Patents by Inventor Joseph T. Evans

Joseph T. Evans has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 8233307
    Abstract: A ferroelectric memory having a plurality of ferroelectric memory cells, each ferroelectric memory cell including a ferroelectric capacitor is disclosed. The ferroelectric memory includes read and write lines and a plurality of ferroelectric memory cell select buses, one select bus corresponding to each of the ferroelectric memory cells. Each of the ferroelectric memory cells includes first and second gates for connecting the ferroelectric memory cell to the read line and the write line, respectively, in response to signals on the ferroelectric memory cell select bus corresponding to that ferroelectric memory cell. A write circuit causes a charge to be stored in the ferroelectric capacitor of the ferroelectric memory cell currently connected to the write line, the charge having a value determined by a data value having at least three states.
    Type: Grant
    Filed: November 30, 2010
    Date of Patent: July 31, 2012
    Assignee: Radiant Technologies, Inc.
    Inventors: Joseph T. Evans, Jr., Calvin B. Ward
  • Publication number: 20120134196
    Abstract: A ferroelectric memory having a plurality of ferroelectric memory cells, each ferroelectric memory cell including a ferroelectric capacitor is disclosed. The ferroelectric memory includes read and write lines and a plurality of ferroelectric memory cell select buses, one select bus corresponding to each of the ferroelectric memory cells. Each of the ferroelectric memory cells includes first and second gates for connecting the ferroelectric memory cell to the read line and the write line, respectively, in response to signals on the ferroelectric memory cell select bus corresponding to that ferroelectric memory cell. A write circuit causes a charge to be stored in the ferroelectric capacitor of the ferroelectric memory cell currently connected to the write line, the charge having a value determined by a data value having at least three states.
    Type: Application
    Filed: November 30, 2010
    Publication date: May 31, 2012
    Inventors: Joseph T. Evans, JR., Calvin B. Ward
  • Patent number: 8023308
    Abstract: A non-volatile memory cell and related system utilize ferroelectric capacitors as data storage elements. Circuitry is provided for writing to a single ferroelectric capacitor storage element, as well as to dual storage elements operating inversely. The storage elements are read by use of a sense amplifier in a configuration which automatically restores the original data states, thereby eliminating the need for a subsequent restore operation. Memory systems are described which include circuitry for driving bit lines, word lines and drive lines to accomplish both the write and read operations.
    Type: Grant
    Filed: September 14, 1990
    Date of Patent: September 20, 2011
    Assignee: National Semiconductor Corporation
    Inventors: Joseph T. Evans, Jr., William D. Miller, Richard H. Womack
  • Patent number: 8018754
    Abstract: A non-volatile memory cell and related system utilize ferroelectric capacitors as data storage elements. Circuitry is provided for writing to a single ferroelectric capacitor storage element, as well as to dual storage elements operating inversely. The storage elements are read by use of a sense amplifier in a configuration which automatically restores the original data states, thereby eliminating the need for a subsequent restore operation. Memory systems are described which include circuitry for driving bit lines, word lines and drive lines to accomplish both the write and read operations.
    Type: Grant
    Filed: September 14, 1990
    Date of Patent: September 13, 2011
    Assignee: National Semiconductor Corporation
    Inventors: Joseph T. Evans, Jr., William D. Miller, Richard H. Womack
  • Patent number: 7924599
    Abstract: A non-volatile memory cell and related system utilize ferroelectric capacitors as data storage elements. Circuitry is provided for writing to a single ferroelectric capacitor storage element, as well as to dual storage elements operating inversely. The storage elements are read by use of a sense amplifier in a configuration which automatically restores the original data states, thereby eliminating the need for a subsequent restore operation. Memory systems are described which include circuitry for driving bit lines, word lines and drive lines to accomplish both the write and read operations.
    Type: Grant
    Filed: November 29, 1989
    Date of Patent: April 12, 2011
    Assignee: Ramtron International Corporation
    Inventors: Joseph T. Evans, Jr., William D. Miller, Richard H. Womack
  • Patent number: 7672151
    Abstract: A non-volatile memory cell and related system utilize ferroelectric capacitors as data storage elements. Circuitry is provided for writing to a single ferroelectric capacitor storage element, as well as to dual storage elements operating inversely. The storage elements are read by use of a sense amplifier in a configuration which automatically restores the original data states, thereby eliminating the need for a subsequent restore operation. Memory systems are described which include circuitry for driving bit lines, word lines and drive lines to accomplish both the write and read operations.
