Sensor for semiconductor device manufacturing process control

DETAILED DESCRIPTION The present invention accordingly provides an apparatus and method for non-invasive in-situ measurements of physical properties of metal and polycrystalline layers as well as semiconductor wafer surface roughness that substantially eliminate and reduce disadvantages and limitations associated with prior semiconductor wafer measurement methods, apparatuses, and systems.
One aspect of the invention is an electromagnetic or optical energy sensing device for semiconductor device manufacturing process control.
The invention comprises a coherent optical or electromagnetic energy source that, through associated circuitry, directs coherent electromagnetic or optical energy in the direction of a semiconductor wafer.
The coherent electromagnetic or optical energy probe beam interacts with the semiconductor wafer.
A portion of the energy is coherently reflected by the wafer in the specular direction.
Depending on the amount of roughness of the semiconductor wafer surface and the incident beam wavelength, a fraction of the reflected electromagnetic or optical energy may be scattered in the non-specular directions.
The sensor of the present invention includes components for measuring the amounts of specular (coherent) and scattered (incoherent) electromagnetic or optical beam powers reflected from the semiconductor wafer surface.
Components within the present invention then extract semiconductor wafer surface roughness and reflectance based on measurements of the incident beam power, the coherently reflected beam power (specular reflection) and the scatter reflected beam power.
It has been shown that chemical-vapor-deposited metal film and other polycrystalline layer thickness to at least a first order of accuracy, are directly related (mostly linearly) to the CVD polycrystalline film surface roughness.
Consequently, by providing a direct measurement of CVD polycrystalline film surface roughness, the method and apparatus of the present invention can perform CVD polycrystalline film thickness measurement