Several Glow Research systems can be used to remove (or strip) photo resist. The most common system used is the quartz chamber AutoGlow system.
Photoresist Stripping: This procedure in Glow Research systems is safe, fast and clean compared to wet-stripping methods. In the stripping of photoresist using an oxygen plasma the following conditions are typical: 75 to 200 watts of RF power, a pressure of .75 to 1.2 torr (the flow rate will determine the chamber pressure) and a time of 15-30 minutes depending of the number of wafers or samples in the chamber.
The photoresist removal can be significantly enhanced by the addition of small amounts of CF4 to the oxygen. This is advantageous in removing thickness of photoresist greater than 1.0 um, and especially for removing resist that have been hardened by either plasma-etching in plasmas containing halogens or by ion implantation. Sometimes ion implantation causes a crust to form on the outer surface of the photoresist and may require one process to remove the hardened crust and another process for removing the bulk photoresist under the crust. Some engineers refer to this as the “M&M” effect. The bulk photoresist can heat up prior to the crust removal and cause a popping of the photoresist.
Some people use a welders grade of oxygen for the removal gas….with the thought that it contains small amounts of H2O. The addition of water vapor to the incoming gas can also increase the removal rate.
Here is a comment from a Customer that uses our system in semiconductor production:
“I wanted to let you know our systems are all running like champs, all 3 have already paid for themselves.”
Brent Shepard is from MicroSemi, Corp., and has been using our AutoGlow type system in a production environment (two shifts/day). The quartz chamber system is used to remove photoresist and achieves a removal rate of 1,600 Angstroms per minute with a load of 25 wafers per run.
Most users use an oxygen plasma to remove photoresist from a variety of wafers types (silicon, GaAs, silicon carbide, silicon nitride substrates). The AutoGlow plasma system’s automated design will allow easy and unattended operation. The system has a quartz gas distribution tube for the incoming gas in the quartz chamber. This improves the uniformity when compared to other plasma systems.