Patents by Inventor Taiji Ema

Taiji Ema 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: 5661340
    Abstract: A method for fabricating a dynamic random access memory comprises the steps of forming a diffusion region in a semiconductor substrate, providing an insulation layer on the semiconductor substrate, forming a contact hole in the insulation layer to expose the diffusion region at the contact hole, depositing a semiconductor layer on the insulation layer in the amorphous state such that the semiconductor layer establishes an intimate contact with the exposed diffusion region via the contact hole, patterning the semiconductor layer to form a capacitor electrode, depositing a dielectric film on the capacitor electrode such that said dielectric film covers the capacitor electrode; and depositing a semiconductor material to form an opposing electrode such that the opposing electrode buries the capacitor electrode underneath while establishing an intimate contact with the dielectric film that covers the capacitor electrode.
    Type: Grant
    Filed: October 26, 1993
    Date of Patent: August 26, 1997
    Assignee: Fujitsu Limited
    Inventors: Taiji Ema, Masaaki Higashitani, Toshimi Ikeda, Michiari Kawano, Hiroshi Nomura, Masaya Katayama, Masahiro Kuwamura
  • Patent number: 5650647
    Abstract: A dynamic random access memory device includes a storage capacitor having a plurality of stacked conductive films which form a storage electrode. A gap is formed between elevationally adjacent conductive films so as to surround the storage electrode. A gap is also formed between an insulating film which covers a gate electrode for insulation and a lowermost film of the storage electrode. Connection between the adjacent films may be established so that an uppermost film elevationally extends so as to make contact with a drain region. Also, connection can be established so that an upper film is mounted directly on an lower film. An end portion of the film may be thicker than the other portion thereof. The stacked film structure may be produced by alternatively forming a film made of a material different from the insulating film covering the gate electrode, and a conductive film.
    Type: Grant
    Filed: October 26, 1994
    Date of Patent: July 22, 1997
    Assignee: Fujitsu Limited
    Inventors: Masao Taguchi, Taiji Ema
  • Patent number: 5641979
    Abstract: A memory cell includes a transfer transistor having a gate which is connected to a word line, a first electrode which is connected to a bit line, and a second electrode, and a storage capacitor having a storage electrode which is connected to the second electrode of the transfer transistor, a confronting electrode, and a charge storage layer which is provided between the storage electrode and the confronting electrode. The storage capacitor has a capacitance which changes with a hysteresis curve which is determined by a bias voltage applied across the storage electrode and the confronting electrode, so that the capacitance takes one of two values depending on the bias voltage.
    Type: Grant
    Filed: January 3, 1994
    Date of Patent: June 24, 1997
    Assignee: Fujitsu Limited
    Inventors: Taiji Ema, Tatsuya Kajita
  • Patent number: 5610854
    Abstract: A method for fabricating a semiconductor memory device includes the steps of forming, in a semiconductor substrate of a first conductivity type, a well of a second opposite conductivity type by protecting the substrate surface except for a part where the well of the second conductivity type is to be formed, oxidizing the exposed surface of the semiconductor substrate while using the same mask pattern to form a thick oxide film on the surface of the well, and removing the thick oxide film by an etching process to form a recessed surface on the well.
    Type: Grant
    Filed: November 21, 1995
    Date of Patent: March 11, 1997
    Assignee: Fujitsu Limited
    Inventor: Taiji Ema
  • Patent number: 5594267
    Abstract: A semiconductor memory device includes a semiconductor substrate, and a memory cell formed on the semiconductor substrate and including two transfer transistors, two driver transistors and two thin film transistor loads. The thin film transistor load includes a first gate electrode, a first insulator layer formed on the first gate electrode, a semiconductor layer formed on the first insulator layer, a second insulator layer formed on the semiconductor layer, and a shield electrode formed on the second insulator layer. This shield electrode shields the thin film transistor.
