Speedfam-ipec Corporation

USA As Represented by Secretary of the Navy

Lsi Logic Corporation

Thomas Frederick Bibby, Jr

John Andrew Adams

Michael J Berman

Jayashree Kalpathy-Cramer

Eric J Kirchner

Christopher E Barns

Robert A Eaton

Ignacio M Perez

Fred E Mitchel

Charles Hannes

An apparatus to generate an endpoint signal to control the polishing of thin films on a semiconductor wafer surface includes a through-hole in a polish pad, a light source, a fiber optic cable, a light sensor, and a computer. A pad assembly includes the polish pad, a pad backer, and a pad backing plate. The pad backer includes a pinhole and a canal that holds the fiber optic cable. The pad backer holds the polish pad so that the through-hole is coincident with the pinhole opening. A wafer chuck holds a semiconductor wafer so that the surface to be polished is against the polish pad. The light source provides light within a predetermined bandwidth. The fiber optic cable propagates the light through the through-hole opening to illuminate the surface as the pad assembly orbits and the chuck rotates. The light sensor receives reflected light from the surface through the fiber optic cable and generates reflected spectral data. The computer receives the reflected spectral data and calculates an endpoint signal. For metal film polishing, the endpoint signal is based upon the intensities of two individual wavelength bands. For dielectric film polishing, the endpoint signal is based upon fitting of the reflected spectrum to an optical reflectance model to determine remaining film thickness. The computer compares the endpoint signal to predetermined criteria and stops the polishing process when the endpoint signal meets the predetermined criteria.

Method and apparatus for endpoint detection for chemical mechanical

A carrier head for a semiconductor wafer polishing apparatus includes a rigid plate which has a major surface with a plurality of open fluid channels. A flexible wafer carrier membrane has a perforated wafer contact section for contacting the semiconductor wafer, and a bellows extending around the wafer contact section. A retaining member is secured to the rigid plate with a flange on the bellows sandwiched between the plate's major surface and the retaining ring, thereby defining a cavity between the wafer carrier membrane and the rigid plate. A fluid conduit is coupled to the rigid plate allowing a source of vacuum and a source of pressurized fluid alternately to be connected to the cavity. An additional wafer carrier membrane is internally located with respect to the cavity formed by the wafer carrier membrane, and forms another cavity with respect to the rigid plate. Another fluid conduit is connected to the internal wafer carrier membrane's cavity, which is selectively pressurized to make the internal wafer carrier membrane contact the wafer contact section.

Semiconductor wafer polishing apparatus with a variable polishing force

A method for determining the thickness of a film in a film stack using reflectance spectroscopy is provided in which one of the films in the stack has unknown optical constants. Conventional methods of using reflectance measurements to determine the thickness of a film require knowledge of the thicknesses and optical constants of all underlying films. An embodiment involves forming a test layer across a substrate having a known thickness and known optical constants. The thickness of the layer is determined using reflectance measurements. A first layer of the same material is then formed across a second layer at the same conditions that the test layer was formed. Thus, the test layer and the first layer can be assumed to have the same thicknesses. A spectral response curve may be determined for the first layer. The first layer is then processed so that its thickness is no longer known. The second layer has unknown optical constants, making it difficult to use reflectance measurements to find the unknown thickness. The values of the unknown optical constants may be guessed and used with the known thickness of unprocessed first layer to create a model spectral response curve. The optical constants may be repeatably varied until the model response curve matches the measured response curve. When this happens, the reasonable optical constants have been found and may be used in determining the thickness of the processed first layer.

Method for determining optical constants prior to film processing to be

A tapped Bragg grating is used to demodulate optical signals reflected by ber optic Bragg gratings in a sensor in which the line spacings in the fiber optic Bragg gratings vary in response to a mechanical stress. A light detector, or light detector array is used to detect variation in the angular pattern of the light scattered by the tapped Bragg grating. Arrangements of mirrors, or alternatively arrangements of lenses, are used to concentrate the scattered light toward the light detectors and to enhance the angular changes in the scattered light.

Fiber optic Bragg grating demodulator and sensor incorporating same

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Gilbert, AZ, United States of America

Thomas Frederick Bibby, Jr