Dynamics of ionized poly(4-hydroxystyrene)-type resist polymers with tert-butoxycarbonyl-protecting group

Okamoto K., Muroya Y., Kozawa T.. Dynamics of ionized poly(4-hydroxystyrene)-type resist polymers with tert-butoxycarbonyl-protecting group. Scientific Reports 14, 16729 (2024); https://doi.org/10.1038/s41598-024-67794-0.The imaging reactions of resist materials used for nano-patterning have become radiation-chemical reactions, with the shortening of wavelengths of the exposure light sources in lithography systems. The most widely used patterning materials in industrial lithography are chemically amplified resists (CAR). Understanding the deprotonation mechanism of ionized polymers (radical cations) is important for acid generation in CARs. In this study, the dynamics of radical cations in poly(4-hydroxystyrene) (PHS)–type resist polymers, partially and totally protected by tert-butoxycarbonyl (t-BOC) groups, are investigated using a combination of electron pulse radiolysis experiments, acid yield measurements, and quantum chemical calculations. The t-BOC(oxy) group exhibits π-electron-donating behavior in the monomer cation but changes to electron-accepting behavior in the polymer cation, owing to the interaction between substituents. The destabilization of radical cations due to decreased intramolecular charge resonance may contribute to the high deprotonation efficiency of t-BOC-capped PHS polymers

Study on resist performance of chemically amplified molecular resists based on cyclic oligomers

Novel resist materials are required for lithographic processing with ionization radiation such as extreme ultraviolet (EUV) and electron beam (EB) exposure tools. In this study, we synthesized positive-tone chemically amplified molecular resist materials with pendant adamantyl ester (AD) and cyclohexyl 2-propyl ether moieties based on cyclic oligomers such as noria, calixarene dimer, cyclodextrin, and pillar arene, and we examined the lithographic performances of sensitivity, etching durability, and patterning under EUV and EB exposure. We clarified that the sensitivity of the resist materials was consistent with the structure of the cyclic oligomers, i.e., the hole size of the molecular structure might be an important factor relevant to high-resolution resist materials. We found that chemically amplified molecular resists based on cyclic oligomers such as noria, calixarene dimer, cyclodextrin, and pillar arene are promising candidates for higher-resolution resist materials

Synthesis and Resist Properties of Calixarene Polymers with Pendant Haloalkyl Groups

We examined the condensation polymerization of t-butylcalix[8]arene (BCA[8]), p-t-butylcalix[4]arene (BCA[4]), and C-(4-t-butylbenz)calix[4]resorcinarene (BCRA[4]) with 1,3-adamantane dibromoacetate (ADB), yielding soluble polymers poly(BCA[8]-co-ADB), poly(BCA[4]-co-ADB), and poly(BCRA[4]-co-ADB), respectively. These polymers had good solubility, good film forming ability, and good thermal stability. It was anticipated that these polymers were applicable to positive-type resist materials. However, by the examination on the resist sensitivity using EUV exposure system, these polymers were applicable to negative type resist materials using THF as a developer. Furthermore, a negative clear resist pattern with 100nm resolution could be obtained by EB exposure system. These results indicated that poly(BCA[8]-co-ADB) and poly(BCRA[4]-co-ADB) have high potential to offer higher resolution negative pattern using EUV lithography system

Quasi-direct Cu–Si3N4 bonding using multi-layered active metal deposition for power-module substrate

Tatsumi H., Moon S., Takahashi M., et al. Quasi-direct Cu–Si3N4 bonding using multi-layered active metal deposition for power-module substrate. Materials and Design 238, 112637 (2024); https://doi.org/10.1016/j.matdes.2024.112637.The advancement of power modules demands more reliable insulating circuit substrates. Traditional substrates, comprising Cu and Si3N4, are produced using active metal brazing (AMB). However, AMB substrates have reliability concerns owing to electrochemical migration and void formation from brazing filler metals. This study introduces a quasi-direct Cu–Si3N4 bonding technique using a Ti/Al bilayer active metal deposition at the bonding interface. A sputtered Ti/Al bilayer was formed on the Si3N4 surface, then heated and pressurized the sputtered Si3N4 substrate with Cu sheets in vacuum to bond each other without voids or delamination. The Ti/Al layers reacted with Si3N4 and Cu, forming a 300 nm intermediate layer. TEM observations show this layer contains segregated Ti–N and Cu–Al phases, with a good lattice match to Si3N4 and Cu–Al. Temperature-cycling tests on the Cu/Si3N4/Cu substrate revealed delamination caused by increased tensile stress at the periphery of the bonding area due to asymmetrical Cu patterns. This novel quasi-direct Cu–Si3N4 bonding technique addresses issues of electrochemical migration and void formation seen in AMB substrates, offering a reliable bonding interface for power electronic substrates

