Patents by Inventor Katsuhiro Shimohigashi

Katsuhiro Shimohigashi has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 5237528
    Abstract: A semiconductor memory comprises a capacitor with a data storage portion, and an insulated-gate field-effect transistor. The capacitor is formed by a plate which is made up of the side walls and base of a groove formed in a semiconductor substrate, and by a capacitor electrode formed on the side walls and the base, over an insulation film, and which is connected electrically to the source or drain of the insulated-gate field-effect transistor. Various embodiments are provided for reducing size and preventing leakage between other memory cells, including forming stacked capacitors, forming the transistor over the capacitor, using a silicon-over-insulator arrangement for the transistor, forming a common capacitor plate and providing high impurity layers within the substrate.
    Type: Grant
    Filed: January 17, 1992
    Date of Patent: August 17, 1993
    Assignee: Hitachi, Ltd.
    Inventors: Hideo Sunami, Tokuo Kure, Masanobu Miyao, Yoshifumi Kawamoto, Katsuhiro Shimohigashi, Yoshio Sakai, Osamu Minato, Toshiaki Masuhara, Mitsumasa Koyanagi, Shinji Shimizu
  • Patent number: 5214496
    Abstract: A semiconductor memory comprises a capacitor with a data storage portion, and an insulated-gate field-effect transistor. The capacitor is formed by a plate which is made up of the side walls and base of a groove formed in a semiconductor substrate, and by a capacitor electrode formed on the side walls and the base, over an insulation film, and which is connected electrically to the source or drain of the insulated-gate field-effect transistor. Various embodiments are provided for reducing size and preventing leakage between other memory cells, including forming stacked capacitors, forming the transistor over the capacitor, using a silicon-over-insulator arrangement for the transistor, forming a common capacitor plate and providing high impurity layers within the substrate.
    Type: Grant
    Filed: December 19, 1989
    Date of Patent: May 25, 1993
    Assignee: Hitachi, Ltd.
    Inventors: Hideo Sunami, Tokuo Kure, Masanobu Miyao, Yoshifumi Kawamoto, Katsuhiro Shimohigashi, Yoshio Sakai, Osamu Minato, Toshiaki Masuhara, Mitsumasa Koyanagi, Shinji Shimizu
  • Patent number: 5170374
    Abstract: A dynamic RAM integrated circuit of the one-element memory cell type is provided with a plurality of data lines, a sense amplifier, a plurality of word lines disposed in a manner to intersect with the data lines, and memory cells disposed at the points of intersection between the data lines and the word lines. The RAM includes a P-type semiconductor substrate and an N-type well region formed in the substrate. The memory cells are disposed within the well, and the sense amplifier, which is connected to the date lines, is constructed of a pair of N-channel MOSFETs formed in the semiconductor substrate and a pair of P-channel MOSFETs formed in the well region.
    Type: Grant
    Filed: April 7, 1992
    Date of Patent: December 8, 1992
    Assignee: Hitachi, Ltd.
    Inventors: Katsuhiro Shimohigashi, Hiroo Masuda, Kunihiko Ikuzaki
  • Patent number: 5148387
    Abstract: A logic circuit includes first, second, third, fourth, fifth and sixth field effect transistors or FETs, input nodes and an output node. The fifth and sixth FETs are connected to the output node. The first and third FETs are connected to the fifth FET. The second and fourth FETs are connected to the sixth FET. The first and second FETs are connected to the first input node. The third and fourth FETs are connected to the second node. A first signal is supplied to the first input node. A second signal is supplied to gate electrodes of the first and fourth FETs. A signal having a phase opposite to the second signal is supplied to gate electrodes of the second and third FETs. A third signal is supplied to the second input node. One signal selected from the first, second and the third signals is supplied to the gate electrode of the fifth FET. A signal having a phase opposite to the signal supplied to the gate electrode of the fifth FET is supplied to the gate electrode of the sixth FET.
    Type: Grant
    Filed: February 15, 1990
    Date of Patent: September 15, 1992
    Assignee: Hitachi, Ltd.
