R. Schmitt

Siemens, München, Bavaria, Germany

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Publications (20)19.48 Total impact

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    ABSTRACT: Electron beam probing is applied for test and analysis of miniaturisedMCM structures. Wiring structures are tested for shorts and opens while fullyassembled MCMs are analysed in order to identify process or design problems[1, 2]. An electron beam short/open tester for laminated substrates has beendeveloped and installed. It allows the test of substrates up to a size of300 × 300 mm2 with a spot size ofbelow 30 µm without mechanical movement. The system is automated for routineapplication in the fabrication line. Electron beam probe stations are common tools for design verification and debugging ofintegrated circuits. This type of system was adapted to MCMrequirements. The travel range was extended to 80 × 100 mm2 to allow for waveform measurements anddiagnostics.
    Journal of Electronic Testing 01/1997; 10:55-63. DOI:10.1023/A:1008270430950 · 0.43 Impact Factor
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    ABSTRACT: IC probing with electron beams is already common practice for design verification and failure analysis. These diagnostic methods can be transferred from IC to MCM application. However, conventional e-beam probe stations cannot handle the size of an MCM substrate. Therefore, a new system was developed allowing the beam to probe an area of 100 mm × 80 mm.E-beams can also be applied to the testing of substrates offering flexibility for further MCM developments. A new electron beam MCM substrate tester has been developed and installed in the Siemens-Nixdorf fabrication line. It provides a spot size of below 25 μm to probe pads in a 30 cm × 30 cm field without mechanical movement and without electrical contact. The tester is automated for fabrication environment and ease of operation. More than hundred substrates have already been tested on the system while not missing any defect.
    Microelectronic Engineering 03/1994; DOI:10.1016/0167-9317(94)90055-8 · 1.34 Impact Factor
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    ABSTRACT: IC probing with electron beams is already common practice for design verification and failure analysis. E-beams can also be applied to substrate testing offering flexibility for further MCM developments. A new electron beam MCM substrate tester has been developed and installed in the Siemens-Nixdorf fabrication line. It provides a spot size of below 25 μm to probe pads in a 30 cm×30 cm field without mechanical movement and without electrical contact. The tester is automated for fabrication environment and ease of operation. More than one hundred substrates have already been tested on the system while not missing any defect. Diagnostic methods using electron beams can be transferred from IC to MCM application, However, conventional e-beam probe stations cannot handle the size of an MCM substrate. Therefore, a new system was developed allowing the beam to probe an area of 100 mm×80 mm
    IEEE Transactions on Components Packaging and Manufacturing Technology Part B 03/1994; DOI:10.1109/96.296432
  • R. Schmitt, M. Brunner, D. Winkler
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    ABSTRACT: A contactless electron-beam AM LCD-substrate test for in-process application has been developed, which includes a short-open test of control lines and pixels, and offers methods for a characterization of the active elements (including TFTs, MIMs and diodes). The technique uses e-beam input to the active elements by charging of pixel electrodes at a speed of more than 106 pixels (1 colour VGA plate) per minute. Detection of line defects, pixel shorts as well as variations in the active element performance are demonstrated. These test sequences do not require any external signals supplied to the matrix. In a real operation with control signals supplied e.g. to the shorting bars, internal matrix and driver signals can be probed for diagnostic purposes. These measurements are contactless and non-loading.
    Microelectronic Engineering 03/1994; DOI:10.1016/0167-9317(94)90052-3 · 1.34 Impact Factor
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    ABSTRACT: Miniaturization in electronics packaging technology require the development of new testing methods. Electron beam techniques have already demonstrated their applicability to the testing of multichip module substrates. Broad application of this technique requires a large scanfield in order to gain flexibility in the size of substrates. The electron optics for beam deflection over an area of 25 cm × 25 cm are being developed. Beam focusing and fast positioning have been experimentally realized. An e-beam spot size of 25 μm is attained in any position within the field at a beam current of 140 nA. The settling time of the beam on a 100 μm pad is 30 μs in the worst case.
