Fet Configuration Adapted For Use As Static Memory Cell Patents (Class 257/903)
  • Patent number: 5668380
    Abstract: Reduced area metal contacts to a thin polysilicon layer contact structure having low ohmic resistance was achieved. The structure involves forming contact openings in an insulating layer over a buffer layer composed of a thick polysilicon layer. A portion of the sidewall in the opening includes a patterned thin polysilicon layer that forms part of a semiconductor device and also forms the electrical connection to the metal contact. The structure provides metal contacts having very low resistance and reduced area for increased device packing densities. The metal contact structure also eliminates the problem of forming P.sup.+ /N.sup.+ non-ohmic junctions usually associated with making P.sup.+ /N.sup.+ stacked contact. The structure further allows process steps to be used that provide larger latitude in etching the contact opening and thereby provides a structure that is very manufacturable.
    Type: Grant
    Filed: March 7, 1996
    Date of Patent: September 16, 1997
    Assignee: Taiwan Semiconductor Manufacturing Company, Ltd
    Inventors: Shou-Gwo Wuu, Mong-Song Liang, Chung-Hui Su, Chen-Jong Wang
  • Patent number: 5659191
    Abstract: A MOS transistor included in a peripheral circuit of a DRAM has conductive layers for interconnection on respective surfaces of a pair of source.multidot.drain regions. The source.multidot.drain interconnection layers are electrically connected to the source.multidot.drain regions through the conductive layers. One of the pair of conductive layers is formed in the same step as a bit line of a memory cell, by the same material as the bit line. The other one of the pair of conductive layers is formed in the same step as a storage node of a capacitor of the memory cell, by using the same material as the storage node. The pair of conductive layers prevent direct connection between the source.multidot.drain interconnection layer and the source.multidot.drain regions, so that reduction in size of the source.multidot.drain regions can be realized.
    Type: Grant
    Filed: June 1, 1995
    Date of Patent: August 19, 1997
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventor: Hideaki Arima
  • Patent number: 5656836
    Abstract: Herein disclosed is a semiconductor integrated circuit device comprising a SRAM having its memory cell composed of transfer MISFETs to be controlled through word lines and drive MISFETs. The gate electrodes of the drive MISFETs and the gate electrodes of the transfer MISFETs of the memory cell, and the word lines are individually formed of different conductive layers. The drive MISFETs and the transfer MISFETs are individually arranged to cross each other in the gate length direction. The word lines are extended in the gate length direction of the gate electrodes of the drive MISFETs and caused to cross the gate electrodes of the drive MISFETs partially.The two transfer MISFETs of the memory cell have their individual gate electrodes connected-with two respective word lines spaced from each other and extended in an identical direction. The region defined by the two word lines is arranged therein with the two drive MISFETs and the source lines.
    Type: Grant
    Filed: June 2, 1995
    Date of Patent: August 12, 1997
    Assignee: Hitachi, Ltd.
    Inventors: Shuji Ikeda, Satoshi Meguro, Soichiro Hashiba, Isamu Kuramoto, Atsuyoshi Koike, Katsuro Sasaki, Koichiro Ishibashi, Toshiaki Yamanaka, Naotaka Hashimoto, Nobuyuki Moriwaki, Shigeru Takahashi, Atsushi Hiraishi, Yutaka Kobayashi, Seigou Yukutake
  • Patent number: 5656841
    Abstract: In a manufacturing method of a semiconductor device, a gate insulating film is grown in an active region. Thereafter, an N-type polysilicon film is formed on the gate insulating film and is patterned so that a gate electrode and a polysilicon electrode are formed. Next, arsenic ions are implanted onto entire faces of the gate and polysilicon electrodes so that a source-drain region is formed on a substrate. An interlayer insulating film is then formed on an entire face of the source-drain region, etc. Thereafter, a contact hole is formed on a drain region in a position in which the drain region partially overlaps the polysilicon electrode. A surface portion of the polysilicon electrode is exposed into the contact hole. Thereafter, phosphoric ions are implanted through the contact hole with the interlayer insulating film as a mask. The implanted ions are thermally processed to activate these implanted ions. Thereafter, metal wiring is formed.
    Type: Grant
    Filed: October 19, 1995
    Date of Patent: August 12, 1997
    Assignee: Ricoh Company, Ltd.
    Inventors: Hirofumi Watanabe, Kaihei Isshiki, Tetsurou Tanigawa, Yasuyuki Shindou, Katsunari Hanaoka
  • Patent number: 5654572
    Abstract: PMOS transistors and NMOS transistors are used to form an SRAM cell. Each cell comprises its own P-well contact (14) and a Vcc contact (18) in its cell area. These contacts are placed between common polysilicon gates (9, 10) of pull-down MOS transistors and pull-up MOS transistors, said gates extending in parallel with two bit lines. The P-well contact consists of a p.sup.+ -type diffusion layer formed within the P-well in contact with an n.sup.+ -type source region of the pull-down MOS transistor, said p.sup.+ -type diffusion layer being positioned closer to the boundary between the P-well and the N-well than the source region.
