A semiconductor device includes a substrate, an integrated passive device (IPD), and a phase-change material (PCM) radio frequency (RF) switch. The PCM RF switch includes a heating element, a PCM situated over the heating element, and PCM contacts situated over passive segments of the PCM. The heating element extends transverse to the PCM, with a heater line underlying an active segment of the PCM. The PCM RF switch is situated over a heat spreader that is situated over the substrate. The heat spreader and/or the substrate dissipate heat generated by the heating element and reduce RF noise coupling between the PCM RF switch and the IPD. An electrically insulating layer can be situated between the heat spreader and the substrate. In another approach, the PCM RF switch is situated over an RF isolation region that allows the substrate to dissipate heat and that reduces RF noise coupling.