Patents by Inventor Takaaki Furuyama
Takaaki Furuyama 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: 7212443Abstract: A non-volatile memory in which a plurality of memory cells connected to a same word line are entirely written with data. Source lines SL separated from each other in column units is arranged on each memory cell of a memory cell array. When writing data, one of either a first or a second source voltage is applied to each source line in accordance with data that is to be written. After a first control voltage of negative voltage is applied, a second control voltage of high voltage is applied to the word line with the voltage of each source line SL in a maintained state. Therefore, each memory cell is erased or programmed in accordance with the voltage applied to the respective source line.Type: GrantFiled: February 23, 2005Date of Patent: May 1, 2007Assignee: Spansion LLCInventor: Takaaki Furuyama
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Publication number: 20060227629Abstract: An access identification circuit (4) identifies a first access operation or a second access operation and outputs an identification signal S. During the first access operation, stored data is read out after detecting a column address CADD, a burst address, and updating a word line to newly select memory cells MC. In the second access operation, the memory cells MC connected to the common word line which has been selected are selected by sequentially switching column selector switches. Operating condition information Dx (DAx and/or DBx) used for setting a load condition in a dummy load circuit (5) and/or setting a pulse width for an equalize signal EQ in an amplification control circuit (6) is stored in each of first and second storage sections (1, 2) that are provided for the first and second access operations, respectively.Type: ApplicationFiled: March 16, 2006Publication date: October 12, 2006Inventors: Koji Shimbayashi, Takaaki Furuyama, Kenji Shibata
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Publication number: 20060227630Abstract: In Step 1, a bias is applied (ON) to all of vertical rows Z1(0) to Z1(2). With respect to the horizontal rows, a bias is not applied (OFF) to a horizontal row Z2(0) where the defective sector exists and a bias is applied (ON) to the other horizontal rows Z2(1) and Z2(2). On the sectors in the horizontal rows Z2(1) and Z2(2), a voltage stress is applied and an access operation is performed. In Step 2, with respect to the vertical rows, a bias is not applied (OFF) to a vertical row Z1(1) where the defective sector exists and a bias is applied (ON) to the other vertical rows Z1(0) and Z1(2). With respect to the horizontal rows, a bias is applied (ON) to the horizontal row Z2(0) where the defective sector exists, and no bias is applied (OFF) to the other horizontal rows Z2(1) and Z2(2). As for the two steps, a voltage stress can be applied once to the sectors other than the defective sector.Type: ApplicationFiled: December 21, 2005Publication date: October 12, 2006Inventors: Kenta Kato, Takaaki Furuyama
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Publication number: 20060209583Abstract: A semiconductor device includes a CAM cell array that stores the operation setting information as to the semiconductor device, a controller that controls read and write of the CAM cell array, a row decoder, and a column decoder. With this structure, different row addresses are allocated to respective functions of the operation setting information. Accordingly, stress is not caused in the CAM cell array of the unselected functions at the time of programming.Type: ApplicationFiled: January 27, 2006Publication date: September 21, 2006Inventors: Shozo Kawabata, Kenji Shibata, Takaaki Furuyama, Satoru Kawamoto
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Patent number: 7068555Abstract: An address identifying memory block is match-compared with address information stored in a to-be-remedied block memory section in a block redundancy judge section. A redundant block select signal is outputted from the block redundancy judge section by judgment of address match. A memory block column select section selects a memory block column having a redundant memory block irrespective of an address signal as the redundant block select signal is activated if block redundancy is activated to output a memory block column select signal. A column redundancy memory section selects address information of column redundancy relating a redundant memory block arranged in a memory block column in accordance with the memory block column select signal.Type: GrantFiled: February 18, 2005Date of Patent: June 27, 2006Assignee: Spansion LLCInventors: Satoru Sugimoto, Takaaki Furuyama, Mitsuhiro Nagao
