Abstract: Methods of and apparatus for detecting pixel element defects in flat panel display (FPDs). Floating pixel elements (FPes) of uncompleted active plates in a manufacturing process are activated with high frequency AC test signals having frequencies higher than frequencies encountered by pixels of completely manufactured FPDs during normal display operation. Application of such high frequency test signals allows detection of pixel defects of pixel elements that exhibit an electrical open circuit at normal display operation frequencies. Because the methods and apparatus allow testing prior to FPD plates being completely manufactured and prior to FPD final assembly, pixel defects can be detected early in the display manufacturing process, thereby resulting in a substantial reduction in production costs.

Abstract: Methods of and apparatus for detecting pixel element defects in flat panel display (FPDs). Floating pixel elements (fpes) of uncompleted active plates in a manufacturing process are activated with high frequency AC test signals. In response to the activation signal, a high frequency output signal is produced by a voltage divider formed by an impedance of the fpe under test and an impedance presented by high frequency elements (e.g. stray capacitances) associated with the fpe under test. A signal characteristic (e.g. the amplitude) of the output signal is compared to an expected characteristic to determine the presence of pixel element defects. The methods of the present invention may be performed prior to completion of the active plate, e.g., prior to forming a liquid crystal between plates of a passive matrix LCD and prior to coating a partially formed OLED active plate with light emitting organic material layers.

Abstract: A CRT gun is used to inspect substrates in a voltage contrast system. The CRT gun directs a beam of electrons at the substrate, which is at least partially disposed in a vacuum chamber. The vacuum chamber is evacuated and provided with an electron detector to sense secondary electron emission due to impingement of the electron stream on the substrate. In an alternative embodiment, a plurality of CRT guns are used in conjunction with a common vacuum chamber. The plural CRTs may share a common electron detector, or may each be provided with an associated electrostatically isolated detector. The system is preferably used to detect flat panel displays (FPDs) during manufacture.

Abstract: A system for testing field effect flat panel displays (FEFPDs) disposes the FEFPD in a vacuum and measures electron stream emission from selectively activated pixels of the FEFPD. Selective activation is effected using a linear stage mechanism associated with each contact pad of the FEFPD. Each linear stage mechanism comprises an electrically conducting ball bearing which is rolled over the associated contact pad to thereby complete an electrical circuit between an activation signal source and the electrodes of the pixel under test.

Abstract: Transport of a workpiece into and out of high vacuum conditions is achieved using a vacuum handler having an ante-chamber which buffers a vacuum lock and other mechanically vulnerable components from high pressure differences. During loading of the workpiece, the ante-chamber is vented to atmospheric pressure while the vacuum lock door is sealed closed. The antechamber is then opened and receives the incoming workpiece from the exterior of the vacuum handler. The ante-chamber is then closed and evacuated to the pressure level of the vacuum lock, which is only opened once this pressure level is achieved. The vacuum lock receives the workpiece and is evacuated to the pressure of the main vacuum chamber of the vacuum handler and then opened thereto. An elevator assembly transports the workpiece into the vacuum chamber for processing. The process is reversed during unloading of the workpiece from the vacuum handler following processing completion.

Abstract: Testing of flat panel displays (FPDS) during manufacture is effected using an E-beam testing system operating in conjunction with unique signal processing and analysis. The E-beam testing system stimulates secondary electron emission by the thin film transistors (TFTs) of the FPD which is proportionate to the voltage of the TFTs. The TFTs, which are simultaneously activated by predetermined activation signal waveforms, exhibit voltage response patterns which are indicative of their operational condition. The response signal patterns are correlated with one or more test signals each associated with a matched filter whose output is dependent on the degree of similarity between the voltage signal and a test signal. The E-beam system uses a CRT gun to direct a beam of electrons at the substrate, which is at least partially disposed in a vacuum chamber.

Abstract: Improved techniques for imaging high-aspect-ratio structures such as contact holes utilize two signal detection sub-systems, one optimized for imaging at the top and another optimized for imaging at the base of submicrometer structures. These detection systems produce signals that can be combined in real-time to produce an image which resembles the "extended focus" images obtained with confocal optical microscopes. Unlike the confocal image, however, the resulting image has the inherent linearity and resolution characteristics of electron-beam technology. Using the new approach, the signal, rather than exhibiting a near-zero minimum at the base of the structure as is typical of the prior art, exhibits its maximum at the base of the structure, allowing high-precision measurement with no need for extrapolation.

Abstract: The precision of measurements of feature dimensions of objects using a particle beam device is improved by setting upper and lower signal reference levels and a signal offset level, performing a preliminary scan of the object using the particle beam device to produce a time-quantized and level-quantized signal indicative of a surface profile of the object, determining a percentage of time intervals during which the signal lies outside a range defined by the upper and lower signal reference levels, and processing the signal by adjusting at least one of the signal reference levels and the offset level such that the foregoing percentage becomes substantially equal to a predetermined percentage. In other words, the percentage of "outliers" in a profile, that is the number of pixels that exceed full scale in a video range, is limited to a predetermined percentage, for example one percent. Clipping distortion is therefore minimized.

Abstract: The present invention describes a loading system for high speed loading of wafers, such as semiconductor wafers, into vacuum chambers for various applications such as inspection or processing using, for example, a SEM. This system provides low contamination from atmospheric conditions both on loading and unloading the wafers.

Abstract: The present invention describes a loading system for high speed loading of wafers, such as semiconductor wafers, into vacuum chambers for various applications such as inspection or processing using, for example, a SEM. This system provides low contamination from atmospheric conditions both on loading and unloading the wafers.

Abstract: A computerized stage assembly for a Scanning Electron Microscope including a support frame, a tilt frame pivotally coupled to the support frame, an X carriage engaged with the tilt frame for movement in an X direction, a Y carriage engaged with the X carriage for movement in a Y direction, and a pedestal carried by the Y carriage and capable of rotation around an axis substantially normal to both the X and Y directions. The tilt frame, X and Y carriages, and pedestal are moved by computer controlled step motors. The tilting and rotating of a specimen secured to the pedestal is non-eucentric, i.e. the axis of rotation or tilt is not necessarily through the point of inspection on the specimen. A method is disclosed for automatically returning an inspection point to the viewing field of the microscope after a non-eucentric rotation or tilt.

Abstract: A system for transfering discs, such as integrated circuit wafers during manufacture, from a location at atmospheric pressure into a vacuum chamber of an electron microscope or the like with a minimum of vacuum loss to the chamber. A wafer is placed on a moveable holder in a small sealable chamber having a sealable top door and which is mounted to the outer surface of the vacuum chamber at the position of a small gate through the chamber wall. The wafer holder carries a magnet that is magnetically coupled to a second magnet outside of the sealable chamber and which is motor driven to transfer the wafer through the gate and into the vacuum chamber and upon a stage that has a three-point grasping mechanism operated by the leading end of the moving wafer holder. The wafer holder includes a solenoid operated clip that engages the leading edge of a wafer during pick-up of the wafer for its removal from the vacuum chamber.

Abstract: In scanning electron microscopes the field established between the focusing lens housing at ground potential and the secondary emission electron detector at a positive potential attracts and carries the secondary electrons to the detector. This field is often displaced from the secondary emission source so that much of the emission is attracted to other areas of the microscope and is lost to the detector. To greatly improve detection efficiency, an electron attracting grid at a potential between that on the detector and the focusing lens housing ground reference potential is interposed between the detector and the specimen and positioned so that the new field established between grid and lens housing dips down toward the specimen surface and thus collects substantially all of the secondary emission electrons which then are attracted to higher potential on the detector.