High‐Resolution Study of Changes in Morphology and Chemistry of Cylindrical PS‐b‐PMMA Block Copolymer Nanomasks during Mask Development

Abstract

Nanolithography with self‐assembled block copolymers (BCPs) is an emerging competitive alternative to conventional lithography, which is currently reaching its limits with regard to resolution and economic feasibility. For high‐resolution lithography, both the abruptness of BCP internal interfaces between self‐assembled polymer nanodomains and the processing steps used to selectively remove one of the polymers are crucial. This paper presents a detailed investigation of the chemistry, the mask wall morphology, and the line edge roughness (LER) of self‐assembled nanomasks from polystyrene‐b‐polymethylmethacrylate (PS‐b‐PMMA) before and after selective removal of the PMMA nanodomains. For the latter, either wet or plasma etching are employed and their impact on both the morphology and chemistry of resulting nanomasks is analysed using analytical (scanning) transmission electron microscopy (STEM), X‐ray photoelectron spectroscopy and polarization‐modulated infrared reflection‐absorption spectroscopy. Dedicated image analysis tools are developed to determine for the first time the LER of cylindrical openings in PS masks from STEM dark‐field images at sub‐nanometer resolution. Applying these tools prior to and after PMMA removal from the BCP films, the statistics of feature sizes, LERs, and interfacial widths are determined. In addition, the impact of wet and dry etching processes on PS‐co‐PMMA random copolymer brushes required for substrate functionalization is evaluated.

Revealing the 3D Structure of Block Copolymers with Electron Microscopy: Current Status and Future Directions

“…An energy filter allows elastically scattered electrons to pass through, thereby removing the noise caused by inelastically scattered electrons, resulting in enhanced image contrast. , The capability to use a narrow-width energy filter (<15 eV) that enables the passage of only the zero-loss peak of the electron energy loss spectrum (EELS) has become a common practice in high-resolution cryo-TEM and in particular in cryo single-particle analysis (SPA) and cryo-TEMT . Utilizing energy filtering for BCP TEMT can enhance the contrast and resolution of the 3D data. − …”

Development of Water-Resistant Autohesive Strength of Polyethylene Plates with Photografting of Alkyl (Meth)Acrylates

“…As a typical example, the C 1s and O 1s spectra for the PE-g-PMMA plate are shown in Figure S3. The C 1s and O 1s spectra were analyzed with the deconvolution process [38,39]. The C 1s spectrum was divided into a peak at 289 eV corresponding to -C-OOH at 289 eV and one at 287 eV corresponding to -CH-COOH in addition to a main -CH 2 -CH-peak at 285 eV.…”

“…The C 1s spectrum was divided into a peak at 289 eV corresponding to -C-OOH at 289 eV and one at 287 eV corresponding to -CH-COOH in addition to a main -CH 2 -CH-peak at 285 eV. In the O 1s spectrum, two peaks arising from -C=O and -C-O-at 532 and 533.5 eV, respectively, were observed [38,39]. The high-resolution spectra with a similar shape were obtained for the other grafted PE plates.…”