International Business Machines Corporation

Jerry D Hayes

Anthony D Polson

David James Hathaway

Peter Anton Habitz

Kanak Behari Agarwal

Eric A Foreman

Ying Liu

Sani Richard Nassif

Fadi Hikmat Gebara

Alvin Wayne Strong

Jeremy Daniel Schaub

John Patrick Keane

Jeffrey H Oppold

Nazmul Habib

John Greg Massey

Sebastian Theodore Ventrone

Joseph Andrew Iadanza

Natesan Venkateswaran

James A Culp

Alvar Antonio Dean

Tad Jeffrey Wilder

Deborah M Massey

Emory D Keller

Amol Anil Joshi

William John Wright

James J Engel

David Bruce White

Kanak B Argawal

A method and test system for fast determination of parameter variation statistics provides a mechanism for determining process variation and parameter statistics using low computing power and readily available test equipment. A test array having individually selectable devices is stimulated under computer control to select each of the devices sequentially. A test output from the array provides a current or voltage that dependent on a particular device parameter. The sequential selection of the devices produces a voltage or current waveform, characteristics of which are measured using a digital multi-meter that is interfaced to the computer. The rms value of the current or voltage at the test output is an indication of the standard deviation of the parameter variation and the DC value of the current or voltage is an indication of the mean value of the parameter.

Method and test system for fast determination of parameter variation statistics

A method and test circuit provide measurements to accurately characterize threshold voltage changes due to negative bias temperature instability (NBTI) and positive bias temperature instability (PBTI). Both the bias temperature instability recovery profile and/or the bias temperature shifts due to rapid repetitions of stress application can be studied. In order to provide accurate measurements when stresses are applied at intervals on the order of tens of nanoseconds while avoiding unwanted recovery, and/or to achieve recovery profile sampling resolutions in the nanosecond range, multiple delay or ring oscillator frequency measurements are made using a delay line that is formed from delay elements that have delay variation substantially caused only by NBTI or PBTI effects. Devices in the delay elements are stressed, and then the delay line/ring oscillator is operated to measure a threshold voltage change for one or more measurement periods on the order of nanoseconds.

Test circuit for bias temperature instability recovery measurements

Mechanisms are provided for characterizing long range variability in integrated circuit manufacturing. A model derivation component tests one or more density pattern samples, which are a fabricated integrated circuits having predetermined pattern densities and careful placement of current-voltage (I-V) sensors. The model derivation component generates one or more empirical models to establish range of influence of long range variability effects in the density pattern sample. A variability analysis component receives an integrated circuit design and, using the one or more empirical models, analyzes the integrated circuit design to isolate possible long range variability effects in the integrated circuit design.

Characterization of long range variability

A method, test circuit and test system provide measurements to accurately characterize threshold voltage changes due to negative bias temperature instability (NBTI) and positive bias temperature instability (PBTI). Both the bias temperature instability recovery profile and/or the bias temperature shifts due to rapid repetitions of stress application can be studied. In order to provide accurate measurements when stresses are applied at intervals on the order of tens of nanoseconds while avoiding unwanted recovery, and/or to achieve recovery profile sampling resolutions in the nanosecond range, multiple delay or ring oscillator frequency measurements are made using a delay line that is formed from delay elements that have delay variation substantially caused only by NBTI or PBTI effects. Devices in the delay elements are stressed, and then the delay line/ring oscillator is operated to measure a threshold voltage change for one or more measurement periods on the order of nanoseconds.

A parallel array architecture for constant current electro-migration stress testing is provided. The parallel array architecture comprises a device under test (DUT) array having a plurality of DUTs coupled in parallel and a plurality of localized heating elements associated with respective ones of the DUTs in the DUT array. The architecture further comprises DUT selection logic that isolates individual DUTs within the array. Moreover, the architecture comprises current source logic that provides a reference current and controls the current through the DUTs in the DUT array such that each DUT in the DUT array has substantially a same current density, and current source enable logic for selectively enabling portions for the current source logic. Electro-migration stress testing is performed on the DUTs of the DUT array using the heating elements, the DUT selection logic, current source logic, and current source enable logic.

Parallel array architecture for constant current electro-migration stress testing

A configurable PSRO measurement circuit is used to measure the frequency dependent capacitance of a target through silicon via (TSV) or other conductive structure. Measurements of the target structure are aided by using adjustable resistors and a de-embedding structure to measure the effects of parasitic capacitance, C. Current is measured to both the device under test (DUT) and the de-embedding structure. From these measurements, the frequency dependent capacitance of the DUT is calculated.

