Toshiaki Ando

Mechanisms of suppression of renal kallikrein activity in low renin essential hypertension and renoparenchymal hypertension.

The mechanism of suppression of renal kallikrein activity in low renin essential hypertensive and renoparenchymal hypertensive patients was investigated in this study. From Sephadex G-200 column chromatography studies, a single kallikrein peak was observed in both kallikrein radioimmunoassay and kininogenase activity in all samples from normal subjects, low renin essential hypertensive and renoparenchymal hypertensive patients, and in purified kallikrein solution. The enzyme-specific activity around the kallikrein peak in all urine samples from each group was significantly lower than that in purified kallikrein, and a significantly lower specific activity was found in both patient groups than was found in normal subjects. Moreover, it was also recognized that the specific activity of kallikrein decreased in all cases with the increase of the molecular weight of kallikrein, and this tendency was observed more obviously in the low renin essential hypertensive and renoparenchymal hypertensive patients than in the normal subjects. These results suggest the presence of a kallikrein-specific inhibitor with a low molecular weight in human urine, although the possibility of a variant form of kallikrein cannot be excluded.

Defectivity and particle reduction for mask life extension, and imprint mask replication for high-volume semiconductor manufacturing

Imprint lithography has been shown to be an effective technique for replication of nano-scale features. Jet and Flash* Imprint Lithography (J-FIL*) involves the field-by-field deposition and exposure of a low viscosity resist deposited by jetting technology onto the substrate. The patterned mask is lowered into the fluid which then quickly flows into the relief patterns in the mask by capillary action. Following this filling step, the resist is crosslinked under UV radiation, and then the mask is removed, leaving a patterned resist on the substrate. Criteria specific to any lithographic process for the semiconductor industry include overlay, throughput and defectivity. The purpose of this paper is to describe the technology advancements made in the reduction of particle adders in an imprint tool and introduce the new mask replication tool that will enable the fabrication of replica masks with added residual image placement errors suitable for memory devices with half pitches smaller than 15nm. Hard particles on a wafer or mask create the possibility of creating a permanent defect on the mask that can impact device yield and mask life. By using material methods to reduce particle shedding and by introducing an air curtain system, test stand results demonstrate the potential for extending mask life to better than 1000 wafers. Additionally, a new replication tool, the FPA-1100 NR2 is introduced. Mask chuck flatness simulation results were also performed and demonstrate that residual image placement errors can be reduced to as little as 1nm.

In-line surface preparation and resist plug removal on NIL templates

Nano Imprint Lithography (NIL) is valued as a cost effective alternative to other Next Generation Lithography (NGL) choices, especially for memory device applications. In order to achieve an attractive Cost of Ownership (CoO), replicas are made from a master and those replicas are then used in the actual pattern transfer onto the device wafer. During the pattern transfer process from a template to a device wafer, droplets of imaging material are applied to the surface of the substrate, in the area where the imaging is to take place. The image to be transferred is then brought into direct contact with the imaging material, at which time it will spread between the two surfaces by means of capillary force, and the imaging material is then solidified through UV irradiation. As the template is pulled away, it leaves its image imprinted into the imaging material. Any resist adhering to the template will cause defects in subsequent imprints, hence such template contamination, so called resist plugs, must either be avoided or removed. This work focuses on the resist removal techniques employing ambient pressure plasma, and their benefit to improve throughput, i.e. CoO. In our studies, we found that resist removal efficiency is highly depending on the process gas mixture and the process temperature. This dry cleaning process has a good potential as an efficient in-line imprint mask cleaning system.