Jingyuan Deng

Conventional chemically amplified resists (CARs) rely on the usage of photoacid generators to serve as the source of chemical amplification. However, acid diffusion inevitably accompanies CARs and has led to the resolution, line edge roughness, and sensitivity (RLS) trade-off, which is the most challenging technical problem for modern photoresists. Herein, we take advantage of the self-immolative property of polyphthalaldehyde (PPA) derivatives to create end-cap enabled chain scissionable resists for extreme ultraviolet (EUV) lithography. The feasibility of this strategy was demonstrated under UV photodegradation experiments. The dose-to-clear (DTC) under EUV radiation was 90 mJ/cm² for the most promising resist, representing more than a 100-fold improvement over previous PPA resists. Density functional theory (DFT) calculations were conducted to understand the structural origin of end-cap EUV sensitivity.

Conventional chemically amplified resists (CARs) rely on the usage of photoacid generators to serve as the source of chemical amplification. However, acid diffusion inevitably accompanies CARs and has led to the resolution, line edge roughness, and sensitivity (RLS) tradeoff, which is the most challenging technical problem for modern photoresists. Herein, we take advantage of the self-immolative property of polyphthalaldehyde (PPA) derivatives to create end-cap enabled chain scissionable resists for extreme ultraviolet (EUV) lithography. The feasibility of this strategy was demonstrated under UV photodegradation experiments. The dose-to-clear (DTC) under EUV radiation was 90 mJ/cm2 for the most promising resist, representing more than a hundredfold improvement over previous PPA resists. Density functional theory (DFT) calculations were conducted to understand the structural origin of end-cap EUV sensitivity.

Scissionable polymers are polymers that will depolymerize under different stimuli including acid, base, and free radicals. These polymers have been investigated in the development of photoresists and other degradable materials. This work focuses on the poly(phthalaldehyde), PPA, a family of scissionable polymers. The PPA backbone consists of acetal linkages that are very sensitive to acids. Upon exposure to acids, the polymer chain depolymerizes to its corresponding monomers. This depolymerization behavior makes PPAs excellent candidates as photoresist materials. Several new PPA photoresists are being explored in this work.

The use of fluorochemicals in lithography and semiconductor patterning plays a critical role in the success of semiconductor technology. The addition of small quantities of fluorinated materials enables patterning capabilities that are otherwise not possible to achieve, and this leads to superior device performance. The compact size of the fluorine atom and its strong electron-withdrawing characteristics make it stand out in the periodic table and gives fluorocarbon materials unique properties, unmatched by other chemical compounds. Fluorochemicals have found use in semiconductor processing for good technical reasons.

Low stochastics, high sensitivity photoresists remain a goal for EUV lithography. Here we present studies of two polymer systems that attempt to make improvements to these resist characteristics using two different chemical approaches. In one system we work on scissionable poly(phthalaldehyde) modified to enable incorporation of photoactive units on each repeat unit of the polymer chain. In a second system we explore peptoid polymers that possess identical molecular size and composition with much higher molecular uniformity than possible by conventional synthetic techniques. We report the results of exposure of these materials to EUV exposures and the chemical changes that occur.

Heteromultimetallic complexes consisting of three Co(II) ions and one lanthanide ion were synthesized and applied to the alternating copolymerization of CO₂ and cyclohexene oxide. Unlike the conventional cobalt(III) salen complexes, the high thermal stability of the present catalyst allowed us to reach a turnover number of 13000, one of the highest values ever reported for multimetallic systems. The chain propagation was first-order to the catalyst, suggesting a cooperative behavior of the metal centers.

Bifunctional Al porphyrins worked as excellent catalysts for the copolymerization of cyclohexene oxide (CHO) and CO ₂ .