The RIE process (reactive ion etching) is a dry etching process used in electronic and microelectronic manufacturing. Applications are for example fast and ultra high surface cleaning, surface activation, photo-resist stripping and semiconductor etching.
For this process usually a planar plate reactor is used (see figure 1). After generating a gas atmosphere with a pressure of 10-2 to 10-1 mbar the gas discharge (plasma) is ignited by applying an RF voltage. Caused by the different mobility of light electrons and heavy ions in the electric field, a negative DC potential builds up at the smaller electrode (substrate carrier). This self bias potential usually is about 10 to a few hundred volts.
The etching effect to the substrate (wafer, PCB etc.) is the sum of at least two processes, a physical and a chemical one:
Chemical etching / removal of the substrate surface or contami-nation by reaction with reactive gas particles generated in the plasma (plasma etching).
Physical etching of the surface by transfer of direct momentum of heavy ions which are accelerated in the electric field (sputter etching)