Patent ID: 8873067

Claim:
An interferometer for measuring a TSV, the interferometer comprising: a beam splitter configured to split an injected light generated from a light source into a first light oriented towards a first direction and a second light oriented towards a second direction that is perpendicular to the first direction, and to combine the first light and the second light to output a combined light; a mirror configured to reflect the first light input from the beam splitter back to the beam splitter and disposed in the first direction, and a measurement object where at least one TSV is formed and configured to reflect the second light input from the beam splitter back to the beam splitter and disposed in the second direction; a photographing means configured to receive the combined light output from the beam splitter after being reflected from the mirror and measurement object, and where an interference signal is formed by the combined light; an object lens disposed between the beam splitter and photographing means or between the beam splitter and measurement object; and a variable field stop disposed between the beam splitter and photographing means, wherein the variable field stop is passed by the second light focused at a reference location that is an inlet of the TSV or at a variable location that is a bottom surface of the TSV to optimize an image obtained as the second light focused at the reference location or the variable location is received at the photographing means, wherein the interferometer measures a diameter and height of the TSV based on an interference signal when the second light towards the measurement object is focused at the reference position and an interference signal when the second light towards the measurement object is focused at the variable position; and wherein the variable field stop comprises a first opening that is passed by the second light focused at the reference location that is the inlet of the TSV and a second opening that is passed by the second light focused at a variable location that is the bottom surface of the TSV, wherein a size of the first opening is optimized to obtain an image for the inlet of the TSV and a size of the second opening is optimized to obtain an image for the bottom surface of the TSV.