Towards 22 nm: fast and effective intra-field monitoring and optimization of process windows and CDU

ITRS lithography's stringent specifications for the 22nm node are a major challenge for the semiconductor industry. With the EUV point insertion at 16nm node, ArF lithography is expected to reach its fundamental limits. The prevailing view of holistic lithography methods, together with double patterning techniques, has targeted bringing lithography performance towards the 22nm node (i.e., closer to the immersion scanner resolution limit) to an acceptable level. At this resolution limit, a mask is the primary contributor of systematic errors within the wafer intra-field domain. As the ITRS CDU specification shrinks, it would be crucial to monitor the mask static and dynamic critical dimension (CD) changes in the fab, and use the data to control the intra-field CDU performance in a most efficient way. Furthermore optimization and monitoring of process windows becomes more critical due to the presence of mask 3D effects. This paper will present double patterning inter- and intra-field data, for CDU and PW monitoring and optimization, measured by Applied Materials' mask inspection and CD-SEM tools. Special emphasis was given to speed and effectiveness of the inspection for a production environment