Homework #2
Assigned: Aug. 12th, 2010
Due: Aug. 19th, 2010
Points: 30

• 15 points
  You have seen in the popwerpoint presentation how in-plane and out-of-plane hinges can be realized in surface micromachining processes. Now, by assuming a surface micromachining process that has two structural layers and two sacrificial layers, describe how a sliding joint can be realized. A sliding joint allows a slider to move freely along a straight line. The slider should not fall out when the substrate is tilted. No assembly or any type of modifications are allowed. It should batch producible through depositing, patterning, and ecthing steps. You should should submit a step-by-step cross-section views and a 3D view also (sketch by hand to the best of your ability or use a CAD software). Give also the mask drawings as view the wafer from the top.
  Can you realize a slider with only one sacrificial layer and one structural layer? Describe if you know how to do it.
• 15 points
  By reading the following description of a microfabrication process, sketch the step-by-step cross-sections and the final device in 3D (sketch by hand or use a CAD software).
  "A silicon-on-insulator (SOI) wafer consists of 150 um thick handle layer and a 20 um thick device layer with a 1 um thick oxide later sandwiched in between. The device layer is ecthed using reactive ion etching to leave out a square of 800 um side while protecting the handle layer. The handle layer is eteched using KOH to make a rectangular hole of 500 um for a long time while protecting the device layer. Subsequently the exposed oxide layer was etched away using HF acid."
  For what purpose can this device be used? What further steps do you need to use it for that purpose?