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Fizeau interferometer (Zygo)
TEMIS Sciences building – Office N3-05
03 63 08 26 22 (Office)
The Verifire GPI XP Fizeau interferometer allows to measure the deflection of a surface relative to a reference surface. In this configuration, the reference surface is a plane and the interferometer will create interference between the light reflected by this plan and that reflected on the wafer to be measured. By using an algorithm based on the phase-shifting and the use of a series of several image, the GPI software will find the profile of the measured object (or more precisely the difference of profile between the reference plane and the object measured). The advantage of this tool is that it allows a quick measurement over the entire surface of a wafer 100mm (4'') with a good spatial resolution thanks to its 1000x1000 camera.
As any optical device, this tool is limited by the need to allow the light to be reflected in the objective of the system. Furthermore the algorithm cannot monitor the profile in case of sudden phase modification. So this tool can only operate on a wafer having a continuous profile without any step. In particular it may check planarity before wafer bonding process, or help evaluate internal stress after thin-film deposition. Special techniques have been developed for measuring profile of transparent or birefringent wafers.
Technical characteristics :
o Fizeau phase-shifting interferometer
o Camera : 1000x1000 pixels
o Motorized zoom : x1-x6
o Working wavelength : 632 nm
o Measurement field : up to 100 mm diameter
o Dynamics : >50 µm
o Accuracy : <0.1 nm
Example of measurement :