The process of by-product formation during silicon film deposition using trichlorosilane gas was studied by two types of the in situ measurement techniques, such as the langasite crystal microbalance (LCM) and the quadrupole mass spectra (QMS) analyzer, installed at the exhaust of the chemical vapor deposition (CVD) reactor. With the increasing hydrogen gas concentration, the QMS showed that the partial pressure related to SiCl 2 decreased. Simultaneously, the deposition on the LCM surface decreased. Because SiCl 2 gradually produces the burnable by-product of (SiCl 2 ) n , an oily silane, at the exhaust, the CVD parameters effective for suppressing the SiCl 2 formation were evaluated. © The Author Semiconductor silicon film is a widely used material in various fields including microelectronics, solar cells and power electronics. In industry, trichlorosilane gas 1-3 is quite often used for producing silicon films by means of chemical vapor deposition (CVD), because the very high purity trichlorosilane is widely available at a reasonable price, and because its storage and use are easier and safer than the other silicon precursors.The silicon film deposition using chlorosilane gases has been studied for many years by various researchers.1-5 They mainly evaluated the chemical species and processes accounting for the deposition rate in order to improve the CVD processes and to design the CVD reactors. In a trichlorosilane-hydrogen system and in a cold wall system, trichlorosilane was shown to directly reach the silicon substrate surface for producing the silicon film.5 Additionally, the silicon deposition rate could be sufficiently described following an Eley-Rideal surface reaction model. 5 Although SiCl 2 was shown to be produced by the thermal decomposition of trichlorosilane in the gas phase of the cold wall environment, its amount was shown to be too low to influence the film deposition rate.However, from a different point of view for achieving a safe operation for the long-term use of the CVD reactor in industry, the by-product, called oily silane, 6 must be taken care. After the repetitive CVD operation for a month or more, an enormous amount of oily silane often fills the exhaust tube. Thus, the exhaust tube is periodically cleaned. However, this operation has several problems. The cleaning operation requires several hours. Additionally, the oily silane is burnable and sometimes explodes.7 In order to avoid disastrous accidents, the conditions producing oily silane should be further studied relating to the SiCl 2 formation, because the oily silane has been identified as polymerized SiCl 2 , 8 (SiCl 2 ) n . (In detail, X-(SiCl 2 ) n -Y. X and Y are end groups). Additionally, when the silicon wafer diameter is enlarged from 300 mm to 450 mm in the future, the by-product problem will become more serious due to the huge consumption of the precursor.Based on empirical information, 9 keeping the exhaust warm is considered to be effective for decreasing the oily silane deposition. Additionally, from the viewpoint o...

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The silicon epitaxial growth behaviour was studied as an application of the parallel-Langmuir process using SiH2Cl2 gas and SiH3CH3 gas. The SiH3CH3 gas was used for in situ producing the SiHx gas by thermal decomposition in the reactor. With the increasing gas concentration of SiH3CH3, several results were obtained, such as (i) the silicon epitaxial growth rate increased exceeding the value saturated using the SiH2Cl2, (ii) the gas phase concentrations of the chlorosilanes at the exhaust decreased, (iii) the byproduct deposition at the exhaust decreased, and (iv) the gas phase concentration of HCl at the exhaust decreased. As a conclusion, the SiHx helped consuming the SiH2Cl2 gas for producing a silicon epitaxial film with reducing the byproduct deposition. Additionally, the SiHx might produce SiH2Cl2 in the gas phase by the reaction with the HCl gas.