Veeco Instruments Inc.

Mountain View Optical Consultant Corp.

Good Advance Industries (h.k.) Limited

Der-Shen Wan

Colin T Farrell

Erik Novak

An illumination system for an interferometer combines a white-light source and a green source with a reflective green dichroic filter. When the green source alone is energized for PSI measurements, the output of the illumination system is green only. When a white-light output is desired for VSI measurements, both sources are energized and the intensity of the green light is judiciously calibrated to match the spectral band filtered out by the dichroic mirror. Therefore, the system can switch between green and white light simply by changing the selection of energized sources, without any mechanical switching and attendant delays and vibrations. Multiple narrowband sources may be combined with white light in a similar manner.

Variable-wavelength illumination system for interferometry

Methods are provided for estimating a surface profile of a sample in an interferometer having a broad bandwidth light source. The interferometer detects interference pattern intensity data over a series of frames of a relative scan between the sample and a reference surface. Particular methods comprise, for each location (x,y) of interest on the sample: determining an envelope of the detected interference pattern intensity data corresponding the location (x,y) of interest based on amplitudes of the detected interference pattern intensity data; determining a rough estimate zof the surface profile of the sample at the location (x,y) of interest based on the envelope; estimating a phase offset &#x3b8; of the detected intensity data using a curve fitting optimization process to fit the detected intensity data to a broad bandwidth interference model; and refining the rough estimate zof the surface profile using the phase offset &#x3b8; to obtain a fine estimate zof the surface profile of the sample at the location (x,y) of interest, the fine estimate zhaving improved resolution over the rough estimate z. Similar methods are used for characterizing films applied to substrates.

Methods and systems for white light interferometry and characterization of films

Thin-film thickness and refractive index are measured using the Fourier amplitude of a broadband interferometric spectrum. Due to the smooth nature of the Fourier amplitude as a function of wavelength, as compared to the fast varying Fourier phase conventionally used to measure thickness, increased stability and repeatability of measurement are achieved. As a result, measurements of ultra-thin films with thickness below 100 nm are possible with reliable results.

Measurement of thin films using fourier amplitude

The movable point source aperture used in conventional autocollimators for measuring tilt in a microscope's test sample is replaced by a fixed laser diode. The diode is turned on only for the duration of the tilt measurement, when light is delivered to the optical system of the microscope without obstruction of the normal illumination path. Similarly, the two switchable optical systems conventionally used in the metrology and tilt-measurement legs of the microscope are replaced by two permanently positioned independent imaging systems. Such optical decoupling of the two types of measurement eliminates the need for switching lens systems, which enables shorter measurement cycles, reduces mechanical vibrations, and simplifies hardware control mechanisms.

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Tucson, AZ, United States of America

Der-Shen Wan