Development of large bulk Silicon Carbide substrates from halogenated precursors

The development of long SiC boules grown from the gas-phase using chlorinated halo-hydrocarbons faces enormous technical hurdles that must be overcome. The hurdles of specific interest are the outlet, the materials degradation, the inlet, and thermal issues. Caracal proposes to find a solution to all of the above mentioned technical obstacles. The outlet is of particular importance since it limits the length of the boules to 2 - 5 mm. Caracal suggests an outlet which can keep a free path for the gas for prolonged growth yielding longer than 75 mm crystals. The inlet needs more development in order to handle the long growth times required. The graphite materials and insulation has historically caused drift in the system due to reactions with silicon vapor and hydrogen. Caracal proposes new crucible material that can withstand these attacks much better. Finally, in order to keep the growth conditions constant, the growing crystal must be pulled upwards into a cooler area which will cause a change in the thermal profile. Heat must be added to the top of the chamber in order to keep the system constant. Caracal will analyze and model the thermal conditions and propose a solution to this.