Patents by Inventor Alan Christensen

Alan Christensen 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: 8860141
    Abstract: A semiconductor chip has shapes on a particular level that are small enough to require a first mask and a second mask, the first mask and the second mask used in separate exposures during processing. A circuit on the semiconductor chip requires close tracking between a first and a second FET (field effect transistor). For example, the particular level may be a gate shape level. Separate exposures of gate shapes using the first mask and the second mask will result in poorer FET tracking (e.g., gate length, threshold voltage) than for FETs having gate shapes defined by only the first mask. FET tracking is selectively improved by laying out a circuit such that selective FETs are defined by the first mask. In particular, static random access memory (SRAM) design benefits from close tracking of six or more FETs in an SRAM cell.
    Type: Grant
    Filed: January 6, 2012
    Date of Patent: October 14, 2014
    Assignee: International Business Machines Corporation
    Inventors: Derick Gardner Behrends, Todd Alan Christensen, Travis Reynold Hebig, Michael Launsbach, Daniel Mark Nelson
  • Patent number: 8754417
    Abstract: Vertically stacked Field Effect Transistors (FETs) are created where a first FET and a second FET are controllable independently. The vertically stacked FETs may be connected in series or in parallel, thereby suitable for use as a portion of a NAND circuit or a NOR circuit. Epitaxial growth over a source and drain of a first FET, and having similar doping to the source and drain of the first FET provide a source and drain of a second FET. An additional epitaxial growth of a type opposite the doping of the source and drain of the first FET provides a body for the second FET.
    Type: Grant
    Filed: September 10, 2012
    Date of Patent: June 17, 2014
    Assignee: International Business Machines Corporation
    Inventors: Todd Alan Christensen, Phil Christopher Felice Paone, David Paul Paulsen, John Edward Sheets, II
  • Patent number: 8467230
    Abstract: A circuit and method erase at power-up all data stored in a DRAM chip for increased data security. All the DRAM memory cells are erased by turning on the transistors for the DRAM storage cells simultaneously by increasing the body voltage of cells. In the example circuit, the body voltage is increased by a charge pump controlled by a power-on-reset (POR) signal applying a voltage to the p-well of the memory cells. The added voltage to the p-well lowers the threshold voltage of the cell, such that the NFET transistor of the memory cell will turn on. With all the devices turned on, the data stored in the memory cells is erased as the voltage of all the cells connected to a common bitline coalesce to a single value.
    Type: Grant
    Filed: October 6, 2010
    Date of Patent: June 18, 2013
    Assignee: International Business Machines Corporation
    Inventors: Derick Gardner Behrends, Todd Alan Christensen, Travis Reynold Hebig, Michael Launsbach, Daniel Mark Nelson
  • Patent number: 8381123
    Abstract: A method and medium are provided for presenting virtualized visible content within a viewport in a user interface. An anchor is received that represents a point on a line of virtualized visible content and a target value is received that represents a location in a viewport of a user interface. The anchor and target values can be received from user input devices or by analyzing the position of a scroll thumb relative to a scroll trough in the user interface. A first line of virtualized visible content that corresponds to the anchor value is realized by loading the line into memory from another source. The line is then positioned in the viewport based on the target value. Additional lines surrounding the first line are realized until the viewport is full. Lines that are not visible in the viewport can be unrealized, thus conserving computing resources.
    Type: Grant
    Filed: June 27, 2008
    Date of Patent: February 19, 2013
    Assignee: Microsoft Corporation
    Inventors: Benjamin Karas, Fabrice A. Debry, Jason Alan Christensen
  • Publication number: 20130001701
    Abstract: Vertically stacked Field Effect Transistors (FETs) are created where a first FET and a second FET are controllable independently. The vertically stacked FETs may be connected in series or in parallel, thereby suitable for use as a portion of a NAND circuit or a NOR circuit. Epitaxial growth over a source and drain of a first FET, and having similar doping to the source and drain of the first FET provide a source and drain of a second FET. An additional epitaxial growth of a type opposite the doping of the source and drain of the first FET provides a body for the second FET.
