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16 April 2012 Cleaning aspects of material choice for high end mask manufacturing
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Proceedings Volume 8352, 28th European Mask and Lithography Conference; 83520S (2012)
Event: 28th European Mask and Lithography Conference (EMLC 2012), 2012, Dresden, Germany
After decades of binary mask manufacturing using Cr absorber the material spectrum was extended by phase shift material in late 90's during introduction of Half Tone Phase Shift Masks (HT-PSM). This change had strong impact on manufacturing flow as well as several unit processes. A consequences of phase shifter introduction was the necessity of introducing a second level litho process, as well as introducing of dry etch processes due to poor etch properties of MoSi using wet chemistry. Less obvious and rather unremarkable was the impact of this change to clean processes, except the impact of the clean process on the phase shift. In recent years we've seen several new materials based on varying chemical composition as well as thickness of the absorber developed by various mask blank vendors namely Hoya and ShinEtsu. These materials are improving resolution, pattern fidelity and to some degree also mask lifetime. Adding the EUV mask blank materials increases further the spectrum of materials, taking into account all the absorber stacks available today on market. Thorough investigation of the clean process performance as a function of surface material shows significant variation in the critical parameters as defectivity, susceptibility to recontamination and relative cleaning efficiency. Goal of this work is to 1) Compare the already mentioned clean related properties together with feature damage and impact on the critical dimension (CD) shift for different materials. 2) Find a compromise between the technology requirements and process limitations resulting from the combination of available processes with material properties. Some aspects of the new materials such as stack height and interface between absorber and substrate are making this task easier, especially with respect to feature damage. On the other hand the most critical parameter - the cleaning efficiency, dropped due to the introduction of the new materials, mainly due to unfavorable sticking coefficients of these materials.
© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Pavel Nesladek, Steve Osborne, and Stefan Rümmelin "Cleaning aspects of material choice for high end mask manufacturing", Proc. SPIE 8352, 28th European Mask and Lithography Conference, 83520S (16 April 2012);


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