Patents by Inventor Mitsufumi Codama

Mitsufumi Codama 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: 6008076
    Abstract: A thin film transistor and a semiconductor device and a method for forming the same. A silicon thin film formed on an insulating substrate is heated at 550 to 800.degree. C. so that it has crystallinity, and a thin film transistor is formed using the crystalline silicon film thus obtained. Thermal contraction of the insulating substrate is set in a range of 30 to 500 ppm in the heating process, so that the thin film transistor has high mobility, low threshold voltage and high off-resistance. Thermal contraction of the insulating substrate may be also set 100 ppm or less in a heating process after a patterning treatment in a thin film transistor producing process.
    Type: Grant
    Filed: November 6, 1996
    Date of Patent: December 28, 1999
    Assignee: Semicoductor Energy Laboratory Co., Ltd.
    Inventors: Mitsufumi Codama, Yukio Yamauchi, Naoya Sakamoto, Takeshi Fukada
  • Patent number: 5904508
    Abstract: Fabrication of TFTs utilizing self-aligned techniques. Although gate electrodes are made of aluminum, source/drain regions can be activated by a heat treatment. Spacers are formed, using dummy gate electrodes. Gate electrodes are defined, using the spacers. Impurity ions are implanted before the gate electrodes are formed. Thus, the source/drain regions, channel formation regions, and offset regions are formed in a self-alignment manner, using the dummy gate electrodes and the spacers as masks. Since the heat treatment is made before the formation of the gate electrodes, the gate electrodes can be formed from aluminum having a low melting point.
    Type: Grant
    Filed: January 21, 1997
    Date of Patent: May 18, 1999
    Assignees: Semiconductor Energy Laboratory Co., Ltd., TDK Corporation
    Inventors: Mitsufumi Codama, Michio Arai
  • Patent number: 5821560
    Abstract: A thin film transistor which includes an insulation base, first and second gate electrodes, first and second insulation layers, an active layer of semiconductor material, a source electrode and a drain electrode, in which a lateral length of the first gate electrode is narrower than a lateral length of the second gate electrode. Also, the first gate is electrically insulated from the active layer of semiconductor material by the first insulation layer so that the drain current saturates in a high drain voltage region.
    Type: Grant
    Filed: March 1, 1996
    Date of Patent: October 13, 1998
    Assignees: TKD Corporation, Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Michio Arai, Kazushi Sugiura, Ichiro Takayama, Yukio Yamauchi, Isamu Kobori, Mitsufumi Codama, Naoya Sakamoto
  • Patent number: 5786796
    Abstract: An image display device which is not affected by image control signal for other pixels and gives adjustable intensity based upon control signal is provided. The image display device has a thin film pixel element EL, a non-linear element 5 for emit control of said thin film pixel element EL, a signal hold capacitor C coupled with a gate electrode of said non-linear element 5, another non-linear element 6 for writing data into said capacitor C, and a resistor R coupled between said capacitor C and a fixed potential source. The resistance of said resistor R is larger than ON resistance and smaller than OFF resistance of said non-linear element 6 for data writing.
    Type: Grant
    Filed: March 1, 1996
    Date of Patent: July 28, 1998
    Assignees: TDK Corporation, Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Ichiro Takayama, Michio Arai, Mitsufumi Codama
  • Patent number: 5757030
    Abstract: A thin film transistor and a producing method therefor having a semiconductor layer which is formed in an islandish form and constitutes a channel forming region, a source region and a drain region, wherein the edge portion of the islandish semiconductor layer is so designed as to be gradually or monotonously thinned toward the edge thereof to prevent the gate insulating film covering the active layer from being thinned at the edge portion of the semiconductor layer. The gate insulating film is also smoothly formed to prevent an electric field concentration phenomenon at the edge portion.
    Type: Grant
    Filed: May 12, 1995
    Date of Patent: May 26, 1998
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Mitsufumi Codama, Noriaki Kondo
  • Patent number: 5741718
    Abstract: In forming a thin film transistor (TFT) having an offset structure or a lightly doped drain (LDD) structure, a blocking material having a lower etching rate than that of a material constructing a gate electrode is formed. By using the blocking material as a mask, a gate electrode material is side-etched selectively to form gate electrodes. The blocking material is processed selectively and remains in a drain region side. Also, an offset region or an LDD region is formed under the blocking material by performing an impurity ion implantation. On the other hand, after the gate electrodes are formed, a resist is added and then light exposure is performed from a source region side using a light blocking material as a mask, so that the resist remains in a drain region side of the gate electrode. Also, by implanting an impurity ion, an offset region or an LDD region is formed in the drain region side.
    Type: Grant
    Filed: July 16, 1996
    Date of Patent: April 21, 1998
    Assignees: Semiconductor Energy Laboratory Co., Ltd., TDK Corporation
    Inventors: Mitsufumi Codama, Ichiro Takayama, Michio Arai
  • Patent number: 5731600
    Abstract: An image sensor device comprising a gate electrode provided on an insulating surface, a gate insulating film provided on the gate electrode, an active region, provided on the gate insulating film, for generating a carrier upon light irradiation, and doped regions provided with the active region between the doped regions. The optical carrier generated in the active region by light irradiation to the active region flows between the doped regions as current. The light irradiation can be deleted from this current with a high sensitivity.