    Type: Application
    Filed: September 10, 2012
    Publication date: January 3, 2013
    Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: Todd Alan Christensen, Phil Christopher Felice Paone, David Paul Paulsen, John Edward Sheets, II
  • Patent number: 8314001
    Abstract: Vertically stacked Field Effect Transistors (FETs) are created where a first FET and a second FET are controllable independently. The vertically stacked FETs may be connected in series or in parallel, thereby suitable for use as a portion of a NAND circuit or a NOR circuit. Epitaxial growth over a source and drain of a first FET, and having similar doping to the source and drain of the first FET provide a source and drain of a second FET. An additional epitaxial growth of a type opposite the doping of the source and drain of the first FET provides a body for the second FET.
    Type: Grant
    Filed: April 9, 2010
    Date of Patent: November 20, 2012
    Assignee: International Business Machines Corporation
    Inventors: Todd Alan Christensen, Phil Christopher Felice Paone, David Paul Paulsen, John Edward Sheets, II
  • Patent number: 8300450
    Abstract: A method and embedded dynamic random access memory (EDRAM) circuit for implementing a physically unclonable function (PUF), and a design structure on which the subject circuit resides are provided. An embedded dynamic random access memory (EDRAM) circuit includes a first EDRAM memory cell including a memory cell true storage capacitor and a second EDRAM memory cell including a memory cell complement storage capacitor. The memory cell true storage capacitor and the memory cell complement storage capacitor include, for example, trench capacitors or metal insulator metal capacitors (MIM caps). A random variation of memory cell capacitance is used to implement the physically unclonable function. Each memory cell is connected to differential inputs to a sense amplifier. The first and second EDRAM memory cells are written to zero and then the first and second EDRAM memory cells are differentially sensed and the difference is amplified to consistently read the same random data.
    Type: Grant
    Filed: November 3, 2010
    Date of Patent: October 30, 2012
    Assignee: International Business Machines Corporation
    Inventors: Todd Alan Christensen, John Edwards Sheets, II
  • Publication number: 20120106235
    Abstract: A method and embedded dynamic random access memory (EDRAM) circuit for implementing a physically unclonable function (PUF), and a design structure on which the subject circuit resides are provided. An embedded dynamic random access memory (EDRAM) circuit includes a first EDRAM memory cell including a memory cell true storage capacitor and a second EDRAM memory cell including a memory cell complement storage capacitor. The memory cell true storage capacitor and the memory cell complement storage capacitor include, for example, trench capacitors or metal insulator metal capacitors (MIM caps). A random variation of memory cell capacitance is used to implement the physically unclonable function. Each memory cell is connected to differential inputs to a sense amplifier. The first and second EDRAM memory cells are written to zero and then the first and second EDRAM memory cells are differentially sensed and the difference is amplified to consistently read the same random data.
    Type: Application
    Filed: November 3, 2010
    Publication date: May 3, 2012
    Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: Todd Alan Christensen, John Edwards Sheets, II
  • Patent number: 8159260
    Abstract: A circuit and method increases the repeatability of physically undetectable functions (PUFs) by enhancing the variation of signal delay through two delay chains during chip burn-in. A burn-in circuit holds the inputs of the two delay chains at opposite random values during the burn-in process. All the PFETs in the delay chains with a low value at the input will be burned in with a higher turn on voltage. Since the PFETs affected in the two delay chains are driven by opposite transitions at burn-in, alternating sets of delay components in the two delay chains are affected by the burn-in cycle. Under normal operation, both of the delay chains see the same input so only one chain has an increase in delay to achieve a statistically reliable difference in the two delay paths thereby increasing the overall repeatability of the PUF circuit.
    Type: Grant
    Filed: October 5, 2010
    Date of Patent: April 17, 2012
    Assignee: International Business Machines Corporation
    Inventors: Derick Gardner Behrends, Todd Alan Christensen, Travis Reynold Hebig, Daniel Mark Nelson
  • Publication number: 20120087176
    Abstract: A circuit and method erase at power-up all data stored in a DRAM chip for increased data security. All the DRAM memory cells are erased by turning on the transistors for the DRAM storage cells simultaneously by increasing the body voltage of cells. In the example circuit, the body voltage is increased by a charge pump controlled by a power-on-reset (POR) signal applying a voltage to the p-well of the memory cells. The added voltage to the p-well lowers the threshold voltage of the cell, such that the NFET transistor of the memory cell will turn on. With all the devices turned on, the data stored in the memory cells is erased as the voltage of all the cells connected to a common bitline coalesce to a single value.
