A semiconductor package that contains an application-specific integrated circuit (ASIC) die and a micro-electromechanical system (MEMS) die. The MEMS die and the ASIC die are coupled to a substrate that includes an opening that extends through the substrate and is in fluid communication with an air cavity positioned between and separating the MEMS die from the substrate. The opening exposes the air cavity to an external environment and, following this, the air cavity exposes a MEMS element of the MEMS die to the external environment. The air cavity separating the MEMS die from the substrate is formed with a method of manufacturing that utilizes a thermally decomposable die attach material.