Controlled deposition of organic contamination and removal with ozone-based cleanings

Organic contamination has an impact on semiconductor product yield. Therefo re, the removal of typical organic contamination, originating from clean ro om air, wafer boxes, and wafer handling, is required. The cleaning efficien cy of ozone-based cleaning processes is evaluated. Different cleans are eff ective in removing monolayers of typical clean room contaminants on silicon wafers. The organic target molecules under study represent some of the typ ical clean room contaminants encountered in silicon technology, i.e., dioct yl phthalate, stearic acid, butylated hydroxy toluene, some siloxanes (octa methylcyclotetrasiloxane and decamethyltetrasiloxane), a surfactant (4-dode cylbenzenesulfonic acid), and n-pentadecane, A prerequisite for measuring t he removal efficiency of ozonated cleans for submonolayer organic contamina tion has been the development of a controlled, reproducible, and quantitati ve deposition method for those species. Exposure to a sealed ambient of org anic compounds and wet chemical exposure were assessed. It is found that de position (contamination) of rather volatile compounds via a sealed gas-phas e ambient (e.g., wafer box) is less likely and thus less effective for a co ntrolled contamination. However, via wet chemical exposure, organic compoun ds could be deposited onto silicon wafers in a reproducible and quantitativ e way. Furthermore, multiple internal reflection Fourier transform infrared spectroscopy and time-of-Right secondary ion mass spectroscopy were effect ively applied to characterize organic material intentionally deposited onto silicon surfaces. (C) 2001 The Electrochemical Society. All rights reserve d.