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US 6,632,124 B2Granted
Optical monitoring in a two-step chemical mechanical polishing process
AssigneeApplied Materials, Inc.
InventorsBret W. Adams, Boguslaw A. Swedek, Rajeev Bajaj, Savitha Nanjangud, Andreas Norbert Wiswesser, Stan D. Tsai, David A. Chan, Fred C. Redeker, Manoocher Birang
Life of this patent
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Abstract
An optical monitoring system for a two-step polishing process which generates a reflectance trace for each of plurality of radial zones. The CMP apparatus may switch from a high-selectivity slurry to a low-selectivity slurry when any of the reflectance traces indicate initial clearance of the metal layer, and polishing may halt when all of the reflectance traces indicate that oxide layer has been completely exposed.
Claims14
A polishing system comprising:
- a polishing surface;
- a carrier to hold a substrate against the polishing surface;
- a motor to move at least one of the polishing surface and the carrier head to generate relative motion between the polishing surface and substrate;
- a dispensing system to dispense a first polishing fluid and a second polishing fluid;
- an optical monitoring system;
- and
- a computer configured to cause the polishing system to
- chemical mechanical polish a first layer of substrate with the first polishing fluid,
- optically monitor the substrate during polishing with the first polishing fluid to generate plurality of intensity traces, with each intensity trace including intensity measurements from a different radial range on the substrate,
- once any of the intensity traces indicates an initial clearance of a first layer on the substrate, chemical mechanical polish the substrate with a second polishing fluid having different polishing properties than the first polishing fluid,
- continue to optically monitor the substrate during polishing with the second polishing fluid, and
- halt polishing after all the intensity traces indicate that a second layer beneath the first layer has been completely exposed.
9 more elements
A polishing system comprising:
- a polishing surface having a window;
- a carrier to hold a substrate against the polishing surface;
- a motor to move at least one of the polishing surface and the carrier head to generate relative motion between the polishing surface and substrate;
- a dispensing system to dispense a first polishing fluid and a second polishing fluid, the second polishing fluid having different polishing properties than the first polishing fluid;
- an optical monitoring system that includes a light source that directs a light beam through the window, wherein the motion of the polishing surface relative to the substrate causing the light beam to move in a path across the substrate, and a detector that detects reflections of the light beam from the substrate and generates a reflectance signal therefrom;
- and
- a computer configured to cause the polishing system to
- polish the substrate with the first polishing fluid in a first polishing step,
- extract a plurality of intensity measurements from the reflectance signal,
- generate a plurality of intensity traces, with each intensity trace including intensity measurements from a different radial range on the substrate,
- once any of the intensity traces indicates an initial clearance of the first layer, polishing the substrate with the second fluid in a polishing second polishing step, and
- halt polishing after all the intensity traces indicate that the second layer has been completely exposed.
9 more elements
A polishing system comprising:
- a polishing surface having a window;
- a carrier to hold a substrate against the polishing surface;
- a motor to move at least one of the polishing surface and the carrier head to generate relative motion between the polishing surface and substrate;
- a dispensing system to dispense a high-selectivity slurry and a low-selectivity slurry to the polishing surface;
- an optical monitoring system that includes a light source that directs a light beam through the window, wherein the motion of the polishing surface relative to the substrate causing the light beam to move in a path across the substrate, and a detector that detects reflections of the light beam from the substrate and generates a reflectance signal therefrom;
- and
- a computer configured to cause the polishing system to
- polish a metal layer on the substrate with the high-selectivity slurry,
- extract a plurality of intensity measurements from the reflectance signal,
- determine a radial position for each intensity measurement,
- divide the plurality of intensity measurements into a plurality of radial ranges according to the radial positions,
- generate a plurality of intensity traces, with each intensity trace including intensity measurements from one of the plurality of radial ranges,
- supply the low-selectivity slurry to the polishing surface when any of the intensity traces indicates an initial clearance of the metal layer, and
- halt polishing when all the intensity traces indicate that the oxide layer has been completely exposed.
11 more elements
Dependencies are inferred from the claim text.