    Type: Application
    Filed: October 6, 2010
    Publication date: April 12, 2012
    Applicant: International Business Machines Corporation
    Inventors: Derick Gardner Behrends, Todd Alan Christensen, Travis Reynold Hebig, Michael Launsbach, Daniel Mark Nelson
  • Publication number: 20120081143
    Abstract: A circuit and method increases the repeatability of physically undetectable functions (PUFs) by enhancing the variation of signal delay through two delay chains during chip burn-in. A burn-in circuit holds the inputs of the two delay chains at opposite random values during the burn-in process. All the PFETs in the delay chains with a low value at the input will be burned in with a higher turn on voltage. Since the PFETs affected in the two delay chains are driven by opposite transitions at burn-in, alternating sets of delay components in the two delay chains are affected by the burn-in cycle. Under normal operation, both of the delay chains see the same input so only one chain has an increase in delay to achieve a statistically reliable difference in the two delay paths thereby increasing the overall repeatability of the PUF circuit.
    Type: Application
    Filed: October 5, 2010
    Publication date: April 5, 2012
    Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: Derick Gardner Behrends, Todd Alan Christensen, Travis Reynold Hebig, Daniel Mark Nelson
  • Patent number: 8138054
    Abstract: An enhanced FET capable of controlling current above and below a gate of the FET. The FET is formed on a semiconductor substrate. A source and drain are formed in the substrate (or in a well in the substrate). A first epitaxial layer of similar doping to the source and drain are grown on the source and drain, the first epitaxial layer is thicker than the gate, but not so thick as to cover the top of the gate. A second epitaxial layer of opposite doping is grown on the first epitaxial layer thick enough to cover the top of the gate. The portion of the second epitaxial layer above the gate serves as a body through which the gate controls current flow between portions of the first epitaxial layer over the drain and the source.
    Type: Grant
    Filed: April 1, 2009
    Date of Patent: March 20, 2012
    Assignee: International Business Machines Corporation
    Inventors: David Howard Allen, Todd Alan Christensen, David Paul Paulsen, John Edward Sheets, II
  • Patent number: 8105940
    Abstract: A first through via is electrically insulated from surrounding wafer substrate material. A second through via is not electrically insulated from the surrounding wafer substrate material. This configuration is advantageous when the non-insulated via serves as the path for either Vdd or GND. By not insulating the through via, a first supply voltage (Vdd or GND) is allowed to flow through the surrounding wafer substrate material thereby decreasing the resistance of the first supply voltage path.
    Type: Grant
    Filed: February 10, 2010
    Date of Patent: January 31, 2012
    Assignee: International Business Machines Corporation
    Inventors: Todd Alan Christensen, John Edward Sheets, II
  • Publication number: 20110248349
    Abstract: Vertically stacked Field Effect Transistors (FETs) are created where a first FET and a second FET are controllable independently. The vertically stacked FETs may be connected in series or in parallel, thereby suitable for use as a portion of a NAND circuit or a NOR circuit. Epitaxial growth over a source and drain of a first FET, and having similar doping to the source and drain of the first FET provide a source and drain of a second FET. An additional epitaxial growth of a type opposite the doping of the source and drain of the first FET provides a body for the second FET.
    Type: Application
    Filed: April 9, 2010
    Publication date: October 13, 2011
    Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: Todd Alan Christensen, Phil Christopher Felice Paone, David Paul Paulsen, John Edward Sheets, II
  • Patent number: 7989918
    Abstract: A method and tamper detection circuit for implementing tamper and anti-reverse engineering evident detection in a semiconductor chip, and a design structure on which the subject circuit resides are provided. A capacitor is formed with the semiconductor chip including the circuitry to be protected. A change in the capacitor value results responsive to the semiconductor chip being thinned, which is detected and a tamper-detected signal is generated.
