Abstract: An interlayer dielectric film is completely buried in a trench, and failures caused by step coverage is prevented because a source electrode can be formed substantially uniformly on an upper portion of a gate electrode. Also, in the processes of forming a source region, a body region and an interlayer dielectric film, only one mask is necessary so that the device size is reduced to account for placement error of only one mask alignment.

Abstract: Provided is an insulated gate semiconductor device. In the device, source regions are provided in the entire operation area and a first back gate region is provided below the source region between trenches. Moreover, a second back gate region connected to the first back gate region is provided outside of the source regions. Thereafter, a first electrode layer coming into contact with the source regions is provided in the entire operation area, and a second electrode layer coming into contact with the second back gate regions is provided around the first electrode layer. Accordingly, potentials can be individually applied to the first electrode layer and the second electrode layer. Thus, it is possible to perform control for preventing reverse flow caused by a parasitic diode.

Abstract: Provided is a semiconductor device in which an insulating region surrounding an element region is provided in an end portion of a semiconductor region with a super junction structure. Since a depletion layer in the element region ends in the insulating region, the end portion of the element region is not formed in a curved surface shape. In other words, the depletion layer has no curved surface in which internal electric fields are concentrated. For this reason, there is no need to take a measure to cause the depletion layer to spread in a horizontal direction by proving a terminal region. Since the terminal region is unnecessary, a chip size can be reduced. Alternatively, an area of the element region can be expanded.

Abstract: Provided is a semiconductor wafer. In the semiconductor wafer, formation and etching of an n type epitaxial layer and formation and etching of a p type epitaxial layer are alternately performed for at least three times, so that all semiconductor layers are formed of epitaxial layers on a semiconductor substrate. Thereby, the respective semiconductor layers can be formed to have reduced widths. Thus, if a required breakdown voltage is the same, dopant concentrations of the respective semiconductor layers can be increased and a resistance value of the wafer can be reduced. In addition, a space portion remaining in the end is buried with an insulating layer, so that a defect can be avoided in a junction surface of the epitaxial layers.

Abstract: Formation and etching of an n type epitaxial layer and formation and etching of a p type epitaxial layer are alternately performed on the semiconductor substrate for at least three times to form all semiconductor layers, of the epitaxial layers. Thereby, impurity concentration profiles of the semiconductor layers can be uniform, and pn junctions can be formed vertically to a wafer surface. Furthermore, the semiconductor layers can each be formed with a narrow width, so that impurity concentrations thereof are increased. With this configuration, high breakdown voltage and low resistance can be achieved.

Abstract: In a MOSFET, after an element region is formed, a wiring layer is formed subsequently to a barrier metal layer, and hydrogen annealing is performed. However, in the case of an n-channel MOSFET, a threshold voltage is lowered due to an occlusion characteristic of the barrier metal layer. Thus, an increased impurity concentration in a channel layer causes a problem that reduction in an on-resistance is inhibited. According to the present invention, after a barrier metal layer is formed, an opening is provided in the barrier metal layer on an interlayer insulating film, and hydrogen annealing treatment is performed after a wiring layer is formed. Thus, an amount of hydrogen which reaches a substrate is further increased, and lowering of a threshold voltage is suppressed. Moreover, since an impurity concentration in a channel layer can be lowered, an on-resistance is reduced.

Abstract: Channel regions continuous with transistor cells are disposed also below a gate pad electrode. The channel region below the gate pad electrode is fixed to a source potential. Thus, a predetermined reverse breakdown voltage between a drain and a source is secured without forming a p+ type impurity region below the entire lower surface of the gate pad electrode. Furthermore, a protection diode is formed in a conductive layer disposed at the outer periphery of an operation region.

Abstract: Channel regions continuous with transistor cells are disposed also below a gate pad electrode. The channel region below the gate pad electrode is fixed to a source potential. Thus, a predetermined reverse breakdown voltage between a drain and a source is secured without forming a p+ type impurity region below the entire lower surface of the gate pad electrode. Furthermore, a protection diode is formed in polysilicon with a stripe shape below the gate pad electrode.

Abstract: Provided is an insulated gate semiconductor device. In the device, source regions are provided in the entire operation area and a first back gate region is provided below the source region between trenches. Moreover, a second back gate region connected to the first back gate region is provided outside of the source regions. Thereafter, a first electrode layer coming into contact with the source regions is provided in the entire operation area, and a second electrode layer coming into contact with the second back gate regions is provided around the first electrode layer. Accordingly, potentials can be individually applied to the first electrode layer and the second electrode layer. Thus, it is possible to perform control for preventing reverse flow caused by a parasitic diode.

Abstract: Channel regions and gate electrodes are also disposed continuously with transistor cells below a gate pad electrode. The transistor cells are formed in a stripe pattern and allowed to contact a source electrode. In this way, the channel regions and the gate electrodes, which are positioned below the gate pad electrode, are kept at a predetermined potential. Thus, a predetermined drain-source reverse breakdown voltage can be secured without providing a p+ type impurity region on the entire surface below the gate pad electrode.