    Inventors: Kazuo Yano, Koichiro Ishibashi, Tetsuya Nakagawa, Katsuhiro Shimohigashi, Osamu Minato
  • Patent number: 5148255
    Abstract: Disclosed is a semiconductor device, such as a semiconductor memory device, having structure wherein invasion of minority carriers from the semiconductor substrate into components of the device, formed on the substrate, can be avoided. The semiconductor memory device can be an SRAM or DRAM, for example, and includes a memory array and peripheral circuit on a substrate. In one aspect of the present invention, a buried layer of the same conductivity type as that of the substrate, but with a higher impurity concentration than that of the substrate, is provided beneath at least one of the peripheral circuit and memory array. A further region can extend from the buried layer, for example, to the surface of the semiconductor substrate, the buried layer and further region in combination acting as a shield to prevent minority carriers from penetrating to the device elements.
    Type: Grant
    Filed: January 23, 1991
    Date of Patent: September 15, 1992
    Assignee: Hitachi, Ltd.
    Inventors: Shinji Nakazato, Hideaki Uchida, Yoshikazu Saito, Masahiro Yamamura, Yutaka Kobayashi, Takahide Ikeda, Ryoichi Hori, Goro Kitsukawa, Kiyoo Itoh, Nobuo Tanba, Takao Watanabe, Katsuhiro Shimohigashi, Noriyuki Homma
  • Patent number: 5134581
    Abstract: In order to obtain a highly stable SRAM cell having a small cell area, a cell ratio R is set to be R=(W.sub.DEFF /L.sub.DEFF)/(W.sub.TEFF /L.sub.TEFF)<3 where L.sub.DEFF and W.sub.DEFF denote an effective channel length and an effective channel width of two driver MOSFETs 3 and 4 respectively, and L.sub.TEFF and W.sub.TEFF denote an effective channel length and an effective channel width of two transfer MOSFETs 5 and 6 respectively. Further, a maximum current I.sub.R flowing into the active loads MOSFETs 1 and 2 is set to be greater than a current I.sub.L (1.times.10.sup.-8 A) that flows into the driver MOSFET 5 when a threshold voltage is applied across the gate and the cource of the MOSFET 5. The pair of active load MOSFETs 1 and 2 are stacked on the driver MOSFETs 3 and 4 and on the transfer MOSFETs 5 and 6.
    Type: Grant
    Filed: October 29, 1990
    Date of Patent: July 28, 1992
    Assignees: Hitachi, Ltd., Hitachi VLSI Engineering Corp.
    Inventors: Koichiro Ishibashi, Katsuro Sasaki, Katsuhiro Shimohigashi, Toshiaki Yamanaka, Naotaka Hashimoto, Takashi Hashimoto, Akihiro Shimizu
  • Patent number: 5132771
    Abstract: A semiconductor static random access memory having a high .alpha.-ray immunity and a high packing density is provided which is also capable of high-speed operation. A semiconductor memory device comprises static random access memory cells each including a flip-flop circuit. Storage nodes of each flip-flop circuit have respective pn-junctions formed at regions sandwiched between gate electrodes of first insulated gate field effect transistors and gate electrodes of second insulated gate field effect transistors, respectively. The pn-junction has an area smaller than that of a channel portion of the first or second insulated gate field effect transistor.
    Type: Grant
    Filed: April 4, 1990
    Date of Patent: July 21, 1992
    Assignees: Hitachi, Ltd., Hitachi VLSI Engineering Corporation
    Inventors: Toshiaki Yamanaka, Naotaka Hashimoto, Takashi Hashimoto, Akihiro Shimizu, Koichiro Ishibashi, Katsuro Sasaki, Katsuhiro Shimohigashi, Eiji Takeda, Yoshio Sakai, Takashi Nishida, Osamu Minato, Toshiaki Masuhara, Shoji Hanamura, Shigeru Honjo, Nobuyuki Moriwaki
  • Patent number: 5126974
    Abstract: A MOS transistor sense amplifier employs cross coupled positive feedback for the load circuit of a differential amplifier with an equalizing switch at the amplifier output, and preferably also at the input. This basis amplifier circuit may be repeated in stages. When stages are employed, it is desirable that the first stage employs current mirror loading of the differential amplifier to reduce the data delay. Data delay is further reduced by providing strong amplification during the sense portion of the read cycle with a preamplifier, which preamplifier has its amplification reduced, preferably to unity by being turned off, when the sense portion of the cycle is finished, and most preferably when the input and output data lines are directly connected independently of the preamplifier, so that the preamplifier may be completely turned off to lower power consumption.
