Abstract: A scroll compressor using helium gas as working gas, has a fixed scroll and an orbiting scroll, engaged with each other, each having a scroll tooth profile shape of a set volume ratio of a scroll wrap portion of 1.8 to 2.3.

Abstract: A method of fabricating a semiconductor device having, for example, a memory cell array portion and a peripheral circuit portion is disclosed. By such a method, a first interlayer insulating film is formed on a semiconductor substrate, a first connection hole is formed by selectively removing a predetermined portion of the first interlayer insulating film, the sides of the first hole being substantially vertical to the bottom thereof, a first plug is formed by padding the first hole with a metallic film and, subsequently, a second interlayer insulating film is formed on the first insulating film, a second hole is formed by selectively removing a predetermined portion of the second interlayer insulating film, the sides of the second hole being substantially vertical to the bottom thereof, and a second plug aligned to be in direct connection with the first plug is formed by padding the second hole with the metallic film.

Abstract: In an optical head for recording on or reproducing from a plurality of kinds of optical information recording media corresponding to a plurality of kinds of different wavelengths, coma aberration is prevented, and low price and high reliability are realized. To that end, in an optical head constituted by laser light sources of three wavelengths and photodetectors corresponding to the laser light sources of the three wavelengths, a two-laser module including laser light sources of two adjacent wavelengths and photodetectors corresponding to the laser light sources, a laser module including a laser light source of the rest one wavelength and a photodetector corresponding to the laser light source, and a dichroic mirror bonded with a rising mirror are combined.