Silicon Bulk Micromachining

Key elements of bulk micromachining are:

• Wet chemical etching
• High rate trench etching (Bosch Process)
• Anodic wafer bonding
• Chemical Mechanical Polishing (CMP)

With these techniques it is possible to fabricate silicon membranes with small tolerances for pressure sensors or air flow sensors. It also enables silicon-glass stacks for more complex structures. Standard automotive sensors are fabricated at Robert Bosch using bulk micromachining techniques in high volume (several tens of millions sensors per year).
 
Numerous devices have also been successfully fabricated using bulk micromachining including microfluidic structures for biological and medical applications.