    Type: Grant
    Filed: October 23, 1995
    Date of Patent: August 5, 1997
    Assignee: NKK Corporation
    Inventor: Yoshihiro Kawase
  • Patent number: 5652441
    Abstract: A semiconductor 110 device includes an array of like base cells wherein each base cell includes at least one source 132 and at least one drain 130 region formed in a semiconductor substrate. At least one gate 126 is formed over and insulated from a channel region 118 which separates the source 132 and drain 130 regions. An insulating layer 190 overlies the structure. A plurality of contacts are formed in the insulating layer in a plurality of substantially parallel; evenly spaced grid lines G1-G5. In addition, at least one additional contact 150 formed between two adjacent ones G2 and G3 of the substantially parallel grid lines is formed. A plurality of interconnect lines 142 and 144 are formed over the insulating layer such that each contact is connected to at least one of the interconnect lines. Modifications, variations, circuit configurations and an illustrative fabrication method are also disclosed.
    Type: Grant
    Filed: October 25, 1994
    Date of Patent: July 29, 1997
    Assignee: Texas Instruments Incorporated
    Inventors: Mashashi Hashimoto, Shivaling S. Mahant-Shetti
  • Patent number: 5652457
    Abstract: Herein disclosed is a semiconductor integrated circuit device comprising a SRAM having its memory cell composed of transfer MISFETs to be controlled through word lines and drive MISFETs. The gate electrodes of the drive MISFETs and the gate electrodes of the transfer MISFETs of the memory cell, and the word lines are individually formed of different conductive layers. The drive MISFETs and the transfer MISFETs are individually arranged to cross each other in the gate length direction. The word lines are extended in the gate length direction of the gate electrodes of the drive MISFETs and caused to cross the gate electrodes of the drive MISFETs partially.The two transfer MISFETs of the memory cell have their individual gate electrodes connected with two respective word lines spaced from each other and extended in an identical direction. The region defined by the two word lines is arranged therein with the two drive MISFETs and the source lines.
    Type: Grant
    Filed: November 30, 1994
    Date of Patent: July 29, 1997
    Assignee: Hitachi, Ltd.
    Inventors: Shuji Ikeda, Satoshi Meguro, Soichiro Hashiba, Isamu Kuramoto, Atsuyoshi Koike, Katsuro Sasaki, Koichiro Ishibashi, Toshiaki Yamanaka, Naotaka Hashimoto, Nobuyuki Moriwaki, Shigeru Takahashi, Atsushi Hiraishi, Yutaka Kobayashi, Seigou Yukutake
  • Patent number: 5646895
    Abstract: The semiconductor memory device as static RAM disclosed comprises a memory cell array, a plurality of load circuits, and a plurality of bit line potential compensation circuits. Each of the bit line potential compensation circuits is a pseudo memory cell and is provided between each of the bit line load circuits and the memory cell array for holding the power supply potential supplied. The pseudo memory cell has an element arrangement equivalent to that of each of the memory cells.
    Type: Grant
    Filed: December 26, 1995
    Date of Patent: July 8, 1997
    Assignee: NEC Corporation
    Inventor: Kazuhiko Abe
  • Patent number: 5646423
    Abstract: A memory cell of the type a pair of cross-coupled CMOS inverters of a SRAM is disclosed in which the load MISFETs are stacked above the semiconductor substrate and over the drive MISFETS. Each load MISFET of a memory cell consists of a source, drain and channel region formed within the same polycrystalline silicon film, and a gate electrode consisting of a different layer conductive film than that of the drive MISFETs. In a memory cell having such a stacked arrangement, the source (drain) region and gate electrode of each load MISFET thereof are patterned to have an overlapping relationship with each other so as to increase the effective capacitance associated with each of the memory cell storage nodes.
    Type: Grant
    Filed: June 6, 1995
    Date of Patent: July 8, 1997
    Assignee: Hitachi, Ltd.
    Inventors: Satoshi Meguro, Kiyofumi Uchibori, Norio Suzuki, Makoto Motoyoshi, Atsuyoshi Koike, Toshiaki Yamanaka, Yoshio Sakai, Toru Kaga, Naotaka Hashimoto, Takashi Hashimoto, Shigeru Honjou, Osamu Minato
  • Patent number: 5644155
    Abstract: A high capacitance field effect transistor for use in an integrated memory circuit is fabricated with an optimized gate electrode and active region overlap, increasing the gate electrode to substrate capacitance thereby minimizing the effect of alpha particle upset. The optimized overlap is accomplished by maximizing the opening in the field oxide layer which defines the active region. In some embodiments, the transistor is also optimized for overall cell layout area.
    Type: Grant
    Filed: September 6, 1994
    Date of Patent: July 1, 1997
    Assignee: Integrated Device Technology, Inc.
    Inventor: Chuen-Der Lien
  • Patent number: 5640037
    Abstract: Local interconnect structures and processes using dual-doped polysilicon. A single implant dopes part of the polysilicon local interconnect layer p-type, and also diffuses through the polysilicon interconnect layer to enhance the doping of the PMOS drain regions, and also (optionally) adds to the doping of the PMOS source regions to provide source/drain asymmetry. The polysilicon interconnect layer is clad to reduce its conductivity, optionally with patterned rather than global cladding so that the diode can be used as a load element if desired.
    Type: Grant
    Filed: November 6, 1995
    Date of Patent: June 17, 1997
    Assignee: SGS-Thomson Microelectronics, Inc.
