Resonant Body Transistors in IBM's 32 nm SOI CMOS Technology

Abstract

This work presents an unreleased CMOS-integrated MEMS resonators fabricated at the transistor level of IBM's 32SOI technology and realized without the need for any post-processing or packaging. These Resonant Body Transistors (RBTs) are driven capacitively and sensed piezoresistively using an n-channel Field Effect Transistor (nFET). Acoustic Bragg Reflectors (ABRs) are used to localize acoustic vibrations in these resonators completely buried in the CMOS stack and surrounded by low-k dielectric. Experimental results from the first generation hybrid CMOS-MEMS show RBTs operating at 11.1-11.5 GHz with footprints < 5µm × 3µm. The response of active resonators is shown to contrast with passive resonators showing no discernible peak. Comparative behavior of devices with design variations is used to demonstrate the effect of ABRs on spurious mode suppression. Temperature stability and TCF compensation due to complimentary materials in the CMOS stack are experimentally verified.

Three-Dimensional Nano-Acoustic Bragg Reflectors for CMOS Embedded NEMS

“…This shows the extreme importance of performing 3D simulations to have a better estimation of the behavior of the designed structures. This is in contrast with some previous works in the literature which have only performed 2D simulations [19,28,29]. Comparing Figure 3.d with Figure 3.b offers also a visual proof that the confinement in 3D is not as good as in the case of 2D.…”

“…We have evaluated the electromechanical coupling of these devices, obtaining 0.015% for a total FOM of 0.46. The use of metal as the structural material for the resonator allows us to better encase the acoustic energy without reducing too much the electromechanical coupling unlike simulated and experimental demonstration in [28]. Further work involves experimental verification of this novel design and scaling down to even smaller nodes than 65 nm, where Q should be able to reach higher values and electromechanical coupling should be boosted.…”

Analysis and Design of Weakly Coupled LC Oscillator Arrays Based on Phase-Domain Macromodels

“…In addition, new emerging technologies will soon allow efficient, large-scale integration of oscillator arrays. One example of such technologies is the CMOS-integrated MEMS device resonant body transistor, which has demonstrated quality factors comparable to LC tanks (Q ∼ 25) while occupying orders of magnitude smaller area (device footprint < 15 µm 2 ) [3]. In practical implementations, weak coupling is particularly appealing since it can be realized with auxiliary devices at the cost of negligible power dissipation.…”

Modeling and Simulation of Vanadium Dioxide Relaxation Oscillators

“…This trajectory corresponds to the projection of the limit cycle onto the (V s1 , V s2 ) subspace. 2 Simulations reveal that the responses of the mismatched os- 2 The two coupled oscillators are a dynamic system with four state variables: the external variables Vs 1 (t), Vs 2 (t) and the intrinsic variables Vc 1 (t), Vc 2 (t) of the VO 2 devices. cillators can still be realigned in phase by gradually increasing the coupling strength.…”