    Type: Grant
    Filed: January 16, 1990
    Date of Patent: June 30, 1992
    Assignee: Hitachi, Ltd.
    Inventors: Katsuro Sasaki, Katsuhiro Shimohigashi, Koichiro Ishibashi, Shoji Hanamura
  • Patent number: 5119332
    Abstract: A dynamic RAM integrated circuit of the one-element memory cell type is provided with a plurality of data lines, a sense amplifier, a plurality of word lines disposed in a manner to intersect with the data lines, and memory cells disposed at the points of intersection between the data lines and the word lines. The RAM includes a P-type semiconductor substrate and an N-type well region formed in the substrate. The memory cells are disposed within the well, and the sense amplifier, which is connected to the date lines, is constructed to a pair of N-channel MOSFETs formed in the semiconductor substrate and a pair of P-channel MOSFETs formed in the well region.
    Type: Grant
    Filed: April 30, 1990
    Date of Patent: June 2, 1992
    Assignee: Hitachi, Ltd.
    Inventors: Katsuhiro Shimohigashi, Hiroo Masuda, Hiroshi Kawamoto
  • Patent number: 5117393
    Abstract: An address multiplexed dynamic RAM device is provided which is capable of initiating (setting) and terminating (resetting) the test mode in response to the signal level combinations of the row address and column address strobe signals and the write enable signal. The signal level combinations employed correspond to those which are unused in the normal operating mode thereby obviating the need for providing additional external control signal terminals. In addition to writing predetermined data in selected memory cells during the test mode, verficiation of the predetermined data is also implemented during the read phase of the test mode.
    Type: Grant
    Filed: January 31, 1991
    Date of Patent: May 26, 1992
    Assignee: Hitachi, Ltd.
    Inventors: Kazuyuki Miyazawa, Katsuhiro Shimohigashi, Jun Etoh, Katsutaka Kimura
  • Patent number: 5107141
    Abstract: An output circuit portion of a BiCMOS logic circuit adapted to operating on a low voltage has an npn transistor Q5 connected between the power source Vcc and an output N6, and has an npn transistor Q6 connected between the output N6 and ground potential GND. The base of the npn transistor Q5 is driven by the drain output of p-channel MOSFETs MP3, MP4, and the base of the npn transistor Q6 is driven by the drain output of p-channel MOSFET QP5. When the power source voltage Vcc drops, the voltage applied between the drain and the source of MOSFET MP5 becomes small by the effect of V.sub.BE of the transistor Q6, but the drain current of the MOSFET MP5 changes little. Therefore, the BiCMOS circuit operates at high speeds (see FIG. 1) even when the power source voltage drops.
    Type: Grant
    Filed: October 29, 1990
    Date of Patent: April 21, 1992
    Assignee: Hitachi, Ltd.
    Inventors: Kazuo Yano, Mitsuru Hiraki, Hisayuki Higuchi, Suguru Tachibana, Makoto Suzuki, Katsuhiro Shimohigashi
  • Patent number: 5047706
    Abstract: In a constant current-constant voltage circuit disclosed herein, gates of MOSFETs Q.sub.1 and Q.sub.2 are connected together, and the gate of the MOSFET Q.sub.1 is connected to the drain thereof. Further, the source of the MOSFET Q.sub.1 is connected to ground potential GND whereas the source of the MOSFET Q.sub.2 is connected to the drain of a MOSFET Q.sub.3 having a gate connected to power supply voltage V.sub.DD and a source connected to the ground voltage GND. A current mirror circuit including Q.sub.4 and Q.sub.5 has an input and an output respectively connected to the drain of the second MOSFET Q.sub.2 and the drain of the first MOSFET Q.sub.1. A first coefficient (W.sub.3 L.sub.2 /L.sub.3 W.sub.2) depending upon channel lengths (L.sub.2, L.sub.3) and channel widths (W.sub.2, W.sub.3) of the MOSFETs Q.sub.2 and Q.sub.3 is set at a value not larger than a predetermined value. Therefore, the MOSFET Q.sub.3 operates in a linear region as high resistance, and the MOSFETs Q.sub.1 and Q.sub.
