Abstract: An apparatus and a method provide a particle monitor mounted in an exhaust line of a loadlock chamber. The apparatus of the present invention comprises a particle monitor and a particle filter mounted down stream from the particle monitor away from the loadlock chamber. In one embodiment, the particle filter can be implemented by a wire-mesh screen, or a perforated stainless steel screen. The particle filter can be mounted in a centering ring of a standard vacuum connection which comprises two flanges, a centering ring, and an O-ring held together by a clamp.

Abstract: A structure and an apparatus are provided for use in particle sensor installed to monitor particle level of a process chamber. The process chamber receives process gas from a supply line and removes gas through an exhaust line. The particle sensor's optical components are prevented from contamination by corrosive or coating species in the effluent from the process, by a gas purge line installed in the particle sensor. The gas purge line allows a flow of gas to purge the optical components at a flux not less than the flux of gas being removed from the process chamber in the exhaust line. The flux out of the particle sensor prevents the undesired species from reaching the optical components of the particle sensor from the sampling area where the particle sensor detects the particle level.

Abstract: A structure and a method use a non-invasive particle monitor to detect particles in a process chamber for a "down sputtering" metal deposition process. In one embodiment, only non-spherical particles are detected using a single laser beam of a predetermined polarization is used, and the phase shift in the polarization due to the passing of a particle through the laser beam is measured. In another embodiment, two closely spaced orthogonally polarized laser beams are used, and the differential intensity of the laser beams is measured when a particle passes through one of the laser beams. In another embodiment, shield tubes for housing optical components are used to prevent coating of the optical components and to prevent deposition to take place outside the shielded area. Internal electric and magnetic fields are used to drive particles through the laser beams for particle detection.

Abstract: A particle sensor which employs the principle that a particle passing through an intense laser beam will scatter light to a photodetector which then generates a measurable signal is provided. The particle sensor uses prisms and a cylindrical lens to compress the laser beam to make it very thin along the axis of particle motion but very wide in the plane perpendicular to particle motion, thereby simultaneously providing high beam intensity for enhanced sensitivity and a large detection area. The optical components of the sensor are mounted on separate sections which allows the optical components to be separately aligned and changed so that the sensor may be easily adapted to various applications.

Abstract: A converging funnel is placed in an exhaust line to direct substantially all the gas flow in the exhaust line to the sensing laser beam of a particle sensor, thereby preventing deposition of species carried by the gas from depositing on the particle sensor. By concentrating substantially all gas flow through the laser beam, the particle count rate is increased because substantially all particles carried by the exhaust gas is channeled through the laser beam. Further, the particle sensor is also prevented from adverse heating effects of the exhaust gas. In one embodiment, the converging funnel is mounted to the interior wall of the exhaust line by a centering ring.

Abstract: A method and an apparatus for synchronizing particle counts to process events provide a trigger signal related to the process events in lieu of a time-based trigger signal. In one embodiment, the controller to a particle counter further subdivides a process event into sub-intervals to allow profiling of particle counts during the process event. In one embodiment, the controller of the particle counter receives multiple trigger signals corresponding to multiple trigger signal sources, each trigger signal source being identified by a source tag. Particle counts and time-stamps are maintained for each source of the trigger signals.

Abstract: A raster scan apparatus provides a scanning assembly capable of moving in a sinusoidal motion along a first direction and stepping in fine steps in a second direction perpendicular to the first direction. In one embodiment, a piezoelectric bimorph sets in scanning motion a scanning assembly formed by a wafer holder and leaf springs. The amplitude of the scanning motion is controlled by a voltage applied across the piezoelectric bimorph. A Hall effect sensor provides an output signal indicating the instantaneous location of the scanning assembly in motion. The output signal of the Hall effect sensor is compared against a predetermined threshold to provide a trigger signal for synchronization. The output signal of the Hall effect sensor is also fed back to the source of sinusoidal voltage to adaptively adjust the sinusoidal voltage so as to achieve a predetermined amplitude for the scanning motion.

Abstract: A housing for a laser based particle monitor comprising a pair of pipes for directing particle flow through a chamber. In one embodiment, elbows are disposed on the piping such that the interior of the chamber cannot be viewed from a point outside the housing.

