Abstract: 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.

Abstract: A test structure for measuring resistances of a large number of interconnect elements such as metal, contacts and vias includes an array of test cells in rows and columns. Power is selectively supplied to test cells in a given column while current is selectively steered from test cells in a given row. A first voltage near the power input node of a device under test (DUT) is selectively sensed, and a second voltage near the current measurement tap is selectively sensed. The resistance of the DUT is the difference of the first and second voltages divided by the current. Additional voltage taps are provided for test cells having multiple resistive elements. This array of test cells can be used to characterize the statistical distribution of resistance variation and to identify physical location of defects in resistive elements.

Abstract: A IC wafer is fabricated using a process of interest to have a plurality of FET devices with different channel lengths (Leff) form a plurality of channel length groups. The threshold voltage (VT) is measured of a statistical sample of the FET devices in each channel length group at two different drain-to-source voltage (VDS). The mean of VT is calculated for each channel length and each VDS. A slope coefficient ? relating VT to Leff is calculated at each VDS. The total variance of VT is calculated at each VDS. Two equations at each VDS, each relating the total variance of VT to the variance of VT with respect to dopant levels and the square of the slope coefficient ? times the variance of Leff, are solved simultaneously to obtain the variance of VT with respect to dopant levels and the variance of Leff.

Abstract: A method of measuring threshold voltage variation using a device array provides accurate threshold voltage distribution values for process verification and improvement. The characterization array imposes a fixed drain-source voltage and a constant channel current at individual devices within the array. Another circuit senses the source voltage of the individual device within the array. The statistical distribution of the threshold voltage is determined directly from the source voltage distribution by offsetting each source voltage by a value determined by completely characterizing one or more devices within the array. The resulting methodology avoids the necessity of otherwise characterizing each device within the array, thus reducing measurement time dramatically.

Abstract: A test structure for statistical characterization of local device mismatches contains densely populated SRAM devices arranged in a row/column addressable array that enables resource sharing of many devices. The test structure includes a built-in sensing mechanism to calibrate or null out sources of error, and current steering to avoid negative effects of current leakage along spurious paths. The gate and drain lines of each column are driven from both the top and bottom to minimizes parasitic effects. The system can handle a large number of devices while still providing high spatial resolution of current measurements.

Abstract: A test system and computer program for measuring threshold voltage variation using a device array provides accurate threshold voltage distribution values for process verification and improvement. The test system and computer program control a characterization array circuit that imposes a fixed drain-source voltage and a constant channel current at individual devices within the array. Another circuit senses the source voltage of the individual device within the array. The statistical distribution of the threshold voltage is determined directly from the source voltage distribution by offsetting each source voltage by a value determined by completely characterizing one or more devices within the array. The resulting methodology avoids the necessity of otherwise characterizing each device within the array, thus reducing measurement time dramatically.

Abstract: A moment-based method and system for evaluation of metal layer transient currents in an integrated circuit provides a computationally efficient evaluation of transient current magnitudes through each interconnect in the metal layer. The determinable magnitudes include peak, rms and average current, which can be used in subsequent reliability analyses. Interconnect path nodes are traversed and circuit moments are either retrieved from a previous interconnect delay analysis or are computed. For each pair of nodes, current moments are computed from the circuit moments. The average current is computed from the zero-order circuit moment and the peak and rms currents are obtained from expressions according to a lognormal or other distribution shape assumption for the current waveform at each node.

Abstract: A method for determining threshold voltage variation rapidly provides accurate threshold voltage distribution values for process verification and improvement. The method operates a characterization away including a circuit for imposing a fixed drain-source voltage and a constant channel current at individual devices within the array, while sensing the source voltage of the individual device. The statistical distribution of the threshold voltage is determined directly from the source voltage distribution by offsetting each source voltage by a value determined by completely characterizing one or more devices within the array. The resulting methodology avoids the necessity of otherwise characterizing each device within the array, thus reducing measurement time dramatically.

