Mitsuhiro Kureishi

Development of low damage mask making process on EUV mask with thin CrN buffer layer

Low damage processes for an EUV mask consisting of an LR-TaBN absorber and a thin CrN buffer layer with a thickness of 10-nm have been successfully demonstrated through a dry etching process with high selectivity for the absorber, AFM and EB repair processes, and damage less dry etching process of the CrN buffer layer. Deploying an ICP etching process using CHF3 gas, we achieved high etching selectivity of 40 between the LR-TaBN absorber and the CrN buffer and LR-TaBN absorber patterns with nearly vertical sidewalls of a feature size of 150-nm in width. Damage to the multilayer film and the CrN buffer induced by repair process was evaluated using a LR-TaBN mask with a 10-nm thick CrN buffer layer via AFM machining and EB etching techniques. Cross sectional TEM analysis of the repaired mask indicated that the multilayer film showed no significant structural damage, against optimized AFM and EB repair processes. Since the CrN buffer lost a mere 1 nm in thickness in the EB etching process, EB repair appear to represent a promising damage-free repair technique for EUV masks with CrN buffer layers. The reflectivity loss on the multilayer film, caused by dry etching of CrN buffer layer with Cl2 and O2 mixed gases, was improved by an etching process under relatively high pressure. The CrN buffer layer can be etched for the patterns of 150-nm in width without footing at 50% overetch. The results confirm that the reflectivity losses on multilayer film are within 1% after undergoing the improved CrN buffer etching process.

The Utility of a Flexible Fluorescence-Cystoscope with a Twin Mode Monitor for the 5-Aminolevulinic Acid-Mediated Photodynamic Diagnosis of Bladder Cancer

Objectives To evaluate the diagnostic value of a new photodynamic diagnosis (PDD) system using 5-aminolevulinic acid (ALA) for the diagnosis of bladder tumors. To validate whether false-positive findings caused by tangent effects in PDD can be resolved, we compared diagnostic accuracies between the new PDD system and a conventional PDD system. Patients and Methods Among 30 transurethral bladder biopsies, 15 cases received ALA-PDD using rigid fluorescence cystoscopy (conventional PDD system), and flexible fluorescence cystoscopy with a twin mode monitor (new PDD system) was used in a separate set of 15 cases. To evaluated the usefulness of ALA-PDD, diagnostic accuracies were retrospectively compared between the conventional PDD system and the new PDD system. Results Of 207 specimens from 30 cases, we obtained 110 specimens using the conventional PDD system and 97 specimens using the new PDD system. Of these samples, we selected 30 distal bladder specimens each from both the conventional PDD system and the new PDD system. The overall sensitivity, specificity and false-positive rate for the new PDD system were 100%, 82.6%, and 17.4%, respectively. Those of the conventional PDD system were 83.3%, 66.2% and 33.8%, respectively. The overall false-positive rate of the new PDD system improved to 16.4% when compared with the conventional PDD system. Furthermore, the false-positive rate of the new PDD system in distal bladder samples improved to 11.8%. The overall AUC of the new PDD system was significantly greater compared with that of the conventional PDD system (P<0.05). We obtained similar significant results in the distal bladder samples (P<0.05). All procedures were well tolerated by all patients without any severe adverse events. Conclusion Flexible cystoscopy had a significantly higher specificity and improved incidence of tangent effects when compared with conventional methods. This preliminary study suggests that the new PDD system using 5-aminolevulinic acid may be more useful than the conventional PDD system.