Abstract: A particle sensor which employs the principle that a particle passing through an intense laser beam will scatter light to a photodetector which then generates a measurable signal is provided. The particle sensor uses prisms and a cylindrical lens to compress the laser beam to make it very thin along the axis of particle motion but very wide in the plane perpendicular to particle motion, thereby simultaneously providing high beam intensity for enhanced sensitivity and a large detection area. The optical components of the sensor are mounted on separate sections which allows the optical components to be separately aligned and changed so that the sensor may be easily adapted to various applications.

Abstract: A velocity measuring system useful for monitoring repetitive bidirectional movements of a carrier, which supports workpieces in production, initially stores the values of a number of velocities representative of normal operation to establish a normal velocity range, and then compares the values of subsequent carrier velocities to the normal range. A continuing deviation from the normal range is indicative of defective actuator operation, allowing repair or replacement prior to hard failure and serious disruption of the production line.

Abstract: A particle detector includes optical fiber for conducting short wavelength radiation received from a radiation source through a chamber in which a semiconductor wafer is being processed. Light that is scattered by contaminant particles in the process chamber is sensed by an optical fiber pickup, and pulse signals are generated by a photosensing means to provide an indication of the number of particles within the process chamber.

Abstract: An apparatus for monitoring particle fallout incorporates a particle flux monitor and a tubular structure. The tubular structure is positioned over an aperture in the housing of the monitor to provide a still air condition so that the particles that descend to the monitor and pass through the light net of the monitor are precluded from being carried back to the light net, which would result in an erroneous count.

Abstract: A surface scanner useful for detecting defects on the surface of a water that is being processed in a vacuum equipment employs a light beam that scans the wafer surface in an arc. The scanning light beam impinges on the wafer surface at a low angle of incidence which permits the beam to pass under photosensing elements disposed in an arcuate array substantially congruous with the arc defined by the scanning light beam. The photosensing elements are patterned close to the wafer surface to receive light scattered by defects on the wafer surface.

Abstract: A compact particle flux monitor is formed with an enclosure through which a laser beam is directed by a lens. An aperture in the enclosure allows free particles which are to be detected to pass through a sensing area at a limiting acceptance angle thereby providing an indication of direction of particle flow. Photodiodes mounted at the sensing area detect the particles, including relatively small particles, by means of the high intensity beam portion at the region of the focal point of the light beam. The response region along the diverging beam is relatively long so that the response as a function of particle size is above background noise level.

Abstract: A system for detection of extremely small particles in a low pressure environment or vacuum includes a vapor column in which a diffusion oil is vaporized, a saturation column in which vaporized oil is cooled and supersaturated, and means for directing a low pressure gas into the saturation column. An optical detector senses the oil droplets that grow around extremely small particles which are introduced in the saturation column by the gas and fall past the detector.

Abstract: A system for detecting contaminant particles in a liquid, such as used for processing wafers during the manufacture of integrated circuits, distinguishes non-contaminant bubbles generally found in liquids from contaminant particles. The system provides a controlled laminar fluid flow of the liquid through a pipe, and the substantially spherical bubbles in the flow path are detected by symmetrically spaced photodiodes. The irregularly shaped contaminant particles are detected, whereas the presence of bubbles are negated by the detection system by virtue of the balanced photodiode assembly.

Abstract: A particle detector includes a laser, a beam shaping lens, and a pair of mirrors which reflect the shaped laser beam back and forth between the mirrors a selected number of times in order to create a sheet of light or light net between the mirrors. The path of the beam is terminated by a beam stop which contains a photodiode to monitor beam intensity and thereby system alignment. Light scattered by a particle falling through the sheet of light is gathered and transmitted to a photodiode. A peak detector provides a measure of the peak intensity of light scattered by such a particle to a microprocessor, which counts the number of particles falling through the light net in a selected time interval. The microprocessor also uses the peak intensity to estimate the size of the particle.

Abstract: A particle detector includes a laser, a beam shaping lens, and a pair of mirrors which reflect the shaped laser beam back and forth between the mirrors a selected number of times in order to create a sheet of light or light net between the mirrors. The path of the beam is terminated by a beam stop which contains a photodiode to monitor beam intensity and thereby system alignment. Light scattered by a particle falling through the sheet of light is gathered and transmitted to a photodiode. A peak detector provides a measure of the peak intensity of light scattered by such a particle to a microprocessor, which counts the number of particles falling through the light net in a selected time interval. The microprocessor also uses the peak intensity to estimate the size of the particle.