    Type: Grant
    Filed: March 14, 1995
    Date of Patent: March 24, 1998
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Mitsufumi Codama, Michio Arai
  • Patent number: 5644146
    Abstract: A thin film transistor comprises a dielectric substrate (1), a semiconductor layer (3) of poly-crystalline silicon layer having a drain region (8), an active gate region (4, 8-0), and a source region (7) placed on said substrate (1), a drain terminal (10) and a source terminal (10A) connected to said respective regions for external connection, a gate electrode (6) coupled with a part of said gate region (4) through a dielectric layer (4A), wherein length (d) of said gate electrode (6) is shorter than the length of gate region (4 plus 8-0), so that an offset region (8-0), where no gate electrode faces with said gate region, is produced.
    Type: Grant
    Filed: March 21, 1995
    Date of Patent: July 1, 1997
    Assignees: TDK Corporation, Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Michio Arai, Mitsufumi Codama, Ichiro Takayama
  • Patent number: 5627364
    Abstract: A linear array image sensor with a light source, includes a first substrate made of a transparent plate, which has a first surface and a second surface, at least one thin-film light emission element disposed on the first surface of the first substrate and linearly elongated in a direction, a second substrate having two surfaces, and a plurality of solid-state image pickup elements disposed on one of the two surfaces of the second substrate and linearly aligned along the elongated direction of the thin-film light emission element. The first and second substrates are fixed to and integrated with each other by a transparent material so that light originated by the thin-film light emission element is emitted from the second surface of the first substrate and reflected by an image carrier to be detected, and that the reflected light is applied to the plurality of the solid-state image pickup elements through the first substrate.
    Type: Grant
    Filed: October 10, 1995
    Date of Patent: May 6, 1997
    Assignees: TDK Corporation, Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Mitsufumi Codama, Michio Arai
  • Patent number: 5604139
    Abstract: In forming a thin film transistor (TFT) having an offset structure or a lightly doped drain (LDD) structure, a blocking material having a lower etching rate than that of a material constructing a gate electrode is formed. By using the blocking material as a mask, a gate electrode material is side-etched selectively to form gate electrodes. The blocking material is processed selectively and remains in a drain region side. Also, an offset region or an LDD region is formed under the blocking material by performing an impurity ion implantation. On the other hand, after the gate electrodes are formed, a resist is added and then light exposure is performed from a source region side using a light blocking material as a mask, so that the resist remains in a drain region side of the gate electrode. Also, by implanting an impurity ion, an offset region or an LDD region is formed in the drain region side.
    Type: Grant
    Filed: February 9, 1995
    Date of Patent: February 18, 1997
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Mitsufumi Codama, Ichiro Takayama, Michio Arai
  • Patent number: 5591988
    Abstract: A substrate (1) has a surface covered with an insulation layer (2), on which an active layer (3') made of non-single crystal silicon through thin film technique is provided. A gate electrode layer (5') is partially provided on said active layer through a gate insulation layer (4). Said active layer (3') is subject to injection of P-type or N-type impurities to provide an image sensor of MOS structure. Bias potential is applied to a gate electrode so that a circuit between a source and a drain is in an On state, so that input light through said substrate or said gate electrode is applied to said active layer, and electrical output depending upon said input light is obtained from said source electrode or said drain electrode. Other MOS transistors for switching element and/or shift registers for operating said image sensor are provided on said substrate (1).
    Type: Grant
    Filed: June 7, 1995
    Date of Patent: January 7, 1997
    Assignees: TDK Corporation, Semiconductor Energy Lab. Co. Ltd.
    Inventors: Michio Arai, Takashi Inushima, Mitsufumi Codama, Kazushi Sugiura, Ichiro Takayama, Isamu Kobori, Yukio Yamauchi, Naoya Sakamoto
  • Patent number: 5574293
    Abstract: A substrate (1) has a surface covered with an insulation layer (2), on which an active layer (3') made of non-single crystal silicon through thin film technique is provided. A gate electrode layer (5') is partially provided on said active layer through a gate insulation layer (4'). Said active layer (3') is subject to injection of P-type or N-type impurities to provide an image sensor of MOS structure. Bias potential is applied to a gate electrode so that a circuit between a source and a drain is in an On state, so that input light through said substrate or said gate electrode is applied to said active layer, and electrical output depending upon said input light is obtained from said source electrode or said drain electrode. Other MOS transistors for switching element and/or shift registers for operating said image sensor are provided on said substrate (1).
    Type: Grant
    Filed: November 22, 1994
    Date of Patent: November 12, 1996
    Assignees: TDK Corp., Semiconductor Energy Laboratory Co. Ltd.