    Microelectronic Engineering 03/1992; 16(1-4):505-512. DOI:10.1016/0167-9317(92)90373-Y · 1.34 Impact Factor
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    ABSTRACT: Sampling-techniques are used by instruments such as sampling-oscilloscopes or electron-beam testers for measuring voltage waveforms [1,2]. In this paper definitions and measurement procedures are proposed to compare the temporal resolution of different methods and instruments [3,4,5] under practical conditions. The main aspects are phase-stability, rise-time resolution, and cut-off frequency. Whereas the limits for defining time intervals depend on the stability of the time base and phase control, both rise time resolution and cut-off frequency are additionally determined by the sampling gate width. Gate width, switching characteristics of the gate and the phase stability of the trigger control together will result in an effective width and shape of the sampling gate. The measured waveform of a signal is the result of the convolution of this effective sampling gate with the original waveform.
    Microelectronic Engineering 03/1992; 16:245-250. DOI:10.1016/0167-9317(92)90345-R · 1.34 Impact Factor
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    ABSTRACT: This paper reports on the internal signal analysis of a GaAs 1K-SRAM by means of a high-speed e-beam test system developed in our laboratories. It allows noninvasive measurements on signal lines within the circuit with a very high spatial resolution (spot diameter: 0.5 μm) and a delay time resolution better than 3.5 ps.With this technique, it is possible for the first time, to our knowledge, to directly measure internal high-frequency signals of a GaAs LSI circuit, thus obtaining information which is inaccessible by other measurement techniques and allowing an extensive circuit analysis.For example, a measured time budget for the memory could be obtained. Furthermore, the comparison between measured and simulated waveforms enables the designer to directly evaluate the accuracy of the transistor and signal-transmission line models. The waveform measurements on the bit lines during the read process and inside an address buffer of the memory were analysed.
    Microelectronic Engineering 05/1991; 14(2):133-148. DOI:10.1016/0167-9317(91)90160-F · 1.34 Impact Factor
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    ABSTRACT: The miniaturization of microwiring substrates which are used for high-density chip packaging imposes increasing problems on electrical testing. Mechanical probes fail to contact pads reliably in the 50 mum range and are limited to a fixed pad configuration. An electron-beam test system has been developed to overcome these problems. It uses CAD data for flexible beam positioning within a 10 cm × 10 cm field. An electron probe with a spot size of 40 mum is used for charging networks and reading pad voltages. The system has already demonstrated its operation by detecting shorts and opens on a limited number of substrates which were rejected as defective by a mechanical prober during the final test of the current production.
    Japanese Journal of Applied Physics 11/1990; 29:2671-2674. DOI:10.1143/JJAP.29.2671 · 1.06 Impact Factor
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    ABSTRACT: Mechanically probing test systems for the electrical testing of microwiring substrates are reaching their technological and economic limits. An electron beam test system for testing microwiring substrates is presented as an alternative. In contrast to other methods it uses only one primary energy for charging networks and reading their voltage, which results in a simpler instrumentation. The primary energy of 10 keV allows reliable charging of all relevant materials. The pad voltage is read by analyzing the energy of the generated electrons to indicate shorts and opens in the networks. An electron probe of 40 μm diameter can be positioned with a fast electrostatic deflection system to an accuracy of 10 μm on an area of 10×10 cm2 in a current laboratory system. Microwiring substrates with pads down to 100 μm in size can be tested. The test is based on CAD data without restrictions on the layout. Experimental results show reliable fault capture.
    Journal of Vacuum Science & Technology B Microelectronics and Nanometer Structures 11/1990; 8(6):2045-2047. DOI:10.1116/1.584871 · 1.36 Impact Factor
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    ABSTRACT: A high-speed electron-beam tester was developed to measure signals inside integrated high-frequency circuits, in particular those on a GaAs basis. This paper describes the current stage of development. Using electron beam pulses down to only 7 ps makes the tester capable of measurements at frequencies of approx. 60 GHz. Simultaneously a probe diameter of 0.5 μm and a noise voltage at the system output of 2 mV/√Hz are achieved at 2.2 keV acceleration voltage and 1 GHz pulse repetition rate. To meet practical demands a wafer prober was designed extending the application of the tester to on-wafer measurements.A GaAs 1k SRAM is used by way of example to demonstrate the possibilities for practical applications. Extending into the ps range, the high temporal resolution of the tester leads to a detailed comparison between calculated and measured signals. While allowing verifacation of the parameters used for simulation, this also yields useful hints on measures for redesigning the circuit.
