Patents Assigned to STMicroelectronics
  • Patent number: 5895237
    Abstract: A high performance CMOS process using grown field oxide for active area isolation takes advantage of process steps used in LDD transistor fabrication to reduce the chip space occupied by the field oxide. Portions of the spacer oxide layer are retained intact over the field oxide during the etching step used to form the oxide spacers on the sides of the polysilicon gates. The retained spacer oxide portions increase the total oxide thickness in the field area to effectively block the ion implantation used to form the heavily doped portions of the source and drain regions. This enables use, in the initial fabrication steps, of a grown field oxide of reduced thickness and advantageously a correspondingly reduced width so as to reduce the chip space allocated to the field oxide.
    Type: Grant
    Filed: December 31, 1996
    Date of Patent: April 20, 1999
    Assignee: STMicroelectronics, Inc.
    Inventors: Tsiu Chiu Chan, Pervez H. Sagarwala
  • Patent number: 5896336
    Abstract: A signal driver receives an input signal and an enable signal, and generates an output signal from the input signal when the enable signal has an active state. When the enable signal has an inactive state, the signal driver draws substantially zero supply current regardless of the level of the input signal. The enable signal may be the sense-amplifier enable signal. The signal driver may also include an input circuit that receives the input signal and generates an intermediate signal from the input signal when the enable signal has the first state. An output circuit is coupled to the input circuit, receives the intermediate signal, and generates the output signal from the intermediate signal. A switch circuit is coupled to the input circuit, receives the enable signal, and cuts off substantially all supply current to the input circuit when the enable signal has the second state.
    Type: Grant
    Filed: November 19, 1997
    Date of Patent: April 20, 1999
    Assignee: STMicroelectronics, Inc.
    Inventor: David C. McClure
  • Patent number: 5894158
    Abstract: A mask is used for lightly doped drain and halo implants in an integrated circuit device. The mask exposes only portions of the substrate adjacent to field effect transistor gate electrodes. Since the halo implant is made only near the transistor channels, where it performs a useful function, adequate device reliability and performance is obtained. Since the halo implant is masked from those portions of the active regions for which it is not necessary, active region junction capacitances are lowered. Such lowered capacitances result in an improved transistor switching speed. The mask used to define the lightly doped drain and halo implant region can be easily formed from a straight forward combination of already existing gate and active area geometries.
    Type: Grant
    Filed: September 30, 1991
    Date of Patent: April 13, 1999
    Assignee: STMicroelectronics, Inc.
    Inventor: Che-Chia Wei
  • Patent number: 5894160
    Abstract: A method is provided for forming an improved landing pad of a semiconductor integrated circuit, and an integrated circuit formed according to the same. A first opening is formed through a first dielectric layer to expose a portion of a diffused region. A first polysilicon landing pad is formed over the first dielectric layer and in the opening. This landing pad will provide for smaller geometries and meet stringent design rules such as that for contact space to gate. A dielectric pocket is formed over the polysilicon landing pad over the active region. A second conductive landing pad is formed over the polysilicon landing pad and the dielectric pocket. A second dielectric layer is formed over the landing pad having a second opening therethrough exposing a portion of the landing pad. A conductive contact, such as aluminum, is formed in the second contact opening. The conductive contact will electrically connect with the diffused region through the landing pad.
    Type: Grant
    Filed: October 3, 1996
    Date of Patent: April 13, 1999
    Assignee: STMicroelectronics, Inc.
    Inventors: Tsiu C. Chan, Frank R. Bryant, Loi N. Nguyen
  • Patent number: 5888908
    Abstract: A method is provided for reducing the reflectivity of a metal layer prior to photolithography. A thin buffer layer, such as oxide, can be deposited over the metal layer. A short plasma etch is performed in order to roughen, but not completely remove, the thin oxide layer. This roughened layer significantly reduces the reflectivity of the underlying metal layer. As an alternative, the brief plasma etch can be applied directly to the metal layer, which results in a significant roughening of its upper surface. This also reduces the reflectivity of the metal layer.
    Type: Grant
    Filed: April 28, 1995
    Date of Patent: March 30, 1999
    Assignee: STMicroelectronics, Inc.
