Characterization of Shock-Sensitive Deposits from the Hydrolysis of Hexachlorodisilane

Abstract

In this work, the shock sensitivity of hexachlorodisilane (HCDS) hydrolysis products was studied. The hydrolysis conditions included vapor and liquid HCDS hydrolysis in moist air. Shock sensitivity was determined by using a Fall hammer apparatus. Extensive infrared studies were done for the hydrolysis products. It was found that the Si–Si bond in HCDS during hydrolysis is preserved and can be cleaved by shock, leading to intramolecular oxidation of the neighboring silanol (Si–OH) groups to form a networked Si–O–Si structure and hydrogen gas. The limiting impact energy for shock sensitivity was also found proportional to the oxygen/silicon ratio in the deposit. Finally, recommendations are given for controlling the shock sensitivity of the hydrolyzed deposit.

Characterization and Hazards of the Silicon-Based Polymers Produced in the Manufacture of Ultrapure Polysilicon

“…Friction testing was conducted with loads up to 360 N and also produced exclusively negative results. Moisture content of these hydrolyzed polymer samples was not measured; however, even dried samples did not produce positive impact tests in contrast with results previously reported for HCDS by Lin et al 6 but in agreement with observations by Zhou et al 5 The lowest energy required to obtain a spark from the hydrolyzed polymer resulted from a capacitance of 9400 pF and 2.5 kV for 0.03 J. Notably, the hydrolyzed polymer was tested for electronic discharge sensitivity in a nitrogen environment and positive results were still observed in the range of 0.135−0.265 J.…”

“…In most cases, keeping hydrolyzed polymer in a humid atmosphere (>100 grains) helps to prevent spontaneous ignition. It should be noted that this conclusion relates to the atmosphere in which the polymer is stored or handled and does not characterize the specific water content of the hydrolyzed polymer as others have done …”

“…HCDS is the main constituent of the silicon polymer formed in the Siemens reactor and the characterization of its hydrolyzed product would aid in the safe treatment of the polymers. The characterization, reactivity, and flammability of the hydrolyzed product of pure HCDS has recently been reported by Zhou et al and Lin et al , Zhou et al were able to produce shock-sensitive popping gels from hydrolyzed HCDS on molecular sieve pellets. Lin et al determined the mechanism of shock sensitivity from hydrolyzed HCDS.…”

“…It should be noted that this conclusion relates to the atmosphere in which the polymer is stored or handled and does not characterize the specific water content of the hydrolyzed polymer as others have done. 6 For piping, raw polymer is best treated by placing the pipe in a heated water bath. Caution should be exercised around the bath as bubbles containing HCl and hydrogen will evolve.…”

Identifying the mechanism of formation of chlorinated silane polymer by‐products during chemical vapor infiltration of SiC from CH3SiCl3/H2

“…4,6 These substances burn slowly in a dry atmosphere, but their hydrolyzed products are extremely dangerous as they can ignite and explode in an inert atmosphere. 4,7,8 Mizushima and Habuka reported that a similar by-product is formed in the exhaust tube of the SiC-CVD reactor due to the reaction between C 3 H 8 /SiH 4 /HCl/H 2 . According to the analysis of the gas that they emitted, the by-products were mainly chlorosilanes consisting of three or four Si atoms.…”