Controlled Deposition of Organic Contamination and Removal with Ozone-Based Cleanings

Abstract

Organic contamination has an impact on semiconductor product yield. Therefore, the removal of typical organic contamination, originating from clean room air, wafer boxes, and wafer handling, is required. The cleaning efficiency of ozone-based cleaning processes is evaluated. Different cleans are effective in removing monolayers of typical clean room contaminants on silicon wafers. The organic target molecules under study represent some of the typical clean room contaminants encountered in silicon technology, i.e., dioctyl phthalate, stearic acid, butylated hydroxy toluene, some siloxanes (octamethylcyclotetrasiloxane and decamethyltetrasiloxane), a surfactant (4-dodecylbenzenesulfonic acid), and A prerequisite for measuring the removal efficiency of ozonated cleans for submonolayer organic contamination has been the development of a controlled, reproducible, and quantitative deposition method for those species. Exposure to a sealed ambient of organic compounds and wet chemical exposure were assessed. It is found that deposition (contamination) of rather volatile compounds via a sealed gas-phase ambient (e.g., wafer box) is less likely and thus less effective for a controlled contamination. However, via wet chemical exposure, organic compounds could be deposited onto silicon wafers in a reproducible and quantitative way. Furthermore, multiple internal reflection Fourier transform infrared spectroscopy and time-of-flight secondary ion mass spectroscopy were effectively applied to characterize organic material intentionally deposited onto silicon surfaces. © 2001 The Electrochemical Society. All rights reserved.