MAGNETICALLY ENHANCED PLASMA ETCH PROCESS USING A HEAVY FLUOROCARBON ETCHING GAS

摘要

An oxide etch process practiced in magnetically enhanced reactive ion etch (MERIE) plasma reactor. The etching gas includes approximately equal amounts of a hydrogen-free fluorocarbon, most preferably C4F6, and oxygen and a much larger amount of argon diluent gas. The magnetic field is preferably maintained above about 50 gauss and the pressure at 40 milliTorr or above with chamber residence times of less than 70 milliseconds. A two-step process may be used for etching holes with very high aspect ratios. In the second step, the magnetic filed and the oxygen flow are reduced. Other flurocarbons may be substituted which have F/C ratios of less than 2 and more preferably no more than 1.6 or 1.5.