High Resistivity Trap-Rich Substrate for RF MEMS Switches

DC-40 GHz single pole double throw (SPDT) microelectromechanical (MEMS) switch designed and manufactured on top of high resistivity (HR) and advanced trap-rich (TR) silicon substrates have been characterized and compared. It has been shown that the passive devices designed on TR substrate sense an effective resistivity 10 times higher than the ones designed on HR substrate. The insertion loss on an SPDT implemented on TR is 0.39 dB lower than the one on HR at 10 GHz and 0.9 dB lower at 40 GHz. Moreover, in terms of device linearity, the level of the second harmonic H2 is 20 dB lower for TR than for HR substrate, demonstrating the high efficiency of trap-rich substrate. To the authors knowledge, this is the first MEMS on TR substrate used for radio-frequency applications.