Cyclized-perfluoropolymer, which is commercialized under the trade name CYTOP (TM), possesses the desirable properties of low dielectric constant (epsilon(r) = 2. 1) and low dissipation factor (tan delta = 0.0007). We have developed a method to integrate CYTOP (TM) dielectric interlayer with state-of-the-art power GaAs-based enhancement mode pseudomorphic high electron mobility transistor. CYTOP (TM) thin films with approximately 3.5 mu m in thickness was spin-coated and patterned on wafers with completed transistor and nitride passivation processes. Au-based interconnect metal was then fabricated using sputtering and plating processes over the CYTOP (TM) dielectric layer. The whole integrated structure was found to be stable at annealing temperatures up to 200 degrees C. Moreover, output power, gain, and power added efficiency of the CYTOP (TM) -integrated 0.5 mu m gate transistor was measured and compared with standard air-bridged devices. The studies show that the CYTOP (TM) low-k dielectric layer has negligible effect on the device performances as compared with the air-bridged devices. (c) 2005 Elsevier Ltd. All rights reserved.