Controlled sequence peptoids as photoresist platforms for high-resolution DUV/EUV photoresists

Abstract

Achieving commercial viability for extreme ultraviolet lithography (EUVL) demands a homogeneous polymeric materials platform for fine pattern microelectronics. However, current polymer systems possess a heterogeneity length scale larger than the 13.5 nm range desired for EUVL leading to line-edge roughness close to the size of a single polymer molecule in less than a nanometer. In this report, we develop polypeptoids in a high-yielding polymer synthesis with low stochastics and enable a high sensitivity environmentally stable chemically amplified photoresist (ESCAP) for large-scale manufacturing using DUV/EUVL. Polypeptoids are bio-inspired, sequence-defined polymers that minimize molecular size and compositional and sequence statistics. Functional monomers, such as photosensitizers, solubility switches, etchresistant units, and Tg modulators, have been programmed to be precisely distributed into the polymer structure using a robotic synthesizer. Positive-tone polypeptoids ESCAPs can thus be tuned via chemical and sequence design. In particular, the arrangement of solubility-switch functional groups relative to adhesion-promoting groups influences synthetic yield and lithographic patternability. Other functional groups, such as phenolic and aromatic, promote a resist's physical properties, film quality, adhesive characteristics, and pattern development by tuning the polymer's polarity, depending on the sequence within the polymer chain. This work bridges the materials design of bioinspired polymers, high throughput manufacturing techniques, and nanolithography enabling polymer uses with high processing fidelity for nanotechnologies.

Sequence-defined polypeptoid CARs for electron-beam and EUV lithography

“…After synthesis the polypeptoids were characterized by DSC to determine the glass transition temperature, and MALDI-TOF was applied to confirm the polypeptoid structure, as previously reported. [7] For the change in solubility upon exposure, tyramine was used as an amine for the polypeptoid synthesis, and the phenolic hydroxyl group was tBOC protected after first cleaving the polypeptoids from their solid support and purifying them. In our previous work we have demonstrated that introduction of hydrophobic units such as propyne alters solubility as well as solubility contrast depending on the sequence of the polypeptoid while otherwise possessing the same chain composition.…”

“…[5] In the past there have been studies addressing these shortcomings by developing new types of resists. Previously we demonstrated the potential of polypeptoids as a new type of photoresist [6,7] whose structure, molecular weight, composition, and microstructure can be precisely controlled as all chains have the same molecular weight and composition. Furthermore, the incorporation of functionalities such as click-handles opens the possibility for polypeptoids used as a modular building block where properties such as adhesion, solubility contrast and thermal properties can be tailored quickly and over a wide range.…”

Atomistic Modeling Approach for Predicting Association of Photoacid Generators in Extreme Ultraviolet Polymeric Photoresists

“…Unless stated otherwise, all simulations with homopolymers and copolymers consist of 70 molecules of 12-mer polymer chains. The chosen length of the polymer was similar to the average length used in experiments ,, and simulations. ,, Figure S2 shows the simulated polymer chain structures in this work. In all the bulk homopolymer and copolymer simulations, the end-to-end distance between the terminal backbone carbon atoms of the chains is within 20–23 Å which is less than half the simulation box length that ranges between 58 and 60 Å.…”

Polypeptoids: Exploring the Power of Sequence Control in a Photoresist for Extreme‐Ultraviolet Lithography

“…Previously we have reported the synthesis of polypeptoids and have demonstrated the potential of polypeptoids as a new generation of welldefined resists for use in electron beam lithography (EBL) and EUVL. [15,16] Scheme 1. Solid phase-supported synthesis of polypeptoids using tyramine and propargylamine as primary amines.…”

“…Previously we have reported the synthesis of polypeptoids and have demonstrated the potential of polypeptoids as a new generation of well‐defined resists for use in electron beam lithography (EBL) and EUVL. [ 15,16 ]…”