A Plasma Reactor for Solid Waste Treatment on Pecvd Production Systems

The growth of particulates within a PECVD (Plasma Enhanced Chemical Vapor Deposition) reactor has been extensively studied in recent years. As one of the early concerns was wafer particle contamination, the attention of industry also shifted to environmental issues. In the particular case of Si 3 N 4 film deposition, the amount of dust particles created within the plasma is great and a significant amount of dust is dragged out of the RF interelectrode region along with the exhausted process gases. On a production system, this results in solid residues accumulation in the exhaust line (or foreline), frequent maintenance and poor vacuum pump lifetime. We developed a DPA (Downstream Plasma Apparatus) placed downstream of the deposition chamber to solve the issue of solid waste treatment for thin films applications such as SiO 2 , Si 3 N 4 , SiC, SiO x N y ,…, α‐Si,…). The DPA is designed to capture all the residue during deposition, using both a passive and an active mode. It consists of two labyrinth‐shaped electrodes that can trap particles by gravitation (passive) and electrostatically (active) by application of a DC electric field. The second function of the device is to vaporize the previously trapped residues using a periodic plasma assisted clean. The vaporization process is performed by re‐ionizing the effluent PFCs gas (PerFluoro‐Coumpounds) from the processing chamber. All byproducts of the reaction are gaseous and water soluble. This results in the elimination of solid waste as well as improving vacuum pump lifetime. There is also better clean gas utilization and the emission of PFCs in the atmosphere is reduced. In this paper, we review the particulate formation, their size and composition. We describe the DPA reactor designed to trap charged particulates with closed to 100% efficiency. We examine the plasma‐assisted cleaning process and the implications of the device in terms of solid waste treatment and environmental impact.