Patents by Inventor Sharad Saxena

Sharad Saxena 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: 10852337
    Abstract: Described are test structures and methods for measuring silicon thickness in fully depleted silicon-on-insulator technologies.
    Type: Grant
    Filed: June 1, 2017
    Date of Patent: December 1, 2020
    Assignee: PDF Solutions, Inc.
    Inventors: Sharad Saxena, Tomasz Brozek, Yuan Yu, Mike Kyu Hyon Pak, Meindert Martin Lunenborg
  • Patent number: 10641804
    Abstract: Described is a CBCM technique that works only with PMOS transistors or only with NMOS transistors. Specifically, a method of monitoring performance of an integrated circuit device using a CBCM technique is disclosed, the method comprising: providing a metrology structure having a pseudo-inverter comprising a pull-up pull-down transistor switch, wherein the transistor switch comprises a pull-up transistor and a pull-down transistor of the same type; charging and discharging a device under test (DUT) coupled to the pseudo-inverter using a non-overlapping clock; measuring capacitance of the DUT with a gate voltage of the pull-up transistor at a preset value; and, using the value of the measured capacitance to estimate a dimension of a structure in the integrated circuit device. The non-overlapping clock is generated by: turning the pull-down transistor off when the pull-up transistor is on; and, turning the pull-down transistor on when the pull-up transistor is off.
    Type: Grant
    Filed: September 19, 2016
    Date of Patent: May 5, 2020
    Assignee: PDF Solutions, Inc.
    Inventor: Sharad Saxena
  • Patent number: 10529631
    Abstract: Methods of measuring fin height electrically for devices fabricated using FinFET technology are disclosed here. One method uses an interleaving comb-like test structure with no gate. The other method extracts fin height from total gate capacitance from FinFETS with varying gate lengths. When a comb-like structure with no gate is used to measure fin height, if there is another structure with a gate is used, then the gate capacitance may be measured to independently measure thickness of gate dielectric.
    Type: Grant
    Filed: September 19, 2016
    Date of Patent: January 7, 2020
    Assignee: PDF SOLUTIONS, INC.
    Inventors: Sharad Saxena, Jianjun Cheng, Yuan Yu
  • Patent number: 9952268
    Abstract: Disclosed are methods for measuring capacitance in presence of leakage in integrated circuits. In particular, it teaches a method of measuring leaky capacitors using charge based capacitance measurement (CBCM) technique taking into account parasitic resistance. Fast and accurate measurement of capacitances allows the estimation of a number of technology parameters like: gate-dielectric thickness, gate critical dimension, trench depth in a damascene metallization process, height of a fin in a Fin FET device etc.
    Type: Grant
    Filed: September 19, 2016
    Date of Patent: April 24, 2018
    Assignee: PDF Solutions, Inc.
    Inventors: Sharad Saxena, Yuan Yu
  • Publication number: 20170309524
    Abstract: Described are test structures and methods for measuring silicon thickness in fully depleted silicon-on-insulator technologies.
    Type: Application
    Filed: June 1, 2017
    Publication date: October 26, 2017
    Inventors: Sharad Saxena, Thomas Brozek, Yuan Yu, Mike Kyu Hyon Pak, Meindert Martin Lunenborg
  • Patent number: 9691669
    Abstract: Described are test structures and methods for measuring silicon thickness in fully depleted silicon-on-insulator technologies.
    Type: Grant
    Filed: August 28, 2015
    Date of Patent: June 27, 2017
    Assignee: PDF Solutions, Inc.
