30 December 1999 Cleaning of SCALPEL next-generation lithography masks using PLASMAX, a revolutionary dry cleaning technology
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Due to mechanical and exposure considerations, NGL mask technology lacks the ability to use a pellicle to prevent mask contamination. The PLASMAX (Plasma Mechanical Activation and Extraction of Particle Contamination) process represents a technology, which acts as the functional replacement of a pellicle for the NGL mask. This dry environmentally benign cleaning technology can be directly integrated into the exposure system and serves as an in-situ creative mask cleaning process. Unlike other, more conventional cleaning methods, PLASMAX lifts surface particles from the mask, then suspends, traps and channels these particles down the vacuum port, thus preventing particle redeposition on the mask surface. Originally demonstrated on wafers, this plasma/mechanical cleaning technology has demonstrated its ability to remove particles from the surface of NGL masks such as SCALPEL (Scattering with Angular Limitation in Projection Electron Beam Lithography) masks. PLASMAX uses the combined action of a gentle plasma with simultaneous vibration to clean the mask. Unlike all other methods of mask cleaning, PLASMAX uses no water or hazardous acids, thus reducing the cost of each cleaning step and eliminating the environmental impact of today's aqueous cleaning technologies. Initial work with SCALPEL masks showed them to be highly stable and robust in the PLASMAX environment while yielding cleaning efficiencies of 90% removal of polyester particles 0.8 micron and larger. The PlASMAX technology was proven to be effective in removing particles from the patterned front side and strutted backside of the mask. This paper focuses on the ongoing development of PLASMAX to enhance the cleaning efficiency of SCALPEL masks down to 0.25-micron particles. In addition, the cleaning efficiency of various particle materials will be studied. Sandia National Laboratories is providing software model simulations of the PLASMAX technology to assist in the development effort.
© (1999) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
John J. Festa, John J. Festa, Anthony E. Novembre, Anthony E. Novembre, Darryl A. Bennett, Darryl A. Bennett, Richard J. Kasica, Richard J. Kasica, Brad Bailey, Brad Bailey, Myrtle I. Blakey, Myrtle I. Blakey, "Cleaning of SCALPEL next-generation lithography masks using PLASMAX, a revolutionary dry cleaning technology", Proc. SPIE 3873, 19th Annual Symposium on Photomask Technology, (30 December 1999); doi: 10.1117/12.373296; https://doi.org/10.1117/12.373296


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