SiO2 thickness measurements

Using the NanoSpec Model 200

Automatic Film Thickness tool

NanoSpec Model 200 AFT

Wafer stage

light source and filter

Reference wafers

Computer control and thickness

reading

The NanoSpec AFT measures optically transparent thin films on silicon wafers. The intensity of a monochromatic reflected light depends on the thickness of the film. The tool uses a photomultiplier tube to measure the reflected optical spectrum from a bare silicon wafer and the wafer under test. Given the refractive index of the film in question (SiO20 and the two measured spectrums, the computer will determine the thickness.

Typically, the tool is set for SiO2 on silicon but addition options are available such as measuring silicon nitride thickness.