Metrology method, target and substrate

A diffraction measurement target, on a substrate, comprising:

• at least a first sub-target, at least a second sub-target and at least third sub-target, wherein:
• the first sub-target comprises a first periodic structure at a first layer of the substrate and a second periodic structure at a third layer of the substrate,
• the second sub-target comprises a first periodic structure at a second layer of the substrate and a second periodic structure at the third layer of the substrate,
• the third sub-target comprises a first periodic structure at the first, second, or third layer of the substrate, wherein the first, second, and third layers are different layers of the substrate,
• the first, second and third sub-targets each have a different design,
• at least two of the sub-targets are respectively designed for determination of a different lithographic process parameter,
• the second periodic structure of the second sub-target at least partly overlays the first periodic structure of the second sub-target and the second periodic structure of the first sub-target at least partly overlays the first periodic structure of the first sub-target.

A method of measuring a parameter of a lithographic process, the method comprising:

• illuminating, at a same time, at least a first sub-target, at least a second sub-target, and at least a third sub-target of a diffraction measurement target on a substrate with radiation,
• wherein the first sub-target comprises a first periodic structure at a first layer of the substrate and a second periodic structure at a third layer of the substrate,
• wherein the second sub-target comprises a first periodic structure at a second layer of the substrate and a second periodic structure at the third layer of the substrate,
• wherein the third sub-target comprises a first periodic structure at the first, second, or third layer of the substrate, wherein the first, second, and third layers are different layers of the substrate, and
• wherein the third sub-target is designed for determination of a correction of the parameter of the lithographic process for which the first sub-target is designed for determination;
• and
• detecting radiation scattered by the at least first, second, and third sub-targets to obtain for that target a measurement representing the parameter of the lithographic process and the correction of the parameter of the lithographic process.

A diffraction measurement target on a substrate, comprising:

• at least a first sub-target, at least a second sub-target, and at least a third sub-target, wherein:
• the first sub-target comprises a first periodic structure at a first layer of the substrate and a second periodic structure at a third layer of the substrate,
• the second sub-target comprises a first periodic structure at a second layer of the substrate and a second periodic structure at the third layer of the substrate,
• the third sub-target comprises a first periodic structure at the first, second, or third layer of the substrate, wherein the first, second, and third layers are different layers of the substrate, and
• the third sub-target is designed for determination of a correction of a lithographic process parameter for which the first sub-target is designed for determination, and
• at least part of each of the periodic structures of the first and second sub-targets is within a contiguous area of less than or equal to 1000 μm2 on the substrate.

A method of measuring a parameter of a lithographic process, the method comprising:

• illuminating at least a first sub-target of a diffraction measurement target on a substrate with radiation,
• wherein a first periodic structure of the first sub-target is at a first layer on the substrate and a second periodic structure of the first sub-target is at a third layer on the substrate,
• wherein the diffraction measurement target further comprises a first periodic structure of at least a second sub-target at a second layer and a second periodic structure of the second sub-target at the third layer on the substrate, and
• wherein the first and second sub-targets are respectively designed for determination of a different lithographic process parameter;
• detecting radiation scattered by at least the first sub-target to obtain a measurement representing its designed lithographic process parameter;
• illuminating at least the second sub-target and a third sub-target of the diffraction measurement target on the substrate with radiation, wherein a periodic structure of the third sub-target is at one of the first, second, or third layer, the first, second, and third layers being different layers on the substrate, and wherein the second and third sub-targets are respectively designed for determination of a different lithographic process parameter;
• and
• detecting radiation scattered by at least the second and third sub-targets to obtain a measurement representing respective different lithographic process parameters.

A diffraction measurement target comprising:

• at least a first sub-target, a second sub-target and a third sub-target that, wherein:
• the first sub-target comprises a first periodic structure at a first layer of the substrate and a second periodic structure at a third layer of the substrate,
• the second sub-target comprises a first periodic structure at a second layer of the substrate and a second periodic structure at the third layer of the substrate,
• the third sub-target comprises a first periodic structure at the first, second, or third layer of the substrate, wherein the first, second, and third layers are different layers of the substrate, and
• the first and second sub-targets are respectively designed for determination of a lithographic process parameter and the third sub-target is designed for determination of a different lithographic process parameter.

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 a diffraction measurement target formed as part of or beside the device pattern on at least one of the series of substrates by illuminating a measurement spot on the diffraction measurement target on the at least one of the series of substrates with radiation, wherein:
• the diffraction measurement target comprises at least a first sub-target, at least a second sub-target and at least third sub-target,
• the first sub-target comprises a first periodic structure at a first layer of the substrate and a second periodic structure at a third layer of the substrate,
• the second sub-target comprises a first periodic structure at a second layer of the substrate and a second periodic structure at the third layer of the substrate,
• wherein the third sub-target comprises a first periodic structure at the first, second, or third layer of the substrate, wherein the first, second, and third layers are different layers of the substrate, and
• the first, second and third sub-targets each have a different design,
• at least two of the sub-targets are respectively designed for determination of a different lithographic process parameter, and
• the measurement spot covers at one time at least part of each of the periodic structures of the first, second and third sub-targets;
• detecting radiation scattered by the at least two sub-targets to obtain for that target a measurement representing the different parameters of the lithographic process;
• and
• controlling subsequent steps of the lithographic process.