Plasma Asher – PVA TEPLA 200

Stefano Bigoni, Elisa Sogne
Authorized user
Back End


The removal of photoresist masks after processes such as etching and ion implantation, is one of the most important and frequently performed steps in front-end semiconductor manufacturing. Depending on the complexity of the devices concerned, the number of lithography cycles can vary typically from 10 to 25. Each cycle requires a photoresist removal process. This process of stripping the photoresist mask is carried out in a dry, eco-friendly process using plasma. Microwave plasma is ideal for resist removal in modern device fabrication, since it produces a very high concentration of chemically active species along with low ion bombardment energy, guaranteeing fast ash rate and a damage-free plasma process at an economic cost level. Microwave plasma systems are suitable for all relevant substrate technologies like Si, III/V-compounds, quartz, ceramic, lithium niobate, copper interconnect devices etc. The inherently isotropic etch characteristic is of advantage for sacrificial layer etch and SU-8 removal in MEMS fabrication.

Working principle

Monatomic oxygen plasma is created by exposing oxygen gas at a low pressure (typically 0.5 – 1.5 mbar) to high power radio waves, which ionize it. This process is performed under vacuum and leads to the formation of a plasma in the chamber. As the plasma is formed, many free radicals are created which are used to strip the resist away from the wafer surface.


  • Wafer size: up to 6 inches
  • Gas species: O2, Ar
  • RF Power: 40 – 400 W
  • Frequency: 2450 MHz