Horiba, Ltd.

Dainichiro Kinoshita

Toyoki Kanzaki

Takashi Hagiwara

Minoru Taniguchi

A signal processing method and an improved defect detecting apparatus which scans a circuit substrate with a laser beam is provided to enable a distinction between a circuit pattern signal and a defect signal. A laser beam is scanned across the surface of a substrate with the reflected light picked up by a photodetector. The photodetector provides an output signal that can comprise both a pattern signal and a defect signal. This output signal is applied to a first signal processing line having a low-pass filter characteristic and a second signal processing line without a low-pass filter characteristic. The signals can be appropriately amplified and/or delayed and are finally submitted to a subtraction circuit so that the resulting output signal enables a ready determination of a defect apart from the existence of any pattern signal.

Signal process method and apparatus for defect inspection

A laser beam particle-detecting apparatus can automatically detect the position of minute particles on a substrate. A laser beam can be scanned across the substrate, and optical detectors can optically detect the laser beam after incidence with the substrate to define the position of any minute particles. Correction factors characteristic of the laser beam particle-detecting apparatus can be utilized to adjust the coordinates of the particle position, whereby any inaccuracies in the detecting apparatus can be compensated.

Optical detecting system wtih self-correction

An apparatus for detecting particles on a substrate incorporates a calibration system to correct any change in the angle of swing of a beam scanning mirror over a period of time. A pair of optical detectors can be positioned within the optical path between the scanning mirror and the substrate to provide a fixed reference point from which positional adjustments or calibrations can be made over the life of the instrument to eliminate any drifting of the positional signals of the actually detected particles on the substrate.

Optical detecting system for determining particle position on a substrate

An indicating device for measuring instruments having a voltage-frequency converter for converting measurement signals expressed as voltage values into frequency signals with a frequency proportional to the voltage values, a counter for counting the frequencies of the frequency signals sent from the voltage-frequency converter and sending the counted number to an indicator for digitally indicating the measured values corresponding to the counted number. A switch is connected between the voltage-frequency converter and the counter, and a controller for holding the switch in the closed state only during a predetermined time is connected to the switch. Analog signals sent from the measuring device can be indicated digitally and the digital values indicated can be held by a simple, inexpensive and miniaturizable construction.

Growing community of inventors

Kyoto, Japan

Dainichiro Kinoshita