    Type: Grant
    Filed: January 26, 2009
    Date of Patent: August 2, 2011
    Assignee: International Business Machines Corporation
    Inventors: Gerald Keith Bartley, Todd Alan Christensen, Paul Eric Dahlen, John Edward Sheets, II
  • Patent number: 7935629
    Abstract: An apparatus and method are disclosed for an improved semiconductor interconnect scheme using a simplified process. In an embodiment of the apparatus, a polysilicon shape is formed on a silicon area. The polysilicon shape is created having a bridging vertex. When a spacer is created on the polysilicon shape, the spacer width is formed to be small enough near the bridging vertex to allow a silicide bridge to form that creates an electrical coupling between the silicon area and the bridging vertex. Semiconductor devices and circuits are created using the improved semiconductor interconnect scheme using the simplified process.
    Type: Grant
    Filed: October 22, 2007
    Date of Patent: May 3, 2011
    Assignee: International Business Machines Corporation
    Inventors: Todd Alan Christensen, Richard Lee Donze, William Paul Hovis, Terrance Wayne Kueper, John Edward Sheets, II
  • Patent number: 7924633
    Abstract: A method and wordline voltage boosting circuit for implementing boosted wordline voltage in memories, and a design structure on which the subject circuit resides are provided. The wordline voltage boosting circuit receives a precharge signal, uses a switching transistor coupled to a bootstrap capacitor, and generates a boosted voltage level responsive to the precharge signal. The boosted voltage level is applied to a voltage supply of an output stage of a wordline driver, causing the wordline voltage level of a selected wordline to be boosted. The switching transistor is controlled by the precharge signal and a node of the bootstrap capacitor supplying the boosted voltage level is driven high by the switching transistor.
    Type: Grant
    Filed: February 20, 2009
    Date of Patent: April 12, 2011
    Assignee: International Business Machines Corporation
    Inventors: Derick Gardner Behrends, Todd Alan Christensen, Travis Reynold Hebig, Daniel Mark Nelson
  • Patent number: 7925950
    Abstract: A method and circuit for implementing substantially perfect array access time tracking with Logic Built In Self Test (LBIST) diagnostics of dynamic memory array and random logic, and a design structure on which the subject circuit resides are provided. The dynamic memory array is initialized to a state for the longest read time for each bit and the dynamic memory array is forced into a read only mode. During LBIST diagnostics with the array in the read only mode, the array outputs are combined with the data inputs to provide random switching data on the array outputs to the random logic.
    Type: Grant
    Filed: February 26, 2009
    Date of Patent: April 12, 2011
    Assignee: International Business Machines Corporation
    Inventors: Todd Alan Christensen, Peter Thomas Freiburger, Jesse Daniel Smith
  • Patent number: 7844869
    Abstract: A method and circuit implement testing of a circuit path including a memory array and logic including Logic Built in Self Test (LBIST) diagnostics, and a design structure on which the subject circuit resides are provided. Testing of the circuit path includes initializing the memory array in the circuit path with an initialization pattern, switching to Logic Built in Self Test (LBIST) mode and providing a read only mode for the memory array, and running Logic Built in Self Test (LBIST) testing of the circuit path.
    Type: Grant
    Filed: January 16, 2008
    Date of Patent: November 30, 2010
    Assignee: International Business Machines Corporation
    Inventors: Louis Bernard Bushard, Todd Alan Christensen, Jesse Daniel Smith
  • Patent number: 7835176
    Abstract: A method and circuit for implementing an enhanced dual-mode static random access memory (SRAM) performance screen ring oscillator (PSRO), and a design structure on which the subject circuit resides are provided. The dual-mode SRAM PSRO includes a plurality of SRAM base blocks connected together in a chain. Each of the plurality of SRAM base blocks includes an eight-transistor (8T) SRAM cell, a local evaluation circuit and a logic function coupled to the SRAM cell. The eight-transistor (8T) static random access memory (SRAM) cell is an unmodified 8T SRAM cell. The dual-mode SRAM PSRO includes one mode of operation, where the output frequency is determined by write-through performance of the 8T SRAM cell; and another mode of operation, where the output frequency is determined by read performance of the 8T SRAM cell.
    Type: Grant
    Filed: January 27, 2009
    Date of Patent: November 16, 2010
    Assignee: International Business Machines Corporation
    Inventors: Chad Allen Adams, Todd Alan Christensen, Peter Thomas Freiburger, Travis Reynold Hebig