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Resist Formulation Optimizer (RFO) is created to optimize resist formulation under EUV stochastic effects. Photosensitized Chemically Amplified ResistTM (PSCARTM) 2.0 reaction steps are included in the resist reaction model in RFO in addition to standard Chemically Amplified Resists (CAR) reaction steps. A simplified resist roughness calculation method is introduced in RFO. RFO uses “fast stochastic resist model” which uses continuous model information for stochastic calculation. “Resist component’s dissolution inhibition model” is also introduced for better prediction of different resist formulations in RFO. The resist component’s dissolution inhibition model is used for calculation of both Dissolution Inhibition Slope (DIS) and Dissolution Inhibition Deviation (DID). By dividing DID by DIS at a pattern edge, Line Edge Roughness (LER) can be predicted. The RFO performance is validated to give low residual errors after calibration even for different resist formulations. RFO is designed to optimize the resist formulation to minimize resist roughness as a cost function with keeping target CD. RFO suggests that PSCAR 2.0 with Polarity Switching photosensitizer precursor (POLAS) in combination with photosensitizer (PS) image enhancement may provide reduced resist roughness. Simulations using a calibrated rigorous stochastic resist model for S-Litho show a good prediction of PSCAR 2.0 process performance.

Photosensitized Chemically Amplified ResistTM (PSCARTM) **2.0’s advantages and expectations are reviewed in this paper. Alpha PSCAR in-line UV exposure system (“Litho Enhancer”) was newly installed at imec in a Tokyo Electron Ltd. (TELTM)’s CLEAN TRACKTM LITHIUS ProTM Z connected to an ASML’s NXE:3300. Using the Litho Enhancer, PSCAR 2.0 sensitization preliminary results show that suppression of roughness enhancement may occur while sensitivity is increased. The calibrated PSCAR 2.0 simulator is used for prediction of resist formulation and process optimization. The simulation predicts that resist contrast enhancement could be realized by resist formulation and process optimization with UV flood exposure.

In order to lower the cost of ownership of EUV lithography, high sensitivity EUV resists , enabling higher throughput of EUV scanners are being explored. The concept that utilizes a Photosensitized Chemically Amplified ResistTM (PSCARTM) is a promising solution for achieving increased resist sensitivity, while maintaining other high performance characteristics of the material (i.e., resolution, line edge roughness (LER), exposure latitude). PSCAR uses a UV exposure after EUV exposure and selective absorption to meet these goals . Preliminary results have been discussed in previous papers 1-8. PSCAR utilizes an area-selective photosensitization mechanism to generate more acid in the exposed areas during a UV exposure. PSCAR is an attempt to break the resolution, line-edge-roughness, and sensitivity trade-off (RLS trade-off) relationships that limit standard chemically amplified resists. The photosensitizer, which is generated in exposed area by a photoacid catalytic reaction, absorbs the UV exposure light selectively and generates additional acid in the exposed area only. Material development and UV exposure uniformity are the key elements of PSCAR technology for semiconductor mass fabrication. This paper will review the approaches toward improvement of PSCAR resist process robustness. The chemistry’s EUV exposure cycle of learning results from experiments at imec will be discussed.

A new type of Photosensitized Chemically Amplified Resist (PSCAR) **: “PSCAR 2.0,” is introduced in this paper. PSCAR 2.0 is composed of a protected polymer, a “photo acid generator which can be photosensitized” (PS-PAG), a “photo decomposable base (quencher) which can be photosensitized” (PS-PDB) and a photosensitizer precursor (PP). With this PSCAR 2.0, a photosensitizer (PS) is generated by an extreme ultra-violet (EUV) pattern exposure. Then, during a subsequent flood exposure, PS selectively photosensitizes the EUV exposed areas by the decomposition of a PS-PDB in addition to the decomposition of PS-PAG. As these pattern-exposed areas have the additional acid and reduced quencher concentration, the initial quencher loading in PSCAR 2.0 can be increased in order to get the same target critical dimensions (CD). The quencher loading is to be optimized simultaneously with a UV flood exposure dose to achieve the best lithographic performance and resolution. In this work, the PSCAR performance when different quenchers are used is examined by simulation and exposure experiments with the 16 nm half-pitch (HP) line/space (L/S, 1:1) patterns. According to our simulation results among resists with the different quencher types, the best performance was achieved by PSCAR 2.0 using PS-PDB with the highest possible chemical gradient resulting in the lowest line width roughness (LWR). PSCAR 2.0 performance has furthermore been confirmed on ASML’s NXE:3300 with TEL’s standalone pre-alpha flood exposure tool at imec. The initial PSCAR 2.0 patterning results on NXE:3300 showed the accelerated photosensitization performance with PS-PDB. From these results, we concluded that the dual sensitization of PS-PAG and PS-PDB in PSCAR 2.0 have a potential to realize a significantly improved resist performance in EUV lithography.