Abstract: Conventional power MOSFETs enables prevention of an inversion in a surrounding region surrounding the outer periphery of an element region by a wide annular layer and a wide sealed metal. Since, resultantly, the area of the surrounding region is large, increase in the element region has been restrained. A semiconductor device is hereby provided which has an inversion prevention region containing an MIS (MOS) structure. The width of polysilicon for the inversion prevention region is large enough to prevent an inversion since the area of an oxide film can be increased by the depth of the trench. By this, leakage current can be reduced even though the area of the region surrounding the outer periphery of the element region is not enlarged. In addition, since the element region is enlarged, on-state resistance of the MOSFET can be reduced.

Abstract: A separation hole is provided in the center of the gate electrode. Accordingly, it is possible to suppress a drastic increase in feedback capacitance Crss in the case where drain-source voltage VDS is decreased and the width of the depletion layer is narrowed. Thus, high-frequency switching characteristics are improved. Moreover, n type impurities are implanted from the separation hole to form an n type impurity region between channel regions. Since a resistance in a portion below the gate electrode can be reduced, an on-resistance can be reduced. The n type impurity region can be formed in a self-aligning manner.

Abstract: A first electrode layer, which comes into contact with a source region, and a second electrode layer, which comes into contact with a body (back gate) region, are provided. The first and second electrode layers are insulated from each other and are extended in a direction different from an extending direction of a trench. It is possible to individually apply potentials to the first and second electrode layers, and to perform control for preventing a reverse current caused by a parasitic diode. Therefore, a bidirectional switching element can be realized by use of one MOSFET.

Abstract: In a peripheral insulating film in a peripheral region, concave parts are provided. At least one of the concave parts is made to have an opening as a contact hole with an Al wiring layer, and a plurality of contact holes may be provided. Accordingly, frictions between the Al wiring layer and the peripheral insulating film are increased. Thus, occurrence of Al slide can be suppressed.

Abstract: An n type impurity region is provided below a gate electrode. By setting a gate length to be less than a depth of a channel region, a side surface of the channel region and a side surface of the n type impurity region adjacent to the channel region form a substantially perpendicular junction surface. Thus, since a depletion layer widens uniformly in a depth direction of a substrate, it is possible to secure a predetermined breakdown voltage. Furthermore, since an interval between the channel regions, above which the gate electrode is disposed, is uniform from its surface to its bottom, it is possible to increase an impurity concentration of the n type impurity region, resulting in an achievement of a low on-resistance.

Abstract: In the present invention, in a pattern in which gate electrodes are provided in a stripe shape and source regions are provided in a ladder shape, body regions are provided in a stripe shape parallel to the gate electrodes. A first body region is exposed to a surface of a channel layer between first source regions adjacent to the gate electrode, and a second body region is provided below a second source region which connects the first source regions to each other. Thus, avalanche resistance can be improved. Moreover, since a mask for forming the body region is no longer required, there is a margin in accuracy of alignment.

Abstract: In a MOSFET, after an element region is formed, a wiring layer is formed subsequently to a barrier metal layer, and hydrogen annealing is performed. However, in the case of an n-channel MOSFET, a threshold voltage is lowered due to an occlusion characteristic of the barrier metal layer. Thus, an increased impurity concentration in a channel layer causes a problem that reduction in an on-resistance is inhibited. According to the present invention, after a barrier metal layer is formed, an opening is provided in the barrier metal layer on an interlayer insulating film, and hydrogen annealing treatment is performed after a wiring layer is formed. Thus, an amount of hydrogen which reaches a substrate is further increased, and lowering of a threshold voltage is suppressed. Moreover, since an impurity concentration in a channel layer can be lowered, an on-resistance is reduced.

Abstract: The invention relates to a thermophilic enzyme having ?-glycosidase activity which comprises the amino acid sequence of SEQ ID NO: 2 in which one or a plurality of amino acid residues may be deleted, replaced or added.

Abstract: An interlayer dielectric film is completely buried in a trench, and failures caused by step coverage is prevented because a source electrode can be formed substantially uniformly on an upper portion of a gate electrode. Also, in the processes of forming a source region, a body region and an interlayer dielectric film, only one mask is necessary so that the device size is reduced to account for placement error of only one mask alignment.

Abstract: Conventional power MOSFETs enables prevention of an inversion in a surrounding region surrounding the outer periphery of an element region by a wide annular layer and a wide sealed metal. Since, resultantly, the area of the surrounding region is large, increase in the element region has been restrained. A semiconductor device is hereby provided which has an inversion prevention region containing an MIS (MOS) structure. The width of polysilicon for the inversion prevention region is large enough to prevent an inversion since the area of an oxide film can be increased by the depth of the trench. By this, leakage current can be reduced even though the area of the region surrounding the outer periphery of the element region is not enlarged. In addition, since the element region is enlarged, on-state resistance of the MOSFET can be reduced.