Optics contamination remains one of the challenges in extreme ultraviolet (EUV) lithography. Dependence of
contamination rates on key EUV parameters was investigated. EUV tools have optics at different illumination angles. It
was observed that at shallower angles, the carbon contamination rate and surface roughness was higher on the optics
surface. This is a concern in EUV optics as higher roughness would increase the scattering of the EUV radiation.
Secondary ion time of flight mass spectrometer (TOF-SIMS) data indicated that the carbon contamination film might be
a polymer. Three chemical species were used to investigate the dependence of polymerization and reactivity on the
contamination rate. Acrylic acid was found to have a measurable contamination rate above background compared to
propionic acid and methyl methacrylate. Secondary electron dissociation is one of the mechanisms considered to be a
cause for the growth of the carbon contamination film. Multiple experiments with two substrates having different
secondary electron yields were performed. The substrate with the higher secondary electron yield was found to give a
higher contamination rate.
Optics contamination remains one of the challenges in extreme ultraviolet (EUV) lithography. In addition to the
desired wavelength near 13.5 nm (EUV), plasma sources used in EUV exposure tools emit a wide range of
out-of-band (OOB) wavelengths extending as far as the visible region. We present experimental results of
contamination rates of EUV and OOB light using a Xe plasma source and filters. Employing heated carbon
tape as a source of hydrocarbons, we have measured the wavelength dependence of carbon contamination
on a Ru-capped mirror. These results are compared to contamination rates on TiO2 and ZrO2 capping layers.
The impact of carbon contamination on extreme ultraviolet (EUV) masks is significant due to throughput loss and
potential effects on imaging performance. Current carbon contamination research primarily focuses on the lifetime of the
multilayer surfaces, determined by reflectivity loss and reduced throughput in EUV exposure tools. However,
contamination on patterned EUV masks can cause additional effects on absorbing features and the printed images, as
well as impacting the efficiency of cleaning process. In this work, several different techniques were used to determine
possible contamination topography. Lithographic simulations were also performed and the results compared with the
Typical extreme ultraviolet (EUV) photoresist is known to outgas carbon-containing molecules, which is of particular
concern to the industry as these molecules tend to contaminate optics and diminish reflectivity. This prompted extensive
work to measure these species and the quantities that they outgas in a vacuum environment. Experiments were
performed to test whether the outgassing rate of these carbon-containing molecules is directly proportional to the rate at
which the EUV photons arrive and whether a very high power exposure will cause the same amount of outgassing as a
much lower power exposure with the dose unchanged.
Carbon contamination of extreme ultraviolet (EUV) masks and its effect on imaging is a significant issue due to lowered
throughput and potential effects on imaging performance. In this work, a series of carbon contamination experiments
were performed on a patterned EUV mask. Contaminated features were then inspected with a reticle scanning electron
microscope (SEM) and printed with the SEMATECH Berkeley Microfield-Exposure tool (MET) . In addition, the
mask was analyzed using the SEMATECH Berkeley Actinic-Inspection tool (AIT)  to determine the effect of carbon
contamination on the absorbing features and printing performance.
To understand the contamination topography, simulations were performed based on calculated aerial images and resist
parameters. With the knowledge of the topography, simulations were then used to predict the effect of other thicknesses
of the contamination layer, as well as the imaging performance on printed features.