Bruker Nano Gmbh

Veeco Instruments Inc.

Wyko, Inc.

Hughes Aircraft Company

Bruke Nano Inc.

Bryan W Guenther

David J Aziz

Erik Novak

Colin T Farrell

Dong Chen Chen

John B Hayes

Eric M Frey

Paul J Caber

Paul R Unruh

Jaime Duran

Richard W Swinford

Henry Fagg

A vacuum mechanism for flattening bowed panel samples includes a support structure with coplanar support elements and a fixture with a movable component actuated by a vacuum source. The movable component has a top surface disposed above the support elements when no vacuum is applied and is capable of being drawn to a substantially coplanar position with the support elements when actuated by the vacuum source. The top surface is fluidly connected to the vacuum source and adapted to adhere to the overlaying surface of the sample when vacuum is applied, thereby flattening the sample when the movable component is drawn in by the same vacuum source.

Method for flattening sample in optical metrology

A reference surface is used to develop an empirical plot between a parameter of interest, such as roughness or modulation, and the position of the reference mirror in an interferometer by repeating measurements of the reference surface at different positions of the reference mirror so as to identify the in-focus position of the reference mirror. Serial quality-control measurements of samples of interest are carried out with the reference mirror in such in-focus position until a predetermined quality-control event triggers an automated system re-calibration by re-measuring the reference surface and, if the result does not correspond to the in-focus position of the reference mirror according to the plot, by finding a new in-focus position for the reference mirror using the same plot or, alternatively, a new similarly produced plot. Sample measurements are then resumed with the mirror placed at that new position.

Automated re-focusing of interferometric reference mirror

A conductive conformable braided wire is used as the edge electrode for material characterization of a semiconductor wafer. The braided wire is adapted to contact the perimeter of the n-GaN layer using a retractable support structure that alternately places the electrode in contact with the edge of the n-GaN layer and retracts it during repeated cycles of operation to test a plurality of similar wafers. The braided wire produced a very stable and higher electrical contact than any prior-art edge electrode.

Edge electrode for characterization of semiconductor wafers

Fixture for flattening sample in optical metrology

A pair of pneumatic cylinders is used to counterbalance the weight of a large gantry supporting the optical head of an interferometric profiler. The gantry is supported by the cylinders within pairs of linear-bearing rail that provide a large vertical travel. The pressure in the cylinders is adjusted so as to provide an upward force sufficient to oppose the weight of the gantry and prevent its descent, but not so great as to cause it to rise. In essence, the counterbalance pressure is adjusted to equilibrate the weight of the gantry in such a way that a small force applied manually upward or downward will cause the gantry to move easily in either direction, thereby making it possible for an operator to position the optical head rapidly and with minimum effort as required for the initial alignment with a test object.

Pneumatic counterbalance for optical head gantry

An interferometric profiler includes an opening adapted to receive a removable compensating element in the reference arm. The compensating element is mounted on a holder adapted for slidable engagement within the opening. A retaining mechanism keeps the holder firmly in place in the opening. The reference mirror of the profiler is mounted on a slidable stage urged away from the compensating element by a spring-loaded mechanism. A knob is provided to manually push the stage inward to its operating position proximate to the compensating element. A stop ensures that the travel of the stage is limited to a safe distance from the compensating element and a lock is provided to releasably hold the stage in place during use. Multiple objectives with different magnifications may be coupled to the module for alternative use according to the needs of particular applications. An illumination module may also be coupled to the reference-arm module.

Mounting mechanism for compensating optics in interferometer

Average fringe contrast is determined by PSI measurements at each step of relatively large translations of the reference optics and mirror of a white-light Linnik interference objective and the resulting data are used to minimize the OPD between the reference and test beam paths of the instrument. Utilizing the same algorithms used in the art to perform conventional vertical scanning interferometry, the position of minimum OPD is determined by finding the position of maximum average fringe contrast. Furthermore, by automating the system with a precise translation mechanism, operator-to-operator variations are completely eliminated and the precision of the process of OPD minimization is greatly improved. In another embodiment of the invention, the optimal focal position of the reference mirror is found at the same time by calculating the average lateral variation of fringe contrast as a function of OPD and focal position. The optimal OPD and focal position correspond to the maximum average lateral variation of fringe contrast in the resulting three-dimensional space.

