Patents Represented by Attorney, Agent or Law Firm Peter J. Meza. Esq.
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Patent number: 5835442Abstract: An EDRAM device includes an EDRAM memory array on a semiconductor chip. A row enable signal generator and a column address latch signal generator are provided on the same semiconductor chip for generating row enable and column address latch signals for application to the EDRAM memory array.Type: GrantFiled: March 22, 1996Date of Patent: November 10, 1998Assignee: Enhanced Memory Systems, Inc.Inventors: James Dean Joseph, Dion Nickolas Heisler, Doyle James Heisler
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Patent number: 5822237Abstract: A reference cell for a 1T-1C memory is disclosed for use in either an open or folded memory cell array. Each reference cell has two outputs each coupled to a bit line that each develop a voltage substantially half of that developed by a ferroelectric memory cell. The reference voltages and memory cell voltage are than resolved by a sense amplifier. Each reference cell includes two ferroelectric capacitors that are the same size and fabricated with the identical process as the memory cell ferroelectric capacitors. Any changes in the memory cell capacitor similarly affects the reference cell capacitor, and thus the reference voltage is always substantially half of that developed by the memory cell. The reference cells include a number of timing inputs, which control charge sharing and configure the cell to operate in either a DRAM or FRAM.RTM. mode. In a first embodiment, one of the reference cell capacitors is poled.Type: GrantFiled: April 18, 1996Date of Patent: October 13, 1998Assignee: Ramtron International CorporationInventors: Dennis R. Wilson, H. Brett Meadows
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Patent number: 5804996Abstract: A test mode circuit for an integrated circuit includes a high voltage detector having an input for receiving a high voltage signal, a Schmitt trigger having an input coupled to the output of the high voltage detector, a latch having an input coupled to the output of the Schmitt trigger and an output for providing a test mode signal in a test operational mode, and additional control circuitry for disabling the high voltage detector and Schmitt trigger so that substantially all of the active current flow in the high voltage detector and Schmitt trigger is eliminated in a normal operational mode. The test mode circuit further includes circuitry for preventing a reset condition in the latch during the test mode until a power-down condition occurs. A glitch filter is also included, which is interposed between the output of the Schmitt trigger and the input to the latch.Type: GrantFiled: February 13, 1997Date of Patent: September 8, 1998Assignees: Ramtron International Corporation, Hitachi, Ltd.Inventors: Donald J. Verhaeghe, William F. Kraus, Yoshihiko Yasu
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Patent number: 5800683Abstract: A lead zirconate titanate ferroelectric film used as the dielectric layer in a ferroelectric capacitor is doped with calcium and/or strontium, and the lead composition selected to improve data retention performance. The chemical formula for the ferroelectric film is: (Pb.sub.v Ca.sub.w Sr.sub.x La.sub.y)(Zr.sub.z Ti.sub.(1-z))O.sub.3 ; wherein v is ideally between 0.9 and 1.3; w is ideally between 0 and 0.1; x is ideally between 0 and 0.1; y is ideally between 0 and 0.1, and z is ideally between 0 and 0.9. In addition, the chemical composition of the ferroelectric film is further specified in that the measured opposite state charge at a specific time and temperature of the ferroelectric capacitor is greater than eight micro-Coulombs per square centimeter, and the rate of imprint degradation is less than fifteen percent per decade.Type: GrantFiled: May 22, 1997Date of Patent: September 1, 1998Assignee: Ramtron International CorporationInventors: Lee Kammerdiner, Tom Davenport, Domokos Hadnagy
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Patent number: 5802560Abstract: A method and apparatus for use in computer systems utilizes a memory chip employing multiple distributed SRAM caches directly linked to a single DRAM main memory block. Each cache is directly linked to a different bus. Each chip further contains a partially distributed arbitration and control circuit for implementing cache policy and arbitrating memory refresh cycles.Type: GrantFiled: August 30, 1995Date of Patent: September 1, 1998Assignee: Ramton International CorporationInventors: James Dean Joseph, Doyle James Heisler, Dion Nickolas Heisler
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Patent number: 5789323Abstract: A method of fabricating a metal-ferroelectric-metal ("MFM") capacitor includes the steps of depositing a silicon dioxide layer on a silicon or other substrate, a lower platinum or other noble metal electrode, a PZT or other ferroelectric material dielectric layer, and an upper platinum or other noble metal electrode. The upper electrode and ferroelectric dielectric layer are patterned and etched according to a first pattern corresponding to the final dimensions of the ferroelectric dielectric layer. The upper electrode and lower electrode are subsequently patterned and etched according to a second pattern corresponding to the final dimensions of one or more upper electrodes and the final extent of the lower electrode. The second etching step leaves a benign vestigial upper electrode feature. An oxide layer is finally deposited over the entire surface of the MFM capacitor structure, which is etched and metalized over desired upper and lower electrode contacts.Type: GrantFiled: April 25, 1995Date of Patent: August 4, 1998Assignee: Ramtron International CorporationInventor: Thomas C. Taylor
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Patent number: 5774392Abstract: A ferroelectric memory array includes a word line coupled to a row of ferroelectric memory cells and a word line driver circuit for establishing a full power supply voltage on the word line. A bootstrapping circuit is coupled between the word line and a boost line for receiving a boost signal. The bootstrapping circuit includes a ferroelectric capacitor and coupling circuitry for coupling the ferroelectric capacitor between the boost line and the word line in a first operational mode such that the peak voltage on the word line is greater than the power supply voltage, and for isolating the ferroelectric capacitor from the boost line in a second operational mode.Type: GrantFiled: March 28, 1996Date of Patent: June 30, 1998Assignee: Ramtron International CorporationInventors: William F. Kraus, Dennis R. Wilson
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Patent number: 5721862Abstract: An enhanced DRAM contains embedded row registers in the form of latches. The row registers are adjacent to the DRAM array, and when the DRAM comprises a group of subarrays, the row registers are located between DRAM subarrays. When used as on-chip cache, these registers hold frequently accessed data. This data corresponds to data stored in the DRAM at a particular address. When an address is supplied to the DRAM, it is compared to the address of the data stored in the cache. If the addresses are the same, then the cache data is read at SRAM speeds. The DRAM is decoupled from this read. The DRAM also remains idle during this cache read unless the system opts to precharge or refresh the DRAM. Refresh or precharge occur concurrently with the cache read. If the addresses are not the same, then the DRAM is accessed and the embedded register is reloaded with the data at that new DRAM address.Type: GrantFiled: June 2, 1995Date of Patent: February 24, 1998Assignee: Ramtron International CorporationInventors: Ronald H. Sartore, Kenneth J. Mobley, Donald G. Carrigan, Oscar Frederick Jones, Jr.
