Analysis of the Failure and Performance Variation Mechanism of MEMS Suspended Inductors with Auxiliary Pillars under High-g Shock.

Lixin Xu,Yiyuan Li,Jianhua Li

doi:10.3390/mi11110957

Abstract

Microelectromechanical systems (MEMS) suspended inductors have excellent radio frequency (RF) performance and they are compatible with integrated circuit (IC). They will be shocked during manufacturing, transportation, and operation; in some applications, the shock amplitude can be as high as tens of thousands of gravitational acceleration (g, 9.8 m/s2). High-g shock will lead to the inductor deformation which affects its performance or even failure of the inductor structure. However, few studies have been carried out on the inductors under high-g shock. In this study, a kind of MEMS suspended inductor with excellent RF and mechanical performance is designed and fabricated. The failure and performance variation mechanism of the inductor under high-g shock is analyzed by measuring and comparing the performance measurement results and the π model parameters extraction results of the inductors before and after air cannon shock test. The results show that the increase of energy loss caused by substrate parasitic effect and the properties variation of the coil material affected by high-g shock are the main reasons for the decrease of RF performance parameters, and the critical stress exceeding the interlayer adhesion is the main reason for the failure of the inductor.

Highlights

The inductor is one of the main passive components in radio frequency integrated circuits (RFIC)
A kind of Microelectromechanical systems (MEMS) suspended inductor with excellent RF and mechanical performance is designed and fabricated, the RF performance variation and failure mechanism of the MEMS suspended inductor under high-g shock of which acceleration amplitude is as high as tens of thousands of g are studied with this kind of inductor
The performance variation is mainly due to the variation of the substrate parasitic effect caused by the deformation of the inductor coil and related to the variation of the properties of the coil material affected by high-g shock

Summary

Introduction

The inductor is one of the main passive components in radio frequency integrated circuits (RFIC). No matter which direction the MEMS suspended inductor coil vibrates and deforms, the position where the coil is connected with the pillar of port 1 (see Figure 1) is the critical point as the maximum stress of the inductor occurs at this position This position will first reach the yield strength or even tensile strength of the coil material, i.e., copper, and lead to plastic deformation and even fracture failure of the coil. Considering the actual shock waveform and the inductor fabrication process, when the positive half sine wave was loaded to the inductor, the inductor coil vibrated downward and the maximum compressive stress occurred at the position where the coil was connected with the pillar of port 1. The failure mode of the inductors in the shock test was the whole inductor coil falling off

Results and Discussion

Analysis of the RF Performance Variation Mechanism of the Intact Inductors

Conclusions