ECE G244, MTM G260, Homework #2, Due Sept. 26, 2006.

Problem 1.

Design a process flow and mask set to fabricate a cantilever beam. Simulate the process using SIMPLer. You should use one dark field mask, and one clear field mask (in a clear field mask, the structures block light and the remaining area (the field) is clear). Note that you do not need to release the structure and free the beam. Turn in the top and cross sectional views. The finished cross section should look something like this:

Problem 2.

Design a process flow and mask set to fabricate a microswitch. The microswitch should have metal leads connected to each end, a metal cantilever beam, and a metal or polysilicon gate. Remember that you generally cannot deposit polysilicon after metal. Simulate your design using SIMPLer. Turn in the top and cross sectional views. Comment on the process requirements to free the structures. What enhancements to your structure are possible?

Problem 3.

Propose 3 different materials systems for building released cantilever beams. What I want are 3 beam/sacrificial layer pairs, with a possible etch process for each pair, with no materials repeated! You may need to refer to a process reference or the literature. Also be careful not to use a high temperature deposition process on top of a material which is not stable at high temperatures!

Problem 4. 3.1, Senturia.

Problem 5. 3.2, Senturia.

Problem 6. Problem 3.3, Senturia.

Problem 7. Problem 3.4, Senturia. Assume that the diaphragm thickness is well-controlled at 20 microns for all the assumed wafer thicknesses. Assume a KOH etch.

Problem 8. 4.6, Senturia.

Problem 9. Find a research paper in the literature that has a good description on a MEMS process flow.

a. Does the process have non-IC fabrication process steps - that is, does the process have steps that are not generally used in integrated circuit fabrication?

b. Is the process compatible with IC fabrication? If so, how? Are the MEMS structures fabricated at the same time, or afterward, or something else? If it is not compatible, why not, and how would you incorporate electronics with the device (if it would have electronics!)?

c. What kind of packaging is used, or would be used if it is unpackaged?

d. How many masks is the process? Try to figure this out by understanding the process, if the answer is not obvious.

e. Turn in a copy of the paper with this problem.