    Inventor: Richard A. Blanchard
  • Patent number: 5640027
    Abstract: A static random access memory (SRAM) device and a manufacturing method thereof are provided. In the SRAM memory device, a first active region of annular shape and a second active region bisecting the annulus are repeatedly formed over the whole cell array. Thus, since the contact hole for connecting the power line to the active region can be formed larger without increasing the cell size, contact resistance can be decreased. Also, the manufacturing method can be simplified since just one gate oxide layer formation process is needed.
    Type: Grant
    Filed: July 26, 1995
    Date of Patent: June 17, 1997
    Assignee: Samsung Electronics Co., Ltd.
    Inventors: Heon-jong Shin, Young-kwang Kim
  • Patent number: 5640342
    Abstract: A pair of thin film transistors formed in adjacent layers of polysilicon. The gate of the first TFT and the source, drain and channel regions of the second TFT are formed in the first polysilicon layer. The source, drain and channel regions of the first TFT and the gate of the second TFT are formed in the second polysilicon layer. A dielectric layer is interposed between the first and second polysilicon layers. The first TFT gate overlaps the second TFT drain region in the first polysilicon layer and the second TFT gate overlaps the first TFT drain region in the second polysilicon layer. In another aspect of the invention, two TFTs are incorporated into a SRAM memory cell.
    Type: Grant
    Filed: November 20, 1995
    Date of Patent: June 17, 1997
    Assignee: Micron Technology, Inc.
    Inventor: Fernando Gonzalez
  • Patent number: 5637884
    Abstract: A thin film transistor includes a first active layer formed on a substrate; a gate electrode formed on a center portion of the first active layer and having a lower side connected to the center portion of the first active layer; a second active layer electrically connected to the first active layer and formed on lateral sides and on an upper side of the gate electrode; and impurity regions formed at opposing lateral sides of the gate electrode.
    Type: Grant
    Filed: April 17, 1996
    Date of Patent: June 10, 1997
    Assignee: LG Semicon Co., Ltd.
    Inventor: Hae C. Yang
  • Patent number: 5635731
    Abstract: SRAM memory cells is provided with high resistance to soft error and no parasitic capacitance due to PN junction.SRAM memory cells comprises the load resister is a thin film transistor having a same conductive type as that of the driver transistor.
    Type: Grant
    Filed: August 7, 1995
    Date of Patent: June 3, 1997
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventor: Motoi Ashida
  • Patent number: 5631863
    Abstract: A radiation resistant random access memory cell which has a coupling circuit between a storage node of a first CMOS pair and a gate node of a second CMOS pair. The coupling circuit is controlled by a word line and provides a first resistive element between the storage node and the body of the coupling circuit and a second resistive element between the gate node and the body of the coupling circuit.
    Type: Grant
    Filed: January 16, 1996
    Date of Patent: May 20, 1997
    Assignee: Honeywell Inc.
    Inventors: Paul S. Fechner, Gregor D. Dougal, Keith W. Golke
  • Patent number: 5629546
    Abstract: A static memory cell having no more than three transistors. A static memory cell is formed by providing a semiconductor substrate; forming a buried n-type layer in the substrate, the n-type layer having a first average n-type dopant concentration of at least 1.times.10.sup.16 ions/cm.sup.3 ; forming an n-channel transistor relative to the substrate over the buried n-type layer, the n-channel transistor having a source, a gate, and a drain, the source having a second average n-type dopant concentration of at least 1.times.10.sup.19 ions/cm.sup.3 and the drain having a third average n-type dopant concentration of at least 1.times.10.sup.19 ions/cm.sup.3, and the source having a depth deeper than the drain so as to be closer to the buried n-type layer than the drain; and forming a p-type region in junction with the source to define a tunnel diode between the p-type region and the source.
    Type: Grant
    Filed: June 21, 1995
    Date of Patent: May 13, 1997
    Assignee: Micron Technology, Inc.
    Inventors: Jeff Z. Wu, Joseph Karniewicz
  • Patent number: 5625200
    Abstract: A complementary device consisting of a PMOS TFT transistor and an NMOS FET transistor uses a conducting layer to shunt drain regions of the transistors to eliminate any detrimental diode or p-n junction effects. The use of the conducting layer significantly improves the current drive capabilities of the PMOS TFT when the complementary device is used to design SRAM cells with NMOS pull-down transistors.
    Type: Grant
    Filed: December 14, 1995
    Date of Patent: April 29, 1997
    Inventors: Kuo-Hua Lee, Chun-Ting Liu
  • Patent number: 5621232
    Abstract: A p-type silicon substrate is provided at its main surface with n-type impurity regions with a space between each other. A gate electrode is formed on a region between the n-type impurity regions with a gate insulating film therebetween. A titanium silicide layer is formed in a region extending from a surface layer of the gate electrode to a surface layer of the n-type impurity region. The titanium silicide layer forms a local interconnection. A side wall insulating film remains on a side wall of the gate electrode on which the titanium silicide layer is not formed. Thereby, the semiconductor device can have a local interconnection which has high reliability and can be formed easily.