A decrease in lacrimal gland secretory function is closely related to aging and leads to an increased prevalence of dry eye syndrome. Since calorie restriction (CR) is considered to prevent functional decline of various organs due to aging, we hypothesized that CR could prevent age-related lacrimal dysfunction. Six-month-old male Fischer 344 rats were randomly divided into ad libitum (AL) and CR (-35%) groups. After 6months of CR, tear function was examined under conscious state. After euthanasia, lacrimal glands were subjected to histological examination, tear protein secretion stimulation test with Carbachol, and assessment of oxidative stress with 8-hydroxy-2 deoxyguanosine (8-OHdG) and 4-hydroxynonenal (HNE) antibodies. CR significantly improved tear volume and tended to increase tear protein secretion volume after stimulation with Carbachol compared to AL. The acinar unit density was significantly higher in the CR rats compared to AL rats. Lacrimal glands in the CR rats showed a lesser degree of interstitial fibrosis. CR reduced the concentration of 8-OHdG and the extent of staining with HNE in the lacrimal gland, compared to AL. Furthermore, our electron microscopic observations showed that mitochondrial structure of the lacrimal gland obtained from the middle-aged CR rats was preserved in comparison to the AL rats. Collectively, these results demonstrate for the first time that CR may attenuate oxidative stress related damage in the lacrimal gland with preservation of lacrimal gland functions. Although molecular mechanism(s) by which CR maintains lacrimal gland function remains to be resolved, CR might provide a novel therapeutic strategy for treating dry eye syndrome.

We present a rare case of perforation of the colon close to an artificial anus probably caused by colostoy irrigation with a review of the literaturs. A 37-year-old man undergoing an operation for a sigmoid colon cancer 6 years before had been controlling his artificial anus by himself by colostomy irrigation for 4 months. He was aware of a mild pain around the artificial anus after irrigation for the last one month. As the pain increased, he was admitted to the hospital. Tenderness and the symptom of peritoneal irritation were observed around the artificial anus. No free air was found by a simple X-ray film and CT scan, but the intraperitoneal leak of contrast medium was found in the adoral site of the artificial anus. He was diagnosed to have peritonitis due to perforation of colon close to artificial anus. Resection of the adanal colon including the perforated site and reconstruction of artificial anus were performed. The perforated site was located at about 7cm oral from the opening of the artificial anus. Histological examination revealed the tear of muscularis propria in the periphery of the perforated site. The site which had become less resistant to the load was probably perforated by the mechanical factor at the time of colostomy irrigation. It is suggested that attention should always be paid to the risk of colonic perforation as a complication of colostomy irrigation.

若年者自然気胸に対してENDO-GIAを用いた胸腔鏡下肺部分切除術を施行した.対象は術前に施行した胸部単純X線, 断層X線および胸部CT検査で肺尖部に限局するブレブが確認された19歳から32歳の6例で, 平均手術時間は70分, ENDO-GIAの使用回数は平均5回, 術後疼痛は軽微で, 4日目にドレーン抜去し, 9日目に退院した.切除したブレブの大きさは2～6cm (平均3.5cm), 切除組織の大きさは5.5～10.5cm (平均7.7cm) であった.ENDO-GIAは操作性と根治性が高く, ほとんどの若年者自然気胸に対して有効と考えられた.

BACKGROUND: Dry eye has shown a marked increase due to visual display terminal (VDT) use. It remains unclear whether reduced blinking while focusing can have a direct deleterious impact on the lacrimal gland function. To address this issue that potentially affects the life quality, we conducted a large-scale epidemiological study of VDT users and an animal study. METHODOLOGY/PRINCIPAL FINDINGS: Cross sectional survey carried out in Japan. A total of 1025 office workers who use VDT were enrolled. The association between VDT work duration and changes in tear film status, precorneal tear stability, lipid layer status and tear secretion were analyzed. For the animal model study, the rat VDT user model, placing rats onto a balance swing in combination with exposure to an evaporative environment was used to analyze lacrimal gland function. There was no positive relationship between VDT working duration and change in tear film stability and lipid layer status. The odds ratio for decrease in Schirmer score, index of tear secretion, were significantly increased with VDT working year (P = 0.012) and time (P = 0.005). The rat VDT user model, showed chronic reduction of tear secretion and was accompanied by an impairment of the lacrimal gland function and morphology. This dysfunction was recovered when rats were moved to resting conditions without the swing. CONCLUSIONS/SIGNIFICANCE: These data suggest that lacrimal gland hypofunction is associated with VDT use and may be a critical mechanism for VDT-associated dry eye. We believe this to be the first mechanistic link to the pathogenesis of dry eye in office workers.

