Use of Flowable Oxides for Mesa Gap Fill and Planarization of AlGaN/GaN HEMT Devices

摘要

Use of Flowable Oxides for Mesa Gap Fill and Planarization of AlGaN/GaN HEMT Devices A device isolation scheme for GaN on Si HEMT structure has been suggested using a novel gap fill technique with flowable oxides. Flowable oxides does not require post deposition CMP. Mesa isolation and gap fill with flowable oxide is accomplished prior to the source, drain and gate definition. Active region is covered with SiO/Si3N4 passivation layer (15) and mesa areas are defined through passivation windows. This technique suggests to deposit an insulating layer (19) in the mesa areas by filling the gap with flowable oxides e.g. SOG or silsesquioxane (HxSiO1.5, where x≤1 ). A further surface planarization is achieved through an etch- back process. Subsequently, necessary steps are carried out for the processing of source-drain and gate using prior art to the complete the HEMT transistor fabrication.