Papers by Author: T. Yamamoto

Abstract: Guaranteeing the reliability of gate oxides is one of the most important topics to realize regarding the SiC power MOSFET. In the case of trench MOSFET, since the gate oxides are formed on the trench sidewall, the damage and roughness on the trench sidewall can affect the lifetime of the gate oxides. Generally speaking, damage removal treatment is processed after trench dry etching in most cases. In Si processes, sacrificial oxidation, H₂ anneal and CDE (Chemical Dry Etching) are adopted commonly. In the case of SiC processes, sacrificial oxidation, H₂ anneal, and SiH₄/Ar anneal have been reported. Neverthless CDE which applied to SiC trench MOSFET has few precedents. We clarified the effect of CDE as a damage removal process. CDE has the effect of flattening the trench sidewall, and CDE makes the lifetime of gate oxides improve. CDE is an effective process for the reliability of SiC trench MOSFET.

Abstract: A new biodegradable adhesive(LYDEX) which is based on Schiff base formation had developed. LYDEX is easy to control the setting time and degradation speed and it has no risk of infection. In the previous study, LYDEX showed high bonding strength and low cytotoxicity in vitro[1]. In the present study, good bone repair was seen in rat bone defect models, especially in rapidly degrading type. On the other hand, slowly degrading type kept its shape longer without excessive inflammation. In rabbit critical defect model with hydroxyapatite granules (HAs), more newly formed bone was seen in rapidly degrading group and hydroxyapatite group, in 3weeks. In 6weeks, more new bone was seen in slowly degrading type group, whereas, almost no new bone was seen in deep area of the fibrin group, in 12weeks. Direct bonding between HAs and bone was seen in HA group and LYDEX groups. These findings suggest that LYDEX with hydroxyapatite granules can be a promising bone substitute.