Low LER Research Articles

Field Quality Improvement of Septum Magnets for SuperKEKB Injection System

The SuperKEKB accelerator is a electron-positron collider consisting of the 7 GeV electron ring (high energy ring or HER) and the 4 GeV positron ring (low energy ring or LER). The commissioning of the SuperKEKB accelerator is underway, aiming to supply a great number of interaction events of electrons and positrons to the Belle II detector which is used for discovering the new physics beyond the standard model. The important milestone is to obtain integrated luminosity of 15 ab–1 in the next decade, so that the luminosity should exceed 2 × 1035 cm–2s–1 in several years. To achieve the goal, both rings have to be filled with high current beam of a few amperes, where the high injection efficiency is vitally important because lifetime is expected to be very short. One of the key components of the injection system is the septum magnet. It has been found that a transverse fringe field near the septum plate has sizable multipole components. A tracking simulation shows such fringe fields generate a vertical non-Gaussian tail, which could cause a beam background as well as a bad injection efficiency. Though quadrupole component in the multipoles could be, in principle, cancelled by adjusting the quadrupole magnets in the upstream of the beam line, it turned out to be difficult in actual operation. Even the quadrupole component was perfectly cancelled, components higher than quadrupole would be still harmful, since it generates a beam halo in the ring after injection, which increases the beam backgrounds to the Belle II detector. This paper describes about improvement of the field quality of the septum magnet.

Genome engineering of Nannochloropsis with hundred-kilobase fragment deletions by Cas9 cleavages.

Industrial microalgae are promising photosynthetic cell factories, yet tools for large-scale targeted genome engineering are limited. Here for the model industrial oleaginous microalga Nannochloropsis oceanica, we established a method to precisely and serially delete large genome fragments of ~100kb from its 30.01 Mb nuclear genome. We started by identifying the 'non-essential' chromosomal regions (i.e. low expression region or LER) based on minimal gene expression under N-replete and N-depleted conditions. The largest such LER (LER1) is ~98kb in size, located near the telomere of the 502.09-kb-long Chromosome 30 (Chr 30). We deleted 81kb and further distal and proximal deletions of up to 110kb (21.9% of Chr 30) in LER1 by dual targeting the boundaries with the episome-based CRISPR/Cas9 system. The telomere-deletion mutants showed normal telomeres consisting of CCCTAA repeats, revealing telomere regeneration capability after losing the distal part of Chr 30. Interestingly, the deletions caused no significant alteration in growth, lipid production or photosynthesis (transcript-abundance change for < 3% genes under N depletion). We also achieved double-deletion of both LER1 and LER2 (from Chr 9) that total ~214kb at maximum, which can result in slightly higher growth rate and biomass productivity than the wild-type. Therefore, loss of the large, yet 'non-essential' regions does not necessarily sacrifice important traits. Such serial targeted deletions of large genomic regions had not been previously reported in microalgae, and will accelerate crafting minimal genomes as chassis for photosynthetic production.

Development of Nickel-Based Negative Tone Metal Oxide Cluster Resists for Sub-10 nm Electron Beam and Helium Ion Beam Lithography.

Hybrid metal-organic cluster resist materials, also termed as organo-inorganics, demonstrate their potential for use in next-generation lithography owing to their ability for patterning down to ∼10 nm or below. High-resolution resist patterning is integrally associated with the compatibility of the resist and irradiation of the exposure source. Helium ion beam lithography (HIBL) is an emerging approach for the realization of sub-10 nm patterns at considerably lower line edge/width roughness (LER/LWR) and higher sensitivity as compared to electron beam lithography (EBL). Here, for the first time, a negative tone resist incorporating nickel (Ni)-based metal-organic clusters (Ni-MOCs) was synthesized and patterned using HIBL and EBL at 30 keV. This resist comprises a nickel-based metal building unit covalently linked with the organic ligand: m-toluic acid (C8H8O2). Dynamic light scattering confirmed a narrow size distribution of ∼2 nm for metal-organic cluster (MOC) formulations. High-resolution ∼9 nm HIBL line patterns were well developed at a sensitivity of 22 μC/cm2 and at a significantly low LER and LWR of 1.81 ± 0.06 and 2.90 ± 0.06 nm, respectively. Analogous high-resolution patterns were also observed in EBL with a sensitivity of 473 μC/cm2. Hence, the Ni-MOC-based resist investigated using HIBL and EBL elucidates the ability of its potential for the sub-10 nm technology node, under standard processing conditions.

