Paper NS-ThM4
Evaluation of High k Dielectric Films for Carbon Nanotube FETs

Thursday, October 18, 2007, 9:00 am, Room 616

Carbon nanotube FETs are promising candidates for future RF applications because they simultaneously offer high speed, high linearity, low power and low noise. Carbon nanotube FETs are projected to have a cut-off frequency of over 1 THz due to their small size and high carrier mobility, 1000x lower dissipated power than current GaAs devices without sacrificing linearity. Successful development of CNT electronics will enable the fielding of RF systems that are not currently possible because of prime power requirements. CNT FETs will have a large impact in RF electronics applications where linearity is critical. Based on our simulations, CNT FETs can be designed to be intrinsically linear provided one uses a gate dielectric material with dielectric constant >15. In our work we have evaluated several candidate materials such as HfO₂, ZrO₂, Ta₂O₅, TiO₂ etc. Thin films of these gate dielectric materials have been grown at various laboratories using different techniques. While sputtering is a standard technique used in the semiconductor industry, sputtering of these materials on to CNT significantly deteriorated the performance of the devices. Dielectric for gate oxide in our CNT IC process must have high dielectric constant, be compatible with CNT, have good dielectric integrity and have reasonable breakdown voltages. We will report our results on atomically smooth TiO₂ films using rf magnetron sputtering with auxiliary magnet under the substrate. In addition we will report on ALD HfO₂ and evaporated Ta₂O₅ films along with our results obtained from CNT FETs using these different gate dielectrics.