Patent ID: 11885609
Assignee: nan
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 0:
1. A Tool for measurement of semiconductor wafer comprising two probes equipped with reflectors positioned on opposite sides of the semiconductor wafer,
where both probes are connected to 2×2 optical coupler to computer-controlled spectrograph, and to a low coherence light source,
where an upper probe is placed at a distance from the semiconductor wafer,
where the distance between the upper probe and semiconductor wafer defined as optical path length from 2×2 coupler through the first probe to the semiconductor wafer is different than a distance between the lower probe from the semiconductor wafer where the distance between the lower probe and semiconductor wafer is defined optical path length from 2×2 coupler through the lower probe to the semiconductor wafer, by more than two coherence lengths of radiation emitted by the low coherence light source, and a computer-controlled spectrograph where computer is equipped with a computer Fourier transform program filtering and separating Fourier transform frequency peaks originating from top and bottom probes.