An ultraviolet (UV) cure chamber enables curing a dielectric material disposed on a substrate and in situ cleaning thereof. A tandem process chamber provides two separate and adjacent process regions defined by a body covered with a lid having windows aligned respectively above each process region. One or more UV sources per process region that are covered by housings coupled to the lid emit UV light directed through the windows onto substrates located within the process regions. The UV sources can be an array of light emitting diodes or bulbs utilizing a source such as microwave or radio frequency. The UV light can be pulsed during a cure process. Using oxygen radical/ozone generated remotely and/or in-situ accomplishes cleaning of the chamber. Use of lamp arrays, relative motion of the substrate and lamp head, and real-time modification of lamp reflector shape and/or position can enhance uniformity of substrate illumination.