Kazushi Yoshimura

Real-time photodisplacement microscope for high-sensitivity simultaneous surface and subsurface inspection

We have developed a new photodisplacement microscope system for practical use that achieves high-sensitivity simultaneous real-time imaging of surface and subsurface structures from a single space-frequency multiplexed interferogram. In this system a linear region of photothermal displacement is excited on the sample surface for subsurface imaging by a line-focused intensity-modulated laser beam. Surface information such as reflectivity and topography along with the displacement is detected with a charge-coupled device sensor-based parallel heterodyne interferometer. Surface and subsurface information components are space-frequency multiplexed into the sensor signal as orthogonal functions based on a frequency-optimized undersampling scheme, allowing each to be discretely reproduced by using a real-time Fourier analysis technique. Preliminary experiments demonstrate that this system is effective, simultaneously imaging reflectivity, topography, and photodisplacement for the detection of subsurface lattice defects in silicon, at a remarkable speed of only 0.26 s/256x256 pixel area. This new microscope is promising for nondestructive hybrid surface and subsurface inspection and other applications.

Automatic screen-printed circuit pattern inspection using connectivity preserving image reduction and connectivity comparison

Describes a new automatic pattern inspection method which can reliably detect fatal circuit defects without giving false alarms due to circuit patterns with slightly jagged edges. Also described is a high-speed automatic inspection system for screen-printed circuit patterns of an unbaked ceramic layer, known as a green sheet. For fatal defect detection, the connectivity comparison method was adopted. In order to speed up this method and to further improve it, connectivity preserving image size reduction, a new concept, was developed.<<ETX>>

Pattern Inspection Techniques for SEM Image

We have developed pattern inspection techniques for Integrated Circuit elements which use an SEMI (Scanning Electron Microscope). In this paper we will discuss the transformation of low SP1 ratio SEM image signals into binary values, detection techniques using the SEM to detect patterns on insulating materials, and detection algorithms for defects.

In‐line automatic defect repair system for TFT‐LCD production

Abstract An automated circuit repair system was developed for enhancing the yield of nondefective liquid crystal panels, focusing on the resist patterns on the circuit material layer of thin‐film transistor (TFT) substrates prior to etching. The developed system has an advantage over the parallel conventional system: In the former, the repair conditions depend on the type of resist whereas in the latter, the repair parameters must be fine‐tuned for each circuit material. The developed system consists of a resist pattern defect inspection system and a pattern repair system for short and open defects. The repair system performs fine corrections of abnormal areas of the resist pattern. The open‐repair system is equipped with a syringe to dispense resist. To maintain a stable resist diameter, a thermal insulator was installed in the syringe system. As a result, the diameter of the dispensed resist became much more stable than when no thermal insulator was used. The resist diameter was kept within the target of 400±100 μm. Furthermore, a prototype system was constructed, and using a dummy pattern, it was confirmed that the system worked automatically and correctly.