Preparation of polycrystalline silicon by Siemens method
Abstract: In semiconductor technology, polycrystalline silicon can be prepared by the Siemens method. This method involves the reduction of a silicon-containing gas in an electron-beam vapor-deposition process. This paper will discuss the preparation of polycrystalline silicon by the Siemens method. The advantages and disadvantages of the method will be discussed, and a brief explanation of how it works will be provided.
Introduction
Polycrystalline silicon is an important material used in semiconductor technology. It is used in a wide range of electronics, including transistors, solar cells, and various other components. In order to produce polycrystalline silicon, a silicon-containing gas must be reduced. This gas is normally composed of silane (SiH4) or a derivative of silane. Several methods are available for reducing the gas into polycrystalline silicon, one of which is the Siemens method.
The Siemens Method
The Siemens method is a process for preparing polycrystalline silicon by reducing a silane-containing gas in an electron-beam vapor-deposition process. The process is comprised of four steps. First, a silane-containing gas is introduced into a vacuum chamber, which is then heated to a predetermined temperature. This temperature varies depending on the type of silicon being synthesized (i.e., polysilicon or amorphous silicon).
In the second step, an electron beam is used to heat the bottom of the chamber, causing the silane gas to become ionized. The ionization of the silane gas is necessary for the chemical reaction. The third step is the reduction of the silane gas by adding electrons that are generated by the electron beam. This results in the formation of polycrystalline silicon. Finally, the polycrystalline silicon is collected on a substrate inside the chamber.
Advantages and Disadvantages of the Siemens Method
The Siemens method is widely used for the preparation of polycrystalline silicon and is considered to be relatively simple and straightforward. One of the advantages of this method is that it does not require a large amount of power, which is beneficial for applications where power consumption must be kept low. Additionally, this method produces large amounts of polycrystalline silicon in a relatively short period of time.
On the other hand, there are some drawbacks to the Siemens method. First, the method is limited with respect to the type of silicon that can be produced. Specifically, only polysilicon or amorphous silicon can be produced by this method. Furthermore, this method is relatively expensive and requires a large vacuum chamber. Finally, the method produces large amounts of hazardous byproducts that are difficult to dispose of.
Conclusion
In conclusion, the Siemens method is a simple and efficient process for preparing polycrystalline silicon. It has several advantages, including low power consumption and quick synthesis. However, there are some drawbacks associated with the method, such as the limited types of silicon that can be produced and hazardous byproducts that are difficult to dispose of. Overall, the Siemens method is a reliable and efficient method for producing polycrystalline silicon.
