Abstract: 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.

Abstract: For observing material structures and/or dynamic processes at surfaces, the known scanning tunneling microscope (STM) is combined with a photoexcitation process leading to photon-assisted tunneling. Thereby, the very fine spatial resolution of the STM is combined with the picosecond or even femtosecond time resolution of laser pulses. The tunnel tip of a scanning tunneling microscope is positioned at tunnel distance with respect to the surface of the sample to be investigated, with an appropriate potential applied across the gap between the tunnel tip and the sample. The tunneling current is gated by means of at least one pulsed laser beam directed at the tuneling region and/or at the tunnel tip.

Abstract: 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.

Abstract: 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.