PVA TePla AG
Alessia Romeo, Claudio Somaschini
Description: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 principleMonatomic 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