3 - Packaging related technologies

The technology shown below is a technique for fabricating polisilicon cap over the micromachined structure on the silicon substarte. The basic concept is to build up a second structure using sacrificial micromachining then applying uniform deposition, which will cover the structure walls and finally closing the narrow tunnel on the cap. First a sacrificial layer is deposited over the ready-made micromachined structure then is is patterned. After that a poly-Si layer is deposited on top of the oxide layer. The next step is etching away sacrificial layer. Finally the tunnel is closed, using uniform deposition. (Source: Micro Nano, Sept. 2003, Vol. 8. No. 9.)