    Type: Grant
    Filed: September 1, 1995
    Date of Patent: April 15, 1997
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventor: Takio Ohno
  • Patent number: 5619055
    Abstract: A memory cell of the type employing a pair of cross-coupled CMOS inverters of a SRAM is disclosed in which the load MISFETs are stacked above the semiconductor substrate and over the drive MISFETs. Each load MISFET of a memory cell consists of a source, drain and channel region formed of a semiconductor strip, such as a polycrystalline silicon film strip, and a gate electrode consisting of a different layer conductive film than that of the drive MISFETs. In a memory cell having such a stacked arrangement, the source region and gate electrode of each load MISFET thereof are patterned to have a widely overlapping relationship with each other to form a capacitor element thereacross such that an increase in the overall capacitance associated with each of the memory cell storage nodes is effected thereby decreasing occurrence of soft error.
    Type: Grant
    Filed: April 27, 1995
    Date of Patent: April 8, 1997
    Assignee: Hitachi, Ltd.
    Inventors: Satoshi Meguro, Kiyofumi Uchibori, Norio Suzuki, Makoto Motoyoshi, Atsuyoshi Koike, Toshiaki Yamanaka, Yoshio Sakai, Toru Kaga, Naotaka Hashimoto, Takashi Hashimoto, Shigeru Honjou, Osamu Minato
  • Patent number: 5619056
    Abstract: The present invention provides an improved static random access memory which can be manufactured into values as designed by photolithography. Second direct contract for connecting active region and ground line for first and second memory cells is provided at a boundary between the first memory cell and second memory cell. Second direct contact is divided into a plurality of portions.
    Type: Grant
    Filed: August 7, 1996
    Date of Patent: April 8, 1997
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Hirotada Kuriyama, Masahiro Ishida, Yoshiyuki Ishigaki
  • Patent number: 5616934
    Abstract: The invention is directed to a thin film transistor (TFT) fabricated by using a planarized poly plug as the bottom gate for use in any integrated circuit and in particular an static random access memory (SRAM). The TFT is used in an SRAM device to form a planarized SRAM cell comprising: a pulldown transistor having a control gate and source/drain terminals; a planarized insulating layer having grooves therein, each groove providing access to an underlying conductive material; a planarized conductive plug residing inside each groove, whereby a first conductive plug forms a thin film transistor gate connecting to an to an adjacent inverter and a second conductive plug provides connection to the gate of the pulldown device; a gate dielectric overlying the first planarized conductive plug; and a patterned semiconductive layer doped such that a channel region aligns to each thin film transistor gate and a source/drain region aligns to each side of the channel region is formed.
    Type: Grant
    Filed: March 22, 1996
    Date of Patent: April 1, 1997
    Assignee: Micron Technology, Inc.
    Inventors: Charles H. Dennison, Monte Manning
  • Patent number: 5616948
    Abstract: A semiconductor device includes a pass transistor (28) electrically coupled to a driver transistor (16) by a common drain region (52). The pass transistor (28) includes the pass gate electrode (44) having a polycrystalline silicon layer (68). The driver transistor (16) includes a driver gate electrode (40) having a polycrystalline silicon layer (74). The dopant concentration in polycrystalline silicon layer (74) is greater than the dopant concentration in polycrystalline silicon layer (68). The differential and dopant concentration between the pass gate electrode (44) and the driver gate electrode (40) results in a greater current gain in the driver transistor (16) relative to the pass transistor (28). When incorporated into an SRAM memory cell (10), the driver transistor (16) and the pass transistor (28) provide greater cell stability by improving the immunity of the cell to electrical disturbance through the pass transistor (28).
    Type: Grant
    Filed: June 2, 1995
    Date of Patent: April 1, 1997
    Assignee: Motorola Inc.
    Inventor: James R. Pfiester
  • Patent number: 5608250
    Abstract: A semiconductor device is described, incorporating electron traps at the interface between a semiconductor substrate and a gate dielectric layer of an insulated gate field effect transistor, such device being capable of retaining charge in the electron traps for a certain time, allowing volatile memory circuits to be produced wherein each cell occupies only the area required for a single transistor.
    Type: Grant
    Filed: November 21, 1994
    Date of Patent: March 4, 1997
    Assignee: SGS-Thomson Microelectronics S.A.
    Inventor: Alexander Kalnitsky
  • Patent number: 5600167
    Abstract: A semiconductor device capable of stably operating even at a low voltage, includes: a semiconductor substrate having a surface region of a first conductivity type; a conductive film directly formed on a surface of the surface region at an area thereof, the conductive film containing impurities of a second conductivity type opposite to the first conductivity type; an oozed diffusion region of the second conductivity type formed by diffusion of the impurities in the conductive film into the substrate, the oozed diffusion region being formed at an area contiguous to the conductive film in the surface region; a low resistivity region of the second conductivity type extending from an area adjacent to the conductive film in the surface region and overlapping the conductive film; and a DDD structure transistor formed on another region of the surface region, wherein a length of a portion of the low resistivity region overlapping the conductive film is substantially the same as a length of a portion of the deep source
    Type: Grant
    Filed: June 6, 1995
    Date of Patent: February 4, 1997
    Assignee: Fujitsu Limited
    Inventor: Takehiro Urayama
  • Patent number: 5598013
    Abstract: A semiconductor device according to the invention includes a first conductivity type of driver transistor, a second conductivity type of load transistor formed on the driver transistor and an insulation layer formed between the driver transistor and the load transistor. The insulation layer is provided thereon with a depression area in which a channel region, a gate insulation layer and a gate electrode of the load transistor are formed.