    Microelectronic Engineering 05/1990; 12:279-286. DOI:10.1016/0167-9317(90)90042-R · 1.34 Impact Factor
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    ABSTRACT: Die Entwicklung integrierter Mikrowellenschaltungen fr analoge und digitale Anwendungen mit hohen Geschwindigkeiten erfordert neue Memethoden. Fr die Proze- und Schaltungsentwicklung ist vor allem die belastungsfreie Messung interner Signale notwendig. Die bereits bewhrte Elektronenstrahlmetechnik konnte diesen neuen Anforderungen angepat werden. Zeitkritische Gren sind sowohl Signalanstiegszeiten als auch Phasenlagen verschiedener Signale zueinander. Signalanstiegszeiten knnen gegenwrtig bis herab zu 15 ps mit einem Fehler unter 10% gemessen werden. Fr Messungen von Phasenlagen zwischen Signalen, die innerhalb von 3 Stunden aufgezeichnet wurden, ergibt sich eine Genauigkeit von2 ps.The development of integrated microwave circuits for analogue and digital applications with higher speeds requires new testing methods. The process and circuit development primarily require non loding measurements of internal signals. The adaptation of the proven technique of e-beam testing to these new requirements was successfull. Signal rise times as well as phase relations between different signals are critical quantities in the time scale. Presently, rise times can be measured down to 15 ps with an error of less than 10%. Measurements between signals being recorded within 3 hours are possible with an accuracy of2 ps.
    Electrical Engineering 04/1990; 73(3):205-211. DOI:10.1007/BF01574027 · 0.35 Impact Factor
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    ABSTRACT: A newly developed picosecond electron-beam tester has now been utilized for noninvasive internal waveform and propagation-delay measurements of complex high-speed IC's. The high time resolution is achieved by stroboscopically chopping the electron beam. This method allows signal sampling with a 7ps pulse width, at the same time using the numerous measuring possibilities of conventional e-beam testing. The thorough analysis of a 1k GaAs-SRAM with a comparison of simulated waveforms and those measured at internal nodes is an example of the capabilities of the system.
    Microelectronic Engineering 04/1990; DOI:10.1016/0167-9317(90)90190-5 · 1.34 Impact Factor
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    ABSTRACT: The effective design and evaluation of high-speed integrated circuits is supported by internal noninvasive voltage-measurement techniques with picosecond time resolution. An electron-beam tester has therefore been developed which approaches the theoretical time-resolution limit of this method. It is based on the well-established e-beam technique for VLSI circuits, allowing for high flexibility in driving different kinds of high-frequency circuits under both conventional and critical conditions. The electron pulses of the stroboscopic test system are generated by a two-stage chopping system which was optimized to obtain very short pulses. It allows for a 7-ps effective pulse width which simultaneously yields a probe diameter of 0.5 µm and a probe current of 1 nA. This current results in a noise voltage of 20 mV when one period of a 1-GHz signal is recorded, with a total acquisition time of 0.1 s. Long-range phase shifting with high resolution is achieved by operating the upper stage of the blanking system at a high frequency and using the lower one as a selective gate. This allows propagation-delay measurements to be performed with a resolution of better than 2 ps over a range of several µs. The test system has thus far been used for that analysis of tunnel diodes, step-recovery diodes, bipolar frequency dividers, ring oscillators, and GaAs memories. Waveform measurement and evaluation at more than 60 different test points of a GaAs 1-kb SRAM in a six-hour session has demonstrated routine handling of complex high-speed circuit analysis.
    Ibm Journal of Research and Development 04/1990; DOI:10.1147/rd.342.0189 · 0.50 Impact Factor
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    ABSTRACT: Electron-beam testing (‘e-beam’ testing) supports the development of new integrated circuits by allowing a comparison between measured and simulated internal waveforms. It avoids loading of the device under test, especially in the high frequency range of several GHz. The use of a wafer prober in combination with a high-speed e-beam test system extends the application to on-wafer measurements with a time resolution of some picoseconds. The demands made on this prober differ from those made on conventional test adapters since the prober is not used to detect signals but only to supply power and input signals to the device under test. Signals are measured exclusively by the e-beam. This offers an additional advantage since the input signals can be corrected by means of direct control by the e-beam. For example, signal losses or phase shifts due to the prober can be compensated for. While the high-frequency demands are reduced by this correction scheme, many other problems arising from the space limitations within the e-beam tester have to be solved. A new prober allows measurements in a frequency range extending to more than 10 GHz directly on the wafer without the need for cutting, mounting or bonding single chips.
