High etch rate, deep anisotropic plasma etching of silicon for MEMS fabrication

MEMS fabrication faces multiple technological challenges before it can become a commercially viable technology. One key fabrication process required is the deep silicon etching for forming high aspect ratio structures. There is an increasing interest in the use of dry plasma etching for this application because of its anisotropic (i. c. independent of silicon crystal orientation) etching behavior, high etch rate, and its compatibility with traditional IC processing. Alcatel has developed a patented inductively coupled high density plasma source which delivers high etch rate, uniform, anisotrop c silicon etching to depths as deep as 500 mum. This plasma source has been used for fabricating devices such as accelerometer, yaw rate sensors etc. Etch process performance data on some of these devices will be presented. Thus the Alcatel deep etching system provides the enabling technology required for deep silicon micromachining of microsensors.