Method and system for measuring a surface of an object comprising different structures using low coherence interferometry
AssigneeUnity Semiconductor Corporation
InventorsJean-François Boulanger, Isabelle Bergoënd
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Abstract
A method for measuring a surface of an object including at least one structure using low coherence optical interferometry, the method including the steps of acquiring an interferometric signal at a plurality of measurement points in a field of view and, for at least one measurement point, attributing the interferometric signal acquired to a class of interferometric signals from a plurality of classes, each of the classes being associated with a reference interferometric signal representative of a typical structure; and analysing the interferometric signal to derive therefrom an item of information on the structure at the measurement point, as a function of its class.
Claims15
A method for measuring a surface of an object comprising at least one structure using low coherence optical interferometry, the method being implemented with a system comprising an interferometric device, a light source, an imaging sensor, and a processing module, the method comprising the following steps:
- acquiring, with the imaging sensor, an interferometric signal formed by the interferometric device between a reference beam and a measurement beam reflected by said surface at a plurality of measurement points in a field of view;
- the following steps being carried out by the processing module:
- distributing the acquired interferometric signals according to homogenous regions of the field of view, where the regions are homogenous according to a predefined criterion;
- identifying, with the processing module, a class associated with a reference interferometric signal, representative of a typical structure, from the acquired interferometric signals in the homogeneous region to which the measurement point belongs;
- attributing the acquired interferometric signal to the class;
- and
- analysing the interferometric signal in order to derive therefrom an item of information on the structure at the measurement point, as a function of its class.
A system for measuring using low coherence optical interferometry, for measuring a surface of an object comprising at least one structure, the system comprising:
- an interferometric device, a light source, and an imaging sensor, for acquiring, with the imaging sensor, an interferometric signal formed by the interferometric device between a reference beam and a measurement beam reflected by said surface at a plurality of measurement points in a field of view;
- and
- a processing module for processing acquired interferometric signals, configured in order to:
- distribute the acquired interferometric signals according to homogenous regions of the field of view, where the regions are homogenous according to a predefined criterion;
- for at least one measurement point:
- identify a class associated with a reference interferometric signal, representative of a typical structure, from the acquired interferometric signals in the homogeneous region to which the measurement point belongs;
- attribute each acquired interferometric signal to the class;
- and
- carry out an analysis of the interferometric signal in order to derive therefrom an item of information on the structure at the measurement point, as a function of its class.
Dependencies are inferred from the claim text.