    Inventors: Gregory Joseph Stagaman, Michael Edward Haslam
  • Patent number: 5889713
    Abstract: A method and circuits for coupling a memory embedded in an integrated circuit to interconnect pads during a memory test mode is disclosed. The integrated circuit contains a processor, an embedded memory and a switching circuit for: (1) temporary coupling the interconnect pads of the integrated circuit, coupled to the processor during normal operation mode of the circuit, to the memory during a memory test mode; (2) and decoupling the external interconnect pads from the memory, after the memory is tested, and coupling them to the processor.
    Type: Grant
    Filed: July 10, 1997
    Date of Patent: March 30, 1999
    Assignee: STMicroelectronics, Inc.
    Inventors: Tsiu Chiu Chan, Lawrence P. Eng
  • Patent number: 5887479
    Abstract: A liquid level sensor unit outputs a voltage value, which corresponds to a measured liquid level, to an anti-slosh circuit that provides a fast timing rate during the initial condition of the circuit and a slow timing rate during the normal operation of the circuit. The anti-slosh circuit further includes a low liquid level warning circuit and a power-on-reset circuit. The system timing rate can be externally controlled by connecting an RC circuit to the improved anti-slosh circuit. A customer defined reference level for low liquid warning is also possible. The entire circuit is included on a single, monolithic integrated circuit. An input pin receives the signal from the fuel tank. An output pin drives a liquid level gauge.
    Type: Grant
    Filed: December 31, 1996
    Date of Patent: March 30, 1999
    Assignee: STMicroelectronics, Inc.
    Inventor: David F. Swanson
  • Patent number: 5889515
    Abstract: A DVD CD-ROM player integrated with a personal computer is provided. When integrating a DVD CD-ROM with a personal computer, there are various problems that must be overcome. For example, the stream from the DVD CD-ROM utilizes a 27 MHz clock. However, a personal computer typically does not have a 27 MHz clock, but instead has a system clock, that runs at the frequency of the processor. Therefore, in order to play a DVD-based audio-visual work in a personal computer, a clock running at 27 MHz is needed. As such, a software clock running at 27 MHz is provided which facilitates the integration of a DVD CD-ROM into a personal computer. By using a software clock, synchronization of the audio-visual stream is facilitated and both cost and development time are reduced.
    Type: Grant
    Filed: December 9, 1996
    Date of Patent: March 30, 1999
    Assignee: STMicroelectronics, Inc.
    Inventors: Darryn D. McDade, Jefferson E. Owen
  • Patent number: 5883544
    Abstract: An integrated circuit includes a plurality of MOSFETs having channels of a first conductivity type, and having active control of an effective threshold voltage of the MOSFETs to be less than an absolute value of an initial threshold voltage. In this embodiment, a first MOSFET has a channel of the first conductivity type, and a second MOSFET is connected to the first MOSFET and has a channel of a second conductivity type. The second MOSFET is preferably biased to a pinch-off region and cooperates with the first MOSFET for generating a control signal related to an effective threshold voltage of the first MOSFET. Moreover, the circuit preferably generates a bias voltage to the plurality of MOSFETs and to the first MOSFET based upon the control signal to set an effective threshold voltage of the plurality of MOSFETs to have an absolute value less than an absolute value of the initial threshold voltage and, more preferably, to a reference voltage. Accordingly, lower supply voltages can be readily accommodated.
    Type: Grant
    Filed: December 3, 1996
    Date of Patent: March 16, 1999
    Assignee: STMicroelectronics, Inc.
    Inventors: Jason Siucheong So, Tsiu Chiu Chan
  • Patent number: 5883838
    Abstract: A signal driver receives an input signal and an enable signal, and generates an output signal from the input signal when the enable signal has an active state. When the enable signal has an inactive state, the signal driver draws substantially zero supply current regardless of the level of the input signal. The enable signal may be the sense-amplifier enable signal. The signal driver may also include an input circuit that receives the input signal and generates an intermediate signal from the input signal when the enable signal has the first state. An output circuit is coupled to the input circuit, receives the intermediate signal, and generates the output signal from the intermediate signal. A switch circuit is coupled to the input circuit, receives the enable signal, and cuts off substantially all supply current to the input circuit when the enable signal has the second state.
    Type: Grant
    Filed: September 15, 1997
    Date of Patent: March 16, 1999
    Assignee: STMicroelectronics, Inc.
