International Business Machines Corporation

Russell W Dreyfus

Gary W Rubloff

Johannes G Beha

Allan Mark Hartstein

Jeffrey Alan Kash

Robert J Von Gutfeld

Jerome J Cuomo

Jerry M Woodall

Francis Charles Burns

John R Susko

Richard A McCorkle

Alfred J Landon

Eugene E Tynan

Nicholas A Penebre

Contactless probing of an integrated circuit is carried out by flooding the surface of the integrated circuit with pulsed ultraviolet laser light, causing photoelectron emission as a function of the potentials at micropoints on the integrated circuit, converting this two-dimensional electron pattern into a corresponding relatively long duration pattern of luminescence by a luminescent target, and reviewing the result by video/computer scanning. Separate embodiments allow testing either in vacuum or in air, with or without insulating passivation layers present on the chip. The result is a contactless oscilloscope which monitors instantaneous voltages (logic states and AC switching waveforms) for a full two-demsnsional array of micropoints simultaneously. A chip with test points and appropriate windows for laser activation and luminescent targeting can be specially designed for optimal testing.

Full chip integrated circuit tester

Covering metal test pads of a passivated integrated circuit process intermediate wafer or completed integrated circuit chip-to-test, with a thin conductive overlayer, and then accessing the test pads through the passivation layer and conductive overlayer, by a pulsed laser to provide voltage-modulated photon-assisted tunneling through the insulation layer, to the conductive overlayer as an electron current, and detecting the resulting electron current, provides a nondestructive test of integrated circuits. The passivation, normally present to protect the integrated circuit, also lowers the threshold for photoelectron emission. The conductive overlayer acts as a photoelectron collector for the detector. A chip-to-test which is properly designed for photon assisted tunneling testing has test sites accessible to laser photons even though passivated. Such a chip-to-test may be nondestructively tested in air at one or several stages of its processing, without the sacrifices of mechanical probing or of bringing test sites out to output pads. The conductive overlayer may be removed after tests have been completed. Integrated circuit process intermediate chips may be specially designed for testability, with test sites grouped for easy access through windows left uncovered by subsequent layers.

Photon assisted tunneling testing of passivated integrated circuits

Testing of integrated circuit process intermediates, such as wafers, dise or chips in various stages of production (test chips) is facilitated by a nonintrusive, noncontact dynamic testing technique, using a pulsed laser, with laser light modification to increase photon energy through conversion to shorter wavelength. The high energy laser light excites electron emissions to pass to the detection system as a composite function of applied light energy and of dynamic operation of the circuit; detecting those emissions by an adjacent detector requires no ohmic contacts or special circuitry on the integrated circuit chip or wafer. Photoelectron energy emitted from a test pad on the test chip is detected as a composite function of the instantaneous input voltage as processed on the test chip, in dynamic operation including improper operation due to fault. The pulse from the laser, as modified through light modification, the parameters of detection of bias voltages, and the distances involved in chip-grid-detector juxtaposition, provides emissions for detection of circuit voltages occurring on the test chip under dynamic conditions simulating actual or stressed operation, with high time resolution of the voltages and their changes on the circuit.

Noncontact dynamic tester for integrated circuits

Contactless probing of an integrating circuit is carried out by flooding the surface of the integrated circuit with pulsed ultraviolet laser light, causing photoelectron emission as a function of the potentials at micropoints on the integrated circuit, converting this two-dimensional electron pattern into a corresponding relatively long duration pattern of luminescence by a luminescent target, and reviewing the result by video/computer scanning. Separate embodiments allow testing either in vacuum or in air, with or without insulating passivation layers present on the chip. The result is a contactless oscilloscope which monitors instantaneous voltage (logic states and AC switching waveforms) for a full two-dimensional array of micropoints simultaneously. A chip with test points and appropriate windows for laser activation and luminescent targeting can be specially designed for optimal testing.

