Porous Silicon Micromachining Techniques for Accelerometer Fabrication

In this paper an epi-micromachining technique is presented which combines the advantages of both surface and bulk micromachining. The process is based on the use of a buried sacrificial porous layer and offers high flexibility. Horizontal and vertical accelerometer structures have been fabricated using the epitaxial layer as construction material. Buried p⁺ silicon was used as sacrificial material by selective porous formation of this layer. P⁺ silicon can be made porous by anodic etching in HF. This porous layer can later be removed using diluted KOH at room temperature.