Exhaust deposit clean process using a remote NF₃ plasma (MAC-ICP)

Polysilicon deposition process byproducts in the form of exhaust powder deposits present time consuming and periodic maintenance that includes manual cleaning of exhaust components. A technology was therefore developed that allows a dramatic reduction in mean time between cleans thereby significantly increasing uptime of polysilicon deposition tools. Powder deposits and accompanying adsorbed gases throughout the entire exhaust line down to the pump inlet and silencer are cleaned in-situ, without trapping, by reacting with fluorine radicals from a remote NF₃ plasma. A novel compact remote plasma unit-a magnetically coupled inductively coupled plasma (MAC-ICP)-was developed for this immediate purpose and successfully integrated into the existing single-wafer polysilicon deposition system. The evaluation, optimization, automation, and process integration of the cleaning technique is presented