Method and apparatus for generating a polishing process endpoint signal using scatterometry

A metrology tool adapted to measure a wafer having a grating structure and a process layer formed over the grating structure after initiation of a polishing process, comprising:

• a light source adapted to illuminate at least a portion of the process layer overlying the grating structure;
• a detector adapted to measure light reflected from the illuminated portion of the process layer and the grating structure to generate a reflection profile;
• and
• a data processing unit adapted to compare the measured reflection profile to a target reflection profile having an acceptable degree of planarity and generate an endpoint signal based on the comparison of the measured reflection profile and the target reflection profile.

A processing line, comprising:

• a polishing tool adapted to polish a process layer formed on a wafer, the process layer overlying a grating structure;
• and
• a metrology tool comprising:
• a light source adapted to illuminate at least a portion of the process layer overlying the grating structure;
• a detector adapted to measure light reflected from the illuminated portion of the process layer and the grating structure to generate a reflection profile;
• and
• a data processing unit adapted to compare the measured reflection profile to a target reflection profile having an acceptable degree of planarity and generate an endpoint signal based on the comparison of the measured reflection profile and the target reflection profile.

A processing line, comprising:

• means for polishing a process layer formed on a wafer, the process layer overlying a grating structure;
• means for illuminating at least a portion of the process layer and the grating structure;
• means for measuring light reflected from the illuminated portion of the process layer and the grating structure to generate a reflection profile;
• means for comparing the measured reflection profile to a target reflection profile having an acceptable degree of planarity;
• and
• means for terminating the polishing of the process layer based on the comparison of the measured reflection profile and the target reflection profile.