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Patent number: 7061816Abstract: A semiconductor memory device includes a memory block having memory cells connected to global bit lines and global word lines are arranged in matrix constitutes a memory block column sharing global bit lines, the memory block column being developed in global word line wiring direction, wherein at least two of memory block columns adjoining each other constitute a to-be-remedied unit, and redundant block(s), which is/are arranged sharing global bit lines with the memory block column(s), which is/are provided in each to-be-remedied unit and number of redundant block(s) is/are smaller than that of memory block column(s) included in the to-be-remedied unit. A minimum number of redundant memory blocks necessary for defectiveness remedy can be provided thereby enhancing the yield with optimization of the manufacturing and circuits. Redundancy remedy efficiency can also be improved while minimizing increased chip die size of the semiconductor memory device.Type: GrantFiled: February 18, 2005Date of Patent: June 13, 2006Assignee: Spansion LLCInventors: Akira Sugiura, Takaaki Furuyama
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Publication number: 20060046373Abstract: The semiconductor device comprises a first well 14 of a first conduction type formed in a semiconductor substrate 10; a second well 16 of a second conduction type formed in the first well 14; and a transistor 40 including a control gate 18 formed of an impurity region of the first conduction type formed in the second well 16, a first impurity diffused layer 26 and a second impurity diffused layer 33 formed with a channel region 25 therebetween, and a floating gate electrode 20 formed on the channel region 25 and the control gate 18 with a gate insulation film 24 therebetween. The control gate 18 is buried in the semiconductor substrate 10, which makes it unnecessary to form the control gate 18 on the floating gate electrode 20. Thus, the memory transistor and the other transistors, etc. can be formed by the same fabricating process. Thus, the fabrication processes can be less and the semiconductor device can be inexpensive.Type: ApplicationFiled: October 13, 2005Publication date: March 2, 2006Applicant: FUJITSU LIMITEDInventors: Masaki Ito, Masaya Katayama, Takaaki Furuyama, Shozo Kawabata
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Publication number: 20060023500Abstract: When an initializing operation starts, a busy state indicative of the disenable of access operation is set (S11), and read operation information is read out by preferentially using a verify sense amplifier 4 or a high-speed read sense amplifier 3 (S12). Upon completion of latching the read operation information (S13: Y), a ready state that announces that the read access operation from a non-redundant memory region is enabled is set (S14), and a ready signal is outputted according to an external read access request to the non-redundant memory region. A boot program or the like which is in the non-redundant memory region can be read out in parallel with the read of the operation information. Subsequently, the redundancy information is read out (S15), and a ready state that announces that the read access operation from all of the memory regions is enabled is set upon completion of reading out the redundancy information (S17). Thereafter, rewrite operation information is read out (S18).Type: ApplicationFiled: July 28, 2005Publication date: February 2, 2006Inventors: Shozo Kawabata, Takaaki Furuyama, Kenta Kato
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Publication number: 20060002196Abstract: A memory system (1A) includes a memory section (2A) and a memory control section (3A). The memory section (2A) includes a test circuit (4A), a data register (5A), a data output section (6A), and a memory core section (9A). Data DI is held in the data resistor (5A). The test circuit (4A) outputs write inhibit signal WINH to the memory core section (9A) in response to test signal TEST. Write instruction recognition signal WR which recognizes that a write command is inputted into the memory section (2A) and select signal S are inverted and, in response thereto, retained data DR of the data register (5A) is outputted as output data DO from the data output section (6A). Thus, it is possible to test whether generation, propagation, or recognition operation of a write command CMD and the data DI is normal or not without executing the operation of writing data into a memory cell of the memory section.Type: ApplicationFiled: July 1, 2005Publication date: January 5, 2006Inventors: Takaaki Furuyama, Satoru Kawamoto
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Patent number: 6977411Abstract: The semiconductor device comprises a first well 14 of a first conduction type formed in a semiconductor substrate 10; a second well 16 of a second conduction type formed in the first well 14; and a transistor 40 including a control gate 18 formed of an impurity region of the first conduction type formed in the second well 16, a first impurity diffused layer 26 and a second impurity diffused layer 33 formed with a channel region 25 therebetween, and a floating gate electrode 20 formed on the channel region 25 and the control gate 18 with a gate insulation film 24 therebetween. The control gate 18 is buried in the semiconductor substrate 10, which makes it unnecessary to form the control gate 18 on the floating gate electrode 20. Thus, the memory transistor and the other transistors, etc. can be formed by the same fabricating process. Thus, the fabrication processes can be less and the semiconductor device can be inexpensive.Type: GrantFiled: December 18, 2003Date of Patent: December 20, 2005Assignee: Fujitsu LimitedInventors: Masaki Ito, Masaya Katayama, Takaaki Furuyama, Shozo Kawabata