Plasmonic lithography for the fabrication of surface nanostructures with a feature size down to 9 nm.

Aiming to further improve the resolution and quality of plasmonic lithography, a self-aligned patterning technique is introduced to it to obtain ultrafine nanopatterns with high contrast and low line edge error (LER). By improving the line edge roughness of the initial plasmonic lithography patterns, 16 nm half-pitch surface nanostructures with a height of 70 nm can be obtained. Moreover, with the help of plasma etching and atomic layer deposition in this process flow, the LER of the 16 nm half-pitch surface nanostructure can achieve 1.3 nm. Further application indicates that this process can also be used to fabricate nanoholes with the feature size as small as 9 nm. This approach provides a new perspective on the manufacture of surface nanostructures with ultrahigh resolution and high aspect ratios, which would find potentially promising applications in metal-air transistors, biosensors, DNA sequencing, etc.

First measurements of the vertical beam size with an X-ray beam size monitor in SuperKEKB rings

This paper reports first measurements of the vertical beam size using an X-ray Beam Size Monitor (XRM) for each of the SuperKEKB rings (Low Energy Ring, LER, and High Energy Ring, HER) during Phase 1 and 2 commissioning of SuperKEKB. The XRM device is dedicated to measuring the e−/e+ vertical beam size using X-ray synchrotron radiation, and will eventually have the capability for single-shot (single bunch, single turn) measurements. The preparation of a deep Si detector and high-speed readout electronics for single-shot measurements is underway. In the meantime for Phase 1 and 2, we used a scintillator screen and CCD camera for multi-bunch measurements. The XRM has been installed in each ring and images X-rays from a bending magnet that pass through optical elements (a single pinhole and coded apertures). Several studies (geometrical scale factors, emittance control knob, and beam lifetime study) were carried out during the commissioning. In Phase 1 (February–June 2016), the measured vertical emittances εy are ∼10 pm for LER (consistent with the optical estimation) and ∼35 pm for HER (3.5 × greater than the optical estimation). Analysis of the beam size and lifetime measurements suggests unexpectedly large point spread functions (PSF), particularly in the HER. The spatial resolution of the imaging system (defect of focus, diffraction, and spherical aberration) and scattering in the beamline (EGS5 simulation) contribute ∼6µm of PSF, which does not adequately account for the observed PSF. The Phase 2 commissioning commenced in May–July 2018, with thinner Be filters, new optical elements, scintillator, and CCD camera with the purpose to reduce the PSF in HER. The Phase 2 study results suggest the PSF σs∼6.6µm in HER (corresponding to the spatial resolution of the imaging system and scattering in the beamline), which is ∼5 × smaller than in Phase 1. The overall performances of XRMs in LER and HER are accurate. The XRM in LER will be able to measure the design beam size at the zero current (14µm). For the HER, the PSF that we observed during the Phase 2 indicates that the minimum measured beam size corresponds to the emittance at the design current (12.9 pm) and the XRM will be able to measure the design beam size at the zero current (7 µm).

Molecular Glass Photoresists with High Resolution, Low LER, and High Sensitivity for EUV Lithography

AbstractNovel molecular glasses (MGs) containing bisphenol A backbone (BPA‐6 and BPA‐10) are synthesized and characterized. BPA‐6 and BAP‐10 are excellent amorphous materials for extreme ultraviolet (EUV) patterning applications with good thermal stability (Td more than 160 °C). The MGs can be used as positive‐tone photoresists combined with triphenylsulfonium perfluoro‐1‐butanesulfonate and trioctylamine dissolved in propylene glycol monomethyl ether acetate. High‐resolution feature sizes as small as 23.1 nm with extremely low line edge roughness (less than 2 nm), high sensitivity (less than 20 mJ cm−2), and good high aspect ratio patterns are obtained by using EUV lithography.

Novel Polymeric Sulfonium Photoacid Generator and Its Application for Chemically Amplified Photoresists

The polymeric PAGs based resist systems which incorporated the PAG units into the main chain showed improved lithographic performance, such as faster photospeed and higher stability, lower outgassing, and lower LER than corresponding blend resists. In this paper, with poly (4-hydroxylstyrene) (PHS) as raw material, a new type of polymeric photoacid generators (PAGs) was synthesized with sulfonuium triflate groups bonded onto part of the benzene rings. The phenolic hydroxyl group was partly esterified to improve its solubility in common organic solvents for resists. Upon irradiation to light, the sulfonium units in the polymer effectively decomposed to generate sulfonic acid. The properties of the novel polymeric PAGs were investigated. Chemically amplified photorssists can be formed by the polymeric PAG and other film forming material containing acid labile groups.