    Inventors: Michio Arai, Takashi Inushima, Mitsufumi Codama, Kazushi Sugiura, Ichiro Takayama, Isamu Kobori, Yukio Yamauchi, Naoya Sakamoto
  • Patent number: 5470762
    Abstract: A thin film transistor and a producing method therefor having a semiconductor layer which is formed in an islandish form and constitutes a channel forming region, a source region and a drain region, wherein the edge portion of the islandish semiconductor layer is so designed as to be gradually or monotonously thinned toward the edge thereof to prevent the gate insulating film covering the active layer from being thinned at the edge portion of the semiconductor layer. The gate insulating film is also smoothly formed to prevent an electric field concentration phenomenon at the edge portion.
    Type: Grant
    Filed: November 20, 1992
    Date of Patent: November 28, 1995
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Mitsufumi Codama, Noriaki Kondo
  • Patent number: 5352921
    Abstract: Image sensors using thin films and having a higher production yield, low production cost and higher reading resolution are provided. In a photoelectric conversion device having a thin film semiconductor layer is provided that performs photoelectric conversion with a first electrode structured mainly by a metallic material on a light transmitting insulating substrate or an insulating film and a second electrode on the thin film semiconductor layer. A thin insulating film is formed at least partially between the second electrode and the thin film semiconductor layer or the thin film semiconductor layer and the first electrode.
    Type: Grant
    Filed: September 14, 1993
    Date of Patent: October 4, 1994
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Mitsufumi Codama, Ichiro Takayama
  • Patent number: 5292675
    Abstract: A method for forming a MOS transistor having LDD structure by a simple and a few number of processes and a structure thereof are described. In accordance with the present invention, a low concentration of an impurity region can be formed in a semiconductor film part between an end of gate electrode and source or drain, by forming an ordinary gate insulating film extending beyond the gate electrode in the direction along the source and drain, in place of a spacer in the side of gate electrode which has been required for a preparation of conventional TFT having LDD structure, and further by forming a thinner insulating film than the gate insulating film in the side thereof, and by utilizing the thickness difference between the gate insulating film part excepting the gate electrode and the thin insulating film in the side thereof.
    Type: Grant
    Filed: December 14, 1992
    Date of Patent: March 8, 1994
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventor: Mitsufumi Codama
  • Patent number: 5187601
    Abstract: A method for forming a resistance-reducing electrode pattern in an electrooptical device includes the steps of: forming a transparent conductive film on a substrate; forming a plurality of opaque conductive strips on the film; and scribing the combined structure with a laser through the two layers to simultaneously divide the conductive strips into two parts and pattern the transparent film. In this manner, a pattern of transparent electrodes bordered with an opaque electrode pattern is formed. In specific embodiments, the opaque strips may comprise chromium, and the opaque conductive strips may be formed prior to application of the steps above by laser scribing an applied opaque film layer.
    Type: Grant
    Filed: December 17, 1991
    Date of Patent: February 16, 1993
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Shunpei Yamazaki, Takeshi Fukada, Mitsunori Sakama, Nobumitsu Amachi, Naoya Sakamoto, Mitsufumi Codama, Takashi Fuki, Ichiro Takayama
  • Patent number: 5103321
    Abstract: An image sensor is described. The sensor comprises a sensor array and an alternating electric power supply. The frequency of the power supply is selected to be equal to or a multiple of the frequency at which the sensor array is scanned.
    Type: Grant
    Filed: December 13, 1988
    Date of Patent: April 7, 1992
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Nobumitsu Amachi, Toshiji Hamatani, Takeshi Fukada, Mitsunri Sakama, Naoya Sakamoto, Mitsufumi Codama
  • Patent number: 5017828
    Abstract: An improved image sensor made of photosensitive semiconductor materials with a number of pixels each including an n-type semiconductor layer, a p-type semiconductor layer and an intrinsic semiconductor layer disposed between the n-type and p-type layers. The n-type and p-type layers are made from a semiconductor material having a high resistivity. The high resistivity of the n-type layer and the p-type layer functions to prevent crosstalk currents from passing between the pixels.
    Type: Grant
    Filed: April 25, 1989
    Date of Patent: May 21, 1991
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Takeshi Fukada, Mitsunori Sakama, Nobumitsu Amachi, Naoya Sakamoto, Mitsufumi Codama, Toru Takayama
  • Patent number: 5014100
    Abstract: A contact image sensor for use in facsimile machines is described. A light window is opened through a photosensitive semiconductor film deposited on a glass sustrate. Light rays are passed through the light window, reflected on an original and absorbed by the semiconductor film in order to produce image signals containing visual information of the original. Provided on the light incident side of the semiconductor film is a light blocking electrode which prevents incident light rays from directly entering the semiconductor film therethrough without reflection on the original. The opposing electrode formed on the other side of the semiconductor film is made of a transparent film covering the side surface of the light window. The opposing electrode on the side surface functions to eliminate noise signals caused by undesirable light rays incident through the side surface, which otherwise, would deteriorate the output signals of the image sensor.
    Type: Grant
    Filed: December 16, 1988
    Date of Patent: May 7, 1991
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Takeshi Fukada, Mitsufumi Codama, Mitsunori Sakama, Nobumitsu Amachi, Naoya Sakamoto, Ichiro Takayama