Metrology method and apparatus, and device manufacturing method

An inspection apparatus comprising:

• an illumination arrangement configured to deliver a beam of radiation to a substrate so as to illuminate a target structure on the substrate, the target structure including one or more periodic structures;
• a detection arrangement configured to form and detect an image of the target structure using radiation diffracted from the substrate;
• and
• a computational arrangement configured to extract intensity values from at least one region of interest within the image of the target structure and to use the extracted values to determine the property the periodic structure,
• wherein the computational arrangement is arranged to recognize locations of a plurality of boundary features in the image of the target structure and to calculating from the recognized locations features a location of the region of interest, and
• wherein, in at least one direction, the number of the boundary features is at least twice a number of boundaries of periodic structures within the target structure.

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,
• an illumination arrangement configured to deliver a beam of radiation to a substrate so as to illuminate a target structure on the substrate, the target structure including one or more periodic structures;
• a detection arrangement configured to form and detect an image of the target structure using radiation diffracted from the substrate;
• and
• a computational arrangement configured to extract intensity values from at least one region of interest within the image of the target structure and to use the extracted values to determine the property the periodic structure,
• wherein the computational arrangement is arranged to recognize locations of a plurality of boundary features in the image of the target structure and to calculating from the recognized locations features a location of the region of interest, and
• wherein, in at least one direction, the number of the boundary features is at least twice a number of boundaries of periodic structures within the target structure,
• wherein the lithographic apparatus is arranged 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 including:

• inspecting at least one periodic structure formed as part of or beside the device pattern on at least one of the substrates:
• forming a target structure on a substrate, the target structure including a periodic structure;
• detecting an image of the target structure while illuminating the target structure with a beam of radiation, the image being formed using a first part of non-zero order diffracted radiation while excluding zero order diffracted radiation;
• and
• determining a property of the periodic structure using an intensity value extracted from a region of interest within the image of the target structure,
• wherein the region of interest is identified in the detected image by recognizing locations of a plurality of boundary features in the image of the target structure and calculating, from the recognized locations, features a location of the region of interest, and wherein, in at least one direction, the number of the boundary features is at least twice a number of boundaries of periodic structures within the target structure, and
• controlling the lithographic process for later substrates in accordance with the result of the inspection method.

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 an illumination arrangement operable to deliver a beam of radiation to the substrate so as to illuminate a target structure on the substrate, the target structure including one or more periodic structures;
• a detection arrangement operable to form and detect an image of the target structure using radiation diffracted from the substrate;
• and a computational arrangement operable to extract intensity values from at least one region of interest within the image of the target structure and to use the
• extracted values to determine the property the periodic structure, wherein the computational arrangement is arranged to recognize locations of a plurality of boundary features in the image of the target structure and to calculating from the recognized locations features a location of the region of interest, and wherein, in at least one direction, the number of the boundary features is at least twice a number of boundaries of periodic structures within the target structure, wherein the lithographic apparatus is arranged 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 including inspecting at least one periodic structure formed as part of or beside the device pattern on at least one of the substrates using an inspection method comprising, using the lithographic process to form a target structure on the substrate, the target structure including one or more periodic structures on the substrate;

• forming and detecting at least one image of the target structure while illuminating the target structure with a beam of radiation, the image being formed using a first part of non-zero order diffracted radiation while excluding zero order diffracted radiation;
• using intensity values extracted from at least one region of interest within the image of the target structure to determine the property of a corresponding one of the periodic structures, wherein to perform step (c), the region of interest is identified in the detected image by recognizing locations of a plurality of boundary features in the image of the target structure and calculating from the recognized locations features a location of the region of interest, and wherein, in at least one direction, the number of the boundary features is at least twice a number of boundaries of periodic structures within the target structure;
• and controlling the lithographic process for later substrates in accordance with the result of the inspection method.