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Publication number: 20050185482Abstract: An address identifying memory block is match-compared with address information stored in a to-be-remedied block memory section in a block redundancy judge section. A redundant block select signal is outputted from the block redundancy judge section by judgment of address match. A memory block column select section selects a memory block column having a redundant memory block irrespective of an address signal as the redundant block select signal is activated if block redundancy is activated to output a memory block column select signal. A column redundancy memory section selects address information of column redundancy relating a redundant memory block arranged in a memory block column in accordance with the memory block column select signal.Type: ApplicationFiled: February 18, 2005Publication date: August 25, 2005Inventors: Satoru Sugimoto, Takaaki Furuyama, Mitsuhiro Nagao
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Publication number: 20050185483Abstract: A semiconductor memory device includes a memory block having memory cells connected to global bit lines and global word lines are arranged in matrix constitutes a memory block column sharing global bit lines, the memory block column being developed in global word line wiring direction, wherein at least two of memory block columns adjoining each other constitute a to-be-remedied unit, and redundant block(s), which is/are arranged sharing global bit lines with the memory block column(s), which is/are provided in each to-be-remedied unit and number of redundant block(s) is/are smaller than that of memory block column(s) included in the to-be-remedied unit. A minimum number of redundant memory blocks necessary for defectiveness remedy can be provided thereby enhancing the yield with optimization of the manufacturing and circuits. Redundancy remedy efficiency can also be improved while minimizing increased chip die size of the semiconductor memory device.Type: ApplicationFiled: February 18, 2005Publication date: August 25, 2005Inventors: Akira Sugiura, Takaaki Furuyama
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Patent number: 6917541Abstract: This invention provides a nonvolatile semiconductor memory device including a novel memory core portion in which an influence of a parasitic element component in a memory cell information reading path is excluded in a reading operation, and novel sensing means accompanying this memory core structure, so as to achieve rapid sensing. In the memory core portion, a selected memory cell is selected by a global bit line through a local bit line and an adjacent global bit line is connected to a local bit line in a non-selected sector. A column selecting portion connects a pair of the global bit lines to a pair of data bus lines. A load portion having a load equivalent to a parasitic capacitance of a path leading from the memory cell and for supplying a reference current to a reference side is connected to a pair of the data bus lines. A current of the memory cell information is compared with the reference current by a current comparing portion and a differential current is outputted.Type: GrantFiled: February 1, 2002Date of Patent: July 12, 2005Assignee: Fujitsu LimitedInventors: Koji Shimbayashi, Takaaki Furuyama
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Publication number: 20050149792Abstract: A semiconductor device capable that shortens test time with a simple circuit configuration and prevents enlargement of the circuit area for testing. The semiconductor device has a macro memory and a logic section mounted thereon. The macro memory includes an operation control circuit for executing a read/write operation of data in accordance with an input signal containing an address, data, and a command. A test register for storing data to select a test mode is arranged in a storage area of the macro memory that is selected by an address. A write circuit generates a control signal enabling the writing of data to the test register in response to a write command provided from the operation control circuit.Type: ApplicationFiled: January 7, 2005Publication date: July 7, 2005Inventor: Takaaki Furuyama
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Publication number: 20050141277Abstract: A non-volatile memory in which a plurality of memory cells connected to a same word line are entirely written with data. Source lines SL separated from each other in column units is arranged on each memory cell of a memory cell array. When writing data, one of either a first or a second source voltage is applied to each source line in accordance with data that is to be written. After a first control voltage of negative voltage is applied, a second control voltage of high voltage is applied to the word line with the voltage of each source line SL in a maintained state. Therefore, each memory cell is erased or programmed in accordance with the voltage applied to the respective source line.Type: ApplicationFiled: February 23, 2005Publication date: June 30, 2005Inventor: Takaaki Furuyama
