Method and Apparatus for Determining Lithographic Quality of a Structure

A method of determining lithographic quality of a first structure processed by a lithographic process that uses formation of a periodic image on a substrate, the method comprising:

• illuminating the first structure with incident radiation having a first characteristic;
• measuring intensity of radiation scattered by the first structure;
• performing a comparison using the measured intensity;
• and
• determining a value of lithographic quality of the first structure based on the comparison.

A computer program product containing one or more sequences of machine-readable instructions for determining lithographic quality of a first structure processed by a lithographic process that uses formation of a periodic image on a substrate, the instructions being adapted to cause one or more processors to perform operations comprising:

• illuminating the first structure with incident radiation having a first characteristic;
• measuring intensity of radiation scattered by the first structure;
• performing a comparison using the measured intensity;
• and
• determining a value of lithographic quality of the first structure based on the comparison.

An inspection apparatus configured to determine lithographic quality of a first structure processed by a lithographic process that uses formation of a periodic image on a substrate, the inspection apparatus comprising:

• an illumination system configured to illuminate the first structure with incident radiation with a first characteristic;
• a detection system configured to measure intensity of radiation scattered by the first structure;
• and
• a processor configured to:
• perform a comparison using the measured intensity;
• and
• determine a value of lithographic quality of the first structure based on the comparison.

The inspection apparatus of 36, wherein:

• the illumination system is further configured to illuminate the first structure with incident radiation by illuminating the first structure separately with incident radiation with the first and a second characteristic;
• the detection system is configured to detect intensity of radiation scattered by the first structure by measuring intensity of radiation scattered by the first structure for each of the first and second characteristics;
• and
• the processor is configured to perform a comparison using the measured intensity by determining a difference between the measured intensity corresponding to the first and second characteristics and to determine a value of lithographic quality of the first structure using the results of the comparison by using the determined difference.

A lithography apparatus comprising an exposure system and an inspection apparatus, the inspection apparatus configured for determining lithographic quality of a first structure processed by a lithographic process that uses formation of a periodic image on a substrate, the inspection apparatus comprising:

• an illumination system configured to illuminate the first structure with incident radiation with a first characteristic;
• a detection system configured to measure intensity of radiation scattered by the first structure;
• and
• a processor configured to:
• perform a comparison using the measured intensity;
• and
• determine a value of lithographic quality of the first structure using results of the comparison.

A lithographic cell comprising:

• a lithographic apparatus comprising an exposure system;
• and
• an inspection apparatus, the inspection apparatus configured to determine lithographic quality of a first structure processed by a lithographic process that uses formation of a periodic image on a substrate, the inspection apparatus comprising:
• an illumination system configured to illuminate the first structure with incident radiation with a first characteristic;
• a detection system configured to measure intensity of radiation scattered by the first structure;
• and
• a processor configured to:
• perform a comparison using the measured intensity;
• and
• determine a value of lithographic quality of the first structure using results of the comparison.