Surface roughness measurement of semi-conductor wafers using a modified total integrated scattering model

Light scattering is a non-contact technique which can be used for characterizing the topography of smooth reflecting surfaces. A proposed technique which incorporates a modified Total Integrated Scattering (TIS) model for surface roughness measurement of semi-conductor wafers has been developed. The technique employs a low power He-Ne laser and incorporates conventional optical components to record surface roughness in the nanometer range (R-a < 45 nm) with a high degree of accuracy. Principle of the technique and the experimental arrangement are described. Results obtained using the proposed technique are compared with those using the conventional direct contact method.