Surface scanner with thin film gauge
AssigneeTencor Instruments
InventorsKenneth P. Gross, George J. Kren, Christopher F. Bevis
Life of this patent
Estimating the term…
Abstract
An optical surface scanner for semiconductor wafers and like substrates having one channel with a detector receiving collected scattered light and another channel with a detector receiving reflected light. The scattered light signal is indicative of surface haze, particle count and size, while the reflected light signals are indicative of film thickness and/or surface properties as in the case of an opaque or absorbing layer. The latter signal may be used to correct the particle count and size determination and may also be used simultaneously for thin film measurement. The reflectivity or thin film measurement signals may be used to characterize a film layer controller to improve the accuracy of the deposited thickness of the layer.
Claims24
An apparatus for surface inspection comprising,
- a focused scanning beam illuminating a spot on a specularly reflective wafer having a film layer and light scattering elements thereon,
- means for providing relative motion between the beam and the wafer,
- a first detector positioned to intercept scattered light from said light scattering elements and producing an electrical signal representing scattering,
- a second detector positioned to intercept specularly reflected light from said film layer and producing an electrical signal representing reflectivity of the film layer in response to said specularly reflected light,
- means for logging the position of the beam on the wafer during scanning,
- means for determining, at said spot, the thickness of said film, using detected reflected light, and the presence of scattering elements, using detected scattered light, said determining means including means for producing a first electrical signal from light received by the first detector, and means for producing a second electrical signal from light received by the second detector,
- means for mapping the signals representing light scattering and reflectivity as a function of the position of the beam, and
- means for adjusting scattered light information carried by the first electrical signal using the second electrical signal.
Optical apparatus for inspection of reflective articles comprising,
- means for directing a focused scanning beam onto a reflective surface having a film coating thereon, the beam impinging on the surface at a spot,
- means for directing light reflected from said spot to a first detector,
- means for directing light scattered from said spot to a second detector,
- means for simultaneously determining, at said spot, the thickness of said film, using detected reflected light, and the presence of scattering elements, using detected scattered light, said determining means including means for producing a first electrical signal from light received by the first detector, representing reflected light, and means for producing a second electrical signal from light received by the second detector, representing scattered light information, and
- means for adjusting scattered light information carried by the second electrical signal using the first electrical signal.
A method of inspecting substrates having thin film coatings comprising,
- directing a focused beam of light toward a substrate having a film coating, the beam impinging on the substrate at a spot,
- measuring light scattered from said substrate, at said spot, with a first detector,
- measuring light reflected from said substrate, at said spot, with a second detector,
- determining, at said spot, the thickness of said film coating, using the measured reflected light, and the presence of scattering elements, using the measured scattered light,
- producing a first electrical signal from light received by the first detector,
- producing a second electrical signal from light received by the second detector,
- adjusting scattered light information carried by the first electrical signal using the second electrical signal, and
- determining the uniformity of said film coating using the measured reflected light from a plurality of spots.
Dependencies are inferred from the claim text.