Particle qualification procedure for the TNO EUV reticle load port module of the HamaTech MaskTrackPro cleaning tool

Before new equipment for handling of EUV reticles can be used, it should be shown that the apparatus is qualified for operating at a sufficiently clean level. TNO developed a qualification procedure that is separated into two parts: reticle handling and transport qualification and the qualification of the equipment. A statistical method was developed to include the results of the handling and transport qualification into the qualification criterion for the equipment. As a result we are able to calculate the minimum required experimental effort to prove that the particle contamination levels of the equipment are within the requirements. The qualification procedure was applied to the TNO EUV reticle load port module of the HamaTech MaskTrack Pro cleaning tool. A Particle per Reticle Pass (PRP) between 0.005 and 0.076 for particles ≥ 80nm was measured for the reticle load port module including handling and transport contribution. However, a high number of particles were found in the transport test. As a result a much higher number of repeat cycles (more than a factor 6) were required to reduce the confidence interval. Therefore, elimination of the transport step is absolutely required for a good qualification procedure. This can be obtained by placing the inspection tool close to the equipment to be qualified. In this way, the required experimental effort can be reduced significantly, saving both machine time and costs. © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).