    Inventors: Sharad Saxena, Thomas Brozek, Yuan Yu, Mike Kyu Hyon Pak, Meindert Martin Lunenborg
  • Patent number: 7932105
    Abstract: Systems and methods for detecting and monitoring Nickel-silicide process and induced failures. In a first method embodiment, a method of characterizing a Nickel-silicide semiconductor manufacturing process includes accessing a test chip including a parallel coupled chain of transistors, wherein the transistors are designed for inducing stress into Nickel-silicide features of the transistors, and for increasing a probability of a manufacturing failure of the Nickel-silicide features. A biasing voltage is applied to one terminal of the parallel coupled chain, all other terminals of the parallel coupled chain and grounded, and current is measured at each of the all other terminals of the parallel coupled chain. This process is repeated for each terminal of the parallel coupled chain. The measured currents from all possible conduction paths are compared to determine a manufacturing defect in the parallel coupled chain of transistors.
    Type: Grant
    Filed: October 14, 2008
    Date of Patent: April 26, 2011
    Assignee: PDF Solutions
    Inventors: Sharad Saxena, Jae-Yong Park, Benjamin Shieh, Mark Spinelli, Shiying Xiong, Hossein Karbasi
  • Patent number: 7644388
    Abstract: A printability simulation is performed on a mask layout over a range of lithography process conditions. A layout configuration capable of inducing functional or parametric failure in a semiconductor device is identified in the mask layout. A test structure representative of the identified layout configuration is obtained. A design of experiment is associated with the test structure. The design of experiment is defined to investigating effects of variations of one or more layout attributes in the test structure. Multiple instance of the test structure are fabricated on a wafer according to the design of experiment. Electrical performance characteristics of the fabricated test structures are measured. Based on the measured electrical performance characteristics, one or more layout attributes of the test structure capable of causing functional or parametric failure are determined.
    Type: Grant
    Filed: September 29, 2006
    Date of Patent: January 5, 2010
    Assignee: PDF Solutions, Inc.
    Inventors: Lidia Daldoss, Sharad Saxena, Christoph Dolainsky, Rakesh R. Vallishayee
  • Patent number: 7047505
    Abstract: A method for selecting a process for forming a device, includes generating a plurality of equations using a response surface methodology model. Each equation relates a respective device simulator input parameter to a respective combination of processing parameters that can be used to form the device or a respective combination of device characteristics. A model of a figure-of-merit circuit is formed that is representative of an integrated circuit into which the device is to be incorporated. One of the combinations of processing parameters or combinations of device characteristics is identified that results in a device satisfying a set of performance specifications for the figure-of-merit circuit, using the plurality of equations and the device simulator.
    Type: Grant
    Filed: October 16, 2001
    Date of Patent: May 16, 2006
    Assignee: PDF Solutions, Inc.
    Inventors: Sharad Saxena, Andrei Shibkov, Patrick D. McNamara, Carlo Guardiani
  • Patent number: 7003742
    Abstract: A method for analyzing an integrated circuit (IC) having at least one of the group consisting of digital and analog components, where the IC is designed to meet a plurality of circuit performance specifications, and fabrication of the IC is monitored by measuring process factors and a previously defined set of electrical test variables. A set of linearly independent electrical test parameters are formed based on a subset of the set of electrical test variables. The set of process factors is mapped to the linearly independent electrical test parameters. A plurality of figure-of-merit (FOM) performance models are formed based on the process factors. The FOM models are combined with the mapping to enable modeling of IC performance based on the linearly independent electrical test parameters.
    Type: Grant
    Filed: January 9, 2003
    Date of Patent: February 21, 2006
    Assignee: PDF Solutions, Inc.
    Inventors: Sharad Saxena, Patrick D. McNamara, Carlo Guardiani, Lidia Daldoss
  • Patent number: 6978229
    Abstract: A computer implemented method for statistical modeling and simulation of the impact of global variation and local mismatch on the performance of integrated circuits, comprises the steps of: estimating a representation of component mismatch from device performance measurements in a form suitable for circuit simulation; reducing the complexity of statistical simulation by performing a first level principal component or principal factor decomposition of global variation, including screening; further reducing the complexity of statistical simulation by performing a second level principal component decomposition including screening for each factor retained in the first level principal component decomposition step to represent local mismatch; and performing statistical simulation with the joint representation of global variation and local mismatch obtained in the second level principal component decomposition step.