    Type: Grant
    Filed: January 4, 1994
    Date of Patent: January 14, 1997
    Assignee: Fujitsu Limited
    Inventors: Taiji Ema, Kazuo Itabashi
  • Patent number: 5591659
    Abstract: A semiconductor device comprising: a semiconductor substrate having a memory cell area containing a memory cell composed of a capacitor element, and a peripheral circuit area containing a peripheral circuit for controlling the memory cell; an insulating layer covering the peripheral circuit area and being absent in the memory cell area; protective layers effective in etching of the insulating layer and covering the top surfaces and side surfaces of word line conductor patters and bit line conductor patterns in the memory cell area; a contact hole having a circumference defined by one of the protective layers that covers side surfaces of the word line conductor patterns in the memory cell area, the contact hole extending to a diffused region in the semiconductor substrate; and a storage electrode of the capacitor element being connected to the diffused region through the contact hole. A process of producing the semiconductor device is also disclosed.
    Type: Grant
    Filed: October 5, 1994
    Date of Patent: January 7, 1997
    Assignee: Fujitsu Limited
    Inventors: Taiji Ema, Toshimi Ikeda
  • Patent number: 5572053
    Abstract: A DRAM device includes bit lines formed on an interlayer insulation film which covers gate electrodes on an insulation film on a semiconductor substrate. Each bit line is in contact with the corresponding source region formed in the substrate through an opening in the insulation films. Another insulation film is formed so as to cover the bit lines. A storage electrode is formed on the insulation film covering the bit line, and is in contact with a drain region in the substrate through another opening in the insulation films. The bit line has a vertical layer level lower than that of the storage electrode. The storage electrode is covered with a dielectric film, which is covered with an opposed electrode.
    Type: Grant
    Filed: August 16, 1994
    Date of Patent: November 5, 1996
    Assignee: Fujitsu Limited
    Inventor: Taiji Ema
  • Patent number: 5570311
    Abstract: An SRAM semiconductor device having a parallel connection of two series circuits each having a driver transistor and a load connected in series, a wiring for connecting an interconnection point between the driver transistor and load of each of the two series circuits to a control terminal of the driver transistor of the other of the two series circuits, and a transfer transistor connected to each interconnection point, wherein the driver transistor and transfer transistor each are an insulating gate field effect transistor having a channel region formed on the surface of a semiconductor substrate at a predetermined area, source/drain regions on both sides of the channel region, and an insulated gate above the channel region, and the transfer transistor has a resistor region having an impurity concentration lower than the source/drain regions on both sides of the channel region of the driver transistor, the resistor region being contiguous to the channel region of the transfer transistor.
    Type: Grant
    Filed: January 31, 1994
    Date of Patent: October 29, 1996
    Assignee: Fujitsu Limited
    Inventors: Taiji Ema, Kazuo Itabashi, Kazuhiro Mizutani
  • Patent number: 5561314
    Abstract: A method of manufacturing a semiconductor device capable of isolating fine pattern elements by using LOCOS. The method includes the steps of: (a) forming a relatively thick first nitride film pattern on the surface of a semiconductor substrate having an oxide film; (b) wet-etching the oxide film by using the first nitride film as a mask; (c) filling the under-etch region of the first nitride film with nitride and forming a second nitride film thinner than the first nitride film on the exposed surface of the semiconductor substrate; (d) thermally oxidizing all the exposed second nitride film in a dry oxygen atmosphere to form an oxide film on the surface of the semiconductor substrate at least at the region not covered with the first nitride film; and (e) forming a thermal oxide film on the semiconductor substrate not covered with the first nitride film at a temperature lower than the oxidation temperature at the step (d).
    Type: Grant
    Filed: June 5, 1995
    Date of Patent: October 1, 1996
    Assignees: Fujitsu Limited, Fujitsu VLSI Limited
    Inventors: Taiji Ema, Masaya Katayama
  • Patent number: 5561623
    Abstract: A semiconductor storage device of a high capacity operating at high speed includes a plurality of memory cell array blocks, each including memory cells disposed in a matrix shape of rows and columns, word lines each connected to memory cells of an associated row, a row decoder for selecting a word line, bit lines each connected to memory cells of an associated select transistor and having an input (source) electrode connected to a bit line, a column select line connected to a gate electrode of the sense amplifier select transistor, a column decoder for selecting a column select line, and data bus lines connected to output (drain) electrodes of the sense amplifier select transistors, wherein the column select lines are disposed intersecting the word lines and the data bus line, the word lines are formed by a first wiring layer, the column select lines are formed by a second wiring layer, and the data bus lines are formed by a third wiring layer.
