Investigating Graphene gNEMS ESD Switch for Design Optimization

Abstract

Traditional in-Silicon PN-junction-based on-chip electrostatic discharge (ESD) protection structures have inherent ESD-induced design overhead problems, including parasitic capacitance, leakage and Si area consumption. A potential solution to the ESD design overhead challenge is to use a non-conventional above-Si graphene-based nano-electrical mechanical system (gNEMS) transient switch structure to protect integrated circuits (ICs) against ESD failures. This paper reports investigation of materials and device structural impacts on gNEMS ESD protection structures. Transmission-line pulse (TLP) testing confirms that single-crystalline graphene gNEMS switch achieves a record high ESD currenthandling capability of J t2 ∼1.03×10 9 A/cm 2 , at least four times higher than J t2 ∼0.24×10 9 A/cm 2 for its poly-crystalline graphene counterpart. Transient 3D finite element method (FEM) simulation reveals that both device dimensions and shapes of the suspended graphene membranes can substantially affect gNEMS ESD discharging characteristics. The discovery offers guidelines for design optimization of gNEMS ESD switch structures.

Graphene-Based ESD Protection for Future ICs

“…Figure 12c illustrates the I-V curve of ESD for gNEMS under ultra-fast VFTLP stress test (t r = 100 ps and t d = 1 ns), which clearly shows that the gNEMS can respond to the ESD pulses of the ultra-fast-charged device model (CDM). According to the VFTLP test results, V t1 ~4.2 V and I t2 ~31.3 mA are observed for the gNEMS device [12,16].…”

“…As temperature increases, V t1 decreases. Higher temperature also affects the current handling capability of gNEMS due to thermally induced defects in the graphene membrane [16].…”

“…This simulation helps to optimize the gNEMS design for which the ESD-induced pull-down force and elastic recovery force are considered to ensure the gNEMS ESD switching function. After the TLP pulse is over, the ESD-induced electrostatic force will immediately disappear, and the intrinsic elastic force will dominate and pull up the bent graphene ribbon back to its original position, thus turning the gNEMS OFF [16].…”

“…This simulation helps to optimize the gNEMS design for which the ESD-induced pull-down force and elastic recovery force are considered to ensure the gNEMS ESD switching function. After the TLP pulse is over, the ESD-induced electrostatic force will immediately disappear, and the intrinsic elastic force will dominate and pull up the bent graphene ribbon back to its original position, thus turning the gNEMS OFF [16]. FEM simulation can also be used to investigate the stress effect of the suspended graphene ribbon in a gNEMS under ESD zapping and hence provide design guidelines for improving the mechanical reliability of gNEMS devices.…”

Electrostatic pull-in application in flexible devices: A review

“…Ng et al [ 66 ] conducted stress tests on the prepared GR-NEM switch and proposed a nail structure to improve reliability. Li et al [ 67 – 70 ] compared the effects of graphene materials on ESD performance. Due to the removal of grain boundaries, the single-crystal GR devices are four times more capable of handling current than polycrystalline GR devices.…”