    Type: Grant
    Filed: September 29, 2000
    Date of Patent: December 20, 2005
    Assignee: PDF Solutions, Inc.
    Inventors: Sharad Saxena, Carlo Guardiani, Philip D. Schumaker, Patrick D. McNamara, Dale Coder
  • Publication number: 20040064296
    Abstract: A method for selecting a process for forming a device, includes generating a plurality of equations using a response surface methodology model. Each equation relates a respective device simulator input parameter to a respective combination of processing parameters that can be used to form the device or a respective combination of device characteristics. A model of a figure-of-merit circuit is formed that is representative of an integrated circuit into which the device is to be incorporated. One of the combinations of processing parameters or combinations of device characteristics is identified that results in a device satisfying a set of performance specifications for the figure-of-merit circuit, using the plurality of equations and the device simulator.
    Type: Application
    Filed: October 14, 2003
    Publication date: April 1, 2004
    Inventors: Sharad Saxena, Andrei Shibkov, Patrick D. McNamara, Carlo Guardiani
  • Publication number: 20040015793
    Abstract: A method for analyzing an integrated circuit (IC) having at least one of the group consisting of digital and analog components, where the IC is designed to meet a plurality of circuit performance specifications, and fabrication of the IC is monitored by measuring process factors and a previously defined set of electrical test variables. A set of linearly independent electrical test parameters are formed based on a subset of the set of electrical test variables. The set of process factors is mapped to the linearly independent electrical test parameters. A plurality of figure-of-merit (FOM) performance models are formed based on the process factors. The FOM models are combined with the mapping to enable modeling of IC performance based on the linearly independent electrical test parameters.
    Type: Application
    Filed: January 9, 2003
    Publication date: January 22, 2004
    Inventors: Sharad Saxena, Patrick D. McNamara, Carlo Guardiani, Lidia Daldoss
  • Patent number: 6530064
    Abstract: An operational lifetime, and also performance characteristics, can be accurately predicted for an experimental transistor design (10) and a specified set of fabrication process conditions (117), without actually fabricating and testing a physical transistor made according to the particular design data and process conditions. With respect to the prediction of an operational lifetime, the operational lifetime can be expressed as a function of the size of a gate overlap (12) of the transistor, and this relationship is valid throughout a selected semiconductor technology for which the transistor is designed. The size of the gate overlap is determined by selecting a combinations of values for two process conditions.
    Type: Grant
    Filed: October 19, 2000
    Date of Patent: March 4, 2003
    Assignee: Texas Instruments Incorporated
    Inventors: Karthik Vasanth, Shian-Wei Aur, E. Ajith Amerasekera, Sharad Saxena, Joseph C. Davis, Richard G. Burch
  • Patent number: 6388288
    Abstract: Integration of dual voltages on a single chip can be accomplished with a minimum of extra masks by optimizing only the MDD implant of the peripheral transistors, while other implants remain the same for both transistor types. This meets lifetime specifications without unnecessary expense.
    Type: Grant
    Filed: March 25, 1999
    Date of Patent: May 14, 2002
    Assignee: Texas Instruments Incorporated
    Inventors: Karthik Vasanth, Sharad Saxena, Richard G. Burch, Purnendu K. Mozumder, Joseph C. Davis, Chenjing L. Fernando, Suraj Rao
  • Patent number: 6381564
    Abstract: A method and system for providing optimal tuning for complex simulators. The method and system include initially building at least one RSM model having input and output terminals. Then there is provided a simulation-free optimization function by constructing an objective function from the outputs at the output terminals of the at least one RSM model and experimental data. The objective function is optimized in an optimizer and the optimized objective function is fed to the input terminal of the RSM. Building of at least one RSM model includes establishing a range for the simulation, running a simulation experiment for the designed experiment, extracting relevant data from said experiment and building the RSM model from the extracted relevant data. The step of running a simulation experiment comprises the step of running a DOE/Opt operation.
