Coherent, Inc.

Mks Instruments, Inc.

Rofin-sinar Laser Gmbh

Nufern

Advanced Metrology Systems LLC

Peter Rosenthal

Gongxue Hua

Florian Engel

Jens Schüttler

Sylvie Charpenay

John T Kennedy

Joel Fontanella

Joseph E Cosgrove

David J Allie

Peyman Ahmadi

Alexei Maznev

Alexander Mazurenko

Vern Seguin

Carlos A Duran

Jiazhan Xu

Victor A Yakovlev

A Q-switched gas laser apparatus with bivariate pulse equalization includes a gas laser, a sensor, and an electronic circuit. A Q-switch that switches the laser resonator between high-loss and low-loss states to generate a pulsed laser beam. The sensor obtains a measurement of the pulsed laser beam indicative of the laser pulse energy. The electronic circuitry operates the Q-switch to (a) repeatedly switch the laser resonator between the high-loss and low-loss states to set a repetition rate of laser pulses of the pulsed laser beam, (b) adjust a loss level of the low-loss state, based on the pulse energy measurement, to achieve a target laser pulse energy, and (c) adjust a duration of the low-loss state to achieve a target laser pulse duration. By adjusting both pulse energy and duration, uniform pulse energy and, if desired, uniform pulse duration are achieved over a wide range of repetition rates.

Pulse equalization in Q-switched gas lasers

A COlaser that generates laser-radiation in just one emission band of a COgas-mixture has resonator mirrors that form an unstable resonator and at least one spectrally-selective element located on the optical axis of the resonator. The spectrally-selective element may be in the form of one or more protruding or recessed surfaces. Spectral-selectivity is enhanced by forming a stable resonator along the optical axis that includes the spectrally-selective element. The COlaser is tunable between emission bands by translating the spectrally-selective element along the optical axis.

Wavelength discriminating slab laser

A high-power fiber laser produces a compound output beam having a center beam and an annular beam. The center beam and the annular beam are independently adjustable in power and wavelength. The output beam is delivered from an output optical fiber having a center core and a concentric annular core. A fundamental beam generated by a seed laser is amplified by a fiber amplifier and partially converted to a second-harmonic beam by a second-harmonic generator. The residual fundamental beam and second-harmonic beam are separated, attenuated, and selectively coupled into the cores of the output optical fiber.

Multi-wavelength adjustable-radial-mode fiber laser

In order to maintain a constant laser output pulse power in a RF-energized, sealed-off, diffusion cooled, pulsed, COgas-discharge laser, each laser output pulse is generated by train or burst of shorter RF pulses. When the time between laser output pulses becomes short enough that the power in one pulse would be reduced by gas-discharge heating effects of a previous pulse, power in the RF pulse trains is varied by varying the duration or duty cycle of pulses in the bursts, thereby keeping output-pulse power in the laser output pulses constant. RF pulses in any burst can have a different duration for tailoring the temporal shape of a corresponding laser-output pulse.

[object Object]

The invention represents an improved method of measuring trenches on semiconductor wafers with optical spectroscopy. According to the described method, it is possible to characterize not only depth but also shape of the trench. The advancement is achieved by improved Effective Medium Approximation-based modeling of the optical response of trench structures.

Method of measuring deep trenches with model-based optical spectroscopy

The method measures the temperature, emissivity, and other properties of relatively smooth surfaces radiating thermal energy, and is especially adapted for monitoring semiconductor fabrication processes. Temperature is determined by relating measured radiance to the predictions of the Planck radiation law, using knowledge of the emissivity determined from an analysis of the polarization of the thermally emitted radiance. Additional information regarding the properties of thin films, such as thickness and composition, can be computed from the emissivity or the ratio of the emissivities measured at two independent polarizations. Because the data are obtained from the intrinsic thermal radiance, rather than from an extrinsic light source, the measurement can be performed when it is inconvenient or impossible to provide a light source for reflectance measurements.

Thermal imaging for semiconductor process monitoring

The composition, free carrier concentrations, and other properties of thin films and graded layers embedded in film stack structures are measured by the method of the invention, which is based upon the application of two novel algorithms to extract the composition of a measured layer independently of the confounding effects of additional layers, and which can be effected even when calibration samples are not available with the same layered structure as the samples to be measured. The method uses sample model-based analysis algorithms to extract the dielectric function of the layer to be measured, combined with model-based analysis to relate the composition of the layer to its dielectric function. Because the dielectric function of a layer is a bulk spectral property of the material, and is inherently independent of the thickness of the layer, the composition of the material can be determined more easily and unambiguously from its dielectric function than from raw spectral quantities such as reflectance, ellipsometry, and transmittance, which spectral data are influenced strongly by the optical properties of the overlayers, the underlayers, and the substrate material. The method enables the measurement of layer composition with significantly fewer calibration samples, it allows product wafer analysis with structures that are significantly more complicated than the calibration samples, and it is intrinsically more reliable for transferring calibrations between tools even when the measurement geometry varies from tool-to-tool.

Method and apparatus for measuring the composition and other properties of thin films utilizing infrared radiation

Growing community of inventors

West Simsbury, CT, United States of America

Peter Rosenthal