    Type: Grant
    Filed: February 7, 1995
    Date of Patent: October 1, 1996
    Assignee: Fujitsu Limited
    Inventor: Taiji Ema
  • Patent number: 5554556
    Abstract: A semiconductor memory device comprises a plurality of memory cell transistors each provided on a substrate in correspondence to a word line and a bit line, and a memory cell capacitor provided in each of the memory cell transistors in electrical connection to a diffusion region formed in the memory cell transistor. The memory cell capacitor comprises a first electrode defined by an upper major surface and a lateral surface that surrounds the first electrode, a dielectric film covering the upper major surface and the lateral surface of the first electrode, and a second electrode covering the dielectric film in correspondence to the upper major surface and the lateral surface of the first electrode, wherein the lateral surface of the first electrode has an undulating form defined by a smooth curve to increase the capacitance of the memory cell capacitor.
    Type: Grant
    Filed: April 18, 1995
    Date of Patent: September 10, 1996
    Assignee: Fujitsu Limited
    Inventor: Taiji Ema
  • Patent number: 5550395
    Abstract: A semiconductor device includes a semiconductor substrate having a memory cell area and a circuit area surrounding the memory cell area with a boundary area interposed therebetween. A first conductive layer covers the memory cell area and extends onto the boundary area. A first insulating layer covers the surrounding circuit area and part of the extended portion of the first conductive layer. A second insulating layer covers the first insulating layer and the first conductive layer. A throughhole is formed through the first and second insulating layers. A second conductive layer is electrically connected with another conductive layer via the throughhole and extends from the memory cell area to the surrounding circuit area. The process of producing the semiconductor device is also disclosed.
    Type: Grant
    Filed: January 20, 1995
    Date of Patent: August 27, 1996
    Assignee: Fujitsu Limited
    Inventors: Taiji Ema, Toshimi Ikeda
  • Patent number: 5539224
    Abstract: A semiconductor device of two or more unit circuit-blocks is formed in a common chip, as a first layer and which has no electrical interconnections between the unit circuit-blocks of the device. An upper, second interconnection layer is formed on the first layer and is patterned to include electrical interconnections between the unit circuit-blocks formed in the first, lower layer.
    Type: Grant
    Filed: June 23, 1994
    Date of Patent: July 23, 1996
    Assignee: Fujitsu Limited
    Inventor: Taiji Ema
  • Patent number: 5525534
    Abstract: A method of producing a semiconductor device includes the steps of (a) preparing a substrate having a semiconductor element formed in a predetermined region of a surface of the substrate, (b) forming a first layer on the substrate, where the first layer is made of silicon oxide including at least one of boron and phosphor, (c) forming a second layer on a surface of the first layer, where the second layer is made of a material selected from a group consisting of silicon nitride and silicon oxide nitride, (d) coating a resist layer on the entire surface of the substrate, (e) exposing and developing a predetermined region of the resist layer using a reticle having a first opening so as to form a second opening in the resist layer, where the first opening has a polygonal shape having n corners respectively having obtuse angles and n is a natural number satisfying n.gtoreq.5, and (f) etching the second and first layers via the second opening.
    Type: Grant
    Filed: January 5, 1995
    Date of Patent: June 11, 1996
    Assignee: Fujitsu Limited
    Inventors: Shinichiro Ikemasu, Taiji Ema, Masaya Katayama
  • Patent number: 5521859
    Abstract: A thin film transistor (TFT) load type static random access memory (SRAM) which includes a memory capacitor in addition to the stray capacitance. The SRAM includes a semiconductor substrate and a memory cell provided on the semiconductor substrate. The memory cell includes first and second transfer transistors, first and second driver transistors, first and second thin film transistor loads and first and second memory capacitors. The first and second memory capacitors include a storage electrode, a dielectric layer which covers the storage electrode, and an opposing electrode formed on the dielectric layer. A connection region is provided in which the storage electrode of the first memory capacitor, the drain region of the second thin film transistor load and the gate electrode of the first driver transistor are connected.
