Silicon/Cellulose Wafers

Silicon wafers are key component in integrated circuits. Integrated circuits are, simply put a composite of various electronic components that are arranged to perform a specific function. Silicon is the principle platform for semiconductor devices. A wafer is a thin slice of the semiconductor material, which serves as the substrate for microelectronic devices built in and over the wafer.

As silicon wafer’s primary use is in integrated circuits. Integrated circuits power many of devices that can be used by society everyday. Computers and smartphones are just two of the devices that are dependent on this technology. Silicon is the stable among all the semiconductors. Other uses include sensors, such as the tire pressure sensor system and solar cells. Silicon wafers absorbs the photons in sunlight and this in turn create electricity.

The wafers serves as the substrates for microelectronic devices built in and over the wafer and undergoes many microfabrication process steps such as doping or ion implantation, etching, deposition of various materials and photolithographic pattering.

Silicon wafers are available in a variety of diameters from 25.4mm (1 inch) to 300mm. The diameter has gradually increased to improve throughput and reduce cost with the current state –of-the-art of fab considered to be 300mm with the next standard projected to be 450mm.

Wafer thickness is determined by the mechanical strength of the material used the wafer must be thick enough to support its own weight without cracking during handling. Wafers are grown from crystals having a regular crystal structure, with silicon having a diamond cubic structure. Orientation is defined by the Miller index with (100) or (111) faces being the most common for silicon. Ion implantation depths depend on the wafer’s crystal orientation, since each direction offers distinct paths for transport.