Inspection Method and Apparatus, Lithographic System and Device Manufacturing Method

An inspection apparatus for determining values of profile parameters of substrate patterns, the inspection apparatus comprising:

• a support for a substrate;
• an optical system configured to illuminate one or more pattern targets on the substrate with radiation and detect scattered radiation to obtain a corresponding pattern signal;
• and
• a processor configured to calculate values of differential pattern profile parameters using a difference between a first pattern signal detected from a first pattern target using the optical system and a second pattern signal detected from a second pattern target using the optical system.

A computer program product comprising machine-readable instructions for causing a processor to perform operations comprising:

• obtaining a first patterned signal corresponding to detected scattered radiation from a first pattern target on a first substrate;
• obtaining a second patterned signal corresponding to detected scattered radiation from a second pattern target on a second substrate;
• and
• calculating values of differential pattern profile parameters using a difference between the first pattern signal and the second pattern signal.

A lithographic system comprising:

• a lithographic apparatus comprising:
• an illumination optical system configured to illuminate a pattern;
• a projection optical system configured to project an image of the pattern onto a substrate;
• and
• an inspection apparatus, comprising:
• a support for the substrate;
• an optical system configured to illuminate one or more pattern targets on the substrate with radiation and detect scattered radiation to obtain a corresponding pattern signal;
• and
• a processor configured to calculate values of differential pattern profile parameters using a difference between a first pattern signal detected from a first pattern target using the optical system and a second pattern signal detected from a second pattern target using the optical system,
• wherein the lithographic apparatus is configured to use the measurement results from the inspection apparatus in applying the pattern to further substrates.

A computer-readable storage device having computer-executable instructions stored thereon, execution of which, by a computing device, causes the computing device to perform operations comprising:

• obtaining a first patterned signal corresponding to detected scattered radiation from a first pattern target on a first substrate;
• obtaining a second patterned signal corresponding to detected scattered radiation from a second pattern target on a second substrate;
• and
• calculating values of differential pattern profile parameters using a difference between the first pattern signal and the second pattern signal.

A lithographic system comprising:

• a lithographic apparatus comprising:
• an illumination optical system arranged to illuminate a pattern;
• a projection optical system arranged to project an image of the pattern onto a substrate;
• and
• an inspection apparatus comprising:
• a support for a substrate;
• an optical system configured to illuminate one or more pattern targets on the substrate with radiation and to detect scattered radiation to obtain a corresponding pattern signal;
• and
• a processor arranged to calculate values of differential pattern profile parameters using a difference between a first pattern signal detected from a first pattern target using the optical system and a second pattern signal detected from a second pattern target using the optical system, wherein the lithographic apparatus is configured to use the measurement results from the inspection apparatus in applying the pattern to further substrates.

A method of manufacturing devices wherein a device pattern is applied to a series of substrates using a lithographic process, the method comprising:

• inspecting at least one periodic structure formed as part of or beside, the device pattern on at least one of the substrates using a method comprising:
• supporting a first substrate comprising a first pattern target;
• illuminating the first pattern target with radiation and detecting scattered radiation to obtain a first pattern signal;
• supporting a second substrate comprising a second pattern target;
• illuminating the second pattern target with radiation and detecting scattered radiation to obtain a second pattern signal;
• and
• calculating values of differential pattern profile parameters using a difference between the first pattern signal and the second pattern signal;
• and
• controlling the lithographic process for later substrates in accordance with the result of the inspecting method.