Micragem – SOI MEMS Process
Micragem™ is a SOI-based MEMS fabrication process with a set of design and process guidelines that can be used by companies to manufacture a number of different types of MEMS components in a standardized fashion.
At the basic level, Micragem™ is a four-mask lithography fabrication process. Depending on the level of customization required, more layers could be added to increase versatility.
The starting point is a 500 μm thick glass wafer. Mask 1 is used to pattern the glass wafer for the first etch. This etch can be used to define cavities, gaps, microfluidic channels, grooves for electrode lines, etc. The glass wafer is then etched isotropically using a wet etch up to a maximum depth of 100 μm.
The substrate is then lithographically patterned with Mask 2 for metallization. This mask is used to define actuation electrodes, metal lines, and bonding pads. The deposited metal is typically gold, however other metals can be used. A SOI MEMS wafer is anodically bonded device side down, to the patterned side of the glass wafer. The thickness of the SOI wafer generally varies from 10-100 μm, depending on the designer’s requirements.
The handle and buried oxide portions of the SOI wafer are etched away in a wet process, leaving a single crystal silicon membrane over the entire glass surface. Micralyne’s proprietary low stress gold is deposited on the silicon surface, and lithographically patterned with Mask 3. The metal is then etched to expose the silicon using a wet etch process.
Mask 4 is used for the final etch in the DRIE (Deep Reactive Ion Etch) tool, where the structures are released in a dry plasma, eliminating stiction problems. In the end is left a reliable, robust, and manufacturable device.
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The potential of this process technology in the MEMS field is profound.
The Micragem™ process is well suited to manufacture miniaturized micro-mirrors, diaphragms, beams and valves for a variety of applications.
Data Sheet Download:
»Micragem™ Data Sheet