Systems and methods for performing phase shift interferometry while a wafer is vibrating
AssigneeSunEdison Semiconductor Limited
InventorsBenno ORSCHEL, Andrey MELNIKOV, John F. VALLEY, Markus Jan Peter SIEGERT
Life of this patent
Estimating the term…
Abstract
A method performs phase shift interferometry to detect irregularities of a surface of a wafer after the wafer has been placed into an interferometer and while the wafer is vibrating. Additionally, a system and a non-transitory computer-readable storage medium have computer-executable instructions embodied thereon for performing phase shift interferometry to detect irregularities of a surface of a wafer after the wafer has been placed into an interferometer and while the wafer is vibrating.
Claims20
A method for performing phase shift interferometry to detect irregularities of a surface of a wafer after the wafer has been placed into an interferometer and while the wafer is vibrating, said method comprising the steps of:
- emitting a beam of light at each of a plurality of wavelengths at a reference plane of the interferometer and at the wafer;
- exposing an image capture device to reflected light from the reference plane and the wafer for each of a plurality of captured image samples to generate an exposed signal;
- cyclically fitting, by at least one computing device, a fitted signal to the exposed signal while the wafer is vibrating;
- cyclically determining, by the at least one computing device, a level of vibration of the wafer, based at least in part on the exposed signal;
- and
- determining, by the at least one computing device, irregularities in the surface of the wafer when reductions in the vibration are below a predefined threshold, based on the fitted signal.
A system comprising at least one computing device coupled to an interferometer including a light source, a reference plane located opposite said light source, a beam splitter located between said light source and said reference plane, and an image capture device configured to receive light from said beam splitter, said at least one computing device configured to perform phase shift interferometry to detect irregularities of a surface of a wafer after the wafer has been placed into said interferometer and while the wafer is vibrating, by:
- causing said light source to emit a beam of light at each of a plurality of wavelengths at said reference plane and at the wafer;
- causing said image capture device to be exposed to reflected light from the reference plane and the wafer for each of a plurality of captured image samples to generate an exposed signal;
- cyclically fitting a fitted signal to the exposed signal while the wafer is vibrating;
- cyclically determining a level of vibration of the wafer, based at least in part on the exposed signal;
- and
- determining irregularities in the surface of the wafer when reductions in the vibration are below a predefined threshold, based on the fitted signal.
A method for detecting irregularities of a surface of an object while the object is vibrating, said method comprising the steps of:
- projecting a moving fringe pattern to the surface of the object;
- exposing an image capture device to the moving fringe pattern for each of a plurality of captured image samples to generate an exposed signal;
- cyclically fitting, by at least one computing device, a fitted signal to the exposed signal while the object is vibrating;
- cyclically determining, by the at least one computing device, a level of vibration of the object, based at least in part on the exposed signal;
- and
- determining, by the at least one computing device, irregularities in the surface when reductions in the vibration are below a predefined threshold, based on the fitted signal.
Dependencies are inferred from the claim text.