Synthesis and Property of Tellurium-Containing Polymer for Extreme Ultraviolet Resist Material

Synthesis, physical properties, and resist properties of tellurium containing polymer with pendant adamantyl ester groups poly(Re-co-Te)-AD were examined, relevant to the application of resist material for extreme ultraviolet laser photolithography (EUVL) system. A tellurium containing polymer with pendant hydroxyl groups poly(Re-co-Te) was synthesized by the condensation reaction of resorcinol (Re) and tellurium tetrachloride (TeCl4), followed by the condensation reaction with adamantyl bromo acetate to give a corresponding polymer poly(Re-co-Te)-AD. Their physical properties (solubility, film-forming ability, thermal stability) and resist properties (thickness loss property after soaking in 2.38 wt% TMAH aq. solution, out-gassing on EUV exposure tool, and resist sensitivity under EUV exposure tool) were also examined

Synthesis and Resist Properties of Hyperbranched Polyacetals

The synthesized noria-AD offered 40 nm resolution resist pattern with LWR = 9.5 nm in the case of EB exposure tool and a clear 26 nm resolution pattern with LWR = 8.3 nm by means of EUV exposure tool. These results indicate that the present poly(THPE-co-BVOC) would have higher potential to offer higher resolution pattern using EUV lithography system

Inhibition of Rho-associated coiled-coil containing protein kinase enhances the activation of epidermal growth factor receptor in pancreatic cancer cells

<p>Abstract</p> <p>Background</p> <p>Rho-associated coiled-coil containing protein kinase (Rho-kinase/ROCK) is involved in various cellular functions including cell proliferation, and is generally considered to be oncogenic, while some studies show that ROCK functions as a negative regulator of cancer progression. As a result, the precise role of ROCK remains controversial. We have previously reported that Rho-kinase/ROCK negatively regulates epidermal growth factor (EGF)-induced cell proliferation in SW480 colon cancer cells. In the present study, we investigated the role of ROCK in EGF receptor (EGFR) signaling in the pancreatic cancer cell lines, Panc1, KP3 and AsPc1.</p> <p>Results</p> <p>In these cells, Y27632, a specific ROCK inhibitor, enhanced EGF-induced BrdU incorporation. The blockade of EGF stimulation utilizing anti-EGFR-neutralizing antibodies suppressed Panc1 cell proliferation. EGF induced RhoA activity, as well as the phosphorylation of cofilin and myosin light chain (MLC), both targets of ROCK signaling, and Y27632 suppressed both of these processes, indicating that the phosphorylation of cofilin and MLC by EGF occurs through ROCK in Panc1 cells. EGF-induced phosphorylation of EGFR at tyrosine residues was augmented when the cells were pretreated with Y27632 or were subjected to gene silencing using ROCK-siRNA. We also obtained similar results using transforming growth factor-α. In addition, EGF-induced phosphorylation of p44/p42 mitogen-activated protein kinase and Akt were also enhanced by Y27632 or ROCK-siRNA. Moreover, an immunofluorescence microscope study revealed that pretreatment with Y27632 delayed EGF-induced internalization of EGFR. Taken together, these data indicate that ROCK functions to switch off EGFR signaling by promoting the internalization of the EGFR.</p> <p>Conclusions</p> <p>While EGF first stimulates the activation of the EGFR and subsequently increases cancer cell proliferation, EGF concurrently induces the activation of ROCK, which then turns off the activated EGFR pathway via a negative feedback system.</p

Synthesis and Property of Tannic Acid Derivatives and Their Application for Extreme Ultraviolet Laser Lithography System

We synthesized tannic acid derivatives with pendant cyclohexyl acetal moieties (TA-CVEn), butyl acetal moieties (TA-BVEn), and adamantyl ester moieties (TA-ADn) by the reaction of tannnic acid (TA) with cyclohexyl vinyl ether (CVE), butyl vinyl ether (BVE), and adamantyl bromo acetate (AD) in various feeds ratios. The synthesized TA-CVEn, TA-BVEn, and TA-ADn had good solubility, good film-forming ability, and high thermal stability relevant to application of photolithography materials. However, only TA-BVE97 and TA-AD74 can be used as positive-type photo-resist materials using 2.38 wt% TMAH aq. as developer due to the result of thickness loss property. Furthermore, their resist-sensitivity upon EUV exposure tool and etching durability were adequate and they have high potential as next-generation resist material for EUV lithography