Matthias Brunner

Electron-beam MCM testing and probing

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 /spl mu/m to probe pads in a 30 cm/spl times/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/spl times/80 mm. >

Application of high-speed electron-beam testing in solid-state electronics

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.

Non-invasive waveform measurements of IC-internal GHz signals in A ps time scale

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.

Electron-beam testing of flat panel display substrates

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 10 6 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.

CAD-based electron-beam testing of micropackaging boards

Abstract Advances in microelectronic packaging towards miniaturization and integration require new substrate-testing techniques to be developed. A new electron-beam test system has been built which allows substrates with pads of less than 200 μm in size to be tested. The test sequence and beam positioning are computer controlled using CAD data of the substrate layout. A test of a micropackaging board with 5000 pads requires less than one minute of testing time. The system avoids switching between different primary beam energies, thus yielding high positional accuracy and simple electron optics. A primary energy of 10 keV was found to allow pads of any material to be charged. System performance and practical results are reported. Relevant effects such as insulator charging, microfields, charge retention and random network charging are investigated to secure reliable operation.

Electron-beam substrate testing approaches 25 cm × 25 cm

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.

63.4: Invited Paper: Issues and Challenges Associated with Electrical Testing of Large LCD-TV Arrays

Manufacturing yields at Generation 6/7/8 TFT-LCD fabs will be a key determinant of LCD TV production costs. Electrical testing of the completed transistor array (“array test”) is a critical element of every manufacturers yield management strategy. Array test equipment vendors face a number of daunting and seemingly contradictory demands from panel makers — faster throughput and better detection despite larger glass and more complicated pixel structures. Meeting these demands requires innovation in test technology and methodology as well as in mechanical design and operation. This paper describes a few of the technical developments and platform improvements pursued by AKTs electron-beam array test group (EBT) as it seeks to meet the challenge of testing large LCD TVs.

Contactless testing of multi-chip modules

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.

Specifications for sampling techniques in the time domain definition and measurement

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.

On-wafer picosecond e-beam testing applied to complex high-speed IC's

Abstract A newly developed picosecond electron-beam tester has now been utilized for noninvasive internal waveform and propagation-delay measurements of complex high-speed ICs. 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.