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Patent number: 5699317Abstract: An enhanced dynamic random access memory (DRAM) contains embedded row registers in the form of latches. The row registers are adjacent to the DRAM array, and when the DRAM comprises a group of subarrays, the row registers are located between DRAM subarrays. When used as on-chip cache, these registers hold frequently accessed data. This data corresponds to data stored in the DRAM at a particular address. When an address is supplied to the DRAM, it is compared to the address of the data stored in the cache. If the addresses are the same, then the cache data is read at static random access memory (SRAM) speeds. The DRAM is decoupled from this read. The DRAM also remains idle during this cache read unless the system opts to precharge or refresh the DRAM. Refresh or precharge occur concurrently with the cache read. If the addresses are not the same, then the DRAM is accessed and the embedded register is reloaded with the data at that new DRAM address.Type: GrantFiled: October 6, 1994Date of Patent: December 16, 1997Assignee: Ramtron International CorporationInventors: Ronald H. Sartore, Kenneth J. Mobley, Donald G. Carrigan, Oscar Frederick Jones
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Patent number: 5610099Abstract: In fabricating a source/drain electrode of an integrated circuit transistor and a contact window for it: (1) establishing a structure with a window over the source/drain region next to a gate electrode and isolation structure; (2) establishing a dielectric layer covering the isolation structure, the window, and gate electrode; (3) implanting a moderate concentration of impurities into the source/drain region through said dielectric layer so that the moderate concentration region extends partially under the gate electrode; (4) removing the horizontal portions of the dielectric layer with an anisotropic etch thereby leaving the dielectric on vertical side walls; (5) establishing a region of titanium silicide over the moderately dosed source/drain region and establishing a titanium nitride layer over the isolation structure, windows, and gate electrode; (6) establishing a layer of silicon nitride over the titanium nitride layer; (7) implanting the substrate with a relatively heavier dose of ions through the siliType: GrantFiled: June 28, 1994Date of Patent: March 11, 1997Assignee: Ramtron International CorporationInventors: E. Henry Stevens, Richard A. Bailey, Thomas C. Taylor
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Patent number: 5578867Abstract: A method for passivating an integrated circuit includes the RF sputtering of a hard passivation layer on the surface of the integrated circuit. The hard passivation layer can be a ceramic material such as various doped and undoped titanates, zirconates, niobates, tantalates, stanates, hafnates, and manganates, in either their ferroelectric or non-ferroelectric phases. Other exotic, hard, and usually non-ferroelectric materials not normally found in integrated circuit processing such as carbides may also be used. If the integrated circuit sought to be passivated contains ferroelectric devices, the hard passivation layer can be fabricated out of the same material used in the integrated ferroelectric devices. An optional silicon dioxide insulating layer can be deposited on the surface of the integrated circuit before the hard passivation layer is deposited. The optional silicon dioxide layer is used to prevent any possible contamination of the integrated circuit by the passivation layer.Type: GrantFiled: February 27, 1995Date of Patent: November 26, 1996Assignee: Ramtron International CorporationInventors: George Argos, Jr., John D. Spano, Steven D. Traynor
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Patent number: 5572459Abstract: A reference cell for a IT-1C memory can be used in either an open or folded memory cell array. Each reference cell has two outputs each coupled to a bit line that each develop a voltage substantially half of that developed by a ferroelectric memory cell. The reference voltages and memory cell voltage are than resolved by a sense amplifier. Each reference cell includes two ferroelectric capacitors that are the same size and fabricated with the identical process as the memory cell ferroelectric capacitors. Any changes in the memory cell capacitor similarly affects the reference cell capacitor, and thus the reference voltage is always substantially half of that developed by the memory cell. The reference cells include a number of timing inputs, which control charge sharing and configure the cell to operate in either a DRAM or FRAM.RTM. mode. In a first embodiment, one of the reference cell capacitors is poled.Type: GrantFiled: September 16, 1994Date of Patent: November 5, 1996Assignee: Ramtron International CorporationInventors: Dennis R. Wilson, H. Brett Meadows