Method and apparatus for monitoring a metal layer during chemical mechanical polishing
AssigneeApplied Materials, Inc.
InventorsHiroji Hanawa, Nils Johansson, Boguslaw Swedek, Manoocher Birang
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Abstract
A sensor for monitoring a conductive film in a substrate during chemical mechanical polishing generates an alternating magnetic field that impinges a substrate and induces eddy currents. The sensor can have a core, a first coil wound around a first portion of the core and a second coil wound around a second portion of the core. The sensor can be positioned on a side of the polishing surface opposite the substrate. The sensor can detect a phase difference between a drive signal and a measured signal.
Claims20
A polishing system, comprising:
- a polishing pad having a polishing surface;
- a carrier to hold a substrate against the polishing surface of the polishing pad;
- and
- an eddy current monitoring system including a ferromagnetic body positioned on a side of the polishing surface opposite the substrate, the ferromagnetic body extending at least partially through the polishing pad.
A polishing pad, comprising:
- a cover layer having a polishing surface, a bottom surface on a side of the cover layer opposite the polishing surface, and a recess formed in the bottom surface;
- and
- a backing layer having an aperture therethrough aligned with the recess.
A method of polishing, comprising:
- bringing a substrate into contact with a polishing surface of a polishing pad;
- positioning a ferromagnetic body on a side of the polishing surface opposite the substrate so that the ferromagnetic body extends at least partially through the polishing pad;
- causing relative motion between the substrate and the polishing pad;
- and
- monitoring a magnetic field using an induction coil that is magnetically coupled to the ferromagnetic body.
Dependencies are inferred from the claim text.