Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – Of individual circuit component or element
Patent
1993-08-03
1995-08-22
Karlsen, Ernest F.
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
Of individual circuit component or element
3241581, G01R 3128
Patent
active
054443849
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention refers to a method as well as to a device for contactless measurement of electric voltages in a unit under measurement including an insulating surface and at least one conducting zone lying below the insulating surface.
In particular, the present invention deals with the contactless measurement of electric voltages of conducting zones within passivated, integrated circuits as a non-destructive measurement method and with a measuring device which is suitable for carrying out such a method.
BACKGROUND OF THE INVENTION
Methods for contactless measurement of electric voltages within integrated circuits having a passivated surface are known from E. Menzel, R. Buchanan "Electron Beam Probing of Integrated Circuits" Solid State Technology, December 1985, pages 63 to 70. The measurement device used for carrying out the known contactless voltage measurement method consists of a modified scanning electron microscope and of an electronic control unit. The integrated circuit to be examined is positioned in an evacuated measuring chamber. A primary electron beam generating device directs a primary electron beam onto the surface of the integrated circuit in the "spot mode". This radiation has the effect that secondary electrons are released from the surface of the integrated circuit, the energy of the secondary electrons depending on the potential of the measuring point in the integrated circuit. This energy of the secondary electrons is measured with the aid of a spectrometer. Conclusions with respect to the voltage at the measuring point can be drawn from the measured energy of the secondary electrons. The practical use of this known measurement method as well as of this known measuring device will, however, entail various measuring errors. An essential cause of these measuring errors is the trajectory contrast, which is caused by an inhomogeneous field distribution above the conducting tracks of the integrated circuit. Such inhomogeneous field distribution may, for example, be caused by a crosstalk of the signals from bonding wires or from a neighboring conducting track. In order to reduce the measuring errors caused by the trajectory contrast, it is also known to make use of an absorption net, which is arranged above the integrated circuit and which has applied thereto a high positive voltage in the order of 1000 to 2000 volts.
The technical publication S. Gorlich, K. D. Herrmann, W. Reiners, E. Kubalek "Capacitive Coupling Voltage Contrast" Scanning Electron Microscopy, 1986, II, pages 447 to 464, already discloses that the above-described principle of contactless voltage measurement may also be used in connection with integrated circuits, which, for reasons of protection, are covered with a glass-like passivation layer. This passivation layer defines an insulating surface covering the conducting zones of the integrated circuit. When the above-described measurement method is applied to passivated, integrated circuits, secondary electrons will be generated on the insulating surface. The measurement of the potentials of the conducting zones below the insulating surface is made possible by a capacitive coupling between the conducting zones and the insulating surface of the passivation layer.
The measurement of potential variations of a conducting track with the aid of capacitive coupling is, however, only possible in the case of low positive voltages of the absorption net. The use of high absorption voltages will result in a charging of the insulating surface, and this will cause a high potential barrier above the circuit. It follows that, in addition to the measuring errors caused by capacitive coupling, described in W. Reiners, "Kapazitiver Potentialkontrast - Theoretische Deutung und technische Nutzung beim Elektronenstrahl-Test passivierter, hochstintegrierter Bausteine" Diss. 1989, Universitat Duisburg, Fachbereich Elektrotechnik, errors caused by the trajectory contrast will occur due to the possible absorption voltages which can be used in such a contactless meas
REFERENCES:
patent: 3535516 (1970-10-01), Munakata
patent: 3628012 (1971-12-01), Plows et al.
patent: 4486660 (1984-12-01), Feuerbaum
patent: 4577147 (1986-03-01), Frosien et al.
patent: 4748407 (1988-05-01), Brunner et al.
patent: 4864228 (1989-09-01), Richardson
Menzel, et al., "Electron Beam Probing of Integrated Circuits," in Dec. ie of Solid State Technology, pp. 63-70, 1985.
Gorlich, et al., "Capacitive Coupling Voltage Contrast," in vol. II, Scanning Electron Microscopy, pp. 447-464.
W. Reiners, "Kapazitiver Potentialkontrast-Theoretische Deutung und technische Nutzung beim Elektronenstrahl-Test passivierter, hochstintegrierter Bausteine" Diss. 1989, Universitat Duisburg, Fachbereich Elektrotechnik.
Lackmann Rainer
Weichert Gerhard
Dougherty Ralph H.
Fraunhofer-Gesellschaft zur Forderung der ange-wandten Forschung
Karlsen Ernest F.
LandOfFree
Method and device of contactless measurement of electric voltage does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and device of contactless measurement of electric voltage, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and device of contactless measurement of electric voltage will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2144501