X-ray thickness gauge

A device for measuring the structure of a thin-film disposed on a substrate, comprising:

• an X-ray reflector defining a focal area proximate to the thin-film;
• a source directing a plurality of X-rays onto the reflector, with the reflector directing the plurality of X-rays as a bundle of monochromatic X-rays onto said thin-film at a plurality of incident angles greater than the critical angle (.psi..sub.c), with each of the monochromatic X-rays reflecting from the thin-film at an angle of reflection corresponding to an angle of incidence, the reflector being a curved monochromator defining at least one focal point proximate to the substrate, whereby the curved monochromator simultaneously directs the plurality of X-rays onto the thin-film at varying angles of incidence;
• a detector positioned to sense X-rays reflected from the thin-film along a plane transverse to the plane of the thin-film, the detector producing a signal corresponding to an intensity and a spatial position of the transverse X-ray in the plane, with each spatial position in the plane corresponding to an angle of reflection;
• and
• a processor means connected to receive signals produced by the detector for determining physical properties of the thin-film based upon all signals received by the detector, the physical properties including the mass per unit area of the thin-film.

A device for measuring the properties of a thin-film disposed on a substrate, defining a substrate-thin-film interface, comprising:

• a source of X-rays adapted to produce X-rays;
• an X-ray reflector positioned in the path of the X-rays and adapted to simultaneously impinge onto at least one point of the thin-film a plurality of said X-rays at a plurality of incident angles with each of the plurality of X-rays reflecting from the thin-film at an angle of reflection, defining reflected X-rays with the angle of reflection corresponding to an angle of incidence;
• a detector positioned to sense said reflected X-rays reflected from the thin-film and produce a signal corresponding to the intensity and an angle of reflection of the reflected X-rays sensed;
• and
• a processor means connected to receive signals produced by the detector for determining properties of the thin-film based upon a comparison of the intensity and the angle of reflection of the reflected X-rays sensed, the properties including thin-film thickness, thin-film density and a relative smoothness between the surface of the thin-film and the smoothness of the substrate-thin-film interface.