Patent ID: 11953450
Assignee: ASML NETHERLANDS B.V.
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 2:
3. The method of claim 1, further comprising:
illuminating, using the first illumination beam, a second composite grating under the first angle of incidence such that the first illumination beam propagates along the direction that has the component along the first horizontal direction along the surface of the substrate; and
measuring a third signal associated with an intensity of a first order diffracted beam from the second composite grating,
wherein:
the second composite grating is formed by a third grating and a fourth grating on top of the third grating, the third grating and the fourth grating having a substantially identical pitch as the first and the second gratings,
the composite grating is biased with a first shift in a shift direction along a grating direction, and
the second composite grating is biased with a second shift in the shift direction along the grating direction, the first shift being different from the second shift.