Binary compounds of certain metals (such as lithium, calcium, magnesium, iron, chromium, etc.) and certain non-metals (such as boron) and silicon. It is generally crystalline, metallic, hard and has a high melting point. A metal or non-metal can produce a variety of silicides. For example, iron can produce FeSi, FeSi2, Fe2Si5, Fe3Si2, Fe5Si3, and the like. It can be obtained by reduction of metal (or non-metal) oxide or metal silicate with silicon in an electric furnace. Metal silicides are widely used for their excellent high temperature oxidation resistance and electrical conductivity and heat transfer:
Silicide for electric heating elements: Metal silicide is one of the earliest applications of electric heating elements. Generally, the lower the silicon content in the metal silicide, the higher the melting point, but the oxidation resistance is lowered. Therefore, it is generally preferred to use a disilicide having a low melting point but good oxidation resistance to produce a heating element.
Silicides for high temperature oxidation resistant coatings: The remarkable oxidation resistance and self-healing properties of MoSi2 coatings on molybdenum have led to extensive research on a large number of other MeSi2 binary silicides and more complex silicides for all refractory metals. And its alloys and graphite materials include anti-oxidation coatings of carbon/carbon composites
It is known that the thickness of the coating is parabolic in relation to the time of use, and the effect of the temperature on the thickness of the coating is more sensitive than time. Further studies have found that the lifetime of silicide coatings is mainly controlled by the interdiffusion ability and coating defects of the elements in the coating system. In this respect, the first is to modify the coating silicide by alloying to obtain a multi-component composite oxide protective film with better oxidation resistance; the second is to use gradient compounding to improve the coating during thermal cycling. Hairline crack defect
Silicides for integrated circuit gate films: As integrated circuits become more integrated, the heat resistance requirements for their gate and interconnect materials are increasing. Conventional polysilicon and aluminum materials have been unable to meet the requirements; although refractory metals W and Mo have good electrical conductivity and high melting point, they are not resistant to oxidation, which limits the preparation temperature of integrated circuits. Thus, refractory metal silicide is attracting attention due to its low electrical resistivity and high stability. The four most noticeable silicides in this regard are TiSi2, TaSi2, MoSi2 and WSi2, of which TaSi2 is the most stable and has a lower resistivity than WSi2 and MoSi2. At the same time, the use of TaSi2 as the metallization of integrated circuit gates and interconnects has its unique advantage that TaSi2 will not be oxidized in dry oxygen. With the advent of ultrafine grain processes, the requirements for high temperature stability may be Reduced, then other silicides will also become useful