Inspection method and apparatus, lithographic apparatus, lithographic processing cell and device manufacturing method, substrate for use in the methods
AssigneeASML Netherlands B.V.
InventorsEverhardus Cornelis Mos, Arie Jeffrey Den Boef, Maurits Van Der Schaar
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Abstract
An overlay marker for use with a scatterometer includes two overlying two-dimensional gratings. The two gratings have the same pitch but the upper grating has a lower duty ratio. Cross-talk between X and Y overlay measurements can therefore be avoided. The gratings may be directly overlying or off set so as to be interleaved in one or two directions.
Claims20
A method of measuring overlay between a first layer and a second layer of a substrate, the first layer having therein a first marker component comprising a two-dimensional grating having a first pitch and a first duty ratio, the second layer having therein a second marker component comprising a two-dimensional grating having a second pitch and a second duty ratio, the second marker component overlying the first marker component, the method comprising:
- directing a measurement beam onto the first and second marker components;
- detecting radiation from the measurement beam diffracted by the first and second marker components;
- determining the overlay from the detected radiation;
- wherein the first pitch is substantially equal to the second pitch and the first duty ratio is different from the second duty ratio.
An inspection apparatus configured to measure overlay between a first layer and a second layer of a substrate, the first layer having therein a first marker component comprising a two-dimensional grating having a first pitch and a first duty ratio, the second layer having therein a second marker component comprising a two-dimensional grating having a second pitch and a second duty ratio, the second marker component overlying the first marker component, the apparatus comprising:
- an illumination optical system configured to direct a measurement beam onto the first and second marker components;
- a detection optical system configured to detect radiation from the measurement beam diffracted by the first and second marker components;
- a computing device configured to determine the overlay from the detected radiation on the basis that the first pitch is equal to the second pitch and the first duty ratio is different from the second duty ratio.
A lithographic apparatus comprising a projections system configured to project an image of a pattern onto a substrate and an inspection apparatus configured to measure overlay between a first layer and a second layer of a substrate, the first layer having therein a first marker component comprising a two-dimensional grating having a first pitch and a first duty ratio, the second layer having therein a second marker component comprising a two-dimensional grating having a second pitch and a second duty ratio, the second marker component overlying the first marker component, the inspection apparatus comprising:
- an illumination optical system configured to direct a measurement beam onto the first and second marker components;
- a detection optical system configured to detect radiation from the measurement beam diffracted by the first and second marker components;
- a computing device configured to determine the overlay from the detected radiation on the basis that the first pitch is equal to the second pitch and the first duty ratio is different from the second duty ratio.
A device manufacturing method comprising:
- forming in a first layer of a substrate a first marker component comprising a two-dimensional grating having a first pitch and a first duty ratio;
- forming in a second layer of the substrate a second marker component comprising a two-dimensional grating having a second pitch and a second duty ratio, the second marker component overlying the first marker component;
- wherein the first pitch is equal to the second pitch and the first duty ratio is different from the second duty ratio.
A substrate having a first layer and a second layer, the first layer having therein a first marker component comprising a two-dimensional grating having a first pitch and a first duty ratio, the second layer having therein a second marker component comprising a two-dimensional grating having a second pitch and a second duty ratio, the second marker component overlying the first marker component;
- wherein the first pitch is equal to the second pitch and the first duty ratio is different from the second duty ratio.
Dependencies are inferred from the claim text.