Hitachi, Ltd.

Masayasu Nihei

Jin Onuki

Kunio Miyazaki

Yasushi Koubuchi

Satoshi Kokura

Tatsuo Itagaki

Eiji Ashida

Akira Onuma

Hiroshi Wachi

Toshiaki Morita

Shinichi Fukada

Jun Sugiura

Masateru Suwa

Takao Funamoto

Akira Sato

Mitsuo Chigasaki

Yuzo Kozono

Katsuhiko Shiota

Motoo Suwa

Izumi Sakurai

Hiromi Mashida

Kousaku Senda

In a method for high frequency pulse welding and an apparatus therefor, a highly directive arc can be obtained by eliminating the effect of the inductance of the welding cable, which tends to make the high frequency electromagnetic pinch force large. In a method and an apparatus for high frequency pulse arc welding which is performed by generating an arc between an inconsumable electrode or a consumable electrode arranged near a portion of a base metal to be welded and the base metal with main pulse current, when the main pulse current is shifted from ON to OFF, a reverse pulse current having a polarity opposite to the polarity of the main pulse is supplied between the electrode and the base metal to improve the stiffness (directivity) of the arc by making the rising and falling edges of the pulses steeper. A rail-car and a nuclear power plant obtained by the method are also provided.

Method of high frequency pulse arc welding and apparatus therefor

A method of solder bonding suitable for a body having a large bonding surface area including the following steps of cleaning off the bonding surfaces in vacuum chamber by impinging accelerated particles such as argon ions through reverse spattering; then covering with an oxidation inhibiting thin silver film over the cleaned off bonding surfaces through spattering; further sandwiching a cleaned off solder foil between the bonding surfaces covered with the oxidation inhibiting thin sliver film; and heating the solder foil in vacuum upto the melting temperature thereof to complete the bonding, whereby defects in the solder bonding is reduced downto about 1/25 and life time of the solder bonding which is affected by thermal fatigue is prolonged twice in comparison with a conventional solder bonding method, thereby reliability of the solder bonding is greatly improved.

Method of solder bonding and power semiconductor device manufactured by

A thin film forming method and apparatus, wherein a negative voltage is applied alternately to a target and a substrate to perform film formation and reverse sputter alternately. Further, a coil is mounted between the target and the substrate and a high frequency current is made to flow therethrough to generate plasma. A negative base voltage smaller in absolute value than that during sputter may be applied to the substrate to make Ar ions flow into the substrate while it is subjected to reverse sputter. Thus, a film whose step coverage is 0.3 or more is possible. It becomes also possible to maintain a stable discharge and perform reverse sputter in a high vacuum region. The pressure of an Ar atmosphere may be lowered to 10.sup.-3 Torr or less. An aluminum wiring film whose peak value of x-ray diffraction strength at a (111) plane is 150 Kcps or more is possible. Also, a barrier layer having a layered structure of granular and columnar crystals or a mixed structure thereof providing an efficient barrier effect and a large specific resistance is possible.

Method of and apparatus for sputtering, and integrated circuit device

A semiconductor device having a high reliability wiring conductor structure applicable to DRAMs and SRAMs. The semiconductor device of the present invention is characterized by comprising a first wiring conductor film wherein a specific resistance is 5.about.15.mu..OMEGA.cm and an allowable current density is 1.times.10.sup.6 .about.1.times.10.sup.8 A/cm.sup.2 ; a second wiring conductor film having a laminated layer structure formed of a layer of high fusing point and low resistance material and a layer of an Al based alloy; and a plug composed of a high fusing point and low resistance material, electrically connecting to the first wiring conductor film and the second wiring conductor film. Thus, a semiconductor device showing almost no increase in electrical resistance in a wiring conductor film due to electromigration even after subjecting to a large current is provided.

Semiconductor device and method for manufacturing the same

A thin film forming method and apparatus is provided, wherein a negative voltage is applied alternately to a target and a substrate to perform film formation and reverse sputter alternately. Further, a coil is mounted between the target and the substrate and a high frequency current is made to flow therethrough to generate plasma. A negative base voltage smaller in absolute value than that during sputter may be applied to the substrate to make a fraction of Ar ions to flow into the substrate while it is subjected to reverse sputter. Thus, a film whose step coverage is 0.3 or more is possible. It becomes also possible to hold stable discharge and reverse sputter at a high vacuum region. The pressure of an Ar atmosphere may be lowered to 10.sup.-3 Torr or less. A film whose peak value of x-ray diffraction strength in the (111) plane is 150 Xcps or more is possible. Also, a barrier layer with a layered structure of granular and columnar crystals or a mixed structure thereof and hence with an efficient barrier effect and a large specific resistance is possible.

Method of and apparatus for sputtering

A method for forming a thin film wherein plural targets of different materials are alternately sputtered througth the switching of the electric powers supplied thereto, the particles produced from the sputtering are ionized and thereafter deposited on a substrate. This method provides an alloy thin film, compound thin film or multi-layer thin film of any composition and enhances adhesion among the particles. A sputtering device for practicing this method is also disclosed.

Thin film forming method through sputtering and sputtering device

In a two electrode welding method wherein welding is carried out by means of arcs struck between two electrodes and a parent metal, the two electrodes being located in side-by-side, spaced-apart relation in a direction in which the welding surface advances and movable relative to the parent metal, a portion of the parent metal is preheated by the arc struck between the leading electrode and the parent metal, and a preheated portion is melted by the heat of the arc struck between the trailing electrode and the parent metal when the former has moved to a position above the preheated portion of the latter to provide a deposited metal. The method has particular utility in applications where metal of high heat conductivity, such as copper, is welded.

Two electrode welding with different currents supplied to the electrodes

In a welding apparatus having a plurality of electrodes and adapted for carrying out welding operation on a workpiece by alternately supplying currents to the individual electrodes through switching elements, an apparatus and method of controlling the currents supplied to the electrodes, comprising selecting the values of the currents supplied to the individual electrodes depending on the material of the workpiece, and carrying out the welding operation on the workpiece by alternately supplying the currents of the selected values to the individual electrodes respectively through the switching elements. The method is featured by the fact that the ratio between the individual currents is selected under the condition that the sum of the values of all the currents is maintained at a predetermined value. It is also featured by the fact that, depending on the welding condition, the values of the individual currents can be freely selected without the limitation of maintaining the sum of all the currents at the predetermined value. Therefore, the apparatus and method are applicable to welding of a variety of materials by selecting the values of the individual currents depending on whether the workpiece has a high or low melting point and also whether the workpiece has a high or low heat conductivity.

Method of electrode current control in welding apparatus having a

Disclosed is a method and apparatus for automatically controlling arc welding, wherein pieces of optical information provided by at least two bands of different wavelengths of light radiated from a weld area being arc-welded under predetermined welding conditions are alternately picked up by an optical device to extract various weld factors representing the actual status of the weld area from these pieces of optical information, and the extracted weld factors representing the actual status of the weld area are compared with the desired values of the weld factors representing the desired status of the weld area to compute the error or errors of the welding conditions, so that the welding conditions can be corrected on the basis of the detected error or errors of the welding conditions, whereby the weld factors can be controlled to the desired values.

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Hitachi, Japan

Masayasu Nihei