    Inventor: David C. McClure
  • Patent number: 5883507
    Abstract: An integrated circuit and method are provided for generating current for low power applications. The integrated circuit preferably includes a current generating circuit responsive to a supply voltage for generating a first reference current and a temperature compensating voltage controlling circuit for generating a temperature compensated voltage control signal during temperature variations. A bias controlling circuit is preferably connected to the current generating circuit and the temperature compensating voltage control circuit for biasingly controlling the temperature compensating voltage control circuit. A current output controlling circuit is connected to the current generating circuit and the temperature compensating voltage controlling circuit for controlling a second temperature compensated reference current responsive to the temperature compensated voltage control signal so as to generate a high output source current even during low temperature conditions.
    Type: Grant
    Filed: May 9, 1997
    Date of Patent: March 16, 1999
    Assignee: STMicroelectronics, Inc.
    Inventor: Rong Yin
  • Patent number: 5883844
    Abstract: An integrated circuit having enhanced testing capabilities and a method of testing an integrated circuit are provided. The integrated circuit preferably includes a substrate and a memory block on the substrate. The memory block preferably has a plurality of memory cells arranged in a plurality of rows and a plurality of columns within a defined area on the substrate, at least one bit line connected to each of the plurality of memory cells and defining a column, at least one word line connected to each of the plurality of memory cells and defining a row, and sense amplifying means connected to the at least one bit line for sensing a state of an addressed memory cell in at least one of the plurality of columns. The integrated circuit also includes a selectable stress tester on the substrate and connected to the memory block for selectively stress testing only portions of the memory block and not other portions so as to determine whether to accept or reject a memory block.
    Type: Grant
    Filed: May 23, 1997
    Date of Patent: March 16, 1999
    Assignee: STMicroelectronics, Inc.
    Inventor: Jason Siucheong So
  • Patent number: 5883008
    Abstract: A semiconductor integrated-circuit die includes a substrate of semiconductor material that has an edge. A conductive layer is disposed on the substrate, and a first insulator layer is disposed between the said substrate and the conductive layer. A functional circuit is disposed in the die. A conductive path is disposed beneath the insulator layer and is coupled to the circuit, the conductive path having an end portion that is located substantially at the edge of the substrate. The wafer on which the die is disposed has one or more signal lines that run along the scribe lines of the wafer. Before the die is scribed from the wafer, the conductive path couples the circuit on the die to one of these signal lines. The end portion of the conductive path is formed when the die is scribed from the wafer.
    Type: Grant
    Filed: November 26, 1997
    Date of Patent: March 16, 1999
    Assignee: STMicroelectronics, Inc.
    Inventor: David C. McClure
  • Patent number: 5883479
    Abstract: A circuit and method to clamp a node of a power device connected to a driving node of a polyphase d-c motor to a reference potential during a powering off of the drive includes a current mirror and a comparator. A first input of the comparator is connected to the reference potential, and a second input is connected to the driving node. The reference potential may be a ground potential, or, preferably, the potential at another driving node of the motor. An output of the comparator is connected to a first side of the current mirror. A circuit is connected to apply a current reflecting the output of the comparator to a low side driver connected to the node.
    Type: Grant
    Filed: July 1, 1997
    Date of Patent: March 16, 1999
    Assignee: STMicroelectronics, Inc.
    Inventors: Paolo Menegoli, Gianluca Colli
  • Patent number: 5881010
    Abstract: A four transistor dynamic memory cell architecture and refresh technique which allows for cell refresh to occur during a read operation. The access and memory transistors of the individual memory cells are fabricated with a relative width-to-length ratio such that it is sufficient to merely activate the associated word line to perform the refresh operation. This is accomplished without activating the read sense amplifier resulting in lower power consumption and the retention of most recently read data. Multiple word lines may be activated concurrently utilizing the technique disclosed to further reduce the refresh rate overhead in a memory array and increase the overall memory array bandwidth.
    Type: Grant
    Filed: May 15, 1997
    Date of Patent: March 9, 1999
    Assignee: STMicroelectronics, Inc.
