International Business Machines Corporation

Hugo K Seitz

Rolf Clauberg

Johannes G Beha

Armin U Blacha

Ernst H Rothauser

Armin U Blancha

This chip-to-test (1) has a passivation layer and an overlayer at test points (4). The system comprises a vacuum chamber (8), means (2) for mounting and connecting the chip-to-test (1), a pulsed light source means (9) operable to scan the chip-to-test (1) for inducing photoelectron (15) emission therefrom, means (14) for exercising the circuits of the chip-to-test (1), means (18) for detecting the photoelectrons (15), having a detection threshold and delivering a sequence of signals representative of voltages at the currently scanned test point (4') or points as a function of the scanned point or scanning time, means (23) for flooding the chip-to-test (1) with electrons of energy lower than the detection threshold, means (21) for analyzing said sequence of signlas and means (22) for deriving therefrom a capacitive voltage contrast. The material of the overlayer has a work function lower than the photon energy and can be BeO, MgO, CaO, TiO2, more preferably SrO, Cs2O, BaO or a mixture thereof. This system facilitates testing of a chip-to-test whose passivation layer has a work function above the photon energy, and prevents charging-up of the passivation layer.

Method and system for contactless testing of electronic activity in an

For testing the integrity of conducting lines on or in a substrate, the following steps are executed: (I) Selected pads are irradiated by a focused optical beam so that they are positively charged due to photon-assisted tunneling of electrons from those pads. The charges propagate through existing conductors so that all selected pads and all pads connected to them assume a specific voltage. (II) The whole surface is irradiated by a flooding optical beam. Photon-assisted tunneling of electrons will now occur from those pads which were not charged previously. (III) The tunneling electrons excite an electroluminescent layer whose illumination reveals the spatial distribution of uncharged pads. This method is performed in air under atmospheric conditions and allows completely contactless testing of circuitry to detect line interruptions as well as shortcuts between separate lines. It is suited for surface lines, buried lines and for via connections.

Method for contactless testing of conducting paths in a substrate using

A method for contactlessly testing for opens and shorts in conducting paths within or on a nonconducting substrate. There are a plurality of conducting pads on the surface of the substrate. Charges are contactlessly generated, e.g., by an optical beam, in at least one selected pad inducing a voltage thereon and on pads electrically connected therewith through one of the conducting paths. A two dimensional electron flux is contactlessly caused to be emitted from the selected pad and at least one other pad of the plurality of pads, e.g., by an optical beam. The flux emitted from the pads depends on the voltage on each pad. The flux is detected to distinguish pads in electrical connection.

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Wollerau, Switzerland

Hugo K Seitz