Monocrystalline silicon (mono-Si) grown by the Czochralski process is often referred to as monocrystalline Czochralski silicon (CZ-Si). CZ-Si higher speed of production, low cost, higher resistance to thermal stress and the high oxygen concentration that offers the possibility of Internal Gettering made it the most commercially grown silicon. The CZ-Si wafers are produced with a method of crystal growth used to obtain single crystals of semiconductors e.g. palladium, platinum, silver, gold and many oxide crystals.
The 99% of all semiconductor devices are made of monocrystalline silicon. Because of the large dependency, users have on technological devices crystal silicon is a tremendously important part of modern world. Due to the importance of the wafer’s purity, the process of growing crystalline materials is very important. There are several different methods of growing necessary crystals for silicon wafers. One of the methods used for growing this crystalline material used in silicon wafers is called the Czochralski Crystal Growth Process.
The Czochralski Process is named after the polish scientist Jan Czochralski who invented the method in 1916 while investigating the crystallization velocity of metals by pulling mono- and polycrystals against gravity out of a melt, which is held in a crucible. The Czochralski process is the preferred method for high volume production of silicon single crystals.
To begin, high purity silicon with additional dopants as required for the final resistivity is melted in the rotating crucible. Dopant impurity atoms such as boron or phosphorus are often added in precise amounts in order to dope the silicon and to change the silicon into p-type or n-type, thus changing the silicon’s electronic properties.
The different process steps of Czochralski crystal growth: Melting of polysilicon with dopants, immersion of the seed crystal, crystal growth.
A seed crystal, mounted on a rod, is dipped into the molten silicon and slowly pulled upwards and rotated at the same time. By controlling the rate of pulling, temperature, and speed of rotation, a large, single crystal, cylindrical ingot can be extracted. Depending on the temperature and pulling speed, the diameter of the crystal is determined. This process is usually performed in an inert atmosphere, such as argon, and in an inert chamber, such as quartz. After the production of the crystal ingots, they are normally cut into slices and polished. Then the wafers can be used as starting materials for chip production.
Thanks to this process, the technology has been made possible.
Electronic devices today are all dependent on silicon wafer technology, and the Czochralski Process is just one of the many processes behind the production of these incredible technological feats.
Electronic devices today are all dependent on silicon wafer technology, and the Czochralski Process is just one of the many processes behind the production of these incredible technological feats.
Applications of (CZ-Si) Czochralski silicon wafers:
- CZ-Si wafers are used in production of integrated circuits (computers, TVs, mobile phones).
- CZ-Si wafers are used in production of solar cells.
- CZ-Si wafers are used in all types of electronic equipment and semiconductor devices.
- CZ-Si wafers are used in large quantities by the photovoltaic industry for the production of conventional mono-Si solar cells.
Comments
Post a Comment