Silicon Wafer Production Process

Our silicon wafer manufacturing process can be divided into two stages, namely, pulling single crystal ingots and slicing and polishing the silicon wafers.

Image of Poly-crystal Silicon (Nuggets)

Poly-Crystaline Silicon (Nuggets)

Image of Pulling Single Crystal Silicon Ingots (CZ Method)

Pulling Single Crystal Silicon Ingots (CZ Method)
In the CZ method, polycrystaline silicon nuggets are placed in a quartz crucible, which is set in a graphite crucible surrounded by graphite heaters in the crystal pulling chamber. These nuggets are melted by heating in an Argon atmosphere under vacuum and then pulled slowly using a seed crystal.

Image of Single Crystal Silicon Ingots

Single Crystal Silicon Ingots
Single crystal silicon ingots, when completely grown, have a shape such as this. It has head and tail cones to prevent dislocations introduced by thermal shock.

Image of Peripheral Grinding
Image of Peripheral Grinding

Peripheral Grinding
The ingot is cut into some blocks having the specified length after its periphery is ground to the specified diameter. Either an orientation flat or a notch is added to a part of the peripheral to indicate the crystal orientation.

The shape of the blocks, following the completion of the peripheral process, can be seen in the diagram on the left. (The diagram shows an ingot with a notch.)

Image of Slicing

In production of large diameter wafers, the block is sliced at once to many wafers with wire-saw. In small diamter wafering process, wafers are sliced one by one from the ingot using a rotating diamond inner peripheral blade.
The image shown on left is slicing with wire-saw.

Image of Beveling (Peripheral Rounding)

Beveling (Peripheral Rounding)
The periphery of a wafer is ground with a diamond tool to attain the required product diameter. Various types of grinding stones are used to shape wafer edge to meet Costomers' unique edge shape.

Image of Lapping (Double Side Lapping)

Lapping (Double Side Lapping)
Wafers are set in a carrier, which spins between two rotating lapping plates. Both surfaces of the wafers are lapped to remove damaged surface layer and to achieve predetermined uniform thickness.

Image of Etching (Chemical Polishing)

Etching (Chemical Polishing)
Wafers are placed and etched in a carrier cage that rotates in an etching solution to completely remove the damaged surface resulting from the previous slicing and lapping. Acid is used for etching solution, but combination with alkaline is recently used also.

Image of Heat Treatment to Remove Unstable Donors

Heat Treatment to Remove Unstable Donors
Donor annihilation heat treatment is applied to eliminate thermal donor in order to restore the originally intended specific resistance. Such Oxygen-derived unstable donors, generated during crystal pulling, are annihilated.

Image of Polishing (Single Side Mirror Polishing)

Polishing (Single Side Mirror Polishing)
A wafer mounted onto a ceramics plate is pressed against the surface of a rotating plate covered with a polishing cloth. It is polished to have a mirror surface by a combined mechanicalchemical action.

Image of Cleaning

Wafers are physically and chemically cleaned using ultra-pure water and chemicals.

Image of Inspections

Wafer flatness and surface cleanliness (particle-free) are key factors as a substrate for recent leading edge ULSI devices. Individual wafer flatness and surface particles are mesured using specially designed inspection tools to assure wafer quality.

Image of Packaging

Wafers are packaged in a clean shipping case, and sealed in a special moisture-proof bag.

Image of Shipping

Wafers are placed in shock-absorbent shipping boxes for protection against damage caused by shock.