Abstract: A trench IGBT is disclosed which meets the specifications for turn-on losses and radiation noise. It includes a p-type base layer divided into different p-type base regions by trenches. N-type source regions are formed in only some of the p-type base regions. There is a gate runner in the active region of the trench IGBT. Contact holes formed in the vicinities of the terminal ends of the trenches and on both sides of the gate runner electrically connect some of the p-type base regions that do not include source regions to an emitter electrode. The number N1 of p-type base regions that are connected electrically to the emitter electrode and the number N2 of p-type base regions that are insulated from the emitter electrode are related with each other by the expression 25?{N1/(N1+N2)}×100?75.

Abstract: A trench IGBT is disclosed which meets the specifications for turn-on losses and radiation noise. It includes a p-type base layer divided into different p-type base regions by trenches. N-type source regions are formed in only some of the p-type base regions. There is a gate runner in the active region of the trench IGBT. Contact holes formed in the vicinities of the terminal ends of the trenches and on both sides of the gate runner electrically connect some of the p-type base regions that do not include source regions to an emitter electrode. The number N1 of p-type base regions that are connected electrically to the emitter electrode and the number N2 of p-type base regions that are insulated from the emitter electrode are related with each other by the expression 25?{N1/(N1+N2)}×100?75.

Abstract: A trench MOSFET includes mesa regions between the trenches. The mesa regions are connected to an emitter electrode to fix the mesa region potential so that the mesa regions do not form a floating structure. P-type base regions are distributed in the mesa regions, and the distributed p-type base regions (e.g., the limited regions in the mesa regions) are provided with an emitter structure. The trench MOSFET can lower the switching losses, reducing the total losses while suppressing the ON-state voltage drop of the trench IGBT as low as the ON-state voltage drop of the IEGT, and improving the turn-on characteristics thereof. The trench MOSFET also can reduce the capacitance between the gates and the emitter thereof, since the regions where the gate electrode faces the emitter structure are reduced. The trench MOSFET can have trench gate structures set at a narrow interval to relax the electric field localization to the bottom portions of the trenches and obtain a high breakdown voltage.

Abstract: A trench IGBT is disclosed which meets the specifications for turn-on losses and radiation noise. It includes a p-type base layer divided into different p-type base regions by trenches. N-type source regions are formed in only some of the p-type base regions. There is a gate runner in the active region of the trench IGBT. Contact holes formed in the vicinities of the terminal ends of the trenches and on both sides of the gate runner electrically connect some of the p-type base regions that do not include source regions to an emitter electrode. The number N1 of p-type base regions that are connected electrically to the emitter electrode and the number N2 of p-type base regions that are insulated from the emitter electrode are related with each other by the expression 25?{N1/(N1+N2)}×100?75.

Abstract: A trench-type IGBT includes a silicon substrate, a lightly doped n-type drift layer on the silicon substrate, and a p-type base layer on the n-type drift layer. The p-type base layer is doped more heavily than the n-type drift layer, and is formed of first regions and second regions. N+-type source regions are formed selectively in the surface portions of the first regions of p-type base layer. Trenches are dug from the surfaces of n+-type source regions down to the n-type drift layer through the p-type base layer. A gate oxide film covers the inner surface of each trench. Gate electrodes are provided in the trenches, wherein the gate electrodes face the p-type base layer via respective gate oxide films. An emitter electrode is in direct contact with the first regions of p-type base layer and n+-type source regions. A collector electrode is provided on the back surface of silicon substrate.

Abstract: A high-speed, soft-recovery semiconductor device that reduces leakage current by increasing the Schottky ratio of Schottky contacts to pn junctions. In one embodiment of the present invention, an n− drift layer is formed on an n+ cathode layer 1 by epitaxial growth, and ring-shaped ring trenches having a prescribed width are formed in the n− drift layer. Oxide films are formed on the side walls of each ring trench. The ring trenches are arranged such that the centers of the rings of the ring trenches adjacent to one another form a triangular lattice unit. A p− anode layer is formed at the bottom of each ring trench. Schottky contacts are formed at the interface between an anode electrode and the surface of the n− drift layer. Ohmic contact is established between the surfaces of polysilicon portions and the anode electrode.

Abstract: A semiconductor device constituting an IGBT exhibits low losses yet can be manufactured using an inexpensive wafer and with high yields, and exhibits low losses. The IGBT is produced by using a wafer, for example an FZ wafer, that is cut form an ingot and has its surface polished and cleaned, wherein an n-type impurity diffusion layer having an enough dose to stop the electric field in turn-off is provided between a collector layer and a base layer as a field-stop layer for stopping an electric field in turn-off. The thickness of this field-stop layer defined by Xfs−Xj is controlled in the range from 0.5 &mgr;m to 3 &mgr;m, where Xfs is the position at which the impurity concentration in the field-stop layer is twice the impurity concentration of the base layer, and Xj is the position of the junction between the filed-stopping layer and the collector layer.