    Inventor: Alain Artieri
  • Patent number: 5880611
    Abstract: A comparator with a built-in offset is disclosed. The claimed comparator includes a bias current circuit, a differential input stage with the built-in of-set, and a hysteresis circuit. The built-in offset is generated by using a resistor in the differential input stage of the comparator such that the resistor is driven by the bias current as well as the current generated by the hysteresis circuit. Additionally, a reset circuit which uses the comparator with the built-in offset is claimed. The reset circuit uses a voltage divider circuit to divide a first input voltage to the comparator. A band-gap voltage reference is used to provide a second input voltage to the comparator. Therefore, the reset circuit generates a reset signal when the divided voltage reaches the value of the band-gap voltage plus the offset. In another embodiment, a comparator having a differential input stage, an output stage, and a bias circuit with a hysteresis circuit is disclosed.
    Type: Grant
    Filed: July 25, 1997
    Date of Patent: March 9, 1999
    Assignee: STMicroelectronics, Inc.
    Inventor: Eric J. Danstrom
  • Patent number: 5877914
    Abstract: An amplifier in which a clamping circuit is an integral part of the output stage structure is used as a voice coil driver for positioning the heads of a memory disk drive. The output stage, operating in class AB, comprises two bipolar transistors, the source and the sink transistors, serially connected between a power supply and a ground terminal, the serial connection between the emitter of the first transistor and the collector of the second transistor being the output terminal of the output stage. The base terminals of the two output transistors are connected to a bias circuit and to an input transistor, used as the signal control element. The clamping circuit is directly connected with the base terminals of the output transistors to limit the voltage on said base terminals between a first and a second voltage reference.
    Type: Grant
    Filed: January 10, 1997
    Date of Patent: March 2, 1999
    Assignee: STMicroelectronics, Inc.
    Inventor: Walter S. Gontowski, Jr.
  • Patent number: 5877541
    Abstract: A method is provided for improving the adhesion between a photoresist layer and a dielectric, and an integrated circuit formed according to the same. A conformal dielectric layer is formed over the integrated circuit. An interlevel dielectric layer is formed over the conformal dielectric layer. The interlevel dielectric layer is doped such that the doping concentration allows the layer to reflow while partially inhibiting the adhesion of the doped layer to photoresist at an upper surface of the doped layer. An undoped dielectric layer is formed over the doped dielectric layer. A photoresist layer is formed and patterned over the undoped dielectric layer which adheres to the undoped dielectric layer. The undoped dielectric, the interlevel dielectric and the conformal dielectric layers are etched to form an opening exposing a portion of an underlying conductive region.
    Type: Grant
    Filed: August 4, 1997
    Date of Patent: March 2, 1999
    Assignee: STMicroelectronics, Inc.
    Inventors: John C. Sardella, Alexander Kalnitsky, Charles R. Spinner III, Robert Carlton Foulks, Sr.
  • Patent number: 5874769
    Abstract: A method is provided for a planar surface of a semiconductor integrated circuit, and an integrated circuit formed according to the same. A conductive layer is formed over a substrate. A silicon nitride layer is formed over the conductive layer. A photoresist layer is then formed and patterned over the silicon nitride layer. The silicon nitride layer and the conductive layer are etched to form an opening exposing a portion of the substrate. The photoresist layer is then removed. The exposed substrate and a portion of the conductive layer exposed along the sidewalls in the opening are oxidized. An planarizing insulating layer such as spin-on-glass is formed over the silicon nitride layer and in the opening. The insulating layer is etched back to expose the silicon nitride wherein an upper surface of the insulating layer is level with an upper surface of the conductive layer. The silicon nitride layer is then removed. A planar silicide layer is then formed over the conductive layer.
    Type: Grant
    Filed: January 14, 1994
    Date of Patent: February 23, 1999
    Assignee: STMicroelectronics, Inc.
    Inventors: Tsiu Chiu Chan, Frank Randolph Bryant
  • Patent number: 5874850
    Abstract: A charge pump MOS voltage booster has reduced voltage drops and ripple. This voltage booster is advantageously used in two applications. The voltage has four MOS transistors instead of diodes in a classical voltage booster, which exhibit an undesired voltage drop. The voltage booster also has an oscillator with two outputs and two corresponding charge transfer capacitors. In this manner, the undesired voltage drops and ripple are reduced without complicating the circuitry structure.
    Type: Grant
    Filed: August 5, 1997
    Date of Patent: February 23, 1999
    Assignee: STMicroelectronics S.r.l.
    Inventors: Francesco Pulvirenti, Roberto Gariboldi