Exploration of Damage Mechanisms in MEMS Based Memory and Logic Devices
Abstract
The beneficial size, weight, and power requirements provided by micro-electromechanical (MEMS) and nanoelectromechanical (NEMS) memory, logic and sensors for military systems operating in extreme radiation environments make it essential that the effects of radiation on MEMS/NEMS devices be investigated. Advanced micromechanical memory, logic, and sensing devices incorporate complicated mechanical structures and sensing mechanisms for their operation. A range of materials including silicon, silicon dioxide and nitrides, polymers, ceramics, and ferromagnetics are used. Radiation exposure can impede the functionality of a mechanically-based memory due to atomic displacements, degradation, and through charge trapping. Mechanical properties, electrostatic interactions, and sensing mechanisms can all be affected. The interplay of damage mechanisms in published experiments of commercial MEMS devices makes it difficult to identify the ultimate cause for failure. Missing is a systematic investigation on the effects of radiation in the mechanical and electrical components that make up the MEMS devices. In this project, we will explore the influence of radiation on critical structures of MEMS memory and logic devices to reveal the extent to which radiation influences the MEMS properties and to determine the mechanisms behind the radiation induced changes. Our team will focus on the fundamental physics of radiation effects as it applies to MEMS/NEMS devices consisting of the following elements: (1) Fundamental Model Systems and Calculations: Microscale resonators and diaphragms are simple enough that the influence of radiation can be determined independent of extraneous complications (e.g. material interactions, built-in potentials, dielectric charging, and measurement electronics). Nevertheless, their operating principle is essential to almost all MEMS memory and logic components. (2) Exposure Source, Time and Energy Dependencies: Exposure to radiation sources that can either induce trapped charge effects only (e.g., x-rays or gamma rays) or trapped charge and displacement damage effects (e.g., protons) will assist in determining the failure mechanisms. Radiation exposure has an immediate impact on MEMS device function. In-situ monitoring of MEMS operation during exposure is essential for predicting function during WMD attack, or nuclear catastrophe, particularly for memory storage and logic devices. Time and temperature healing experiments will determine the energy distribution of trapped charge. (3) Bi-stable Memory and Logic Elements The knowledge gained in previous sections provides the basis for a study of memory and logic elements relying on bi-stable mechanical structures. These are particularly sensitive to radiation induced changes in their switching voltage and transition to chaotic motion. The non-linear forces allow for a more sensitive determination of structural changes than is possible using a simple resonator. (4) Device Geometry and Materials Dependencies: As the dimensions of the resonators are reduced—transitioning from micro to nano electromechanical systems—new damage mechanisms and increased sensitivity to existing mechanisms arise. Resonators coated with a variety of dielectrics, disordered semiconductors, piezoelectrics, and ferromagnetics are used to determine the influence of radiation on under-characterized material systems of interest for MEMS application
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- May 26, 2016
- Source ID
- HDTRA11510027
Entities
People
- Bruce Alphenaar
Organizations
- Defense Threat Reduction Agency
- University of Louisville