The Versaline Series FDRIE is used to fast etch deep anisotropic trenches in silicon substrates using the patented Bosch process. An inductively coupled plasma (ICP) generates a very dense plasma near the top of the electrode. A 2nd RIE generator which is capacitively coupled to the wafer chuck is used to independently bias the substrate. In this way, high selectivities and high etch rates can be obtained. 

The Bosch process uses a series of alternating depositions and etches to maintain very low undercut and very vertical sidewalls. However a slight rippling of the sidewalls results from this sequence and also results in a polymer which must be removed subsequent to the etch. The chemistry can only etch silicon or (polysilicon). 

All samples must be mounted to a 4 inch wafer. Through-wafer etching also requires a 4 inch carrier wafer since backside He cooling is used. Metals must not be directly exposed in the plasma. After long runs or many short runs the chamber may get dirty as evidenced by a poor base pressure (>8.0 E-6). Do not proceed if the base pressure is too high or the leakback rate is too high (>.3 mT in 1 minute).