Disclosed are integrated circuit (IC) chip structures (e.g., radio frequency (RF) IC chip structures) and methods of forming the structures with an electrically insulative molding compound handler substrate. Each structure includes at least: an electrically insulative molding compound handler substrate; an insulator layer on the handler substrate; and one or more semiconductor devices (e.g., RF semiconductor devices) on the insulator layer. Each method includes at least: attaching a temporary carrier above back end of the line (BEOL) metal levels, which are over an interlayer dielectric layer covering one or more semiconductor devices; removing at least a portion of a semiconductor handler substrate, which is below the semiconductor device(s) and separated therefrom by an insulator layer; replacing the semiconductor handler substrate with a replacement handler substrate made of an electrically insulative molding compound; and removing the temporary carrier. The molding compound handler substrate provides backside isolation that prevents unwanted noise coupling.