Quantifying global and local CD variation for an advanced 3D NAND layer (Conference Presentation)

Abstract

All chipmakers understand that variability is the adversary of any process and reduction is essential to improving yield which translates to profit. Aggressive process window and yield specifications necessitate tight inline variation requirements on the DUV light source which impact scanner imaging performance. Improvements in reducing bandwidth variation have been realized with DynaPulse™ bandwidth control technology as significant reduction in bandwidth variation translates to a reduction in CD variation for critical device structures. Previous work on a NAND Via layer has demonstrated an improvement in process capability through improve source and mask optimization with greater ILS and reduced MEEF that improved CDU by 25%. Using this Via layer, we have developed a methodology to quantify the contribution in an overall CDU budget breakdown. Data from the light source is collected using SmartPulse™ allowing for the development of additional methodologies using predictive models to quantify CD variation from Cymer’s legacy, DynaPulse 1 and DynaPulse 2 bandwidth control technologies. CD non-uniformities due to laser bandwidth variation for lot to lot, wafer to wafer, field to field and within field is now available based on known sensitivities and modeled. This data can assist in understanding the contribution from laser bandwidth variation in global and local CDU budgets.