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Patent number: 6879521Abstract: It is intended to provide a nonvolatile semiconductor memory device which maintains the maximum number of over-erase memory cells which are conductive when adjusting the threshold voltage after data erase by controlling the gate voltage of a memory cell continuously in order to adjust the threshold voltage in a short time and a nonvolatile voltage adjustment method. There is formed a feedback loop for controlling the number of memory cells to be conductive in a memory cell group by controlling a gate voltage generating circuit through a differential amplifier from a drain terminal and the gate voltage generating circuit is controlled by the differential amplifier so as to maintain the drain voltage at a predetermined drain voltage VRF. A variable gate voltage can be controlled continuously by a feedback loop for controlling the variable gate voltage based on a difference voltage between the drain voltage and the predetermined drain voltage.Type: GrantFiled: February 21, 2003Date of Patent: April 12, 2005Assignee: Fujitsu LimitedInventor: Takaaki Furuyama
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Publication number: 20040129970Abstract: The semiconductor device comprises a first well 14 of a first conduction type formed in a semiconductor substrate 10; a second well 16 of a second conduction type formed in the first well 14; and a transistor 40 including a control gate 18 formed of an impurity region of the first conduction type formed in the second well 16, a first impurity diffused layer 26 and a second impurity diffused layer 33 formed with a channel region 25 therebetween, and a floating gate electrode 20 formed on the channel region 25 and the control gate 18 with a gate insulation film 24 therebetween. The control gate 18 is buried in the semiconductor substrate 10, which makes it unnecessary to form the control gate 18 on the floating gate electrode 20. Thus, the memory transistor and the other transistors, etc. can be formed by the same fabricating process. Thus, the fabrication processes can be less and the semiconductor device can be inexpensive.Type: ApplicationFiled: December 18, 2003Publication date: July 8, 2004Inventors: Masaki Ito, Masaya Katayama, Takaaki Furuyama, Shozo Kawabata
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Publication number: 20040008567Abstract: It is intended to provide a nonvolatile semiconductor memory device which maintains the maximum number of over-erase memory cells which are conductive when adjusting the threshold voltage after data erase by controlling the gate voltage of a memory cell continuously in order to adjust the threshold voltage in a short time and a nonvolatile voltage adjustment method. There is formed a feedback loop for controlling the number of memory cells to be conductive in a memory cell group by controlling a gate voltage generating circuit through a differential amplifier from a drain terminal and the gate voltage generating circuit is controlled by the differential amplifier so as to maintain the drain voltage at a predetermined drain voltage VRF. A variable gate voltage can be controlled continuously by a feedback loop for controlling the variable gate voltage based on a difference voltage between the drain voltage and the predetermined drain voltage.Type: ApplicationFiled: February 21, 2003Publication date: January 15, 2004Applicant: FUJITSU LIMITEDInventor: Takaaki Furuyama
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Patent number: 6643758Abstract: According to one aspect of the present invention, the flash memory comprises a memory region divided into a plurality of real banks, wherein from among the plurality of products which consists of a plurality of combinations of virtual banks having at least one real bank; and a combination of the top boot in which the most significant address is allocated to the boot bank having the boot sector and the bottom boot in which the least significant address is allocated to the boot bank, product information data are set in a product information record section, whereby any product can be configured.Type: GrantFiled: October 30, 2001Date of Patent: November 4, 2003Assignee: Fujitsu LimitedInventors: Takaaki Furuyama, Mitsuhiro Nagao
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Publication number: 20030043623Abstract: This invention provides a nonvolatile semiconductor memory device including a novel memory core portion in which an influence of a parasitic element component in a memory cell information reading path is excluded in a reading operation, and novel sensing means accompanying this memory core structure, so as to achieve rapid sensing. In the memory core portion, a selected memory cell is selected by a global bit line through a local bit line and an adjacent global bit line is connected to a local bit line in a non-selected sector. A column selecting portion connects a pair of the global bit lines to a pair of data bus lines. A load portion having a load equivalent to a parasitic capacitance of a path leading from the memory cell and for supplying a reference current to a reference side is connected to a pair of the data bus lines. A current of the memory cell information is compared with the reference current by a current comparing portion and a differential current is outputted.Type: ApplicationFiled: February 1, 2002Publication date: March 6, 2003Applicant: FUJITSU LIMITEDInventors: Koji Shimbayashi, Takaaki Furuyama