    Type: Grant
    Filed: September 5, 1990
    Date of Patent: September 10, 1991
    Assignee: Hitachi, Ltd.
    Inventors: Koichiro Ishibashi, Katsuro Sasaki, Katsuhiro Shimohigashi
  • Patent number: 5041892
    Abstract: In a homo-junction bipolar transistor suitable for a low temperature operation below 200 K. (particularly below 77 K.), the maximum value of the impurity concentration of an intrinsic base region is set to be at least 1.times.10.sup.18 /cm.sup.3 and the impurity concentration of an emitter region is set to a value lower than this maximum value. Thus, a base resistance can be reduced and a high speed operation becomes possible. Furthermore, bandgap narrowing develops in the intrinsic base region and a common-emitter current gain in the low temperature operation can be kept at a sufficient value. When this homo-junction bipolar transistor is formed together with complementary insulated gate field effect transistors on the surface of a semiconductor substrate, there can be obtained a Bi-CMOS device capable of a high speed operation even in the low temperature operation.
    Type: Grant
    Filed: May 14, 1990
    Date of Patent: August 20, 1991
    Assignee: Hitachi, Ltd.
    Inventors: Kazuo Yano, Masaaki Aoki, Toshiaki Masuhara, Katsuhiro Shimohigashi
  • Patent number: 5021944
    Abstract: A method and apparatus for quickly masking defective memory elements with substitute memory elements includes first and second memory blocks. The first memory block includes a first memory array and a second spare memory array. The second memory block includes a second memory array and a first spare memory array. A first word from the first memory array is selected concurrently with a first substitute word from the first spare memory. An address signal is decoded and then compared with data representative of a defective word. In the event it is determined, as a result of this comparison, that the first word is defective, the first substitute word is then communicated to a common data bus. Alternatively, the first word is communicated to the common data bus.
    Type: Grant
    Filed: July 6, 1989
    Date of Patent: June 4, 1991
    Assignee: Hitachi, Ltd.
    Inventors: Katsuro Sasaki, Katsuhiro Shimohigashi, Shoji Hanamura
  • Patent number: 4992677
    Abstract: A semiconductor integrated circuit includes: a data output terminal; a first semiconductor element connected between a first operating potential point and the data output terminal; a second semiconductor element connected between the data output terminal and a second operating potential point; first control means connected to a control input terminal of the first semiconductor element; second control means connected to a control input terminal of the second semiconductor element; first generating means for generating a first predetermined voltage; and second generating means for generating a second predetermined voltage higher than the first predetermined voltage.
    Type: Grant
    Filed: March 20, 1989
    Date of Patent: February 12, 1991
    Assignee: Hitachi, Ltd.
    Inventors: Koichiro Ishibashi, Osamu Minato, Katsuhiro Shimohigashi
  • Patent number: 4992985
    Abstract: An address multiplexed dynamic RAM device is provided which is capable of initiating (setting) and terminating (resetting) the test mode in response to the signal level combinations of the row address and column address strobe signals with the write enable signal, which signal level combinations correspond to those which are otherwise left unused in the normal operating mode thereby obviating the requirement of an additional external control signal terminal. Such initiating of the test mode can be effected by setting the RAS signal of the DRAM at a logic "low" level when the CAS signal and the WE signal are at a logic "low" level. Clearing or resetting thereof is effected by the same combination sequence, except that the WE signal is at a logic "high" level. The setting or initiating of a test mode is also implemented by the additional combination of one of the row address signal bits, e.g. the most significant bit.