An end point detection technique indicates when a pulsed excimer laser, operating on a chromium clad copper substrate in the presence of chlorine gas, has etched through the chromium layer. The excimer laser vaporizes successive layers of the chromium chloride reaction product, which form on the region being etched, until, when all of the chromium has been removed from the region, a copper chloride reaction product layer forms on the region and is vaporized. A dye laser directs a probe beam into a zone spaced above the region being etched and is pulsed about 12 microseconds after each pulse of the excimer laser to allow time for the vaporized reaction products to reach the zone. The probe beam has a first wavelength of 433.3 nm. which induces the vaporized copper chloride in the zone to fluoresce at a second wavelength of 441.2 nm. A narrow band photodetector detects the fluoresced 441.2 nm. wavelength light to indicate that the end point has been reached, and the detection of the end point is used to terminate the pulsing of the excimer laser to end the etching process.

End point detection and control of laser induced dry chemical etching

Simultaneous noncontact testing of voltages across a full line of test sites on an integrated circuit chip-to-test is achieved with high time resolution using photoelectron emission induced by a pulsed laser focussed to a line on the chip-to-test, together with high speed electrostatic deflection perpendicular to the line focus. Photoelectrons produced by the line focus of pulsed laser light are imaged to a line on an array detector, the measured photoelectron intensities at array points along this line representing voltages at corresponding points along the line illuminated by the laser focus. High speed electrostatic deflection applied during the laser pulse, perpendicular to the direction of the line focus, disperses the line image (column) on the array detector across a sequence of sites at right angles (rows), thereby revealing the time-dependence of voltages in the column of test sites with high time resolution (in the picosecond range).

Noncontact full-line dynamic AC tester for integrated circuits

A high brightness, essentially monoenergetic electron source is constructed in solid state material by providing a semiconductor body with an electron confinement barrier over most of the surface, the barrier having a relatively small opening exposing the semiconductor body, in the relatively small opening a material is placed in contact with the semiconductor body that has a work function that is lower than the energy of excited electrons in the semiconductor. In this structure electrons from hole-electron pairs generated in the semiconductor are repelled and recombination is inhibited by the barrier except in the relatively small opening where they are injected into the surrounding environment through the lower work function material. The hole-electron pair generation may be by irradiation or by electrical injection. The electron source is useful for such applications as high brightness sources, digital communications, cathode ray tube electron sources and scanning electron microscopes.

Electron source

Pulsed light is applied through a plano concave lens to a thin metal film, which is evaporated on the concave side of the lens. The lens, which is formed of a high thermally insulating material such as glass, for example, and the film are disposed within a liquid such as water, for example. The pulsed light is absorbed by the metal film, which converts the thermal energy produced by the pulsed light into elastic waves in the form of acoustic waves and simultaneously focuses the acoustic waves on an object within the water at a selected focal plane. The metal film is as thin as possible, consistent with complete absorption of the light energy by the metal film, so as to utilize the high thermal expansion coefficient of the water.

Method and apparatus for focusing elastic waves converted from thermal

The present invention describes an ion gun which is capable of producing relatively high density ion currents. The ion gun employs at least one capillary duct the surface of which is semiconducting and has secondary electron emission coefficient greater than one to generate ions from a source of an ionizable material and to accelerate the ions so generated.

Microchannel ion gun

A versatile microsecond multiple framing camera generates a switched beam of illumination derived from a laser and switched by an acousto-optic modulator. The illumination is focused on a subject, and illumination from the subject is caused to scan over a predetermined field by a mechanical or electromechanical scanner. Located in the field is an image recording device for recording the illumination directed over the field by the scanner. The image recording device, in one embodiment, includes a vidicon tube, for short term storage, and a video recorder for longer term storage. A video monitor may be driven from the video recorder. The versatility of the camera is exemplified by the ability to vary exposure times or frame rates by adjusting operator controls which drive the acousto-optic modulator and/or the electromechanical scanner. In other embodiments, the vidicon tube and video recorder can be replaced or supplemented by photographic film.

Versatile microsecond multiple framing camera

An electron beam pumped gas laser includes an evacuated cavity adapted to house a lasing gas and an electron beam launching means (such as a field emission diode). Means are provided to insert a lasing gas into the cavity so as to produce a traveling density discontinuity. The diode is energized prior to the time the traveling density discontinuity reaches it so as to launch an electron beam under substantially evacuated conditions. The principles of the invention can also be applied to gaseous electron beam transport.

Growing community of inventors

Mt. Kisco, NY, United States of America

Russell W Dreyfus