Back to results
US 6,806,959 B2Granted
Measurement of surface defects on a movable surface
AssigneeKoninklijke Philips Electronics N.V.
InventorTeunis Willem Tukker
Life of this patent
Estimating the term…
Loading patent…
Loading patent…
AssigneeKoninklijke Philips Electronics N.V.
InventorTeunis Willem Tukker
Estimating the term…
A device for the inspection of one or more movable surfaces (8), more in particular for the inspection of a rotating surface (8) of a wafer, which device includes at least one light source (1), notably a laser light source, and a beam splitter (4) for splitting a light beam that is emitted by said laser light source into at least one reference beam (6) that is applied to a detector (16) and at least one measuring beam (5) that is applied to the surface (surfaces) and contains at least one component in the direction of movement (U) of the respective surface or in the opposite direction, the light (15) that is reflected by the surface (8) having, upon detection of a defect (14), a frequency (υ′) that has been shifted relative to the measuring beam (5) and on which the reference beam (6) can be superposed. The device includes an evaluation unit (29) for determining the velocity (v) of a defect (14) on the surface (8) from the shifted frequency (υ′) and for determining the position of the defect on the surface therefrom.
A device for the inspection of a rotating surface (8) of a wafer (13), which device includes at least one light source (1), and a beam splitter (4) for splitting a light beam (2) that is emitted by said source into at least one reference beam (6) that is applied to a detector (16) and at least one measuring beam (5) that is applied to the surface (surfaces), the at least one measuring beam (5) containing at least one component in the direction of movement (U) of the relevant surface (8) or in the opposite direction, and the light (15) that is reflected by the surface (8) having, at least upon detection of a defect (14) on the surface (8), a frequency (ν′) that has been shifted relative to th at least one measuring beam (5) and that the at least one reference beam (6) can be superposed thereon, characterized in that the device includes an evaluation unit (29) for determining the velocity (v) of a defect (14) on the surface (8) from the shifted frequency (ν′) and from this velocity the position of the defect on the surface (8).
A method for the inspection of one or more moving surfaces, where a light beam that is emitted by a light source, is split by means of a beam splitter into at least one reference beam that is applied to a detector and a measuring beam that is applied to the surface, the measuring beam containing at least one component in the direction of movement of the relevant surface or in the opposite direction, the light that is reflected by the surface having, at least upon detection of a defect on the surface, a frequency that has been shifted relative to the measuring beam, and the at least one reference beam being superposed on said reflected light, characterized in that the speed of a defect on the surface is determined from the superposed signal formed from the at least one reference beam and the reflected light, and that the position of the defect on the surface is determined therefrom.
Dependencies are inferred from the claim text.