    Type: Grant
    Filed: December 5, 1994
    Date of Patent: January 28, 1997
    Assignee: NEC Corporation
    Inventor: Hiroaki Yokoyama
  • Patent number: 5598020
    Abstract: A semiconductor integrated circuit device includes a first conductor formed on a main-surface of a semiconductor substrate with an insulating film therebetween, and a second conductor formed with an insulating film therebetween so as to be placed near one side of the first conductor and to have its one end extended over a top surface of the one side of the first conductor. The semiconductor integrated circuit device further includes an impurity diffusion layer at the main surface of the semiconductor substrate under a region where first and second conductors are close to each other. In accordance with this structure, higher degree of integration of a memory cell can be readily achieved by a relatively simple manufacturing process.
    Type: Grant
    Filed: February 3, 1995
    Date of Patent: January 28, 1997
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventor: Ryuichi Matsuo
  • Patent number: 5596212
    Abstract: A memory cell of an SRAM prevents imbalance between GND potentials of a pair of driver transistors. In the memory cell, the driver transistors Q.sub.1 and Q.sub.2 in a pair have the common source region.
    Type: Grant
    Filed: July 21, 1995
    Date of Patent: January 21, 1997
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventor: Hirotada Kuriyama
  • Patent number: 5594270
    Abstract: A semiconductor memory device having a plurality of memory cells each comprising two CMOS inverters cross-coupled to each other and arranged at intersections between a plurality of word lines extending in a column direction and a plurality of complementary data line pairs extending in a row direction; wherein p-channel type load MISFETs of the memory cells arranged in the column direction are formed on the main surface of an n-type well region in the direction in which the word lines extend, the source regions of the p-channel type load MISFETs of the memory cells arranged in the column direction are electrically connected to the n-type well region through conductor layers, and each of the conductor layer is formed independently of the memory cells arranged in the column direction.
    Type: Grant
    Filed: September 29, 1994
    Date of Patent: January 14, 1997
    Assignee: Hitachi, Ltd.
    Inventors: Toshiro Hiramoto, Nobuo Tamba, Motoki Kasai
  • Patent number: 5594683
    Abstract: This invention presents a new SRAM cell comprising only two MOSFETs: one is the access device for data transfer; and the other is operated as a high gain gated lateral BJT in the reverse base current mode so as to constitute the role of the storage flip-flop or latch. This invention also requires only one-sided peripheral circuitry for Read/Write function. Thus the chip area is greatly saved. In addition, the invention is fully compatible with the existing low-cost, high-yield standard CMOS process.
    Type: Grant
    Filed: April 7, 1995
    Date of Patent: January 14, 1997
    Inventors: Ming-Jer Chen, Tzuen-Hsi Huang
  • Patent number: 5592013
    Abstract: In a semiconductor memory device, an n-well is formed in the memory cell area on the surface of a p-type semiconductor substrate. A p-well is formed on the surface of the n-well, and a memory cell transistor is formed on the surface of the p-well. Another p-well is formed in the peripheral circuit area on the substrate surface, and a peripheral transistor is formed on the surface of the p-well. The p-wells are connected electrically by a conductor layer so that these regions have the same voltage level. The memory cell transistor has its threshold voltage set higher than that of the peripheral transistor. The memory device consumes less power, has less decay of gate oxide film, and is suitable for high-density integration.
    Type: Grant
    Filed: June 6, 1995
    Date of Patent: January 7, 1997
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventor: Hiroki Honda
  • Patent number: 5581093
    Abstract: A silicon layer in a lower layer and an interconnection layer arranged in an upper layer are electrically connected through an opening for contact. A silicon plug layer having the same conductivity type as that of the silicon layer is embedded in the opening. The silicon plug layer is embedded in the opening by an etch back method after deposited using a CVD method. The interconnection layer in the upper layer has conductivity type different from that of the silicon plug layer. A refractory metal silicide layer is formed between the upper interconnection layer and the silicon plug layer.The refractory metal silicide layer prevents pn junction from being formed between the upper interconnection layer and the silicon plug layer.
    Type: Grant
    Filed: November 7, 1995
    Date of Patent: December 3, 1996
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventor: Osamu Sakamoto
  • Patent number: 5578873
    Abstract: An integrated circuit includes: a) a semiconductor substrate; b) a first conductivity type substrate diffusion region within the semiconductor substrate, the first conductivity type substrate diffusion region being electrically conductive and having an outer first total area; c) a thin film polysilicon layer of the first conductivity type overlying and being in ohmic electrical connection with the substrate diffusion region; and d) a pillar of electrically conductive material extending outwardly from the thin film polysilicon layer over the electrically conductive diffusion region, the pillar having a total cross sectional second area where the pillar joins the thin film polysilicon layer, the second area being less than the first area and being received entirely within the confines of the first area.
    Type: Grant
    Filed: May 22, 1995
    Date of Patent: November 26, 1996
    Assignee: Micron Technology, Inc.
