Abstract: A system and a method provide a vacuum seal to be used when mounting an optical device onto a process chamber or a pump line removing exhaust gas from a process chamber. The system of the present invention includes: (a) a threaded nipple, having an internal mating surface and a threaded external surface, that is attached to the process chamber or to the pump line; (b) an internally threaded coupling, provided for accommodating the optical device, that is screwed onto the threaded external surface of the nipple, and having internally a first mating surface touching the internal mating surface of the nipple and a second mating surface; (c) a window placed on the second mating surface of the coupling; (d) means for creating a vacuum seal, e.g. an elastomer O-ring, between the first mating surface of the coupling and the mating surface of the nipple; and (e) means for creating a vacuum seal, e.g. an elastomer O-ring, between the second mating surface of the coupling and the mating surface of the window.

Abstract: A structure and a method provide a quasi bright field particle sensor for the detection of non-spherical particles, using a laser beam of predetermined polarization. A phase shift caused by non-spherical particles passing through the laser beam is utilized to detect the presence of such particles. In one embodiment, a single laser beam is used to detect the concentration of non-spherical particles in the pump line receiving the exhaust gas from a process chamber.

Abstract: A structure and a method provide a quasi bright field particle sensor, using a laser beam of predetermined polarization. A phase shift caused by a particle passing through a laser beam is utilized to detect the presence of a particle. In one embodiment, the laser beam is split into two components of laser beams of orthogonal polarization separated by a predetermined distance, so as to allow detection of both spherical and non-spherical particles. In another embodiment, where only non-spherical particles are detected, a single laser beam is used.

Abstract: A method for accomplishing particle monitoring above the throttle valve of a turbo pump provides a particle sensor which is built into the throttle valve in such a way that it is insensitive to local plasma glows. Furthermore, the particle sensor is placed such that a particle monitoring laser beam of the particle sensor is offset from the centerline of the pipe, so as to maximize exposure to process gas flow which is diverted to the periphery of the pipe by the position of a butterfly valve plate.

Abstract: An apparatus and a method provide a modular design for a particle monitor of external design used in a vacuum process equipment. In one embodiment, the key elements, i.e. laser assembly, the detection module, the beam stop and a darkened surface opposite the detection module, can be independently mounted on a pump line. The particle monitors of the present invention can be mounted on both straight sections and bends of the pump line. Each key element can be accessed independently of other key elements for repair and service.

Abstract: A method and an apparatus allow dynamic tuning of a particle sensor. The particle sensor provides output signals indicating particle detection to a controller, which includes an amplifier whose bandwidth and gain can be adjusted. The bandwidth and the gain of the amplifier are adjusted in accordance with predetermined optimal performance levels under the varying process conditions in which the particle sensor is placed. The optimal signal-to-noise ratio is maintained by adjusting the bandwidth and the gain according to both expected particle velocities and whether a plasma glow is present in the exhaust line for carrying gasses out of a process chamber.

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 real-time particle sensor is provided which can monitor particles near the surface of a disk in a computer disk drive system and in the region between disks in a multiple disk stack. A laser and lens are housed in a compact cartridge which is mounted on an actuator arm of a disk. Photocells which are also mounted on the actuator arm detect light scattered by particles passing through the laser beam, and so generate an electrical signal used to count the detected particles. The sensor's small size allows a separate sensor to fit in each of the regions between adjacent disks in a stack of disks, or near the surface of a single disk.

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: A real-time particle counter apparatus for monitoring contaminant particles in liquids includes a nebulizer, a drying chamber and a counter. The nebulizer provides an aerosol of droplets containing particles to the drying chamber, and the droplets are evaporated leaving solid particles to be counted and sized by the counter. Liquid is recirculated in a closed loop by pumping means that moves the liquid between the liquid source and the nebulizer. A constant air flow containing particles is provided to the counter and the apparatus is self-regulating so that no operator is required to maintain the level of liquid in the nebulizer.

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.