A photograph showing a wire saw machine alongside an illustration depicting the mechanism of the wire-saw cutting process.
  • 02

    Lapping

    The sliced wafers are polished by alumina abrasive in a lapping machine to the desired thickness, while improving the surface parallelism.

    A photograph of a lapping machine alongside a structural diagram Illustration
  • 03

    Etching

    Mechanical damage to the wafer surface resulting from the earlier steps is removed by chemical etching.

  • 04

    Polishing

    The wafer surfaces are made perfectly flat and given a mirror finish by means of mechano-chemical polishing using colloidal silica.

    A photograph of a polishing machine and a structural diagram illustration
  • 05

    Cleaning and inspection

    After cleaning, stringent inspections are performed, and the SUMCO polished wafer is completed. The exceptionally high quality of the polished wafers manufactured by SUMCO ensures they are favored by customers all over the world.

    A series of images showing: wafer cleaning equipment, a technician performing a visual inspection, a particle measurement system, a flatness measurement system, and a final polished wafer.

Specialized processing

Specialized wafer processing for specific applications

On request from customers, we perform additional processing on polished wafers, producing the following four kinds of wafers.

Four kinds of specialized processing for specific applications

  • 01

    Epitaxial
    Wafers

    Polished wafers are heated to around 1200℃ in an epitaxial furnace. Vaporized silicon tetrachloride (SiCl4) and trichlorosilane (SiHCl3) are circulated in the furnace, causing vapor phase (epitaxial) growth of a monocrystalline silicon film on the wafer surface. An epitaxial wafer is a high-quality wafer for customers requiring an exceptionally perfect crystal structure or multiple layers having different resistivity.

    A photograph and structural schematic of a single-wafer epitaxial reactor, illustrating the production flow from polished wafers to epitaxial wafers.
  • 02

    Annealed
    Wafers

    A polished wafer undergoes high-temperature annealing in an atmosphere of hydrogen or argon. As this process removes oxygen near the wafer surface, the resulting wafer has improved crystal perfection.

    Exterior photo and structural diagram of a hydrogen annealing furnace, showing the process of producing annealed wafers from polished wafers.
  • 03

    Junction Isolated Wafers
    (JIW)

    Photolithography, ion implantation, and thermal diffusion techniques are used in accordance with customer design needs. After a layer for embedding integrated circuits is formed on the surface, another layer is formed on top of it by epitaxial growth.

    Interior photograph and structural schematic of a diffusion furnace, illustrating the production process of epitaxial wafers with buried layers.
  • 04

    Silicon-On-Insulator
    Wafers

    An oxide layer is formed for one or both of the handle wafer and the active wafer on which semiconductor devices will be built. The two wafers are then bonded together by annealing. Next the active wafer is ground and polished to the desired thickness.

    By forming an oxide layer with high electrical insulation inside the wafer, semiconductor devices with high integration, low power consumption, high speed, and high reliability can be realized. A diffusion layer of arsenic (As) or antimony (Sb) can be formed in the active layer as necessary.

    Illustrating the step-by-step manufacturing process of SOI wafers.

Products

Product Lineup Production Processes