    Type: Grant
    Filed: March 7, 1989
    Date of Patent: February 12, 1991
    Assignee: Hitachi, Ltd.
    Inventors: Kazuyuki Miyazawa, Katsuhiro Shimohigashi, Jun Etoh, Katsutaka Kimura
  • Patent number: 4949145
    Abstract: In a homo-junction bipolar transistor suitable for a low temperature operation below 200.degree.K. (particularly below 77 K), the maximum value of the impurity concentration of an intrinsic base region is set to be at least 1.times.10.sup.18 /cm.sup.3. The impurity concentration of an emitter region is set to a value lower than this maximum value. Thus, a base resistance can be reduced and high speed operation becomes possible. Furthermore, bandgap narrowing develops in the intrinsic base region and a common-emitter current gain in the low temperature operation can be kept at a sufficient value. When this homo-junction bipolar transistor is formed together with complementary insulated gate field effect transistors on the surface of a semiconductor substrate, there can be obtained a Bi-CMOS device capable of a high speed operation even in the low temperature operation.
    Type: Grant
    Filed: October 4, 1988
    Date of Patent: August 14, 1990
    Assignee: Hitachi, Ltd.
    Inventors: Kazuo Yano, Masaaki Aoki, Toshiaki Masuhara, Katsuhiro Shimohigashi
  • Patent number: 4930112
    Abstract: A semiconductor device comprising a plurality of circuits driven by at least one external power source, and at least one voltage converter transforming the voltage of the external power source into another voltage. At least a part of the plurality of circuits are driven by the output voltage of the at least one voltage converter, which is provided with a controller for controlling its load driving power, corresponding to the operation of the part of the plurality of circuits. The voltage converter includes a voltage limiter which is used exclusively for each of the different natures of the loads, and its operation and load driving power are controlled, depending on the operations of each of the loads.
    Type: Grant
    Filed: November 24, 1986
    Date of Patent: May 29, 1990
    Assignees: Hitachi, Ltd., Hitachi VLSI Engineering Corporation
    Inventors: Hitoshi Tanaka, Ryoichi Hori, Kiyoo Itoh, Katsutaka Kimura, Katsuhiro Shimohigashi
  • Patent number: 4901128
    Abstract: A semiconductor memory comprises a capacitor with a data storage portion, and an insulated-gate field-effect transistor. The capacitor is formed by a plate which is made up of the side walls and base of a groove formed in a semiconductor substrate, and by a capacitor electrode formed on the side walls and the base, over an insulation film, and which is connected electrically to the source or drain of the insulated-gate field-effect transistor. Various embodiments are provided for reducing size and preventing leakage between other memory cells, including forming stacked capacitors, forming the transistor over the capacitor, using a silicon-over-insulator arrangement for the transistor, forming a common capacitor plate and providing high impurity layers within the substrate.
    Type: Grant
    Filed: November 24, 1986
    Date of Patent: February 13, 1990
    Assignee: Hitachi, Ltd.
    Inventors: Hideo Sunami, Tokuo Kure, Masanobu Miyao, Yoshifumi Kawamoto, Katsuhiro Shimohigashi, Yoshio Sakai, Osamu Minato, Toshiaki Masuhara, Mitsumasa Koyanagi, Shinji Shimizu
  • Patent number: 4894696
    Abstract: A very highly integrated semiconductor memory which enables the dynamic random access memory to develop less soft error and to eliminate margin for aligning the masks, that hinders the device from being highly integrated. The memory cell capacitor is constituted by a trench which is provided at a position defined by an insulator formed on the side of gate electrode of a MOS transistor that constitutes the memory cell. Therefore, the MOS transistor and the trench capacitor are self-aligned, and no margin is required for alignment.
    Type: Grant
    Filed: December 8, 1986
    Date of Patent: January 16, 1990
    Assignee: Hitachi, Ltd.
    Inventors: Eiji Takeda, Kiyoo Itoh, Ryoichi Hori, Katsuhiro Shimohigashi, Katsutaka Kimura