Abstract: A scannable virtual rail method and ring oscillator circuit for measuring variations in device characteristics provides the ability to study random device characteristic variation as well as systematic differences between N-channel and P-channel devices using a ring oscillator frequency measurement. The ring oscillator is operated from at least one virtual power supply rail that is connected to the actual power supply rail by a plurality of transistors controlled by a programmable source. The transistors are physically distributed along the physical distribution of the ring oscillator elements and each can be enabled in turn and the variation in ring oscillator frequency measured. The ring oscillator frequency measurements yield information about the variation between the transistors and N-channel vs. P-channel variation can be studied by employing positive and negative virtual power supply rails with corresponding P-channel and N-channel control transistors.

Abstract: A test structure for statistical characterization of local device mismatches contains densely populated SRAM devices arranged in a row/column addressable array that enables resource sharing of many devices. The test structure includes a built-in sensing mechanism to calibrate or null out sources of error, and current steering to avoid negative effects of current leakage along spurious paths. The gate and drain lines of each column are driven from both the top and bottom to minimizes parasitic effects. The system can handle a large number of devices while still providing high spatial resolution of current measurements.

Abstract: 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 columnns 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.

Abstract: A characterization array circuit provides accurate threshold voltage distribution values for process verification and improvement. The characterization array includes a circuit for imposing a fixed drain-source voltage and a constant channel current at individual devices within the array. A circuit for sensing the source voltage of the individual device is also included within the array. The statistical distribution of the threshold voltage is determined directly from the source voltage distribution by offsetting each source voltage by a value determined by completely characterizing one or more devices within the array. The resulting methodology avoids the necessity of otherwise characterizing each device within the array, thus reducing measurement time dramatically.

Abstract: An error detection circuit for a latch precharges two dynamic nodes whose discharge paths are gated by true and complement storage nodes of the latch, such that one and only one of the dynamic nodes always discharges when the clock signal transitions from an active state to an inactive state. If a soft error flips the contents of the latch during storage mode the other dynamic node will discharge. A gate having inputs coupled to the dynamic nodes produces an error signal when both nodes have discharged. The error signal can then be used to select between true and complement outputs of the latch. The invention can be implemented in a more robust embodiment which examines the outputs of two error detection circuits to generate a combined error signal that ensures against false error detection when an upset occurs within one of the detection circuits.

Abstract: A IC wafer is fabricated using a process of interest to have a plurality of FET devices with different channel lengths (Leff) form a plurality of channel length groups. The threshold voltage (VT) is measured of a statistical sample of the FET devices in each channel length group at two different drain-to-source voltage (VDS). The mean of VT is calculated for each channel length and each VDS. A slope coefficient ? relating VT to Leff is calculated at each VDS. The total variance of VT is calculated at each VDS. Two equations at each VDS, each relating the total variance of VT to the variance of VT with respect to dopant levels and the square of the slope coefficient ? times the variance of Leff, are solved simultaneously to obtain the variance of VT with respect to dopant levels and the variance of Leff.

Abstract: A characterization array and method for determining threshold voltage variation rapidly provides accurate threshold voltage distribution values for process verification and improvement. The characterization array includes a circuit for imposing a fixed drain-source voltage and a constant channel current at individual devices within the array. A circuit for sensing the source voltage of the individual device is also included within the array. The statistical distribution of the threshold voltage is determined directly from the source voltage distribution by offsetting each source voltage by a value determined by completely characterizing one or more devices within the array. The resulting methodology avoids the necessity of otherwise characterizing each device within the array, thus reducing measurement time dramatically.

Abstract: A test structure for statistical characterization of local device mismatches contains densely populated SRAM devices arranged in a row/column addressable array that enables resource sharing of many devices. The test structure includes a built-in sensing mechanism to calibrate or null out sources of error, and current steering to avoid negative effects of current leakage along spurious paths. The gate and drain lines of each column are driven from both the top and bottom to minimizes parasitic effects. The system can handle a large number of devices while still providing high spatial resolution of current measurements.

Abstract: Embodiments may include a duty cycle controller to adjust the duty cycle of the clock signal based upon a delay signal and an input clock signal. A duty cycle detector may determine signals with frequencies based upon the duty cycle of the output signal and a correction module may compare the frequencies of the detector signals to generate the delay signal. In some embodiments, once the duty cycle of the output clock signal reaches the desired duty cycle such as fifty percent, the correction module may be turned off.