Bulk Micromachining - An Etch Process Kit

(Formerly Anisotropic Etch Kit)


This kit supports the Etch Overview and the MTTC Micro Pressure Sensor Process Learning Modules.

This kit provides the opportunity for participants to perform and observe a bulk micromachining process - an anisotropic etch - using an actual pressure sensor process chip.  The chip has been patterned with silicon nitride to identify the areas to be etched.  This particular etch process is used to form a cavity on the backside of a silicon wafer.  The cavity is the reference chamber for a micro pressure sensor.
The kit contains seven chips as well as a Teflon chip holder.  It also contains a scale for measuring sodium hydroxide and a 1 liter beaker for the process chemical (supplied by the instructor).  The Etch Overview for
Microsystems Learning Modules are included.  See more….

Note: Because the sodium hydroxide is hazardous, a fume hood and special personal protective equipment is required.  Participants are required to study the Material Safety Data Sheet for sodium hydroxide prior to starting the activity.  All lab and chemical safety rules must be observed while completing this activity. The instructor must supply a gallon of distilled water and, due to regulations concerning the shipping of hazardous materials, the sodium hydroxide (heavy duty drain cleaner).
Kit refills are available which consist of replacement, un-etched chips.

Where can I use this kit?

If you teach any of the following topics, this kit can add an exciting hands-on element to your students' learning:
  1. Crystallography (materials science) - We all are familiar with the diamond and how various facets are cut depending on the orientation of the various crystal planes.  This is also true in etching complex structure while making Microsystems devices.  The fact that different planes etch at different rates is used to fabricate different types of structures, from cavities and microfluidic channels to nozzles and microscale proof masses.
  2. Chemistry and Chemical Etching - The use and application of proper safety procedures including personal protective equipment is a key skill and knowledge component that is reinforced with this kit.  The etching of crystalline silicon involves a multi-step process to dissolve the silicon diamond structure.  By varying the temperature and concentration of the solution, students can run a series of experiments to optimize the etch time and quality of the resulting etched surfaces.
  3. MEMS Fabrication - Bulk Micromachining is one of several main processes used in the fabrication of MEMS devices.  One way to remove large quantities of material on the macro scale is to use anisotropic etching of crystal silicon.  This brings together chemistry and materials science applied to create a micro device.



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