/EUV time-resolved spectroscopy and interference lithography of a model resist

EUV time-resolved spectroscopy and interference lithography of a model resist

Research & development - Leuven | More than two weeks ago

Explore the radiolysis of EUV exposure of photoresists using femtosecond time-resolved infrared spectroscopy study and look for relationships to results attained with interference lithography at pitches smaller than 22 nanometers

 ​Historically, the wavelength and Numerical Aperture of a projection lens are the key drivers to the ultimate lithographic resolution that is used to produce next-generation semiconductor chips. At exposure with 193 nm light, the industry has exhausted techniques to increase NA and solutions to stitch patterns as additional processing steps inherently induce device performance problems due to edge placement and sizing errors. The way then to improve resolution is to shorten the wavelength to 13.5 nm, EUV. Critical to success in migration to EUV is the photoresists, the imaging material needed to record the circuitry patterns at the lithography step. First, EUV absorption in photoresists is limited by the necessary use of thin-films (10’s of nm) to prevent pattern collapse when printing nanoscale structures. More importantly, the high photon energy of 92 eV leads to photon absorption that launches ultrafast (i.e., sub-picosecond) radiative processes. These spawn generations of secondary electrons that ultimately thermalize to low enough energies to enable resonant chemical processes to form the desired photoproducts(being the same as at 193 nm), but also unwanted radiolysis products that are formed during the energy transfer cascade from 92 eV to sub-10 eV. These radiolysis species create print defects that will create device short and open failures. These radiative processes have been hypothesized, but never tested in real-time, because until now the technologies did not exist to explore sub-picosecond time scales that is required to do so. As such, the complex, ultrafast nature of these reactions had made observing the in-situ electrochemical dynamics a “nearly impossible” task. These compounding issues have stymied the integration of EUV lithography and led to semiconductor companies exploring different resist formulations (e.g.chemically amplified resists, CARs, and metal oxide resists, MORs) that serves to increase the knowledge gap of their fundamental photophysics. This master’s research will develop methods to use time-resolved infrared spectroscopy to observe and track the radiolysis process, apply it, and then try to provide interpretation to what is observed with interference lithographic imaging of the resist.


Type of project: Internship


Duration: three and six months are available

Required degree: Master of Science, Master of Engineering Science, Master of Engineering Technology

Required background: Chemistry/Chemical Engineering, Physics, Nanoscience & Nanotechnology

Supervising scientist(s): For further information or for application, please contact: John Petersen (John.Petersen@imec.be) and Esben Witting Larsen (Esben.WittingLarsen@imec.be)

Imec allowance will be provided for students studying at a non-Belgian university.