Analysis of MEMS Structure Sidewalls for Carbon and Fluorinated Residue with SEM, EDS and TSA

The transition of MEMS and MOEMS devices from the laboratory to laminate-based (PCB) highvolume manufacturing is challenging. Devices now must be manufactured with low defect rates and high reliability. Micromanufacturing techniques used for deep reaction ion etching (DRIE) typically use fluorine plasma chemistries and can leave fluorinated sidewall residues that may release in the form of flakes. Sidewall residues that release as flakes can interfere with moving parts in fluidic and optical pathways, rendering the devices useless. Analysis of fluorine and other contamination can be quantified using Scanning Electron Microscopy (SEM) equipped with Electron Dispersive Spectroscopy (EDS). New EDS techniques, using fast DSP (Digital Signal Processor) controlled systems, add additional power to conventional EDS, capturing and analyzing significantly more X-Ray CPS (counts per second) than the older systems. Digital systems controlled by software provide additional analytical capability through post-processing. Trace Element Sensitivity Analysis (TSA), a new post-processing technique for chemical mapping of surfaces, enables detection of low level contamination that formerly would have been lost in the noise. It is capable of determining individual particle chemistry with excellent accuracy and traceability.