Nippon Steel Corporation

United Microelectronics Corp.

Taro Muraki

Yasushi Hasegawa

Tomoyuki Uchiyama

Kazuhisa Sasaki

Takuya Hara

Akira Kawakami

Hiroshi Tamehiro

Taishi Fujishiro

Junichi Okamoto

Asahi Hitoshi

Go Suzuki

A semiconductor device includes first and second conductive layers which are electrically connected to each other through a contact plug. A first insulating film is formed on the first conductive layer and has a first opening which reaches the surface of the first conductive layer. A second insulating film is formed on the first insulating film and has a second opening at the same position as the first opening. The contact plug is filled in the first and second openings and has the surface which is substantially flush with the surface of the second insulating film and also contains a metal having a high melting point. The second conductive layer is formed on the second insulating film and on the contact plug.

Semiconductor device and fabrication method thereof

This invention provides a boiler steel pipe that exhibits a high creep rupture strength on a high-temperature high-pressure side and is excellent in electric weldability, and an electric welded boiler steel pipe having fewer defects at an electric welded portion. The boiler steel contains, in terms of wt %, C: 0.01 to 0.20%, Si: 0.01 to 1.0% and Mn: 0.10 to 2.0%, contains further Cr: 0.5 to 3.5%, and limits p&lE;0.030%, S&lE;0.010% and 0&lE;0.20%, wherein a weight ratio of (Si %)/(Mn %) or (Si %)/(Mn %&plus;Cr %) is from 0.005 to 1.5, the balance Fe and unavoidable impurities, and the melting point of the mixed oxide of SiO and MnO, or SiO , MnO and Cr O , is not higher than 1,600&deg; C. The oxide that would otherwise result in the defects of the electric welded portion is molten and squeezed out as slag components. Therefore, a boiler steel excellent in electric weldability and the electric welded boiler steel pipe having fewer welding defects, excellent in creep rupture strength and toughness, and using the former, can be obtained.

Electric welded boiler steel pipe

BN-precipitation-strengthened low-carbon-ferritic heat-resistant steel

High-corrosion-resistant martensitic stainless steel having excellent

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Tokyo, Japan

Taro Muraki