Low-κ BCB passivation on AlGaN-GaN HEMT fabrication

Due to the stress-induced polarization effect on the GaN HEMTs, the surface passivation of the device is critical and is deserved to conduct a detailed study. It has been proven that the GaN HEMTs demonstrate nondispersive pulsed current-voltage (I-V) characteristics and better microwave power performances after passivating the Si₃N₄ film on the GaN surface. In this letter, we proposed to use the BCB material, a negative photoresist with a low-κ characteristic, as the surface passivation layer on GaN HEMTs fabrication. After comparing the dc I-V, pulsed I-V, RF small-signal, microwave power characteristics, and device reliability, this BCB-passivated GaN HEMT achieved better performance than the Si₃N₄ passivated device.