Alignment Target Contrast in a Lithographic Double Patterning Process

A method comprising:

• developing a first radiation-sensitive layer on a substrate to form a first lithography pattern;
• coating the first lithography pattern with a second radiation-sensitive layer;
• providing a dye compound below, together with, on, or any combination thereof, the second radiation-sensitive layer;
• detecting a location of the first lithography pattern based on the dye compound providing an optical contrast between the first lithography pattern and the second radiation-sensitive layer;
• and
• aligning the substrate with respect to a patterning device based on the location of the first lithography pattern.

An alignment system comprising:

• an illumination source to provide an alignment beam for reading an alignment mark in a double patterning process;
• a detection system configured to detect a location of a first lithography pattern on a substrate formed from a first radiation-sensitive layer coated on the substrate based on a dye compound provided to the first radiation-sensitive layer or a second radiation-sensitive layer coated on the first lithography pattern, the dye compound providing a contrast between the first lithography pattern comprising the alignment mark and the second radiation-sensitive layer;
• and
• a positioning system configured to align the substrate with respect to a patterning device based on the detected location of the alignment mark formed in the first lithography pattern.