Ultra-high-throughput inline probe metrology and inspection on EUV resist

The accelerating pace of adoption of EUV lithography and in particular the imminent introduction of High NA EUV lithography have resulted in the need for new metrology capability applied to EUV resist images post exposure and develop, prior to pattern transfer. Long established metrology and inspection techniques based on optical or electron imaging are reaching the limits of their resolution both laterally and vertically. They are not easily capable of producing detailed images of local variations in linewidth, resist height and roughness caused by EUV photon stochastics, materials inhomogeneities and mask variations. Understanding and controlling these local variations is key in achieving the required precision in CD, EPE and other dimensional or positional parameters that must be attained in semiconductor device fabrication. In this work, we will also present a novel, contactless probe metrology technique that simultaneously achieves very high spatial resolution and does so at data rates far superior to existing probe metrology solutions. This new technique uses ultra - fine probes, achieves lateral and vertical resolution of below 0.1 nm and has been able to successfully image L/S structures to a pitch of 24 nm. Also presented are examples of microbridges and microbreaks in EUV resist images resolved over the full depth of the photoresist. Dimensional analysis of EUV resist profiles such as LWR, LER, Line Top and Line Bottom (scumming) roughness are also presented. Complete resist profiles are presented, and it will be demonstrated that such profiles allow the extraction of hitherto unavailable data such as LWR as a function of vertical position on the line. The emerging metrology gap is not limited to photolithography. Within an increasing requirement for surface flatness prior to resist coating, CMP performance requirements are approximately three times as stringent for High NA EUV than for its predecessor. In this work we will demonstrate results for several applications, achieving high throughput without sacrificing metrology accuracy and image fidelity. Using an innovative thermally actuated cantilever and displacement interferometer system in three axes, high speed probe operation and long probe lifetime can be achieved, the latter by reducing the tip/sample contact time. The typical image time on $50 \mu \mathrm{m}$ images is below 2 seconds. By taking 9 sites per wafer and $50 \mu \mathrm{m}$ FoV images, a high throughput probe microscopy system measuring more than 20 wafers per hour is achieved.