Nanoparticle detection limits of TNO's Rapid Nano: modeling and experimental results - (PPT)

摘要

The lack of a suitable pellicle material for EUV lithography makes EUV reticles very sensitive to deposited particles. For this reason, EUV reticle handling equipment should have strict requirements on number of added particles per reticle pass (PRP). Before being taken into production, such equipment should undergo particle tests and qualification. TNO has developed the Rapid Nano reticle blank scanner as a tool to aid in the particle qualification of reticle handling equipment [1-3]. Due to the very strict requirements on PRP, much tool-time is required on the equipment to be qualified [4]. The inspection equipment should add the minimum possible number of particles to the test blanks, as introducing extra background noise increases the required tool-time even more. The Rapid Nano was designed specifically with particle cleanliness in mind [5]. Here, we present an end-to-end model of the detection sensitivity of our scanner. All illumination, collection, substrate, particle and noise parameters are included in this model. The outcome of the model is a capture rate curve for a given particle type on a given substrate. The model correctly predicts the current performance and it can be used to make accurate predictions of future generations of the scanner.