Method of detecting degradation in photolithography processes based upon scatterometric measurements of grating structures, and a device comprising such structures

A method, comprising:

• providing a wafer comprised of a plurality of grating structures arranged in a linear array, each of said grating structures being comprised of a plurality of photoresist features, each of said grating structures having a different critical dimension;
• illuminating at least one of said plurality of grating structures;
• measuring light reflected off of at least one of said grating structures to generate an optical characteristic trace for said at least one grating structure;
• and
• determining the presence of residual photoresist material between said features of said at least one grating structure by comparing said generated optical characteristic trace to at least one optical characteristic trace from a library.

A method, comprising:

• providing a wafer comprised of a plurality of grating structures, each of said grating structures being comprised of a plurality of spaced-apart photoresist features, each of said grating structures having a different spacing between said photo-resist features, at least one of said grating structures having a spacing between said photoresist features that is less than an anticipated range of critical dimensions for integrated circuit devices to be formed on a wafer;
• illuminating at least one of said plurality of grating structures;
• measuring light reflected off of at least one of said grating structures to generate an optical characteristic trace for said at least one grating structure;
• and
• determining the presence of residual photoresist material between said features of said at least one grating structure by comparing said generated optical characteristic trace to at least one optical characteristic trace from a library.

A method, comprising:

• providing a wafer comprised of a plurality of grating structures arranged in a linear array, each of said grating structures being comprised of a plurality of features, each of said grating structures having a different critical dimension, at least one of said grating structures having a critical dimension that is less than an anticipated range of critical dimensions for integrated circuit devices to be formed on a wafer;
• illuminating at least one of said plurality of grating structures;
• measuring light reflected off of said at least one grating structure to generate an optical characteristic trace for said at least one grating structure;
• and
• determining the presence of residual photoresist material between said features of said at least one grating structure by comparing said generated optical characteristic trace to at least one optical characteristic trace from a library.