Credence Systems Corporation

Schlumberger Technologies, Inc.

Dcg Systems Gmbh

Nptest, Inc.

University of Rochester

Kenneth R Wilsher

Steven Kasapi

William K Lo

Gary Leonard Woods

Nina Boiadjieva

Roman Sobolewski

Oleg V Okunev

Grigory N Gol'tsman

Nagamani Nataraj

Alexey D Semenov

Theodore R Lundquist

Neil W Richardson

Romain Desplats

Philippe Perdu

Francis Ho

Praveen Vedagarbha

Felix Beaudoin

Radu Ispasoiu

Suresh N Rajan

Martin D Leibowitz

A system for probing a DUT is disclosed, the system having a pulsed laser source, a CW laser source, beam optics designed to point a reference beam and a probing beam at the same location on the DUT, optical detectors for detecting the reflected reference and probing beams, and a collection electronics. The beam optics is a common-path polarization differential probing (PDP) optics. The common-path PDP optics divides the incident laser beam into two beams of orthogonal polarization&#x2014;one beam simulating a reference beam while the other simulating a probing beam. Both reference and probing beams are pointed to the same location on the DUT. Due to the intrinsic asymmetry of a CMOS transistor, the interaction of the reference and probing beams with the DUT result in different phase modulation in each beam. This difference can be investigated to study the response of the DUT to the stimulus signal.

Apparatus and method for probing integrated circuits using polarization difference probing

An apparatus and method for laser probing of a DUT at very high temporal resolution is disclosed. The system includes a CW laser source, a beam optics designed to point two orthogonally polarized beams at the same location on the DUT, optical detectors for detecting the reflected beams, collection electronics, and an oscilloscope. The beam optics defines a common-path polarization differential probing (PDP) optics. The common-path PDP optics divides the laser beam into two beams of orthogonal polarization. Due to the intrinsic asymmetry of a CMOS transistor, the interaction of the beams with the DUT result in different phase modulation in each beam. This difference can be investigated to study the response of the DUT to the stimulus signal.

Apparatus and method for probing integrated circuits using laser illumination

A system for probing a DUT is provided, the system comprising a tunable or CW laser source, a modulator for modulating the output of the laser source, a beam optics designed to point a probing beam at a designated location on the DUT, optical detector for detecting the reflected beam, and collection and signal processing electronics. The system deciphers perturbations in the reflected beam by detecting beat frequency between operation frequency of the DUT and frequency of the modulation. In an alternative embodiment, the laser is CW and the modulation is applied to the optical detector.

Method and apparatus for measuring high-bandwidth electrical signals using modulation in an optical probing system

PICA probe system apparatus is described, including apparatus for calibrating an event timer having a coarse measurement capability in which time intervals defined by clock boundaries are counted and a fine measurement capability in which time between boundaries is interpolated using a voltage ramp.

PICA system timing measurement and calibration

A single-photon detector includes a superconductor strip biased near its critical current. The superconductor strip provides a discernible output signal upon absorption of a single incident photon. In one example, the superconductor is a strip of NbN (niobium nitride). In another example, the superconductor strip meanders to increase its probability of receiving a photon from a light source. The single-photon detector is suitable for a variety of applications including free-space and satellite communications, quantum communications, quantum cryptography, weak luminescence, and semiconductor device testing.

Superconducting single photon detector

A method and system of testing integrated circuits (IC) via optical coupling. The optical system includes an optical fiber, fixture and focusing element. In addition, channels are provided in the fixture mounted on the integrated circuit to accommodate the optical system. The fixture acts as a heat sink. As such, one or more photosensitive elements/targets on the integrated circuit are probed using light that is brought to a focus on each target site. The light causes latching of data into the integrated circuit (which is operating under influence of a test program) and formation of a test pattern output from the integrated circuit that is used to confirm proper functioning of the IC.

Optical coupling for testing integrated circuits

A method and system of testing integrated circuits (IC) via optical coupling. The optical system includes an optical fiber, fixture and focussing element. In addition, channels are provided in the fixture mounted on the integrated circuit to accommodate the optical system. The fixture acts as a heat sink. As such, one or more photosensitive elements/targets on the integrated circuit are probed using light that is brought to a focus on each target site. The light causes latching of data into the integrated circuit (which is operating under influence of a test program) and formation of a test pattern output from the integrated circuit that is used to confirm proper functioning of the IC.

A method and apparatus for laser-assisted fault mapping which synchronizes the laser control with the tester unit. The inventive method provides for laser-assisted pseudo-static fault mapping to localize defects in a device whose inputs are being stimulated dynamically by a tester. It further provides for laser-assisted dynamic soft error mapping, to localize in terms of location and to correlate with respect to a specific test vector, sensitive areas in a device by utilizing device performance criteria such as pass-fail status outputs. The apparatus includes a fully controllable dynamic laser stimulation apparatus connected to a control unit that provides complete synchronization with a tester unit.