    Inventor: Monte Manning
  • Patent number: 5578854
    Abstract: An SRAM cell consisting of a cross coupled transistors, a pair of transfer gate transistors and, a pair of load resistors, loading the cross-coupled transistors. Where soft error immunity is desired, the SRAM cell has a buried oxide layer isolating the devices from the silicon substrate. The load resistor is integrated into a contact stud, connecting a diffusion region of the SRAM cell to a power supply. An opening, in an insulating layer overlying the substrate and in contact with parts of the transistors including some diffusion regions, exposes a selected diffusion region of the SRAM cell. The contact stud with an integral resistor, consists of a core of a conductive material, and a highly resistive thin layer between the conducting core and the sides of the opening in the insulator and the selected contact areas. The conductive layer and the resistive layer are nearly planar with the top of the insulating layer.
    Type: Grant
    Filed: August 11, 1995
    Date of Patent: November 26, 1996
    Assignee: International Business Machines Corporation
    Inventors: Bomy A. Chen, Gorden S. Starkey
  • Patent number: 5576560
    Abstract: An integrated circuit memory for a color lookup table for a display system. The memory has a video port and path for reading data identifying colors for pixels at >100 or even >200 MegaHertz, and a CPU port and path for reading and writing data identifying colors at locations in the memory.Each memory cell includes a flip-flop with true and complement terminals. The CPU port includes two pass transistors, each having a first channel terminal coupled to the true or complement terminal, a second channel terminal coupled to a bidirectional bit line of the CPU path, and a gate coupled to a word line of the CPU path. The video port includes an isolated sensing terminal and two transistors. A first transistor has a first channel terminal coupled to the isolated sensing terminal, a second channel terminal coupled to a reference, and a gate coupled to the true or complement terminal.
    Type: Grant
    Filed: June 27, 1994
    Date of Patent: November 19, 1996
    Assignee: Advanced Micro Devices, Inc.
    Inventors: Thomas J. Runaldue, William Plants
  • Patent number: 5572480
    Abstract: Herein disclosed is a semiconductor integrated circuit device comprising a SRAM having its memory cell composed of transfer MISFETs to be controlled through word lines and drive MISFETs. The gate electrodes of the drive MISFETs and the gate electrodes of the transfer MISFETs of the memory cell, and the word lines are individually formed of different conductive layers. The drive MISFETs and the transfer MISFETs are individually arranged to cross each other in the gate length direction. The word lines are extended in the gate length direction of the gate electrodes of the drive MISFETs and caused to cross the gate electrodes of the drive MISFETs partially.
    Type: Grant
    Filed: June 2, 1995
    Date of Patent: November 5, 1996
    Assignee: Hitachi Ltd.
    Inventors: Shuji Ikeda, Satoshi Meguro, Soichiro Hashiba, Isamu Kuramoto, Atsuyoshi Koike, Katsuro Sasaki, Koichiro Ishibashi, Toshiaki Yamanaka, Naotaka Hashimoto, Nobuyuki Moriwaki, Shigeru Takahashi, Atsushi Hiraishi, Yutaka Kobayashi, Seigou Yukutake
  • Patent number: 5572461
    Abstract: The present invention is a three-transistor (3-T) SRAM cell that is made up of a half latch in combination with a dynamic random access memory (DRAM) cell. In a DRAM cell, the "0" bit state is represented by a discharged cell capacitor--a stable state. The "1" bit state, on the other hand, is represented by a charged cell capacitor--an unstable state, since the capacitor leaks rapidly toward the discharged "0" bit state. The new 3-T SRAM cell incorporates a latch which maintains the charge on the cell capacitor when the cell is in a "1" bit state. The cell circuitry includes a cell access transistor coupled to a capacitor, a pull-down transistor, and a P-channel thin film transistor (TFT) which acts as the capacitor pull-up device, the gate of the P-channel TFT also being the drain of the pull-down transistor. A separate polycrystalline silicon layer functions as the substrate of the TFT pull-up device. The 3-T SRAM cell is one half the size of a 4-T SRAM cell and about twice the size of a DRAM cell.
    Type: Grant
    Filed: February 14, 1995
    Date of Patent: November 5, 1996
    Assignee: Micron Technology, Inc.
    Inventor: Fernando Gonzalez
  • Patent number: 5567963
    Abstract: A multi-bit data storage location 201 is formed at the face of a layer 502 of semiconductor of a first conductivity type. Storage location 201 includes a first transistor 210 having a source/drain region 308 of a second conductivity type formed in layer 502 and a gate 306 disposed insulatively adjacent a first channel area of layer 502 laterally adjacent source/drain region 308. A second transistor 210 is included having a gate 306 disposed insulatively adjacent a second channel area of layer 502. A first capacitor 211 is provided which includes a capacitor conductor 311 disposed insulatively adjacent a first capacitor area 509 of layer 502, first capacitor area 509 being disposed lateral to the first channel area of first transistor 210. A second capacitor 211 is provided which includes a capacitor conductor 211 disposed insulatively adjacent a second capacitor area 509 of layer 502, the second capacitor area 509 disposed lateral to the second channel area of second transistor 210.
    Type: Grant
    Filed: March 27, 1995
    Date of Patent: October 22, 1996
    Assignee: Cirrus Logic, Inc.
