Patent ID: 11929291
Assignee: NOVA LTD.
Field: Measurement (Instruments)
Classification: CPC H  G | IPC G  H

Claim 0:
1. A metrology system for controlling an etch process applied by an etch apparatus to a multi-layered structure, the metrology system comprises:
an optical profile monitor that is configured to (a) illuminate a region of interest of the multi-layered structure during an etch process applied to the multi-layered structure; and (b) measure a spectral reflectance of the region of interest of the multi-layered structure;
an etch layer detector that is configured to (a) calculate a spectral derivative of a spectral reflectance signal obtained from the measuring; (b) identify, in the spectral derivative, a discontinuity indicative of a of crossing a layer boundary of the multi-layered structure; and
a controller that is configured to (a) determine that the layer boundary corresponds to a preselected layer boundary of the multi-layered structure; and (b) generate control signals for applying a predefined control action to the etch process responsive to determining that the crossed layer boundary corresponds to the preselected layer boundary of the multi-layered structure.