Tencor Instruments

Hewlett-packard Company

John L Vaught

Armand P Neukermans

David K Donald

Michael E Fein

John D Meyer

Ralph C Wolf

Brian C Leslie

Howard H Taub

Josef Berger

Franklin R Koenig

Lee K Galbraith

Frank L Cloutier

William P Kruger

Michael J Lee

Herman F Keldermann

An inspection apparatus for a light diffracting surface employs a planar array of individually addressable light valves for use as a spatial filter in an imaged Fourier plane of a diffraction pattern, with valves having a stripe geometry corresponding to positions of members of the diffraction pattern, blocking light from those members. The remaining valve stripes, i.e. those not blocking light from diffraction order members, are open for transmission of light. Light directed onto the surface, such as a semiconductor wafer, forms elongated curved diffraction orders from repetitive patterns of circuit features. The curved diffraction orders are transformed to linear orders by a Fourier transform lens. The linear diffraction orders from repetitive patterns of circuit features are blocked, while light from non-repetitive features, such as dirt particles or defects is allowed to pass through the light valves to a detector. Patterns of stripes can be recorded corresponding to the repetitive features of different integrated circuits. Different filters may be rapidly switched electronically in synchronization with a beam scanning a patterned surface inspecting different light diffracting patterns in different positions, allowing scattered or diffracted light from non-repetitive features to pass through the filter to a detector. A logical AND combination of two filters may be used so that two regions may be inspected in a single scan of the beam.

Adaptive spatial filter for surface inspection

An apparatus used to inspect patterned wafers and other substrates with periodic features for the presence of particles, defects and other aperiodic features in which a spatial filter placed in the Fourier plane is used in combination with either broadband illumination, angularly diverse illumination or both. In contrast to prior devices that direct light from a single monochromatic source through a pinhole aperture stop, embodiments are describes that illuminate a patterned substrate using (1) a single monochromatic source with a slit-shaped aperture stop for angularly diverse illumination, (2) a single broadband source with a pinhole aperture stop for broadband illumination, (3) a single broadband source with a slit-shaped aperture stop for both broadband and angularly diverse illumination, or (4) multiple sources with an aperture stop for each source for at least angularly diverse illumination. The spatial filters for these illumination systems are characterized by opaque tracks in an otherwise transmissive filter for blocking the elongated bands produced by diffraction from the periodic features on the illuminates substrate. The filter may be made photographically by exposing high contrast film placed in or near the Fourier plane to the diffracted light from a defect and particle frame substrate having only periodic features. Light scattered from the aperiodic features is able to substantially pass through the filter and be imaged onto, a CCD array, vidicon camera or TDI sensor.

Speckle reduction track filter apparatus for optical inspection of

An apparatus and method using laser induced shock waves to dislodge particles from a wafer surface. The apparatus includes a wafer support, a particle detector and computer for locating and storing the locations of particles on the wafer, a laser, and focusing optics. Laser beam pulses are directed toward the wafer surface at a shallow angle or with a large beam convergence angle to avoid damage to the wafer.

Shock wave particle removal method and apparatus

A method and apparatus for detecting and classifying particles on a surface in which condensation is used to enlarge particles. An apparatus of the present invention includes a heatable wick disposed over a test surface and in fluid communication with a source of volatile liquid. A zone of vapor supersaturation is thus created in which condensation on particles on the surface can occur. A light beam directed onto the surface scans the surface. Droplets are detected by means of light scattered from the droplets. In an alternate embodiment a stream of carrier gas may be provided around the wick or bubbled through a jar of volatile liquid to direct a vapor toward the test surface. In another embodiment, multiple wicks communicate with different sources of volatile liquids. In a method of the invention, mulitple scans are made with either different levels of vapor supersaturation or different vapor compositions. Comparing particles in each scan allows one to classify particles into different size ranges or chemical type.

