Determination of bulk discharge current in the dielectric film of MEMS capacitive switches

Abstract

The present work presents a new method to calculate the discharge current in the bulk of dielectric films of MEMS capacitive switches. This method takes into account the real MEMS switch with non uniform trapped charge and air gap distributions. Assessment of switches with silicon nitride dielectric film shows that the discharge current transient seems to obey the stretched exponential law. The decay characteristics depend on the polarization field's polarity, a fact comes along with experimental results obtained from thermally stimulated depolarization currents (TSDC) method used in MIM capacitors.

Characterization of Dielectric Charging in MEMS Using Diffusive Representation

“…Accordingly, characterization of the charging dynamics is an important issue that has been studied using different methods. For instance, in [2] iterative measurements of pull-in voltage have been used to monitor the charge evolution with time. However, this strategy alters the amount of trapped charge and is not compatible with normal operation of the devices.…”

“…The use of this type of models is appropiate since diffusion processes have been associated with dielectric charging in MEMS [5]. Furthermore, there is a link in [6] between fractional systems and the typically observed multiexponential or stretched-time exponential type responses [2], [7] usually found in dielectric charging.…”

Charge induced by ionizing radiation understood as a disturbance in a sliding mode control of dielectric charge

“…This implies that an indirect measurement of the dielectric charge, Q n , is available at each sampling time nT S . This kind of measurement is insensitive to vertical shifts of the C-V that can be caused by charge inhomogeneity [18] or by changes in environmental factors such as temperature or humidity [19], [20]. Note that charge sensing is built-in with device actuation, so it is less invasive than other common methods used to detect the total charge, such as measuring V sh as the displacement of the pull-in voltage (which involves applying voltage stress to close the device and thus takes time and dramatically alters the charge status) or performing shortrange C-V measurements to detect the displacement of the minimum of the curve [21].…”

Identification of the transient stress-induced leakage current in silicon dioxide films for use in microelectromechanical systems capacitive switches

“…8,10 Dielectric charging of the intermetal dielectric of capacitive switches is most commonly studied; however, charging of the substrate layers in ohmic 12 and dielectricless capacitive 9 switches has also been reported. The evolution of pull-in voltage with stress time has been modeled by either exponential, 7 stretched exponential, [12][13][14] or power-law equations. 9,15 Both the pull-in and release voltages of capacitive switches can be simultaneously affected by mechanical degradation and dielectric charging.…”

“…2 However, mechanical degradation in the form of air gap change can affect V Cmin measurements by changing the value of the minimum capacitance and therefore the calculated amount of charge. 4,13 The devices used in this work are shunt capacitive switches fabricated over co-planar waveguide structures. 16 The substrate was composed of high-resistivity silicon wafers with 2 lm thick initial oxide deposited by plasma enhanced chemical vapor deposition (PECVD).…”