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Hands-on design training for MultiMEMS
D. Lapadatu and P. Ohlckers

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| 4.1 Step by step

Open the emptied layout file provided under Support material, Files, Layout with emptied cells | After opening the file, you should see an overview of the emptied file. |
Open the cell 'THROUGH_HOLE' | When you open the cell 'THROUGH_HOLE' you will se an empty rectangle. This is the cell outline. If you position your hole inside this rectangle, it will automatically be correctly positioned in the final assembly. This is done to simplify the exercise. |
Define a NOWEL rectangle | To define a region that is possible to etch through with the 10 micron deep front side DRIE, a rectangle of NOWEL must be added over the region. Due to lateral diffusion, the deep n-well will diffuse under the mask opening, so we should add 100 micron clearing to the mask feature. Knowing that the dimensions of the hole are to be at least 400 X 750, we draw a rectangle of 600 X 950 centred in the cell. |
Your design should now look like this |

Use the bulk etch calculator to calculate dimensions for BETCH

- Open the Bulk etch calculator which you can download from http://www.multimems.com/Downloads/BETCH_Calculator.htm
- Switch to the 'MEMBRANES' sheet.
- In the field WME and LME, under thin membrane size, enter the desired values.These values correspond it the dimensions on the help mask [BETCH].
- Under outputs you will find the nominal dimensions required for BETCH to produce a thin membrane of 400 X 750 microns size.

Draw the BETCH and [BETCH] mask features and your design should look something like this. |

Add a rectangle on the RETCH mask layer

- Select the RETCH layer and add a 400 microns X 750 microns rectangle in the centre of the cell.
- Your result should look something like illustrated to the right.

Your top level cell should now look something like this. |

Save the file

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STIMESI training on MULTIMEMS |
Last updated: June. 2009 24.06.2009