Chronic low back pain patients with accompanying leg pain: The relationship between pain extent and pain intensity, disability and health status

Accompanying leg pain is commonly observed in patients with chronic low back pain (CLBP) and is assumed to be an indicator for the disorder severity. However, it is still unknown whether it is possible to estimate a patient's functional status by the extent of leg pain present. In a post rehabilitation cohort of 132 patients with CLBP (mean age 44.3 years) the relationship between pain extent and functional status was determined using pain drawings scored for pain extent by a simplified scoring system (Lower Extremity Region: LER) and several function related questionnaires. Primary outcomes were pain extent, pain intensity ratings (Visual Analog Scale: VAS), disability status (Oswestry Disability Index: ODI) and physical and mental health (Short Format 12: SF-12). Statistically significant differences between patients with low (1-2) and high (≥ 3) LER scores were found in VAS, ODI and SF-12 physical health scores, however, the LER score has a poor diagnostic accuracy in predicting desirable versus undesirable VAS, ODI and SF-12 scores. Pain intensity (VAS), back disability (ODI) and physical health are worse in CLBP patients with high LER scores. However LER scores cannot be used to predict elevated VAS, ODI and SF-12 scores in an individual patient.

Effect of Potato/Maize Intercropping on Photosynthetic Characteristics and Yield in Two Potato Varieties

The intercropping of potato and maize is widely practiced in China. In the potato/maize system, competition for light is an issue as the leaves of potato and maize become different strata within the canopy. The potato/maize intercropping trials using two potato varieties including Zhongshu 5 (early-maturing variety with erect branches) and Mila (mid-late maturing variety with spread branches) with the sole cropping potato as contro1 were carried out to determine the dynamic changes of LAI, SLW, Chl a+b, Chl a/b ratio, photosynthetical active radiation (PAR), gas exchange attributes in leaves at three position levels at tuber initiation stage and tuber expanding stage and yield. The results indicated that intercropping led to decrease LAI, SLW and Chl a/b ratio and increase Chl a+b. In addition, the gradual decrease in PAR, water use efficiency (WUE), stomatal limitation (L s =1–C i /C a , C a : ambient CO 2 concentration) and the increase in net photosynthetic rate (P n ), stomatal conductance (G s ), intercellular CO 2 (C i ) and transpiration rate (T r ) were observed from tuber initiation stage to tuber expanding stage. There was a continuous significant reduction in PAR, P n , G s and T r from the upper leaves to the middle and lower leaves in all treatments, with a lower reduction under intercropping than under sole cropping. The variations in P n , G s , C i , and L s indicated the decreased photosynthetic activity in the middle and lower leaves pertaining, to both stomatal and non-stomatal mechanisms. Intercropping also declined P n in the upperleaves and elevated P n in the middle and lower leaves. Furthermore, there were higher Chl a+b in vegetative growth stage and tuber initiation stage and lower Chl a+b in tuber expanding stage and starch accumulation stage in Zhongshu 5/maize than in Mira/maize system, with the opposite changing trend for SLW. Higher LAI and Chl a/b ratio at all developmental stages, higher PAR in the upper leaves and lower PAR in the middle and lower leaves were observed, and higher P n in the middle and lower leaves in Zhongshu 5 than in Mira in intercropping systems but the similar Pn in the upper leaves. In comparison with Mira, there were lower Gs , Ci , and T r and higher WUE and L s in leaves at the same position levels in Zhongshu 5. In summary, intercropping led to substantial reduction in tuber yield at harvest time due to the change on the light environment and the photosynthetic characteristics of potato in potato/maize systems. Nonetheless, intercropping deteriorated the light environment for Zhongshu 5/maize system while improved the light environment for Mira/maize system, which led to lower LER in the former (1.24) than in the latter (1.40), showing the stronger intercropping superiority for Mira/maize system in the production.

