Design-aware nanophotonic substrates for surface-enhanced, ultrafast spectroscopy of EUV photoresists

Extreme ultraviolet (EUV) lithography serves as the bedrock patterning technology that produces the world’s most advanced nanoelectronic structures and devices. While EUV lithography is already adopted in high-volume manufacturing of advanced chips, the underlying physical and chemical mechanisms of how EUV photons transform light-sensitive materials (photoresists) into nanoscale circuitry patterns remain elusive. The mysteries of EUV reaction mechanisms in nanometer-scale thin films have their origins in the highly energetic and complex reaction landscape of EUV lithography, which involves (among others) ionization, formation of transient species, electron interactions, and chemical reactions. Resolving this complex reaction landscape within the confined volume of nanometer-scale films and with a time-resolution to “see” the transformation in real time is a scientific grand challenge.

In imec’s AttoLab, we are tackling this grand challenge by developing femtosecond time-resolved spectroscopy to track EUV photoresist dynamics in real-time. However, the limited interaction volume of at-scale EUV photoresists (<30 nm thickness) severely degrades the signal-to-noise ratio (SNR) and prevents detection of key molecular events occuring during the exposure process. In this project, you will help to tackle the SNR challenge by exploiting the benefits of localized surface plasmon resonances (LSPR’s) of nanostructured arrays to enhance spectroscopic signals (i.e., surface-enhanced infrared absorption spectroscopy, SEIRA). Working closely with imec experts in lithography, materials chemistry, and ultrafast optical science, you will design and simulate nanostructured arrays that support LSPR’s to boost IR signals at key reactive modes for EUV photoresists. The design and simulations will be performed using finite element or finite-difference time-domain methods, which take into account realistic material properties and CMOS compatibility. You will then translate the simulation design and results into a real-world process flow that will be used to produce the substrates. Time permitting, you will also have the opportunity to characterize the designed and produced substrates using a suite of microscopies (e.g., AFM, SEM, etc.) and spectroscopies (e.g, FTIR).