    Type: Grant
    Filed: July 10, 1989
    Date of Patent: March 2, 2010
    Assignee: Ramtron International Corporation
    Inventors: Joseph T. Evans, Jr., William D. Miller, Richard H. Womack
  • Patent number: 6505137
    Abstract: A method for operating a data processing system to control a device under test and to collect data from that device. The user is provided with a first display having a list of elementary tasks having first and second tasks from which a user selects one or more elementary tasks. The first task applies a signal to the device under test when that task is executed and the second task causes the data processing system to receive data from the device under test. The user edits task parameters using a second display to provide a current test definition. In response to user input, the data processing system executes each of the tasks in the current test definition and stores any data received from the device under test in a data set that includes the current test definition and which is displayed in a third display.
    Type: Grant
    Filed: September 20, 1999
    Date of Patent: January 7, 2003
    Assignee: Radiant Technologies, Inc.
    Inventors: Joseph T. Evans, Jr., Scott P. Chapman
  • Patent number: 6225654
    Abstract: An improved ferroelectric FET structure in which the ferroelectric layer is doped to reduce retention loss. A ferroelectric FET according to the present invention includes a semiconductor layer having first and second contacts thereon, the first and second contacts being separated from one another. The ferroelectric FET also includes a bottom electrode and a ferroelectric layer which is sandwiched between the semiconductor layer and the bottom electrode. The ferroelectric layer is constructed from a perovskite structure of the chemical composition ABO3 wherein the B site comprises first and second elements and a dopant element that has an oxidation state greater than +4 in sufficient concentration to impede shifts in the resistance measured between the first and second contacts with time. The ferroelectric FET structure preferably comprises Pb in the A-site. The first and second elements are preferably Zr and Ti, respectively.
    Type: Grant
    Filed: May 1, 1996
    Date of Patent: May 1, 2001
    Assignee: Radiant Technologies, Inc
    Inventors: Joseph T. Evans, Jr., William L. Warren, Bruce A. Tuttle
  • Patent number: 6194751
    Abstract: A ferroelectric memory cell for storing information. The information is stored in the remnant polarization of a ferroelectric dielectric layer by setting the direction of the remnant polarization. The ferroelectric memory cell is designed to store the information at a temperature less than a first temperature. The memory cell includes top and bottom contacts that sandwich the dielectric layer which includes a ferroelectric material having a Curie point greater than the first temperature and less than 400° C. The dielectric layer is encapsulated in an oxygen impermeable material such that the encapsulating layer prevents oxygen from entering or leaving the dielectric layer. One of the contacts typically includes a platinum electrode. The other contact may include a similar electrode or a semiconductor layer having electrodes spaced apart thereon.
    Type: Grant
    Filed: January 29, 1998
    Date of Patent: February 27, 2001
    Assignee: Radiant Technologies, Inc
    Inventor: Joseph T. Evans, Jr.
  • Patent number: 6121648
    Abstract: A ferroelectric memory cell for storing information and a method for fabricating the same. The information is stored in the remnant polarization of a ferroelectric dielectric layer by setting the direction of the remnant polarization. The ferroelectric memory cell is designed to store the information at a temperature less than a first temperature. During the fabrication process, the memory cell is subjected to an annealing operation in the presence of hydrogen at a second temperature and a packaging operation at a third temperature. The memory cell includes top and bottom contacts that sandwich the dielectric layer which includes a ferroelectric material having a Curie point greater than the first temperature and less than the second and third temperatures. The dielectric layer is encapsulated in an oxygen impermeable material such that the encapsulating layer prevents oxygen from entering or leaving the dielectric layer.
    Type: Grant
    Filed: May 25, 1999
    Date of Patent: September 19, 2000
    Assignee: Radiant Technologies, Inc
    Inventor: Joseph T. Evans, Jr.