    Microelectronic Engineering 01/1990; 10(2-10):107-113. DOI:10.1016/0167-9317(90)90003-C · 1.34 Impact Factor
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    ABSTRACT: Propagation delay measurements of high-speed digital devices require high accuracy and excellent stability. At the same time, long-range phase shifts are necessary because signals in these circuits may have very long periods. This can be achieved with a newly developed phase shift method, where a blanking capacitor acts as a gate to select one out of a larger number of pulses. A delay of several hundred nanoseconds with picosecond accuracy was demonstrated with this technique. Ultimately, the resolution of propagation delay measurements is limited by variations in the secondary electron transit time. This leads to a shift of the measured waveform, depending on the test point geometry. Errors then result if the propagation delay is measured between points of different dimensions. This effect was evaluated theoretically and experimentally. A difference in conductor width between two test points of a factor of 2 was found to lead to an error of 3ps for propagation delay measurements.
    Microelectronic Engineering 05/1989; 9:453-456. DOI:10.1016/0167-9317(89)90099-3 · 1.34 Impact Factor
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    ABSTRACT: Electron beam testing has recently started to gain importance in GHz integrated-circuit characterization. It competes in this application with several other techniques. The advantages of the e-beam technique are: 1) its flexibility of device operation - pulses, logic signals or sine waves can be input to the device under test and may be changed in frequency between dc and several GHz, 2) its non-loading probe does not affect the function of the device under test, 3) its capability for probing lines below 1 μm. Currently an effective sampling-gate width of 8 ps is achieved, including the influence of pulse duration, timing jitter and transit time effect of secondary electrons. The system bandwidth is therefore approximately 80 GHz. Signal propagation delays of less than 3.5 ps can be resolved. The noise amplitude is 2 mV/√Hz at a 1GHz pulse repetition rate. This allows typical waveforms to be measured within several seconds.
    Microelectronic Engineering 05/1989; 9(1-4-9):405-410. DOI:10.1016/0167-9317(89)90088-9 · 1.34 Impact Factor
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    ABSTRACT: Process technology and internal electron-beam test measurements of fast GaAs ring oscillators in buffered FET logic (BFL) are described. Specifically, the authors fabricated a series of 15-stage BFL ring oscillators consisting of MESFETs with 0.5-μm gates defined by electron-beam lithography. The precise phase shift control of the electron beam sampling system used was the basis for an excellent 3.5-ps resolution of propagation delays. This made it possible to observe not only the time delay effected by individual oscillator stages but even the delay by single transistors. It is shown that the full width of the propagation time distribution comprising circuits on a number of different wafers is already completely reflected by the scatter between neighboring inverters in a single circuit. It is concluded that this result proves the importance of electron-beam measurements to the analysis of which mechanisms influence the behavior of fast digital ICs
    Gallium Arsenide Integrated Circuit (GaAs IC) Symposium, 1988. Technical Digest 1988., 10th Annual IEEE; 12/1988
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    ABSTRACT: An electron beam test system has been developed which allows internal waveform measurements on integrated circuits operating with GHz frequencies. Internal signals of a 7 GHz frequency divider have been recorded. The e-beam system produces 15 ps electron pulses which allow rise time measurements down to 30 ps with less than 10% error and delay measurements below 5 ps
    Electronics Letters 03/1988; 24(4-24):235 - 236. DOI:10.1049/el:19880158 · 1.07 Impact Factor
  • B. Lischke, D. Winkler, R. Schmitt
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    ABSTRACT: The development of new types of very high-speed integrated circuits, such as those based on GaAs, makes extremely high demands on electron beam measuring technology. The limits of this measurement method for the time, voltage and spatial resolution were theoretically investigated. It is found that these parameters are mutually dependent on each other and that improvements in the time resolution can be made only at the expense of the voltage or spatial resolution. The theory allows specific optimization of the electron beam measuring devices inclusive of their electron-optical properties. An experimental system was realized for high speed measurements on GaAs devices. Electron pulse widths of 15 ps were experimentally attained with measuring probes of 0.5 μm diameter and an effective noise voltage of 30 mV. This device was used to investigate various components in the GHz range.
    Microelectronic Engineering 01/1987; DOI:10.1016/0167-9317(87)90004-9 · 1.34 Impact Factor