Super-resolution fluorescence nanoscopy opportunities for EUV resist inspection and metrology (Conference Presentation)

Abstract

Stochastic print failures are a serious potential yield limiter for the 5 nm and 3 nm technology node. To attain the detection limits that ensure yield requires inspection of square centimeters of area, which will challenge even the fastest anticipated e-beam tools. Optical techniques help but lack the ability to resolve actual defects. Applying super-resolution fluorescence nanoscopy techniques may provide a solution for both rapid inspection and defect identification capable of inspecting hundreds of wafers per hour. The technique first developed by Stephan Hell in 1994 for the life sciences uses the ability to toggle a molecules fluorescence on and off by activating with actinic light and deactivating via stimulated-depletion. By surrounding activating light with deactivating light, the former’s spot size reduces to nanometers allowing resolutions that far exceed the Abbe limit. In 2014, Professor Hell shared the Nobel Prize in chemistry for this technique, Stimulated-Emission-Depletion, STED nanoscopy. This paper will explain the technique, propose a method in its use for the inspection of EUV resists, and demonstrate proof-of-concept where we imaged with 775 nm deactivation and 640 nm activation morphological structures in a polymer film that are smaller than 5 nm.