    Type: Grant
    Filed: May 3, 1999
    Date of Patent: April 30, 2002
    Assignee: Texas Instruments Incorporated
    Inventors: Joseph C. Davis, Karthik Vasanth, Sharad Saxena, Purnendu K. Mozumder, Suraj Rao, Chenjing L. Fernando, Richard G. Burch
  • Patent number: 6317640
    Abstract: Method for adequately modeling process induced variabilities is disclosed that comprises the steps of acquiring experimental data and defining a particular design space. Values for the mean and standard deviation of the experimental data at each of the points defining the design space are calculated. The experimental values of the output parameters at each of the design points is normalized to extract the shape of the distribution of each of the design points. The normalized values are then merged to form a cumulative distribution function associated with the data. The cumulative distribution function is applied to a new design point in a predicted fashion by first calculating a mean and standard deviation value for the new point by interpolating from the mean and standard deviation values from the experimental data. The cumulative distribution function is then scaled and centered using the interpolated mean and standard deviation values to provide a predicted data distribution for the new design point.
    Type: Grant
    Filed: January 5, 1999
    Date of Patent: November 13, 2001
    Assignee: Texas Instruments Incorporated
    Inventors: Suraj Rao, Sharad Saxena, Pushkar P. Apte, Purnendu K. Mozumder, Richard Gene Burch, Karthik Vasanth, Joseph Carl Davis, Chenjing L. Fernando
  • Patent number: 6311096
    Abstract: A statistical design method is provided for minimizing the impact of manufacturing variations on semiconductor manufacturing by statistical design which seeks to reduce the impact of variability on device behavior. The method is based upon a Markov representation of a process flow which captures the sequential and stochastic nature of semiconductor manufacturing and enables the separation of device and process models, statistical modeling of process modules from observable wafer states and approximations for statistical optimization over large design spaces. The statistical estimation component of this method results in extremely accurate predictions of the variability of transistor performance for all of the fabricated flows. Statistical optimization results in devices that achieve all transistor performance and reliability goals and reduces the variability of key transistor performances.
    Type: Grant
    Filed: April 1, 1999
    Date of Patent: October 30, 2001
    Assignee: Texas Instruments Incorporated
    Inventors: Sharad Saxena, Karthik Vasanth, Richard G. Burch, Purnendu K. Mozumder, Suraj Rao, Joseph C. Davis
  • Patent number: 6157062
    Abstract: A dual voltage chip is fabricated with no intermediate-doped (LDD or MDD) area in the high-voltage transistors by adjusting the gate sidewall spacer thickness and the source/drain implant.
    Type: Grant
    Filed: April 6, 1999
    Date of Patent: December 5, 2000
    Assignee: Texas Instruments Incorporated
    Inventors: Karthik Vasanth, Richard G. Burch, Sharad Saxena, Purnendu K. Mozumder, Chenjing L. Fernando, Joseph C. Davis, Suraj Rao
  • Patent number: 5912678
    Abstract: Methods and processes to reduce the cost and cycle time of designing manufacturing flows are described, particularly for microelectronic integrated circuit processes. One embodiment of the present invention is a method which divides the task of designing process flows into a number of abstraction levels and provides mechanisms to translate between these levels of abstraction. The process is divided into a number of modules each having process constraints. Process constraints are propagated backwards from the final module to the first module, and may also be propagated forward from earlier modules to later modules of needed. This approach results in a top-down design methodology where requirements from higher levels of abstraction are successively reduced to lower abstraction levels, while meeting the constraints imposed by the lower levels.
    Type: Grant
    Filed: April 14, 1997
    Date of Patent: June 15, 1999
    Assignee: Texas Instruments Incorporated
    Inventors: Sharad Saxena, Amy J. Unruh, Purnendu K. Mozumder, Richard G. Burch