Method and apparatus for detecting and sizing particles on surfaces

A particle detection on a periodic patterned surface is achieved in a method and apparatus using a single light beam scanning at a shallow angle over the surface. The surface contains a plurality of identical die with streets between die. The beam scans parallel to a street direction, while a light collection system collects light scattered from the surface with a constant solid angle. The position of the collection system as well as the polarization of the light beam and collected scattered light may be arranged to maximize the particle signal compared to the pattern signal. A detector produces an electrical signal corresponding to the intensity of scattered light that is colelcted. A processor constructs templates from the electrical signal corresponding to individual die and compares the templates to identify particles. A reference template is constantly updated so that comparisons are between adjacent die. In one embodiment, the templates are made up of registered positions where the signal crosses a threshold, and the comparison is between corresponding positions to eliminate periodic pattern features, leaving only positions representing particles.

Particle detection on patterned wafers and the like

An optical scanning device for flaw detection or the like having a suspension system including at least two pairs of flexure legs. A first pair has flexure legs diagonally crossed in spaced-apart relation and fixed at one end to a stationary body and at an opposite end to a vibratory body. A second pair of spaced-apart cross-flexure legs link the stationary base to a magnetic driver for varying the angular position of the vibratory body about an axis of rotation. Each of the four flexure legs has a radial stiffness exceeding a torsional stiffness. The first pair of cross-flexure legs and the supported mass have characteristics corresponding to the characteristics of the second pair of cross-flexure legs and associated mass, thereby providing identical resonant frequencies of distortional bending. Any torque exerted on the stationary base by the first pair of cross-flexure legs is compensated by a torque which is equal in magnitude but opposite in direction translated through the second pair of flexure legs.

Suspension assembly for a scanning mirror

An ink jet system using a single transducer chamber is disclosed which can produce a wide variation in visual print density (gray scale) without a reduction in print resolution. Vehicle is mixed with the ink during the actual jet printing process to produce the desired gray scale. The system is also readily adapted to produce multi-color prints.

Gray scale printing with ink jets

A new type of apparatus for dispensing 'frozen' solid ink and the ink for use therein for printing on paper is disclosed. The ink dye vehicle is chosen to have a melting point above room temperature, so that the ink which is melted in the apparatus will not be subject to evaporation or spillage during periods of non-printing. The vehicle is also chosen to have a low critical temperature to permit the use of the solid ink in a thermal ink jet printer.

Ink dispenser with 'frozen' solid ink

A thermal ink jet printer is disclosed in which ink droplets are ejected from an orifice by the explosive formation of a vapor bubble within the ink supply due to the application of a two part electrical pulse to a resistor within the ink supply. The electrical pulse comprises a precurser pulse and a nucleation pulse; the precurser pulse preheats the ink in the vicinity of the resistor to a temperature below the boiling temperature of the ink so as to preheat the ink while avoiding vapor bubble nucleation within the ink supply and the subsequently occuring nucleation pulse very quickly heats the resistor to near the superheat limit of the ink.

Thermal ink jet printer

An apparatus is disclosed for propelling ink droplets from an ink jet nozzle which uses an expanding bubble as a driving mechanism. Unlike other thermal ink jet devices, the ink itself is not used to provide the driving bubble. Rather a two fluid system is disclosed whereby a flexible membrane is used to maintain separation between a working fluid and the ink. A bubble is thermally created in the working fluid which distends the membrane and causes ink on the other side of the membrane to be expelled from an ink jet orifice. The membrane is in direct physical contact with the surface of the bubble-generating resistor and a quantity of the working fluid lies between the resistor and the membrane in pockets created by roughening the surface of the membrane or by roughening the surface of the resistor; alternatively, pockets between the membrane and the resistor may be provided by particulates contained within the working fluid which provide local separations of the membrane and the resistor.

Ink jet printer with bubble driven flexible membrane

A drop-on demand ink jet printer and a method of ink jet printing are disclosed which produce drops whose diameter have a ratio to the internal diameter of their print nozzles of 1:2 instead of the standard ratio of 2:1. This change in the basic ratio of drop diameter to print nozzle diameter is a result of the motion imparted to the print liquid by the actuation of the print nozzle. The print nozzle is cocked, released, and abruptly stopped to impart forward momentum to the print liquid near the orifice of the print nozzle. This momentum urges the liquid to be expelled from the print nozzle. Cutting the orifice of the print nozzle at an oblique angle to the run of the print nozzle creates a leading edge on the print nozzle which increases control of drop placement. The leading edge encourages formation of a single umbilicus of expelled print liquid from which a drop will be severed.

Growing community of inventors

Palo Alto, CA, United States of America

John L Vaught