About silane process

Is this method currently used to produce silane in China?

Silane is difficult to make. . . . . . . . . .

Please check the UCC method introduction. However, due to foreign technical limitations, the purification aspect is very complicated, but the reaction aspect is relatively easy.

At present, there are two companies in the country that are re-building, and there are also several companies that are interested. They are all new silane process technologies from the United States, but instead of hydrogenating SiCl4, they react with SiF4 and sodium aluminum hydride, and the reaction is relatively thorough.

Who is in charge of the new Silane France?

Let’s start with the silicon-magnesium alloy, and then silane gas.

Zhongning Silicon and Liujiu Silicon have the same technology. 6#Minos

It is not possible to use silane gas to make polycrystalline silicon, but to make amorphous silicon solar cells, which is relatively simple. It is made by coating glass or stainless steel plates with silane plasma gas and rapid cooling.

At present, in the research of silicon-based films, the reason why people generally use hydrogen-diluted silane (SiH4) as the reaction gas is because the silicon-based film material generated in this way contains a certain amount of hydrogen. H plays a very important role in silicon-based films. It can fill the dangling bonds in the material structure.* * The defect energy level is reduced and the valence electron control of the material is easily achieved. Since Spear et al. first realized the doping effect of silicon films and prepared the first pn junction in 1975, the preparation and application research of silicon-based films based on PECVD technology has developed rapidly. Therefore, the chemical reactions in the silane plasma during the deposition process of silicon-based films PECVD technology will be described and discussed below. Under glow discharge conditions, since the electrons in the silane plasma have energies above several ev, H2 and SiH4 will decompose due to the collision of electrons. This type of reaction is a primary reaction. If the intermediate excited state during decomposition is not considered, the following dissociation reactions that generate SiHm (m=0,1,2,3) and atomic H can be obtained: e+SiH4→SiH2+H2+e (2.1) e+SiH4→SiH3+ H+e (2.2) e+SiH4→Si+2H2+e (2.3) e+SiH4→SiH+H2+H+e (2.4) e+H2→2H+e (2.5) Calculated according to the standard heat of production of ground state molecules, the energy required for each of the above dissociation processes (2.1)~(2.5) is 2.1, 4.1, 4.4, 5.9 eV and 4.5eV respectively. High-energy electrons in plasma can also undergo the following ionization reactions: e+SiH4→SiH2(+)+H2+2e (2.6) e+SiH4→SiH3(+)+ H+2e (2.7) e+SiH4→Si++2H2+2e (2.8) e+SiH4→SiH++H2+H+2e (2.9) The energy required for each of the above ionization reactions (2.6) ~ (2.9) is 11.9, 12.3, 13.6 and 15.3 eV respectively. Due to the difference in reaction energy, the probability of occurrence of each reaction (2.1) ~ (2.9) is extremely uneven. In addition, the SiHm generated during the reaction process (2.1)~(2.5) will also undergo the following secondary reactions and become ionized, such as SiH+e→SiH(+) +2e (2.10) SiH2+e→SiH2(+)+2e (2.11) SiH3+e→SiH3(+) +2e (2.12) If the above reaction is carried out with the help of a single electron process, it will require approximately 12 eV or more energy. In view of the fact that under the normal pressure conditions for preparing silicon-based films (10~100Pa), the number of high-energy electrons above 10eV in a weakly ionized plasma with an electron density of about 1010cm-3 is small, and the probability of cumulative ionization is generally smaller than the excitation probability. Therefore, in silane plasma, the proportion of the above ionized species is very small, and the neutral groups of SiHm dominate. The results of mass spectrometry analysis also prove this conclusion. The experimental results of Bourquard et al. further pointed out that the concentration of SiHm decreases in the order of SiH3, SiH2, Si, and SiH, but the concentration of SiH3 is at most 3 times that of SiH. Robertson et al. reported that among the neutral products of SiHm, Si is the main product when using pure silane for high-power discharge, and SiH3 is the main product when low-power discharge is used. The order from high to low concentration is SiH3, SiH, Si, SiH2. Therefore, plasma process parameters strongly affect the composition of SiHm neutral products. In addition to the above-mentioned dissociation reactions and ionization reactions, secondary reactions between ion molecules are also important: SiH2++SiH4→SiH3++SiH3 Therefore, in terms of ion concentration, SiH3+ is more than SiH2+. It can explain why there are more SiH3+ ions than SiH2+ ions in normal SiH4 plasma. In addition, a molecule-atom collision reaction in which the hydrogen atoms in the plasma capture the hydrogen in SiH4 will also occur.: H+ SiH4→SiH3+H2 (2.14) This is an exothermic reaction and a precursor reaction to form disilane Si2H6. Of course, the above groups are not only in the ground state, but will also be excited to the excited state in the plasma. The results of the emission spectrum study of silane plasma show that there are optically allowed transition excited states of Si, SiH, H, etc., as well as vibrational excited states of SiH2 and SiH3. §1.3.3 Film-forming reactions on the growth surface Although various very complex elementary reactions occur simultaneously in silane plasma, it is very difficult to study the growth process and mechanism of silicon thin film materials. However, as stated earlier, the following facts have been confirmed: The ionized groups in the silane plasma are only at low pressure (

Haha, our laboratory has been conducting research on plasma and silicon materials for several years, but we have not yet figured out the reaction rules...

No matter which process is used, there will be the danger of silane gas explosion, as well as the embarrassing situation of low price caused by low product purity. Human operations in the entire process flow are particularly important. The distillation part is also a flaw in the current domestic silane industry. Companies that have introduced foreign technology can only achieve level 5~6N. Domestic manufacturers that have not introduced technology are basically hovering at level 3~5N.