Apparatuses and methods for cleaning a semiconductor processing chamber is provided. The semiconductor processing chamber may include a UV radiation source, a substrate holder, and a UV transmissive window. The UV transmissive window may include one or multiple panes. One or more panes of the UV transmissive window may be non-reactive with fluorine containing chemistries. In multi-pane windows a purge gas flow path may be formed in the gap between windows. A purge gas may be flowed through the purge gas flow path to prevent process gases used in the chamber interior from reaching one or more panes of the UV transmissive window.