Abstract: A method for manufacturing a semiconductor device constituting an JGHT is provided that allows to manufacture the device using an inexpensive wafer and with high yields, and achieves low losses. Specifically, after an emitter electrode is formed, a reverse principal surface is polished to a specified thickness. The center line average height Ra of the polished surface is controlled to be not more than 1 &mgr;m, and the filtered center line waviness Wca is kept within 10 &mgr;m. The polished surface is selectively cleaned with an aqueous chemical solution to remove particles. To the cleaned surface, phosphorus ions arc implanted for forming a field-stop layer and boron ions are implanted for forming a collector layer. The wafer is then put into a diffusion furnace and annealed at a temperature from 300° C. to 550° C. to form a field-stop layer and a collector layer. Finally, a collector electrode is formed.

Abstract: A high-speed, soft-recovery semiconductor device that reduces leakage current by increasing the Schottky ratio of Schottky contacts to pn junctions. In one embodiment of the present invention, an n− drift layer is formed on an n+ cathode layer 1 by epitaxial growth, and ring-shaped ring trenches having a prescribed width are formed in the n− drift layer. Oxide films are formed on the side walls of each ring trench. The ring trenches are arranged such that the centers of the rings of the ring trenches adjacent to one another form a triangular lattice unit. A p− anode layer is formed at the bottom of each ring trench. Schottky contacts are formed at the interface between an anode electrode and the surface of the n− drift layer. Ohmic contact is established between the surfaces of polysilicon portions and the anode electrode.

Abstract: An IGBT that exhibits a low on-voltage and a sufficient short circuit withstand capability and to provide a method of manufacturing such an IGBT. The p-type well region and the n-type emitter region are not formed by the self-alignment technique using the gate electrode as a common mask but by distributing the impurity ions using masks, the edges thereof being displaced for an offset length, by that the channel region is widened. The preferable offset length d is from 0.5 to 5.0 &mgr;m.

Abstract: A method for manufacturing a semiconductor device constituting an IGBT is provided that allows to manufacture the device using an inexpensive wafer and with high yields, and achieves low losses. Specifically, after an emitter electrode is formed, a reverse principal surface is polished to a specified thickness. The center line average height Ra of the polished surface is controlled to be not more than 1 &mgr;m, and the filtered center line waviness Wca is kept within 10 &mgr;m. The polished surface is selectively cleaned with chemicals-dissolved water to remove particles. To the cleaned surface, phosphorus ions are implanted for forming a field-stop layer and boron ions are implanted for forming a collector layer. The wafer is then put into a diffusion furnace and annealed at a temperature from 300° C. to 550° C. to form a field-stop layer and a collector layer. Finally, a collector electrode is formed.

Abstract: A semiconductor device constituting an IGBT exhibits low losses yet can be manufactured using an inexpensive wafer and with high yields, and exhibits low losses. The IGBT is produced by using a wafer, for example an FZ wafer, that is cut form an ingot and has its surface polished and cleaned, wherein an n-type impurity diffusion layer having an enough dose to stop the electric field in turn-off is provided between a collector layer and a base layer as a field-stop layer for stopping an electric field in turn-off. The thickness of this field-stop layer defined by Xfs-Xj is controlled in the range from 0.5 &mgr;m to 3 &mgr;m, where Xfs is the position at which the impurity concentration in the field-stop layer is twice the impurity concentration of the base layer, and Xj is the position of the junction between the filed-stopping layer and the collector layer.

Abstract: A trench-type IGBT includes a silicon substrate, a lightly doped n-type drift layer on the silicon substrate, and a p-type base layer on the n-type drift layer. The p-type base layer is doped more heavily than the n-type drift layer, and is formed of first regions and second regions. N+-type source regions are formed selectively in the surface portions of the first regions of p-type base layer. Trenches are dug from the surfaces of n+-type source regions down to the n-type drift layer through the p-type base layer. A gate oxide film covers the inner surface of each trench. A gate electrodes are provided in the trenches, wherein the gate electrodes face the p-type base layer via respective gate oxide films. An emitter electrode is in direct contact with the first regions of p-type base layer and n+-type source regions. A collector electrode is provided on the back surface of silicon substrate.

