It is estimated that 99% of all semiconductor devices are made of monocrystalline silicon. Crystal silicon is an incredibly important part of modern life due to the large dependency users have on technological devices. There are different methods used in growing the necessary crystals for silicon wafers. The process in which crystalline materials are grown is incredibly important for the end use of the wafer in terms of its purity. One of the processes used for growing this crystalline material used in silicon wafers is called the Czochralski Crystal Growth Process.
History of Czochralski Method
It was in 1916 that a Polish metallurgist published a method for measuring maximum crystallization rates of metals. He was pulling metal wires vertically from melts with increasing velocities, and in these single crystalline wires occurred. He realized that with this pulling technique, single crystals could be grown successfully if single crystal seeds are used. First, single geranium crystals were grown using this method in 1948. In 1949, it was recognized that silicon was a better semiconductor material and so in 1951 Silicon crystals were grown using the Czochralski Method. Crystals grown using this method are often referred to as monocrystalline Czochralski silicon (Cz-Si).
Czochralski Process Overview
To begin, high purity silicon is melted in a crucible. At this point, dopants can be added in, depending on the end result of the wafer. Boron or phosphorus are often added to change the silicon into p-type or n-type and thus changing the silicon’s electronic properties. Dipped into the molten silicon is a rod mounted seed crystal which is slowly pulled upwards and rotated. By controlling the speed of rotation and pulling rate, a large, single crystal, cylindrical ingot can be extracted. The pull rate and temperature profile determines the diameter of the crystal.
The Czochralski process is the preferred method for high volume production of silicon single crystals. After the crystals are produced, they can be cut into slices and polished and the wafers can be used as starting materials for chip production. Depending on the purpose of the silicon wafers, its diameter and thickness need to be precisely measured.
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!
For any questions you may have regarding the production of silicon wafers or for more information about obtaining silicon wafers for your business, you can connect with Wafer World online today! We are a leader in silicon wafer manufacturing and serve customers in over 45 countries! Contact us about your wafer needs today!