    Type: Grant
    Filed: January 17, 1995
    Date of Patent: May 28, 1996
    Assignee: Fujitsu Limited
    Inventors: Taiji Ema, Kazuo Itabashi
  • Patent number: 5516715
    Abstract: A method of producing a semiconductor memory cell. The memory cell includes two transfer transistors, two driver transistors, two thin film transistor loads and two word lines respectively coupled to gate electrodes of the transfer transistors.
    Type: Grant
    Filed: October 27, 1994
    Date of Patent: May 14, 1996
    Assignee: Fujitsu Limited
    Inventors: Kazuo Itabashi, Taiji Ema
  • Patent number: 5514615
    Abstract: A method of producing a memory cell on a semiconductor substrate. The memory cell includes two transfer transistors, two driver transistors, two thin film transistor loads, and two memory capacitors. A field insulator layer is formed on the semiconductor substrate. A gate insulator layer is formed above the field insulator layer. A gate electrode of a driver transistor is produced by forming a first conductor layer above the gate insulator layer. Impurity regions are formed in the semiconductor substrate using the field insulator layer and the first conductor layer as masks. A first insulator layer is then formed. Source, drain and channel regions of a thin film transistor load are produced by forming a second conductor layer and injecting impurities into the second conductor layer. A second insulator layer is formed above the second conductor layer. A contact hole is formed to extend from the second insulator layer, through the second conductor layer, and to the first conductor layer.
    Type: Grant
    Filed: May 15, 1995
    Date of Patent: May 7, 1996
    Assignee: Fujitsu Limited
    Inventors: Taiji Ema, Kazuo Itabashi
  • Patent number: 5496758
    Abstract: A method for fabricating a semiconductor memory device includes the steps of forming, in a semiconductor substrate of a first conductivity type, a well of a second opposite conductivity type by protecting the substrate surface except for a part where the well of the second conductivity type is to be formed, oxidizing the exposed surface of the semiconductor substrate while using the same mask pattern to form a thick oxide film on the surface of the well, and removing the thick oxide film by an etching process to form a recessed surface on the well.
    Type: Grant
    Filed: December 14, 1994
    Date of Patent: March 5, 1996
    Assignee: Fujitsu Limited
    Inventor: Taiji Ema
  • Patent number: 5453397
    Abstract: A method of manufacturing a semiconductor device capable of isolating fine pattern elements by using LOCOS. The method includes the steps of: (a) forming a relatively thick first nitride film pattern on the surface of a semiconductor substrate having an oxide film; (b) wet-etching the oxide film by using the first nitride film as a mask; (c) filling the under-etch region of the first nitride film with nitride and forming a second nitride film thinner than the first nitride film on the exposed surface of the semiconductor substrate; (d) thermally oxidizing all the exposed second nitride film in a dry oxygen atmosphere to form an oxide film on the surface of the semiconductor substrate at least at the region not covered with tile first nitride film; and (e) forming a thermal oxide film on the semiconductor substrate not covered with the first nitride film at a temperature lower than the oxidation temperature at the step (d).
    Type: Grant
    Filed: September 12, 1994
    Date of Patent: September 26, 1995
    Assignees: Fujitsu Limited, Fujitsu VLSI Limited
    Inventors: Taiji Ema, Masaya Katayama
  • Patent number: 5438008
    Abstract: A semiconductor device includes a semiconductor substrate, a first transistor formed on the semiconductor substrate and having a first source diffusion region, a first drain diffusion region and a first gate electrode, a second transistor formed on the semiconductor substrate adjacent to the first transistor and having a second source diffusion region, a second drain diffusion region and a second gate electrode, a field oxide layer formed on the semiconductor substrate for isolating the first and second transistors, a first insulator layer which covers a surface of the semiconductor substrate including a surface of the first transistor but excluding a surface of the second transistor, where the first insulator layer has a side wall portion, and a second insulator layer formed at the side wall portion of the first insulator layer and a side wall portion of the second gate electrode of the second transistor.
    Type: Grant
    Filed: November 9, 1993
    Date of Patent: August 1, 1995
    Assignee: Fujitsu Limited
    Inventor: Taiji Ema