    Inventor: G. R. Mohan Rao
  • Patent number: 5567958
    Abstract: A thin-film transistor and SRAM memory cell include thin-film source and drain regions (12, 14) separated by an opening (22) and overlying and insulating layer (11). A thin-film channel layer (16) overlies the thin-film source and drain regions (12, 14) and a portion of the insulating layer (11) exposed by the opening (22). A thin-film gate electrode (20) is positioned in the opening (22) and defines a thin-film channel region (24) in the thin-film channel layer (16). The thin-film gate electrode (20) is separated from the thin-film channel region (24) by a gate dielectric layer (18). The thin-film channel region (24) extends along vertical wall surfaces (26, 28) of the thin-film source and drain regions (12, 14) providing an extended channel length for the thin-film transistor.
    Type: Grant
    Filed: May 31, 1995
    Date of Patent: October 22, 1996
    Assignee: Motorola, Inc.
    Inventors: Marius Orlowski, James D. Hayden, Bich-Yen Nguyen
  • Patent number: 5554874
    Abstract: A static RAM memory is arranged into groups of four cells sharing a single active region with a contact to one of the bit lines. The shared active region forms the sources of four access transistors. The group of four cells requires only one pair of bit lines instead of the usual two pairs of bit lines. Thus a pair of bit lines occurs for every two cells rather than for every cell. This increases the bit-line pitch and facilitates design and layout of the sense amps. Since only one of the four cells can drive the bit lines at any time, four word lines are used instead of only two. Each cell has two word lines crossing over it, and the cells in a row alternately connect to one or the other word line. Since word-line drivers and decoders are simpler and easier to lay out than the sense amps, the tighter word-line pitch is acceptable. An unused metal line occurs for every two columns of cells. The bit lines are shielded from this unused metal line by power and ground lines.
    Type: Grant
    Filed: June 5, 1995
    Date of Patent: September 10, 1996
    Assignee: Quantum Effect Design, Inc.
    Inventor: Sinan Doluca
  • Patent number: 5543652
    Abstract: Negative characteristic MISFETs, which are of the same channel conductivity type and which have different threshold voltages, are formed in a doped silicon thin film deposited over a substrate and are connected in channel-to-channel series with each other. The pair of series-connected negative characteristic MISFETs, a resistive element, an information storage capacitive element and a transfer MISFET constitute an SRAM memory cell. Equivalently, a negative characteristic MISFET having a current-voltage characteristic defined by a negative resistance curve can be used in lieu of the pair of series-connected negative characteristic MISFETs in the formation of the individual memory cells of the SRAM. The negative resistance curve of the negative characteristic MISFET is shaped such that the linear current-voltage characteristic curve corresponding to the resistive element of the memory cell intersects the negative resistance curve at at least three location points.
    Type: Grant
    Filed: July 29, 1993
    Date of Patent: August 6, 1996
    Assignee: Hitachi, Ltd.
    Inventors: Shuji Ikeda, Makoto Saeki
  • Patent number: 5541427
    Abstract: A storage latch comprising a gate insulating layer over the substrate, shallow trenches formed through the insulating layer and in the substrate to provide device insulation; and doped regions in the substrate between the shallow trenches. The doped regions define sources and drains. Gate stacks are formed over regions of oxide adjacent the doped regions. A planarized insulator is formed between the gate stacks. Openings are provided in the planarized insulator for contacts to the doped regions and the gate stacks. Conductive material fills the openings to form contacts for the doped regions and for the gate stacks. A patterned layer of conductive material on the planarized insulator connects selected ones of the contacts for wiring portions of the latch.
    Type: Grant
    Filed: December 3, 1993
    Date of Patent: July 30, 1996
    Assignee: International Business Machines Corporation
    Inventors: Barbara A. Chappell, Bijan Davari, George A. Sai-Halasz, Yuan Taur
  • Patent number: 5536962
    Abstract: A semiconductor device (10) includes first and second electrically coupled MOS transistors (16, 28) in which the current gain of the second MOS transistor (16) is greater than the current gain of the first MOS transistor (28). Higher carrier mobility is obtained in the second MOS transistor (16) relative to the first MOS transistor (28) by fabrication of the second MOS transistor (16) as a buried channel device. The first MOS transistor (28) includes a gate electrode (44) of the second conductivity type separated from a channel region (46) of the first conductivity type by a gate electric layer (48). The second MOS transistor (16) includes a gate electrode (40) of a first conductivity type overlying a substrate (11) also of the first conductivity type. A channel surface layer (60) of a second conductivity type resides in the substrate (11 ) and is separated from the gate electrode (40) by a gate dielectric layer (58).
    Type: Grant
    Filed: October 24, 1995
    Date of Patent: July 16, 1996
    Assignee: Motorola, Inc.
    Inventor: James R. Pfiester
  • Patent number: 5536960
    Abstract: A static random access memory (SRAM) has a plurality of static memory cells each of which has a set of cross coupled inverters having first and second inverters. The first inverter has first and second transistors. The second inverter has primary and secondary transistors. Each of the first and the primary transistors may be, for example, a P-channel transistor. Each of the second and the secondary transistors may be, for example, an N-channel transistor. The static memory cell further has a first diode having a first forward direction and a second diode having a second forward direction. The first forward direction is directed from drains of the primary and secondary transistors to a gate of the first transistor. The second forward direction is directed from drains of the first and the second transistors to a gate of the primary transistor.
