Characterization of frequency tuning using focused ion beam platinum deposition

Abstract

This paper presents and characterizes focused ion beam (FIB) platinum (Pt) deposition as a novel frequency tuning method for micromechanical resonators. FIB Pt deposited tuning was performed at room temperature and in contrast to other reported methods, frequency changes were achieved without any device failure. To perform the tuning, Pt was deposited on a 13 µm× 5 µm surface area at the free end of 3C silicon carbide (SiC) and polysilicon cantilever resonators in thicknesses ranging from 0.5 µm to 2.6 µm. To determine the amount of tuning, the resonant frequency of SiC and polysilicon devices was measured before and after Pt deposition. Frequency measurements performed before Pt deposition found that SiC resonators operated at higher resonant frequencies and quality (Q)-factors than their polysilicon counterparts. Measurements after Pt deposition on SiC and polysilicon resonators confirmed the predicted maximum frequency change of −15.5% made by FEM simulations and analytical modelling. Due to their lower mass, polysilicon resonators showed a larger frequency change than their SiC counterparts. A Q-factor decrease was observed for SiC and polysilicon resonators due to thermoelastic damping associated with the deposited Pt and surface contamination.

Single-crystalline 4H-SiC micro cantilevers with a high quality factor

“…Q of all 4H-SiC cantilevers was nearly 200,000, while Q of the 3C-SiC cantilevers was nearly 20,000. Enderling et al reported Q of a 3C-SiC cantilever in vacuum condition to be 14,755 [16], and Q of our 3C-SiC cantilevers was similar to this reported value. Q of 4H-SiC cantilevers was 10 times that of 3C-SiC.…”

Electrical Characterization of Microelectromechanical Silicon Carbide Resonators

“…Silicon-based MEMS resonators are used as timing references in applications that require a device technology that can range from very low to ultra-high frequencies. Silicon carbide (SiC) is a promising material for RF MEMS because it has a high Young's modulus-to-density ratio, resulting in an acoustic velocity that is significantly above that of Si [3, 4]. Furthermore, SiC is more resistant to mechanical wear, more electrically stable at higher temperatures, and significantly more inert to environmental conditions than Si, making it a potential substitute for Si in harsh environment applications [5].…”

Nonvolatile Rewritable Frequency Tuning of a Nanoelectromechanical Resonator Using Photoinduced Doping

“…Although differs by ~27 V between the two states, the gate-dependence of each mode relative to doesn't change, as seen in Figure 1d-e. Thus, apart from the shift, the phototuning process does not appear to alter the mechanical characteristics of the device in a significant way, unlike most passive tuning methods 25,26 . The individual resonance curves corresponding to the erased and = 30 states are shown in Figure 1f.…”