Spatial and temporal selective laser assisted fault localization

A system and method for determining precisely in-situ the endpoint of halogen-assisted charged particle beam milling of a hole or trench in the backside of the substrate of a flipchip packaged IC. The backside of the IC is mechanically thinned. Optionally, a coarse trench is then milled in the thinned backside of the IC using either laser chemical etching or halogen-assisted charged particle beam milling. A further small trench is milled using a halogen-assisted charged-particle beam (electron or ion beam). The endpoint for milling this small trench is determined precisely by monitoring the power supply leakage current of the IC induced by electron-hole pairs created by the milling process. A precise in-situ endpoint detection signal is generated by modulating the beam at a reference frequency and then amplifying that frequency component in the power supply leakage current with an amplifier, narrow-band amplifier or lock-in amplifier. The precise, in-situ, endpoint signal is processed and displayed for manual or automatic precise in-situ endpoint detection. This approach avoids or minimizes unintentional damage or perturbation of the active diffusion regions in the IC. A range of further operations on the IC can then be performed.

Precise, in-situ endpoint detection for charged particle beam processing

PICA probe system methods and apparatus are described, including methods and apparatus for calibrating an event timer having a coarse measurement capability in which time intervals defined by clock boundaries are counted and a fine measurement capability in which time between boundaries is interpolated using a voltage ramp.

PICA system timing measurement & calibration

A single photon detector includes a superconductor strip biased near its critical current. The superconductor strip provides a discernible output signal upon absorption of a single incident photon. In one example, the superconductor is a strip of NbN (niobium nitride). In another example, the superconductor strip meanders to increase its probability of receiving a photon from a light source. The single-photon detector is suitable for a variety of applications including free-space and satellite communications, quantum communications, quantum cryptography, weak luminescence, and semiconductor device testing.

A method and apparatus for accessing internal nodes of an integrated circuit using a package substrate are provided. Embodiments of the present invention include an integrated circuit comprising an integrated circuit die comprising a principal side; a conductive element formed on the principal side of the integrated circuit die; a package substrate comprising a principal side facing the principal side of the integrated circuit die; a conductive element located on the principal side of the package substrate; a transmission path wherein a first end of the transmission path is coupled to the conductive element of the integrated circuit die and wherein a second end of the transmission path is coupled to the conductive element of the package substrate.

Method and apparatus for accessing internal nodes of an integrated circuit using IC package substrate

A method of probing voltage comprises: establishing electrical connectivity between a conductor to be probed and a first terminal of a photoconductive switch; during a sampling interval n, applying a laser pulse to the photoconductive switch while applying a voltage to a second terminal of the photoconductive switch corresponding to a voltage sample taken during a prior sampling interval n&minus;1, such that current flow through the photoconductive switch is dependent on any difference between voltage of the conductor and the applied voltage; converting the current flow to a voltage signal; passing the voltage signal during a gating interval and sampling the passed voltage signal to produce a voltage sample for the sampling interval n. A repetitive test pattern applied to the conductor and the sampling interval is synchronized with the repetitive test pattern. Converting the current flow to a voltage signal can comprise applying the current flow to a current-to-voltage converter having a rise time which is less than the gating interval. The voltage signal can be passed only during the gating interval so that the voltage sample is insensitive to any leakage through the photoconductive switch outside of the gating interval. Passing the voltage signal during a gating interval can comprise applying the voltage signal to a first transistor Q of a differential pair of transistors Q Q applying a reference voltage to a second transistor Q of the differential pair of transistors, and controlling common emitter current of the differential pair of transistors with an electronic switch so as to pass the voltage signal when the electronic switch is closed. Sampling the voltage signal can comprises applying the voltage signal to an analog-to-digital converter and enabling the analog-to-digital converter to prepare a digital sample of the voltage signal representing voltage on the conductor. Apparatus for carrying out the method is also provided.

Photoconductive-sampling voltage measurement

Method and on chip circuitry for testing integrated circuits, for instance, flip chip integrated circuits. Provided on the integrated circuit in addition to the conventional circuitry is additional circuitry including a photosensitive element such as a photodiode, the output terminal of which is connected via a Schmidt trigger to the clock terminal of an on-chip flip-flop. The node of the integrated circuit to be tested, for instance, the output terminal of a logic gate, is connected to the D input terminal of the same flip-flop. Hence, light incident on the photosensitive element clocks the flip-flop, allowing sampling of the state of the output signal from the logic gate. Advantageously, the photodiode need not be a specially made structure but in one version is the conventional PN junction provided by, e.g., the drain of a standard CMOS transistor.

On-chip optically triggered latch for IC time measurements

Optical interferometery is used to probe an integrated circuit device under test (DUT). During each cycle of a repetitive electrical test pattern applied to the DUT a reference pulse is provided at a fixed time relative to the test pattern, and a probe pulse is provided at a time scanned through the test pattern in the manner of equivalent time sampling. The probe and reference light pulses are each split to provide at least a second probe pulse and a second reference pulse. One probe pulse and one reference pulse interact with the DUT at the same physical location, but at displaced times with respect to each other. The second probe pulse and the second reference pulse travel an optical delay path with length controlled to compensate for motions of the DUT. The probe pulses are recombined and detected to provide a probe interference signal. The reference pulses are recombined and detected to provide a reference interference signal. For each cycle, electrical activity in the DUT is detected by preparing a ratio of the probe interference signal and the reference interference signal.

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Palo Alto, CA, United States of America

Kenneth R Wilsher