Kelvin probe microscopy for reliability investigation of RF-MEMS capacitive switches

Abstract

probe microscopy for reliability investigation of RF-MEMS capacitive switches. Microelectronics Reliability, Elsevier, 2008, 48, pp.1232-1236 Kelvin probe microscopy for reliability investigation of RF-MEMS Capacitive Switches Abstract: In this work, we investigate the charging and reliability of interlayer dielectric materials that are used in the fabrication process of advanced RF-MEMS switches. In particular, the charge stored on the surface of a dielectric and the dynamic of this charge at Nanometric scale are studied. More attention is given to the decay of the deposited charge by a variety of means: (1) surface conduction, (2) surface charge spreading due to self repulsion and (3) charge injection in the bulk of dielectric material. EFM measurement was performed for various injection time and bias to recorded surface potential. These results suggest a dynamic charge and allow predicting the amount of charge injected into the dielectric.

Physics of Charging in Dielectrics and Reliability of Capacitive RF-MEMS Switches

“…On the other hand the surface potential induced by charges injected with the Kelvin probe tip was found to decay following the stretched exponential law. Finally, the decay time constant was reported to depend on the dielectric material and practically not affected by the tip potential (Belarni 2008).…”

“…A method that approximates more precisely the charging process through asperities and surface roughness in MEMS and allows the monitoring of the discharging process is the Kelvin Probe Force Microscopy (Nonnenmacher 1991). This method has been recently employed for the investigation of the charging and discharging processes in capacitive switches , Belarni 2008. The charging of the dielectric film occurs independently of the actuation scheme and the ambient atmosphere (Czarnecki et al 2006).…”

New insights into reliability of electrostatic capacitive RF MEMS switches

“…FT-IR spectroscopy has been performed to provide information about the chemical bonds of the dielectric film and their variations. The infrared spectra were acquired in the 400-4000 cm 21 range with BIORAD FTS60A spectrometer with the samples under nitrogen flow to avoid the effect of humidity and ambient. The reflection and transmission modes were employed for SiN x layers deposited on metal and silicon, respectively.…”

“…Also, the wavenumber of each bond for HF-Evap Au and LF-Evap Au is listed in Table 4. It is evident that there is a strong Si-H bond at around 2150 cm 21 and N-H bond at around 3356 cm…”

“…First, it efficiently simulates charging and discharging conditions of MEMS capacitive switches providing qualitative information on dielectric free surface charge distribution and decay [20][21][22][23][24][25][26]. Second, the KPFM-based methodology provides a low cost and quite fast solution compared to the currently available assessment methods since the required samples for this approach consist only of thin dielectric films deposited over planar substrates, and no photolithography steps are required during the sample preparation [26].…”