Polysilazane Waste Handling: Navigating Safety and Environmental Considerations
Deena Starkel, P.E.; Bob Gross
(Micron Technology, Inc. Boise, ID)
Spin on dielectric (SOD) or spin on glass (SOG) is an interlevel-dielectric material that is applied in liquid form. Spin on dielectrics are a class of coated films that are spin cast by dispensing a liquid dielectric material on to a rotating wafer. Silicon dioxide (SiO2) film deposition by SOD provides benefits through simple processing, lower defect density, higher throughput, relatively low cost and elimination of hazardous gases. Polysilazanes are a common category of SOD chemistries that provide a silicon source for SiO2 film deposition. Despite the reduced risk associated with eliminating hazardous gases, polysilazanes present unique challenges for safe handling and waste disposal due to their physical properties and chemical reactivity. Polysilazanes are moisture reactive and decomposition results in the formation of hazardous byproducts including ammonia, hydrogen and silane gases. Byproduct gas generation from decomposition impacts safe handling, storage and transportation of waste. Polysilazane chemicals present unique hazards and risks that need to be understood when considering facilitation requirements for waste handling. Process safety impacts and environmental considerations can influence decisions regarding the best management strategy of polysilazane waste for a facility. Presented will be an overview of the physical properties and chemical reactivity of polysilazanes and methods to handle polysilazane waste based on process safety and environmental considerations.