Siemens Aktiengesellschaft

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Hans D Brust

Johann Otto

A method and apparatus provide compensation of frequency drift phenomenon of a signal to be investigated in an electron beam measuring unit. A regulating signal is acquired from the signal to be investigated and the modulation frequency (f.sub.b) of a beam blanking generator in the electron beam measuring arrangement is modified therewith in accordance with the frequency drift in the investigated signal.

Automatic frequency follow-up in particle beam metrology upon employment

In the method and apparatus for the phase measurement of arbitrary signals at a measuring point, for example, of surface waves on piezoelectrical substrates, the surface waves are excited on the surface of a specimen having piezoelectrical features. The measuring point on the specimen surface is scanned by a particle beam and a secondary electrical signal at the measuring point is supplied to an evaluation circuit via a detector. A phase detector within the evaluation circuit is operated in a linear region of its output characteristic curve with the use of a feedback. This makes it possible to keep the phase at the phase detector constant. The phase of the signal to be examined, for example, of the surface wave, which is produced at a interdigital transducer is influenced due to the feedback.

Method and apparatus for phase measurement of signals at a measuring

Voltage measurement with a particle probe without external trigger signal. Methods and apparatus are provided for voltage measurement with a particle probe without an external trigger signal of a signal having at least one fixed frequency, fs. The known arrangements for voltage measurement with an external trigger signal remain fundamentally unaltered; however, the required trigger signal is derived from the measured signal itself.

Voltage measurement with an electron probe without external trigger

Method and arrangement for recording periodic signals with a laser probe. The application of stroboscopic methods in laser metrology requires the synchronization of the measuring arrangement (scanning laser microscope) with the periodic signal excited in the electronic component to be investigated. Since short laser pulses are very difficult to generate in response to a trigger signal, an attempt is made to derive the module clock from the pulse repetition rate of the laser. This type of synchronization requires complex apparatus particularly when the required clock frequency lies above the pulse repetition rate of the laser. In accordance with the present invention, therefore, a synchronization of the measuring arrangement and of the component is eliminated. In order to assign the proper point in time within the period of the signal to the measured values, the chronological spacing of the laser pulses allocated to the measured values are identified relative to a trigger signal that is synchronous with the signal to be recorded.

Method and arrangement for recording periodic signals with a laser probe

A method for function checking microelectronic components inside LSI circuits, particularly during the development phase, provides localization and imaging of regions of a specimen which carry defined signals that depend on the operating status of the cirucit. For localizing the points carrying the defined electrical signals, a primary beam reads the signal at the measuring point and a secondary signal derived therefrom is compared in a detector arrangement to the anticipated or sought-after signal by a correlation method. For the correlation, the intensity of the primary beam or the current of the secondary particles are modulated alternately with the sought-after or anticipated signal and, respectively, with the negation of the sought-after or anticipated signal and the measured secondary signal is integrated. Part of the integrated secondary signal changes with the frequency prescribed by the signal change, which is filtered out and supplied to an evalutor circuit which controls the intensity of a display, such as a picture screen.

Method and apparatus for identifying points on a specimen having a

Evaluating method and apparatus for a test voltage by use of a bandwidth-limited evaluation circuits. For evaluation of a measured signal dependent on a variable parameter, an identification is first undertaken with a broad-band evaluation circuit to determine whether an interesting sub-region of the overall variation region of the parameter has been reached. When this is the case, then a reduction of the bandwidth of the evaluation circuit and a reduction of the variation rate of the parameter occurs in order to be able to evaluate with high sensitivity in the interesting sub-region.

Method and arrangement for evaluating a test voltage by means of a

During line-by-line scanning of a specimen surface by a primary beam of a scanning microscope, a predetermined specimen region is emphasized by comparing deflection voltages of a deflection means of the primary beam to variable comparison voltages and thereby generating a control signal which indicates whether a scanned point on the specimen surface lies within a predetermined region. The control signal is used to vary one or more scan parameters, such as the scan rate, the bandwidth of an evaluation circuit, or the intensity of the primary scan beam. An alternate embodiment includes an analog function network to generate the control signal.

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Dudweiler, Germany

Hans D Brust