Nanoparticle photoresists from HfO2 and ZrO2 for EUV patterning

Performance requirements for EUV resists will demand the development of entirely new resist platforms. A challenge in designing these new HfO2 and ZrO2 nanoparticle resists is the selection of molecular structures that will provide both superior performance in imaging and etch resistance while maintaining optimal absorbance at EUV wavelengths. We have previously described the use of inorganic nanoparticle photoresists for 193 nm and e-beam lithography. These inorganic photoresists are made of oxide nanoparticles and have shown etch resistance that is 25 times higher than polymer resists. The high etch resistance of these materials allow the processing of very thin films (< 40 nm) and will help push the resolution limits below 20 nm without pattern collapse. Additionally, the small size of the nanoparticles (< 5 nm) leads to low LER. In this presentation we show that these inorganic resists can be applied to EUV lithography. We have successfully achieved high resolution patterning (<30 nm) with very high sensitivity and low LER.

Delta lithography method to increase CD uniformity and throughput of SLM-based maskless lithography

To increase the CD uniformity and throughput of SLM-based maskless lithography, the delta lithography method (DLM) has been developed. The basic idea of the DLM is to create a delta configuration by using a rectangular point array. The DLM enables irradiation in a honeycomb structure with equilateral triangles or a square structure with right-angled isosceles triangles. To verify the DLM, lithography simulations and a lithography experiment to fabricate a photomask were performed. The pattern appeared to be well defined with extremely low LER. The potential of the DLM to increase the CD uniformity and throughput is confirmed.

Development of EUV Resists in University of Hyogo

It is reviewed that research and development of resist for extreme ultraviolet lithographic in University of Hyogo. It is focused on the mitigation of the development of high sensitive and low line edge roughness EUV resist. To achieve high sensitivity, it is found that cyclo(1,3-per-fluoropropanedisulfone) imidate employed as an anion of PAG is beneficial in EUV exposure to achieve high sensitivity. To achieve low LER and high sensitivity simultaneously, PAG bonded resist is proposed. We demonstrate Eo sensitivity of higher than 2 mJ/cm2 under EUV exposure. PAG bonded resist which has LER of around 2.0 nm and 6.8 μC/c2 are demonstrated. Furthermore, design concept of low outgassing resist is introduced.

Chemically Amplified Main Chain Scission: Chopping the Influence of Polymer Dimensions on Line Edge Roughness

The concept of Main Chain Scission of photoresist polymers (MCS) is used to reducing the influence of molecular dimensions on the quality of photoresist patterns. Independent from the wavelength or lithography technique, the concept will raise in relevance as critical dimensions approach molecular dimensions. After the introduction of the MCS concept on last years conference of photopolymer science and technology, initial results are given in this paper to verify this concept.[1] Starting with polymer synthesis, after optimization of resist formulation and process conditions, ebeam patterns with the MCS resist and a commercial ebeam resist were generated. The patterns were compared with respect to their roughness. It was found, that lines printed in the MCS resist show a significant lower LER than the same patterns in the ebeam resist.

An Advanced Combustion Controller

Abstract In the past ten years there have been significant advances in technologies that are relevant to improving gas-fire combustion controls for industrial applications. These technologies include sensors, electronics, and packaging. Sensors that can measure the constituents in the products of combustion (e.g., CO and O 2 ) can be made less expensive, more reliable, and require less effort in calibration and maintenance. The use of digital technology in the electronics area has substantially reduced the electronics cost while increasing its functional capability and reliability. Lower-cost fabrication and packaging techniques are available now because of the use of new materials and manufacturing processes. Combining these technologies can result in a combustion controller that is significantly lower in cost than existing devices and therefore applicable to a much wider range of applications. The work the Bailey Controls Company is performing on a new low cost combustion control ler is described. This work has been ongoing for the last two years and significant ad vances have been made. Two sensors, one for CO and the other O 2 , using the latest electrochemical and catalytic technologies, have been integrated into a sensor assembly designed for ease of installation and routine maintenance. The electronic assembly uses the latest microcontroller technologies to control sensor assembly conditions, process sensor signals, execute control algorithms, and send out signals to control actuators and recorders. The total design of the system is being implemented with manufacturing automation as a key criteria. The use of advanced materials and manufacturing processes are being evaluated to ensure a low cost device. To date, the feasibility of all critical components has been verified and a demonstra tion unit has been designed and fabricated. Initial test data is very encouraging. With our continued success, a product will be available which will allow for optimum combustion control on a wider range of applications. In addition, many end user cus tomers will be able to realize greater product utilization and improved product quality by having a better understanding of the environment in which their product is being treated.