Thickness Monitor
FE-300

Otsuka Electronics provides non-contact and non-destructive thickness measurements with high accuracy using light interference method and own high performance spectrometer. Light interference method is the optical thickness analysis technique using the reflectance in the spectrophotometer optics. Given an example of the coated film on metal substrate, the beam irradiated from above reflects on the coating surface (R1).Also, transmitted beam reflects on the substrate or boundaries (R2). From the light interference behavior caused by optical path difference and phase shift, film thickness can be calculated using reflectance spectrum and refractive index. Analytical algorisms are Peak-Valley Method, Fast Fourier Transformation (FFT) Method, Non-linear Least-Squares Method and Optimization Method.

The semiconductor transistor transmits signals by controlling the current conduction state. There is a built-in insulation film in between the transistors to prevent the current leakage and to avoid the accidental current inflow from another transistor. The insulation film is made of SiO₂ or SiN. SiN has higher dielectric constant than SiO₂ and can be used as a stopper to remove unnecessary SiO₂ in CMP. To assess the efficiency as an insulation film and to keep the precise process management, it is mandatory to make a measurement of these film thicknesses.