Silicon is an abundant element that is ideal for mass manufacturing. This makes it a cost-effective alternative for electronic products and machines. Creating a silicon wafer begins with a single crystal of pure silicon, called a seed crystal. This seed crystal is positioned on top of a molten silicon melt.
The Slicing Process
The slicing process is an important step in the production of silicon wafers, which are used to manufacture semiconductors. It consists of several steps, including surface grinding and critical edge grinding.
Slicing the wafer reduces the amount of material wasted and decreases the risk of breakage. It also minimizes bow and warp defects.
After slicing, the wafer is polished with an abrasive to reduce the roughness and improve the flatness of the surface. It is then etched to remove microscopic cracks, which could cause damage during the next processing step.
The next manufacturing step involves lapping, which removes saw marks and other surface defects. It also thins the wafer and relieves some of the stress created by the slicing process.
The Lapping Process
Silicon Wafer is one of the most important materials for making semiconductors and it is difficult to produce a good quality product without properly preparing the silicon. To do so, a number of different machining processes are used, such as slicing, edge profiling, lapping and grinding.
The lapping process is the most effective and economical method to thin and flatten the surface of silicon wafer that are less than 200 mm in size. This is done by using a hard metal lapping plate and an abrasive slurry that is applied to the specimens' surfaces.
This slurry is made up of alumina abrasive grains with a defined size distribution. The wafers are placed between the two plates and the abrasive grains grind the silicon surface.
After the wafers are lapped, they are then treated with an oxidizing agent to oxidize organic contaminants that may be present on the silicon wafer's surface. Next, the silicon wafers are immersed in an aqueous bath comprised of citric acid into which sonic energy is directed to remove metallic contaminants that may be present on the silicon wafer's surfaces.
The Etching Process
The etching process is used to remove layers of material from a surface of a wafer. Etching is a key microfabrication process for the production of semiconductor micro devices.
Etching can be performed with a variety of different chemicals. Each one has its own advantages and disadvantages.
Dry etching is an extremely common method for removing silicon from silicon wafers and can be achieved using a chemically active gas mixture containing fluorine atoms or noble gases such as xenon and argon.
In addition to removing silicon, the etching process can also be used for removing oxide layers from microelectronic devices. Oxide removal is a standard silicon wafer etching step and involves immersing the wafer into an acidic nitride bath with a hot phosphoric acid strip to achieve precision temperature control and to regulate the deionized water to phosphoric acid ratio.
The Polishing Process
The polishing process is an important step in the production of silicon wafer. It removes micro particles, surface metals, and other surface damage and produces a smooth, mirror-like finish.
The first step in the polishing process is rough polishing, which uses a coarse slurry, aggressive etchant, and hard polishing pad to remove stock quickly. It is followed by a second polishing step, known as finish polishing, which uses finer abrading agents in the slurry and less aggressive etchant.
A final step in the polishing process is drying, which is important to reduce etching stain defects. This can be done by exposing the polished surface of the disengaged wafer to an infrared lamp or by contacting it with a flow of warm drying gas.