Abstract: An insulated gate bipolar transistor (IGBT) device is a semiconductor device comprising a main IGBT 1, a sub IGBT 20, and a current limiting circuit 30 on one chip. It has an n-channel main IGBT 1, sub IGBT 20, and sensor IGBT 2 connected in parallel, whose current is controlled by a gate signal IN, an emitter resistor RE of the sensor IGBT 2, and an n-channel MOSFET 7 to which a voltage drop of the emitter resistor RE is applied as a gate voltage for fast discharging gate capacities C1, C2, and C20 of the IGBT 1, IGBT 2, and IGBT 20. Threshold voltage VTHB of the sub IGBT 20 is set high on the order of 1 V as compared with threshold voltage VTHA of the main IGBT 1 and the sensor IGBT 2. When a load 6 is discharged, the gate capacities C1, C2, and C20 are discharged dominantly, thus only the sub IGBT 20 is cut off and the main IGBT 1 and the sensor IGBT 2 perform the current limit operation, so that the load short-circuiting current can be stepped down drastically.

Abstract: A semiconductor device is provided which includes a first-conductivity-type collector layer having a rear surface on which a collector electrode is formed, a second-conductivity-type buffer layer laminated on the collector layer, a second-conductivity-type conductivity modulation layer formed on the buffer layer, a first-conductivity-type emitter layer formed as a well in a surface of the conductivity modulation layer, a second-conductivity-type source region formed in a surface of a well edge portion of the emitter layer, a gate electrode formed through a gate insulating film to overlap the source region and the conductivity modulation layer, and an emitter electrode that is in ohmic contact with both the emitter layer and the source region.

Abstract: In a semiconductor device, in addition to a first emitter layer, a second emitter layer is formed on the surface side of a p-type base in spaced-apart relation with the first emitter layer. The first emitter layer is the source region of a first MOSFET, while the second emitter layer is the source region of a second MOSFET. Through signals imparted to first and second gate electrodes, the device, when turned on, operates with a low on-state voltage drop in a thyristor state and, when turned off, undergoes a turn-off in a short time by changing to a transistor state. The main current in the transistor state flows by being offset toward the first emitter layer side with respect to a main-current path on the lower side of the second emitter layer in the thyristor state. Since the current paths in each mode are separated, it is possible to reduce the resistance in the current path in the transistor state without increasing the on-voltage, thereby making it possible to obtain a large latch-up withstand capability.

Abstract: A second region 3 is formed via a buffer layer 3a on a first region 2 formed with an anode electrode 1 on the rear and a third region 4 like a well is formed on the surface of the second region 3. A fourth region 15 like a well is formed at the center on the surface of the third region 4 and a fifth region 16 is formed along the well end. A sixth region 17 like a well is formed on the surface of the fourth region 15. Cathode electrodes 18 as metal electrodes of the first layer come in conductive contact with the fifth region 16 and the sixth region 17. A MOSFET 12 of n channel type for injecting majority carriers (electrons) is disposed from the first region 16 to the surfaces of the third region 4 and the second region 3, and a MOSFET 23 of p channel type is disposed from the sixth region 17 to the surfaces of the fourth region 16 and the third region 4. The second MOSFET 23 has a double diffusion type structure.

Abstract: A semiconductor device having a thyristor structure including a first semiconductor region of a first conductivity type, a second semiconductor region of a second conductivity type, a third semiconductor region of the first conductivity type and a fourth semiconductor region of the second conductivity type; a first MISFET capable of injecting majority carriers from the fourth semiconductor region into the second semiconductor region; and a second MISFET capable of being turned on and off independently of the first MISFET and extracting majority carriers from the third semiconductor region into the fourth semiconductor region, wherein the fourth semiconductor region is divided into the source region of the first MISFET and the source region of the second MISFET, the latter being formed in a portion isolated from the former, characterized in that the depth of the source region of the second MISFET is different from that of the drain region thereof.

Abstract: To reduce the required diffusion depth of impurities in manufacturing a protective diode for protecting an insulated gate transistor from overvoltage so that the diode can be easily built in a chip of the transistor. A plurality of p-type diode layers are built in by diffusion through the windows in an insulation film disposed on an n-type region into which a depletion layers spread when the vertical field effect transistor to be protected is turned off, and a diode terminal A is led out from an electrode film that is in electrical contact with the diode layers. This configuration prevents depletion layers, spreading from the diode layers into the semiconductor region by the applied overvoltage, from joining with each other, and sufficiently lowers the breakdown voltage of the protective diode with respect to the withstand voltage of the transistor 10 or 20 even when the diffusion depth of the diode layer is one order of magnitude shallower than in conventional devices.

Abstract: A control device for controlling a double gate semiconductor device having a second gate electrode for controlling transition from a thyristor operation to a transistor operation, and a first gate electrode for controlling transition from transistor operation to an ON/OFF operation, and for controlling a current passing from a collector electrode to an emitter electrode, includes a first gate control circuit for delaying a turn-off signal to the double gate semiconductor device and applying the turn-off signal to the first gate electrode.