RF devices with enhanced performance and methods of forming the same

An apparatus comprising:

• a mold device die comprising a device region and a first mold compound, wherein:
• the device region includes a front-end-of-line (FEOL) portion and a back-end-of-line (BEOL) portion underneath the FEOL portion, wherein the FEOL portion comprises an active layer and isolation sections, which surround the active layer and extend vertically beyond a top surface of the active layer to define an opening within the isolation sections and over the active layer;
• the active layer is formed from a strained silicon epitaxial layer, wherein a lattice constant of silicon is greater than 5.461 in the strained silicon at a temperature of 300K;
• a passivation layer over the top surface of the active layer and within the opening, wherein the passivation layer is formed of silicon dioxide, silicon nitride, or a combination of both;
• and
• the first mold compound fills the opening and is in contact with the passivation layer, wherein silicon crystal, which has no germanium, nitrogen, or oxygen content, does not exist between the first mold compound and the active layer;
• a multilayer redistribution structure formed underneath the BEOL portion of the mold device die, wherein:
• the multilayer redistribution structure extends horizontally beyond the mold device die;
• and
• the multilayer redistribution structure comprises a plurality of bump structures, which are on a bottom surface of the multilayer redistribution structure, and electrically coupled to the FEOL portion of the mold device die;
• and
• a second mold compound residing over the multilayer redistribution structure to encapsulate the mold device die.