Analysis on the low-k benzo-cyclo-butene passivation of pseudomorphic high electron mobility transistors

In pseudomorphic high electron mobility transistors (PHEMT's), surface passivation for the devices is very important for ensuring the DC and RF performances as well as the reliability. We performed the comparative study on the DC, RF and noise characteristics of the 0.1 /spl mu/m gate length PHEMT's passivated by either the conventional Si/sub 3/N/sub 4/ or the low dielectric constant benzo-cyclo-butene (BCB)layers. The noise performance of the BCB passivation for the PHEMT's was much superior to that of the Si/sub 3/N/sub 4/, whereas the DC and other RF properties were not significantly affected by the passivation materials.