Determining physical property of substrate

A computer program product tangibly embodied in a computer-readable storage device, the computer program product including instructions that, when executed, cause a processor to perform operations comprising:

• recording a first spectrum obtained from a substrate, the first spectrum being obtained during a polishing process that alters a physical property of the substrate;
• identifying, in a database, at least one of multiple previously recorded spectra that is similar to the recorded first spectrum, each of the spectra in the database having a physical property value associated therewith;
• generating a signal indicating that a first value of the physical property is associated with the first spectrum, the first value being determined using the physical property value associated with the identified previously recorded spectrum in the datebase;
• and
• establishing the database before the steps of recording, identifying and generating are performed, wherein establishing the database comprises:
• performing a first measurement of a physical property of a substrate specimen before it is polished, the physical property being measured in multiple predefined zones on the substrate specimen:
• polishing the substrate specimen after measuring the physical property, the polishing being done in multiple rotations;
• and
• collecting spectra from the substrate specimen while it is being polished.

A system for determining a physical property of a substrate, the system including:

• a polishing machine for performing a polishing process that alters a physical property of a substrate;
• a module for recording at least a first spectrum obtained from the substrate during the polishing process;
• and
• a database having stored therein multiple spectra, each associated with a value of the physical property, wherein at least one spectrum in the database that is similar to the first spectrum is identified, and the module receives a value determined using the physical property value associated with the identified spectrum, wherein the database is established, before the recording is performed, by performing a first measurement of a physical property of a substrate specimen before it is polished, the physical property being measured in multiple predefined zones on the substrate specimen:
• polishing the substrate specimen after measuring the physical property, the polishing being done in multiple rotations:
• and collecting spectra from the substrate specimen while it is being polished.