Comparison of multi-level metallization structure and conventional metallization structure in lateral-type AlGaN/GaN HFETs

This paper reports on the comparison of AlGaN/GaN heterostructure field-effect transistors (HFETs) with multi-level metallization structures and conventional metallization. The epitaxial structures were grown on a 150-mm Si substrate. Photosensitive polyimide (PSPI) was used for a patterned inter-metal dielectric (IMD) layer of multi-level metallization. Maximum drain current of the HFETs with the multi-level metallization structure is ∼24 A, which is ∼3.4 times higher than that of the conventional M1-structured HFETs with the same size of chip. In addition, the reliability of the HFETs with the multi-level metallization is improved by using the PSPI-IMD layer, which successfully reduces the wire bonding and epoxy molding process. These results clearly show that the multilevel-metallization structure is an effective way to increase the output power and to improve reliability during plastic package process in AlGaN/GaN HFETs.