A bonded multi-layer RF window may include an external layer of dielectric material having desired thermal properties, an internal layer of dielectric material exposed to plasma inside a reaction chamber, and an intermediate layer of bonding material between the external layer and the internal layer. Heat produced by the chemical reaction inside the chamber and by the transmission of RF energy through the window may be conducted from the internal layer to the external layer, which may be cooled during a semiconductor wafer manufacturing process. A bonded multi-layer RF window may include cooling conduits for circulating coolant to facilitate cooling of the internal layer; additionally or alternatively, gas distribution conduits and gas injection apertures may be included for delivering one or more process gases into a reaction chamber. A system including a plasma reaction chamber may employ the inventive bonded multi-layer RF window.