Purpose To investigate whether oxidative stress is involved in the etiology of the corneal disorder in blink-suppressed dry eye in a clinically relevant in vivo rat model. Methods A series of treatments were performed under continuous exposure to low-humidity airflow. Rats were placed on a jogging board (JB) made of a plastic pipe for 7.5 h/d, and for 16.5 hours, they were placed in individual cages without a JB. This protocol was repeated for up to 30 days. Corneal surface alteration was evaluated by the score of punctate fluorescein staining. To assess oxidative stress status, the levels of damaged DNA, and the protein modification by reactive aldehydes in corneal epithelia were detected by immunohistochemistry, using 8-hydroxy-2-deoxyguanosine, 4-hydroxynonenal- and malondialdehyde-specific antibodies. Results Significant increases in the fluorescein staining score were observed from days 1 to 30 compared with the initial value. The average score for the dry eye group was significantly increased compared with that for the nontreatment group at all time points throughout the experiment. Immunoreactivity of all oxidative stress markers increased in the dry eye treatment. Quantitative analysis of the positive-stained cells showed a significant increase in the number of positive cells after 10 and 30 days in the dry eye treatment group compared with the nontreatment group. Conclusions These results suggest a relationship between the accumulation of oxidative stress and the etiology of corneal epithelial alterations in blink-suppressed dry eye.

Purpose The purpose of this study was to establish a rat dry eye model of corneal epithelial disorders by inducing improper tear dynamics and change in blink frequency. The protective effect of d-beta-hydroxybutyrate (HBA) on the corneal epithelia was also investigated. Methods A series of treatments were performed under continuous exposure to low-humidity airflow. Rats were placed on a jogging board (JB) made of a plastic pipe for 7.5 h/d, and, for 16.5 hours, they were placed in individual cages without JB treatment. The resultant changes in tear dynamics and corneal epithelial structure were then analyzed. Five days after the rats were exposed to the treatment, eyes that showed corneal fluorescein staining were examined, to investigate the effect of HBA, by administration of eye drops containing 80 mM HBA four times daily during JB treatment for 5 days. Results Significant reductions in blink frequency, Schirmer score, and tear clearance were recorded during JB treatment in eyes that showed persistent punctate staining of almost one half of the corneal surface. The application of HBA-containing eye drops significantly reduced the punctate staining compared with the initial or phosphate-buffered saline-treated eyes. Conclusions This rat dry eye model, established by repeated JB treatment in desiccating conditions, induced abnormal tear dynamics and superficial punctate keratopathy similar to that in humans. These findings suggest the potential clinical application of HBA in corneal surface epithelial disorders in patients with moderate to mild dry eye.

Purpose To investigate the effect of D-beta-hydroxybutyrate (HBA) on ocular surface epithelial disorders induced by tear fluid deficiency, the potency of HBA and serum, the efficacy of which has been well documented in clinical application, were compared. Methods Rat corneal epithelial erosion was induced by exposure of rat eyes to continuous low-humidity airflow, which accelerated the tear evaporation. During desiccation, one eye of each rat was treated with HBA (20, 40, or 80 mM) or rat serum (5%, 20%, or 100%), and in the other eye a drop of phosphate-buffered saline (PBS) was instilled as the control. Histopathologic examination and quantification of the epithelial defect area were performed. The apoptosis in the epithelia was determined by chromatin condensation using the Hoechst 33342 fluorescein probe. Results In PBS-treated eyes, thinning in the cell layer was seen on the periphery of the initial wound after 6 hours, and it progressed to defects after 12 hours. In the 80-mM HBA and 20% serum applications, the pathologic change in the epithelia was moderate, and the structure was maintained in an almost normal state in the 100% serum application. Significant decreases in the defect areas were observed in the 5%, 20%, and 100% serum and 40- and 80-mM HBA treatment groups compared with the PBS-treated eyes (n=12). A significant suppression of chromatin condensation was observed with HBA and serum treatment. Conclusions These results suggest the potential clinical application of HBA for ocular surface epithelial disorders to maintain epithelial cell viability in patients with dry eye.