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).
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Patent number: 6008076Abstract: 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: GrantFiled: November 6, 1996Date of Patent: December 28, 1999Assignee: Semicoductor Energy Laboratory Co., Ltd.Inventors: Mitsufumi Codama, Yukio Yamauchi, Naoya Sakamoto, Takeshi Fukada
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Patent number: 5904508Abstract: 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: GrantFiled: January 21, 1997Date of Patent: May 18, 1999Assignees: Semiconductor Energy Laboratory Co., Ltd., TDK CorporationInventors: Mitsufumi Codama, Michio Arai
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Patent number: 5821560Abstract: 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: GrantFiled: March 1, 1996Date of Patent: October 13, 1998Assignees: TKD Corporation, Semiconductor Energy Laboratory Co., Ltd.Inventors: Michio Arai, Kazushi Sugiura, Ichiro Takayama, Yukio Yamauchi, Isamu Kobori, Mitsufumi Codama, Naoya Sakamoto
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Patent number: 5786796Abstract: 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: GrantFiled: March 1, 1996Date of Patent: July 28, 1998Assignees: TDK Corporation, Semiconductor Energy Laboratory Co., Ltd.Inventors: Ichiro Takayama, Michio Arai, Mitsufumi Codama
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Patent number: 5757030Abstract: 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: GrantFiled: May 12, 1995Date of Patent: May 26, 1998Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Mitsufumi Codama, Noriaki Kondo
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Patent number: 5741718Abstract: 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: GrantFiled: July 16, 1996Date of Patent: April 21, 1998Assignees: Semiconductor Energy Laboratory Co., Ltd., TDK CorporationInventors: Mitsufumi Codama, Ichiro Takayama, Michio Arai
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Patent number: 5731600Abstract: 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: GrantFiled: March 14, 1995Date of Patent: March 24, 1998Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Mitsufumi Codama, Michio Arai
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Patent number: 5644146Abstract: 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: GrantFiled: March 21, 1995Date of Patent: July 1, 1997Assignees: TDK Corporation, Semiconductor Energy Laboratory Co., Ltd.Inventors: Michio Arai, Mitsufumi Codama, Ichiro Takayama
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Patent number: 5627364Abstract: 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: GrantFiled: October 10, 1995Date of Patent: May 6, 1997Assignees: TDK Corporation, Semiconductor Energy Laboratory Co., Ltd.Inventors: Mitsufumi Codama, Michio Arai
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Patent number: 5604139Abstract: 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: GrantFiled: February 9, 1995Date of Patent: February 18, 1997Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Mitsufumi Codama, Ichiro Takayama, Michio Arai
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Patent number: 5591988Abstract: 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: GrantFiled: June 7, 1995Date of Patent: January 7, 1997Assignees: TDK Corporation, Semiconductor Energy Lab. Co. Ltd.Inventors: Michio Arai, Takashi Inushima, Mitsufumi Codama, Kazushi Sugiura, Ichiro Takayama, Isamu Kobori, Yukio Yamauchi, Naoya Sakamoto
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Patent number: 5574293Abstract: 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: GrantFiled: November 22, 1994Date of Patent: November 12, 1996Assignees: TDK Corp., Semiconductor Energy Laboratory Co. Ltd.Inventors: Michio Arai, Takashi Inushima, Mitsufumi Codama, Kazushi Sugiura, Ichiro Takayama, Isamu Kobori, Yukio Yamauchi, Naoya Sakamoto
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Patent number: 5470762Abstract: 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: GrantFiled: November 20, 1992Date of Patent: November 28, 1995Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Mitsufumi Codama, Noriaki Kondo
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Patent number: 5352921Abstract: 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: GrantFiled: September 14, 1993Date of Patent: October 4, 1994Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Mitsufumi Codama, Ichiro Takayama
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Patent number: 5292675Abstract: 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: GrantFiled: December 14, 1992Date of Patent: March 8, 1994Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventor: Mitsufumi Codama
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Patent number: 5187601Abstract: 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: GrantFiled: December 17, 1991Date of Patent: February 16, 1993Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Shunpei Yamazaki, Takeshi Fukada, Mitsunori Sakama, Nobumitsu Amachi, Naoya Sakamoto, Mitsufumi Codama, Takashi Fuki, Ichiro Takayama
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Patent number: 5103321Abstract: 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: GrantFiled: December 13, 1988Date of Patent: April 7, 1992Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Nobumitsu Amachi, Toshiji Hamatani, Takeshi Fukada, Mitsunri Sakama, Naoya Sakamoto, Mitsufumi Codama
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Patent number: 5017828Abstract: 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: GrantFiled: April 25, 1989Date of Patent: May 21, 1991Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Takeshi Fukada, Mitsunori Sakama, Nobumitsu Amachi, Naoya Sakamoto, Mitsufumi Codama, Toru Takayama
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Patent number: 5014100Abstract: 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: GrantFiled: December 16, 1988Date of Patent: May 7, 1991Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Takeshi Fukada, Mitsufumi Codama, Mitsunori Sakama, Nobumitsu Amachi, Naoya Sakamoto, Ichiro Takayama