Yasin Ekinci

Cryo-computing – both classical and quantum, is severely limited by the absence of a suitable cryo-memory. The challenges both in terms of energy efficiency and speed have been known for decades, but so far conventional technologies have not been able to deliver adequate performance. Here we present a non-volatile memory device which incorporates a superconducting nanowire and an all-electronic charge configuration memristor (CCM) based on switching between charge-ordered states in a layered dichalcogenide material. We numerically investigate the time-dynamics and current-voltage characteristics of such a device by modelling of the superconducting order parameter. The observed current-voltage response is faithfully reproduced by fabricated devices using a NbTiN nanowire and a 1 T -TaS ₂ CCM element. The inherent ultrahigh energy efficiency and speed of the device, which is in principle compatible with single flux quantum logic, leads to a promising memory concept for use in cryo-computing and quantum computing peripheral devices.

Van der Waals materials exhibit a variety of states that can be switched with low power at low temperatures, offering a viable cryogenic ‘flash memory’ required for the classical control electronics for solid-state quantum information processing. In 1 T -TaS ₂ , a non-volatile metallic ‘hidden’ state can be induced from an insulating equilibrium charge-density wave ground state using either optical or electrical pulses. Given that conventional memristors form localized, filamentary channels which support the current, a key question for design concerns the geometry of the conduction region in highly energy-efficient 1 T -TaS ₂ devices. Here, we report in operando micro-beam X-ray diffraction, fluorescence, and concurrent transport measurements, allowing us to spatially image the non-thermal hidden state induced by electrical switching of 1 T -TaS ₂ . The results reveal a long-range ordered switching region that extends well below the electrodes, implying that the self-organized, collective growth of the hidden phase is driven by charge rearrangement and concomitant lattice strain. Our combination of techniques showcases the potential of non-destructive, three-dimensional X-ray imaging to study bulk switching in microscopic detail, exemplified here by electrical control of the charge-density wave state of a van der Waals material.

This study investigates the differences in the lithographic impact of particles on the pellicle surface depending on the type of extreme ultraviolet (EUV) mask pattern. Using an EUV ptychography microscope, we analyzed how mask imaging performance is affected by locally obstructed mask diffraction caused by a 10 μm × 10 μm patterned tin particle intentionally fabricated on the pellicle surface. The resulting critical dimension variations were found to be approximately three times greater in line-and-space patterns than in contact hole patterns. Based on these findings, we recommend defining the critical size of particles according to the mask pattern type to optimize lithographic quality.

Resists that enable high-throughput and high-resolution patterning are essential in driving the semiconductor technology forward. The ultimate patterning performance of a resist in lithography is limited because of the trade-off between resolution, line-width roughness, and sensitivity; improving one or two of these parameters typically leads to a loss in the third. As the patterned feature sizes approach angstrom scale, the trade-off between these three metrics becomes increasingly hard to resolve and calls for a fundamental rethinking of the resist chemistry. Low-molecular-mass monodispersed metal-containing resists of high atom economy can provide not only very high resolution but also very low line-width roughness without sacrificing sensitivity. Here we describe a modular metal-containing resist platform (molecular mass 2. In both of these patterning techniques, the line-width roughness was found to be ≤2 nm, a record low value for any resist platform, also leading to a low-performance trade-off metric, Z factor, of 0.6 × 10^-8 mJ·nm³. With the ultimate resolution limited by instrumental factors, potential patterning at the level of a unit cell can be envisaged, making low-molecular-mass resists best poised for angstrom-scale lithography.

Our mirror-based lithographic technique achieves 5 nm half-pitch patterning with EUV light. This breakthrough pushes EUV lithography boundaries beyond the high-NA specifications and serves as a benchmarking platform for novel photoresists.

Organometallic tin-oxo-hydroxo cage compounds offer a promising photoresist platform for extreme ultraviolet photolithography (EUVL). Their reactivity is dominated by the facile breaking of the tin-carbon bonds upon photon or electron irradiation. As the cage is dicationic, it exists as a complex with anions for charge compensation. In the present work, we explore the n-butyltin-oxo cage with two tetrakis(pentafluorophenyl)borate counteranions (TinPFPB). In contrast to the small counterions that are typically used, the bulky PFPB anion absorbs a substantial fraction (∼30%) of the impinging EUV radiation (13.5 nm, 92 eV), and it has its own reactivity upon photoionization. When thin films of the complex are irradiated with EUV radiation at low doses, a positive-tone development is possible, which is rather unique as all other known tin-oxo cage resists show a negative tone (cross-linking) behavior. We propose that the initial positive tone behavior is a result of the chemical modification of the Sn cluster by fragments of the borate anions. For comparison, we include the tetrakis(p-tolyl)borate anion (TB) in the study, which has similar bulkiness, and its complex with the n-butyltin-oxo cage (TinTB) shows the usual negative tone EUV resist behavior. This negative-tone behavior for our control experiment rules out a hypothesis based purely on the steric hindrance of the anion as the cause of the different EUV reactivity.

BackgroundTraditional chemically amplified resists (CARs) often suffer from high line-edge roughness (LER), primarily due to acid diffusion and the uneven distribution of reactive components. Nonchemically amplified resists (n-CARs) emerge as a promising solution to overcome the limitations. Molecular glasses (MGs), a type of organic compounds known for their distinct and well-defined structures, are particularly noteworthy for their homogeneity. The innovative design of MG-based n-CARs represents a significant stride toward overcoming the limitations inherent in CAR systems.AimDevelopment and performance evaluation of n-CARs utilizing the multi-sulfonium modified triptycene molecule for advanced lithography techniques, such as electron beam lithography (EBL) and extreme ultraviolet lithography (EUVL).ApproachA multi-sulfonium modified triptycene (TPESF6) was synthesized and characterized. This compound undergoes a photochemical reaction in which the sulfonium groups are transformed into thioethers, resulting in a substantial switch in polarity and thereby in solubility. The lithography performance of the TPESF6 resist was evaluated by EBL and EUVL. The lithographic patterns were analyzed by scanning electron microscopy and atomic force microscopy.ResultsTPESF6 resist demonstrated remarkable performance in EBL, achieving a 20 nm line/space (L/S) patterns as a negative-tone resist developed by water. Further evaluations using EUVL yielded an impressive 13 nm L/S pattern at a dose of 372.6 mJ/cm2 with a very low LER of 1.8 nm. Mechanistic studies show that the change in solubility of TPESF6 resist depends on the decomposition of the sulfonium cation and triflate anion groups.ConclusionsThe TPESF6 molecular resist shows high resolution and low LER, as evidenced by tests conducted using both EBL and EUVL. The integration of MG resist characteristics with the concept of n-CARs significantly improves the resolution and reduces the LER, offering a promising pathway for high-performance materials for advanced lithography.