This de-oxygenating step is commonly called “hot hydrogen pre-treatment”. This step is performed to mitigate the growth of silicon dendrites on the growing silicon rods during the main decomposition stage. In this step, the silicon filaments are energized with 45 amps current by the electrical power control system and heated to a temperature above approximately 1475 °F while pure hydrogen flows through the reactor.
The hot hydrogen reduces and evaporates trace hydrocarbons on the silicon surface, removes residual moisture from surfaces, and reduces some of the surface oxides on the silicon filaments by converting them to volatile silicon monoxide. During this step, it is