Automated minimization of optical path difference and reference mirror focus in white-light interference microscope objective

A laser interferometer is embedded into an interference microscope to precisely determine the in-focus position of the microscope objective's reference mirror. A collimated laser beam is introduced into the microscope system and split into two beams directed toward a calibration reference surface and the interference objective. The light reflected from the calibration reference surface is returned to the camera. The light into the interference objective is focused onto the reference mirror and returned to the camera. For the purpose of calibration, the two beams are combined at the camera to produce interference fringes. When the reference mirror is in focus, the returned beam is collimated; if the mirror is on either side of focus, the beam is either converging or diverging. Accordingly, the interferogram produced at the camera reflects the in-focus or out-of-focus condition of the reference mirror. The curvature of the wavefront returned from the reference mirror is determined electronically by analyzing the interference fringes produced with the beam returned from the calibration reference surface. By minimizing the curvature of the reference-mirror wavefront as the mirror is translated along the optical path, the reference mirror can be focused with an accuracy greater than possible by visual observation. Furthermore, by automating the focusing system with a precise translation mechanism driven by closed-loop control, operator-to-operator variations are completely eliminated.

Embedded interferometer for reference-mirror calibration of interferometric microscope

A crash protection mechanism for a microscope objective includes a tapered, self-centering combination of sleeves interposed between the objective and its housing in an interferometric profiler. A three-lobed, tapered inner sleeve is affixed to the objective, while a matingly tapered outer sleeve is attached to the objective housing. A spring-loaded mechanism urges the objective outward toward the sample surface, so that it can move inward axially under crash conditions and then return to its original axial position. The mating tapered sleeves create an outward seated position that provides a high degree of repeatability when the objective is returned to its position after a crash.

Self-centering crash protection mechanism for interference microscope objective

A broad-bandwidth interferometric device is adapted for longitudinal insertion into a cylinder cavity to produce irradiance signals at multiple vertical-scanning positions as a function of optical path differences between a reference mirror incorporated in the probe and the cylinder-wall surface. The light-source beam is passed through an objective lens placed longitudinally in the cylinder and then divided by a beam splitter disposed in fixed relation to the cylinder wall to produce a test beam directed radially to the wall and a reference beam directed axially to a reference mirror disposed in fixed relation to the lens. During scanning, the objective lens and reference mirror are translated together, while the beam splitter remains stationary with respect to the cylinder wall, thereby varying the position of the focal point of the test beam and providing the vertical-scanning effect required to produce interference fringes and a corresponding map of the tested cylinder surface. In order to reduce the length of the instrument, the reference beam may be folded to the side by a reflective surface and the reference mirror may be positioned perpendicularly to the main axis of the instrument. In that case, the lens, fold mirror and reference mirror are all translated together, while the beam splitter remains stationary and fixed with the test surface.

Orthogonal-scanning microscope objective for vertical-scanning and

A scanning interferometer that utilizes a DC gear motor instead of a PZT translator in closed-loop configuration with an LVTD position sensor. The DC motor is connected to the scanning mechanism so that a rotational motion of the motor shaft produces a translation along the optical axis of either the sample or the objective of the interferometer. During scanning, the motor is driven by the input of a ramp signal into the system. The closed-loop configuration is such that a constant, or nearly constant voltage is applied to the DC motor to produce a constant-speed scan in response to the ramp input. Any non-linearity in the speed of motion is corrected by an adjustment to the motor voltage. At the completion of the scan, the ramp input is removed and the motor is automatically returned to the starting position to satisfy the closed-loop condition. In order to maintain the image in focus on the sensor over the wide range of scanning, a pair of relay lenses is inserted in the optical path between the interferometer and the light detector.

Combination of motorized and piezoelectric translation for long-range

A mask for protecting edge conductors of printed circuit boards from the spray coating which is sprayed on the board. The mask is molded from a soft silicone-based-elastomer material in a configuration which presents a sharp sealing edge and a large interior angle adjacent the seal which effectively limits migration due to capillary action.

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Tucson, AZ, United States of America

Bryan W Guenther