Configurable PSRO structure for measuring frequency dependent capacitive loads

System and method for obtaining statistics in a fast and simplified manner at the wafer level while using wafer-level test equipment. The system and method performs a parallel stress of all of the DUTs on a given chip to keep the stress time short, and then allows each DUT on that chip to be tested individually while keeping the other DUTs on that chip under stress to avoid any relaxation. In one application, the obtained statistics enable analysis of Negative Temperature Bias Instability (NTBI) phenomena of transistor devices. Although obtaining statistics may be more crucial for NBTI because of its known behavior as the device narrows, the structure and methodology, with minor appropriate adjustments, could be used for stressing multiple DUTs for many technology reliability mechanisms.

Measurement methodology and array structure for statistical stress and test of reliabilty structures

A method, system, and computer usable program product for in an integrated circuit are provided in the illustrative embodiments. A signal to be measured is identified in the IC. The signal is provided as a first control voltage input to a first VCO in the IC. A first output frequency is generated from the first VCO, the first output frequency having a first frequency value corresponding to the signal. The signal is provided as a second control voltage input to a second VCO in the IC. A second output frequency is generated from the second VCO, the second output frequency having a second frequency value corresponding to the signal. The first and the second output frequency values are exported from the IC. A mean value and a standard deviation of the signal are computed using the output first and second frequency values.

On-chip measurement of signals

Methods for analyzing the timing in integrated circuits and for reducing the pessimism in timing slack calculations in static timing analysis (STA). The methods involve grouping and canceling the delay contributions of elements having similar delays in early and late circuit paths. An adjusted timing slack is calculated using the delay contributions of elements having dissimilar delays. In some embodiments, the delay contributions of elements having dissimilar delays are root sum squared. Embodiments of the invention provide methods for reducing the pessimism due to both cell-based and wire-dependent delays. The delays considered in embodiments of the invention may include delays due to the location of elements in a path.

Method and system for evaluating timing in an integrated circuit

Delay-based bias temperature instability recovery measurements for characterizing stress degradation and recovery

A method and test circuit provide measurements to aid in the understanding of time-varying threshold voltage changes such as negative bias temperature instability and positive bias temperature instability. In order to provide accurate measurements during an early stage in the threshold variation, a current generating circuit is integrated on a substrate with the device under test, which may be a device selected from among an array of devices. The current generating circuit may be a current mirror that responds to an externally-supplied current provided by a test system. A voltage source circuit may be included to hold the drain-source voltage of the transistor constant, although not required. A stress is applied prior to the measurement phase, which may include a controllable relaxation period after the stress is removed.

Array-based early threshold voltage recovery characterization measurement

A method, system and program product are disclosed for improving an IC design that prioritize failure coefficients of slacks that lead to correction according to their probability of failure. With an identified set of independent parameters, a sensitivity analysis is performed on each parameter by noting the difference in timing, typically on endpoint slacks, when the parameter is varied. This step is repeated for every independent parameter. A failure coefficient is then calculated from the reference slack and the sensitivity of slack for each of the timing endpoints and a determination is made as to whether at least one timing endpoint fails a threshold test. Failing timing endpoints are then prioritized for modification according to their failure coefficients. The total number of runs required is one run that is used as a reference run, plus one additional run for each parameter.

Slack sensitivity to parameter variation based timing analysis

A method and service of balancing delay in a circuit design begins with nodes that are to be connected together by a wiring design, or by being supplied with an initial wiring design that is to be altered. The wiring design will have many wiring paths, such as a first wiring path, a second wiring path, etc. Two or more of the wiring paths are designed to have matching timing, such that the time needed for a signal to travel along the first wiring path is about the same time needed for a signal to travel along the second wiring path, the third path, etc. The method/service designs one or all of the wiring paths to make the paths traverse wire segments of about the same length and orientation, within each wiring level that the first wiring path and the second wiring path traverse. Also, this process makes the first wiring path and the second wiring path traverse the wire segments in the same order, within each wiring level that the first wiring path and the second wiring path traverse.

Method of generating wiring routes with matching delay in the presence of process variation

A unified test structure having a large number of electronic devices under test is used to characterize both capacitance-voltage parameters (C-V) and current-voltage parameters (I-V) of the devices. The devices are arranged in an array of columns and rows, and selected by control logic which gates input/output pins that act variously as current sources, sinks, clamps, measurement ports and sense lines. The capacitance-voltage parameter is measured by taking baseline and excited current measurements for different excitation voltage frequencies, calculating current differences between the baseline and excited current measurements, and generating a linear relationship between the current differences and the different frequencies. The capacitance is then derived by dividing a slope of a line representing the linear relationship by the excitation voltage. Different electronic devices may be so tested, including transistors and interconnect structures.

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Georgetown, TX, United States of America

Jerry D Hayes