  • Patent number: 6117688
    Abstract: A ferroelectric based capacitor structure and method for making the same. The capacitor includes a bottom electrode having a layer of Pt in contact with a first layer of an ohmic material. The capacitor dielectric is constructed from a layer of lead zirconium titanate doped with an element having an oxidation state greater than +4. The top electrode of the capacitor is constructed from a second layer of ohmic material in contact with a layer of Pt. The preferred ohmic material is LSCO; although RuO.sub.2 may also be utilized. The capacitor is preferably constructed over the drain of a FET such that the bottom electrode of the capacitor is connected to the drain of the FET. The resulting capacitor structure has both low imprint and low fatigue.
    Type: Grant
    Filed: May 8, 1998
    Date of Patent: September 12, 2000
    Assignee: Radiant Technologies, Inc.
    Inventors: Joseph T. Evans, Jr., Richard Womack
  • Patent number: 6074885
    Abstract: A method for constructing a device having a bottom electrode in contact with a layer of a ferroelectric dielectric material. In the method of the present invention, a layer of a field ferroelectric material is deposited on a substrate and etched to form a trench in which the bottom electrode is constructed. The bottom electrode is then deposited and a layer of the ferroelectric dielectric material is deposited over the bottom electrode and at least a portion of the field ferroelectric material. The ferroelectric layers are deposited in a perovskite state. These layers are etched back to the substrate in those areas that are outside of the device.
    Type: Grant
    Filed: November 25, 1997
    Date of Patent: June 13, 2000
    Assignee: Radiant Technologies, Inc
    Inventors: Leonard L. Boyer, Joseph T. Evans, Jr., Naomi B. Velasquez
  • Patent number: 6066868
    Abstract: A ferroelectric memory cell for storing information. The information is stored in the remnant polarization of a ferroelectric dielectric layer by setting the direction of the remnant polarization. The ferroelectric memory cell is designed to store the information at a temperature less than a first temperature. The memory cell includes top and bottom contacts that sandwich the dielectric layer which includes a ferroelectric material having a Curie point greater than the first temperature and less than 400.degree. C. The dielectric layer is encapsulated in an oxygen impermeable material such that the encapsulating layer prevents oxygen from entering or leaving the dielectric layer. The memory also includes a hydrogen barrier layer that inhibits the flow of oxygen to the top and bottom electrodes when the memory cell is placed in a gaseous environment containing hydrogen. In one embodiment of the invention, a hydrogen absorbing layer is included.
    Type: Grant
    Filed: March 31, 1999
    Date of Patent: May 23, 2000
    Assignee: Radiant Technologies, Inc.
    Inventor: Joseph T. Evans, Jr.
  • Patent number: 5977577
    Abstract: A ferroelectric memory cell for storing information. The information is stored in the remnant polarization of a ferroelectric dielectric layer by setting the direction of the remnant polarization. The ferroelectric memory cell is designed to store the information at a temperature less than a first temperature. The memory cell includes top and bottom contacts that sandwich the dielectric layer which includes a ferroelectric material having a Curie point greater than the first temperature and less than 400.degree. C. The dielectric layer is encapsulated in an oxygen impermeable material such that the encapsulating layer prevents oxygen from entering or leaving the dielectric layer. One of the contacts is typically includes a platinum electrode. The other contact may include a similar electrode or a semiconductor layer having electrodes spaced apart thereon.
    Type: Grant
    Filed: July 29, 1996
    Date of Patent: November 2, 1999
    Assignee: Radiant Technologies, Inc
    Inventor: Joseph T. Evans, Jr.
  • Patent number: 5963466
    Abstract: A memory for storing a plurality of words of data. The memory is constructed from one or more storage blocks. Each storage block includes a plurality of storage words, each storage word storing one of the words of data. Each storage word includes a plurality of single bit storage cells. The single bit storage cells include a ferroelectric capacitor and a pass transistor having a gate, source, and drain. The ferroelectric capacitor includes a bottom electrode, a layer of ferroelectric material, and a top electrode, the layer of ferroelectric material being sandwiched between the top and bottom electrodes. One bit of data is stored in the direction of polarization of the ferroelectric material in contact with the bottom electrode. The bottom electrode is connected to the source of the pass transistor. The top electrode of each single bit storage cell is part of a continuous conducting layer covering all of the ferroelectric capacitors in the storage block.
    Type: Grant
    Filed: April 13, 1998
    Date of Patent: October 5, 1999
    Assignee: Radiant Technologies, Inc.
    Inventor: Joseph T. Evans, Jr.