    Type: Grant
    Filed: December 22, 1994
    Date of Patent: July 16, 1996
    Assignee: NEC Corporation
    Inventor: Fumihiko Hayashi
  • Patent number: 5535155
    Abstract: In a static random access memory device including a flip-flop having first and second load thin film transistors whose drains are connected via first and second transfer bulk transistors to first and second bit lines, respectively, the second bit line is arranged over the first load thin film transistor, and the first bit line is arranged over the second load thin film transistor.
    Type: Grant
    Filed: July 5, 1995
    Date of Patent: July 9, 1996
    Assignee: NEC Corporation
    Inventor: Kazuhiko Abe
  • Patent number: 5526303
    Abstract: The semiconductor memory device of the present invention relates to an SRAM, is object to secure a saturation drain current of a driver transistor large enough for a saturation drain current of a transfer transistor while keeping the area occupied by a memory cell within a predetermined range, and has a memory cell comprising a strip-shaped word line which includes a gate electrode of a first transistor, extends in a definite direction on a semiconductor substrate, and bends diagonally to the definite direction and widens at a first transistor region; an active region which has source/drain regions of the first transistor and intersects the word line which is formed between the source/drain regions.
    Type: Grant
    Filed: November 30, 1993
    Date of Patent: June 11, 1996
    Assignee: Fujitsu Limited
    Inventor: Yoshinori Okajima
  • Patent number: 5525814
    Abstract: A three dimensional latch and bulk silicon pass transistor for high density field reconfigurable architectures is provided utilizing bulk silicon with a layer of polysilicon or silicon on insulator (SOI) thereover. The pass transistor, which must have very low resistance to provide a good short circuit path between the metal runs and fast switching speed, is fabricated in the bulk silicon wherein the resistivity can be made very low relative to polysilicon and because only the pass transistor is disposed in the bulk silicon, thereby permitting the dimensions thereof to be increased to provide even lower resistance. Since only the latch is fabricated in the layer of polysilicon or SOI and is disposed over the pass transistor, the amount of chip area utilized can be the same or less than required in the prior art wherein all circuitry was in the bulk silicon.
    Type: Grant
    Filed: January 19, 1995
    Date of Patent: June 11, 1996
    Assignee: Texas Instruments Incorporated
    Inventor: Satwinder Malhi
  • Patent number: 5526304
    Abstract: A semiconductor device which comprises plural memory cells, said memory cell comprising: a flip-flop circuit including a pair of drive transistors each having a gate, a gate oxide film and source/drain regions, and a pair of load TFTs connected to said pair of drive transistors, each of said load TFTs having a gate electrode, a gate oxide film and an active layer including source/drain regions all of which are deposited sequentially in that order; and a pair of access transistors connected to said flip-flop circuit; wherein either one of the source/drain regions of said each TFT is connected to at least either one drive transistor at either one of the source/drain regions thereof or the other drive transistor at the gate thereof via a semiconductor pad, and the other of the source/drain regions of the TFT is connected to a wiring layer via a semiconductor pad; and at least surface layer of said semiconductor pad has the same conductivity type as that of the source/drain regions of the TFT.
    Type: Grant
    Filed: November 1, 1994
    Date of Patent: June 11, 1996
    Assignee: Sharp Kabushiki Kaisha
    Inventor: Akio Kawamura
  • Patent number: 5521860
    Abstract: Two intracell wiring serving as the gate electrodes of driver transistors and load transistors and arranged substantially parallel to each other between two word lines substantially parallel to each other so as to be perpendicular to the word lines are arranged as the first layer. Ground wiring and a power supply wiring are arranged as the second layer on the first layer through an insulating film. Each intracell wiring serves as the gate electrodes of one driver transistor and one load transistor and is connected to the drain regions of the other driver transistor and the other load transistor. The ground wiring are connected to the source regions of the driver transistors, and the power supply wiring is connected to the source regions of the load transistors.
    Type: Grant
    Filed: December 16, 1994
    Date of Patent: May 28, 1996
    Assignee: NEC Corporation
    Inventor: Hiroaki Ohkubo
  • Patent number: 5521416
    Abstract: A poly-crystal silicon layer is formed on an N-type silicon substrate via an oxide film. A contact hole is formed on the poly-crystal silicon layer by applying a photoresist mask and further by patterning a predetermined contact portion between a polyside gate and a diffusion layer. Thereafter, a P.sup.+ diffusion layer is formed by ion implantation with the use of the same photoresist mask. Further, a tungsten siliside layer is deposited all over the substrate. Or else, after the contact hole has been formed, the tungsten siliside layer is deposited, and then the P.sup.+ diffusion layer is formed by ion implantation. Alternatively, after the contact hole has been formed, a first ion implantation is made; and after the tungsten siliside layer has been deposited, a second ion implantation is made to form the P.sup.+ diffusion layer.
    Type: Grant
    Filed: April 18, 1995
    Date of Patent: May 28, 1996
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Fumitomo Matsuoka, Yukari Unno