Method for manufacturing heterojunction field effect transistor device

Abstract

A method for manufacturing a hetero-junction field effect transistor (HFET) device, which includes sequentially forming a non-doped GaN semiconductor layer and an AlGaN semiconductor layer on a substrate, separating devices from each other by etching the substrate, forming a photoresist layer pattern on the AlGaN semiconductor layer and forming gate electrodes by depositing a material on the substrate using the photoresist layer pattern, treating the surface of the AlGaN semiconductor layer, and forming a photoresist layer pattern on the substrate and forming ohmic electrodes by depositing a metal on the substrate using the photoresist layer pattern, is provided. Accordingly, it is possible to overcome a difficulty in aligning the gate electrode with the ohmic electrodes and prevent a substrate from having a step difference introduced by the ohmic electrodes because the gate electrode is formed before the ohmic electrodes are formed. It is possible to form a finer photoresist layer pattern used to form the gate electrode and improve the degree, to which the gate electrode is aligned with the ohmic electrodes. In addition, since the surface of an AlGaN semiconductor layer is treated with ICP before the ohmic electrodes are formed. Thus, it is possible to obtain ohmic characteristics without heat-treating a metal deposited on the AlGaN semiconductor layer to form the ohmic electrodes. Finally, since the maximum transconductance and maximum drain current characteristics of the AlGaN/GaN HFET device are good, the AlGaN/GaN HFET device can have improved amplification capability.