  • Patent number: 5926412
    Abstract: Architectures for a ferroelectric memory which avoids the half select phenomenon and the problems associated with destructive readout. Non-destructive readout is provided by measuring current through the ferroelectric memory as a measure of its resistance. Information is stored in the ferroelectric memory element by altering its resistance through a polarizing voltage. The half select phenomenon is avoided by using isolation techniques. In various embodiments, zener diodes or bipolar junction transistors are used for isolation.
    Type: Grant
    Filed: April 2, 1992
    Date of Patent: July 20, 1999
    Assignee: Raytheon Company
    Inventors: Joseph T. Evans, Jr., Jeff A. Bullington, Stephen E. Bernacki, Bruce G. Armstrong
  • Patent number: 5892255
    Abstract: A ferroelectric based capacitor structure and method for making the same. The capacitor includes a bottom electrode having a layer of Pt in contact with a first layer of an ohmic material. The capacitor dielectric is constructed from a layer of lead zirconium titanate doped with an element having an oxidation state greater than +4. The top electrode of the capacitor is constructed from a second layer of ohmic material in contact with a layer of Pt. The preferred ohmic material is LSCO; although RuO.sub.2 may also be utilized. The capacitor is preferably constructed over the drain of an FET such that the bottom electrode of the capacitor is connected to the drain of the FET. The resulting capacitor structure has both low imprint and low fatigue.
    Type: Grant
    Filed: October 12, 1997
    Date of Patent: April 6, 1999
    Assignee: Radiant Technologies
    Inventors: Joseph T. Evans, Jr., Richard H. Womack
  • Patent number: 5804850
    Abstract: A ferroelectric based capacitor structure and method for making the same. The capacitor includes a bottom electrode having a layer of Pt in contact with a first layer of an ohmic material. The capacitor dielectric is constructed from a layer of lead zirconium titanate doped with an element having an oxidation state greater than +4. The top electrode of the capacitor is constructed from a second layer of ohmic material in contact with a layer of Pt. The preferred ohmic material is LSCO; although RuO.sub.2 may also be utilized. The capacitor is preferably constructed over the drain of an FET such that the bottom electrode of the capacitor is connected to the drain of the FET. The resulting capacitor structure has both low imprint and low fatigue.
    Type: Grant
    Filed: April 16, 1996
    Date of Patent: September 8, 1998
    Assignee: Radiant Technologies, Inc.
    Inventors: Joseph T. Evans, Jr., Richard Womack
  • Patent number: 5789775
    Abstract: A high density non-volatile ferroelectric-based memory based on a ferroelectric FET operated in a two terminal write mode. Storage words may be constructed either from one or two bit storage cells based on a ferroelectric FET. A memory using either the one or two bit storage cells includes a plurality of word storage cells organized into a rectangular array including a plurality of columns and rows. Each of the word storage cells includes N single bit memory cells. Each of the single bit memory cells includes a pass transistor and a ferroelectric storage element. All of the gate electrodes in the circuit are connected to a common gate electrode, and all of the source electrodes are connected to a common source electrode. If the memory is built from two bit storage cells as described herein, each storage cell is one half of a two bit storage cell.
    Type: Grant
    Filed: January 26, 1996
    Date of Patent: August 4, 1998
    Assignee: Radiant Technologies
    Inventors: Joseph T. Evans, Jr., Richard Womack
  • Patent number: 5757042
    Abstract: A memory based on a ferroelectric FET, the ferroelectric FET includes a gate electrode, a layer of ferroelectric material, layer of semiconducting material, a source electrode and a drain electrode. The layer of ferroelectric material is sandwiched between the gate electrode and the layer of semiconducting material, the source and drain electrodes being in contact with the layer of semiconducting material and spaced apart from one another. The memory includes a circuit for setting the ferroelectric FET to one of two states. The first state is set by applying a first voltage to the source and drain electrodes and a second voltage to the gate electrode. The second state is set by applying a third voltage to the gate and drain electrodes and fourth voltage to the source electrode. This arrangement reduces the number of pass transistors needed per ferroelectric FET to one plus a simple pulsing circuit that must be included with each word of memory.
    Type: Grant
    Filed: June 14, 1996
    Date of Patent: May 26, 1998
    Assignee: Radiant Technologies, Inc.
    Inventors: Joseph T. Evans, Jr., Richard Womack