Question

differences between bulk micromachining and surface micromachining

Answer 1

The bulk process
 offers many advantage


Out of plane displacement.
Precision gap control 1.5 %...
Gap of 2 um..
Mass weight 5 to 15 milligrammes..
Capacitor 15 to 50 p..
FLow noise and high stability..
Surface micromachining are characterized by the following properties:

In plane displacement
Precision gap control 17 %
Gap of 4 to 6 um
Mass weight 0.03 to 0.3 milligrammes
Capacitor 2 to 5 pF


Bulk vs Surface micromachining can be resumed into these points:

Weight vs precision – as more weight offers more capacitance, thus more accuracy
Single axis vs multi-axis – surface micromachining can measure 2D and 3D acceleration
Cost vs stability – the bulk design is more expensive, but is also more stable than surface micromachining