Plasma Asher

In semiconductor manufacturing plasma asher/stripper is the process of removing the photoresist from an etched wafer. Using a plasma source, a monatomic reactive species is generated. Oxygen or fluorine are the most common reactive species. The reactive species combines with the photoresist to form ashing which is removed with a vacuum pump.

Typically, monatomic (single atom) oxygen plasma is created by exposing oxygen gas (O2) to ionizing radiation. At the same time, many free radicals are formed which could damage the wafer. Newer, smaller circuitry is increasingly susceptible to these particles. Originally, plasma was generated in the process chamber, but as the need to get rid of free radicals has increased, many machines now use a downstream plasma configuration, where plasma is formed remotely and channeled to the wafer. This allows electrically charged particles time to recombine before they reach the wafer surface, and prevents damage to the wafer surface.

Monatomic oxygen is electrically neutral and although it does recombine during the channeling, it does so at a slower rate than the positively or negatively charged free radicals, which attract one another. Effectively, this means that when all of the free radicals have recombined, there is still a portion of the active species available for process. Because a large portion of the active specie is lost to recombination, process times may take longer. To some extent, these longer process times can be mitigated by increasing the temperature of the reaction area.

We can provide the following refurbished plasma asher/descum equipment.

• Matrix 105;
• Matrix 10;
• Gasonics Aura 1000;
• Gasonics Aura 3010;
• Gasonics Aura 2000LL;
• Branson IPC 3000;
• Branson IPC L3200;
• Drytek Megastrip 6 H.F;
• LFE PDS/PDE 301/PDE 504;
• Tok Plasma Asher.

We provide our own proprietary AW Control Software and Superior Temperature Control Technology to upgrade the refurbished equipment which provides the following significant advantages.

• Integrated process control system
• Real time graphics display
• Real time process data acquisition, display, and analysis
• Programmed comprehensive calibration and diagnostic functions
• Better performance and maintenance than the original systems