On chip sensor for wafer overlay measurement

1 . A method for correcting a processing error by measuring a characteristic of a diffraction target on a substrate using a sensor comprising a sensor chip comprising a first side and a second side opposite the first side, the method comprising:

using a first optical system, disposed on the sensor chip and comprising a first integrated optic to transmit an illumination beam toward the diffraction target on the substrate that is disposed adjacent to the sensor chip, to generate a signal beam comprising diffraction order sub-beams generated from the diffraction target along a signal path;

using a second optical system, disposed on the sensor chip and comprising a second integrated optic, to collect and transmit the signal beam from the first side to the second side of the sensor chip; and

using a detector system to measure the characteristic of the diffraction target based on the signal beam transmitted by the second optical system;

determining, by a processor coupled to each sensor, the characteristic of the diffraction target; and

correcting the processing error of a lithographic apparatus, a sensor, or the substrate based on the characteristic of the diffraction target.

2 . The method of claim 1 , further comprising measuring characteristics of a plurality of diffraction targets on the substrate simultaneously.

3 . The method of claim 1 , further comprising adjusting the first integrated optic configuration to an out-of-focus position on the diffraction target, wherein the first integrated optic configuration comprises a microelectromechanical system-based adjustable mirror configured to focus the illumination beam toward the diffraction target.

4 . The method of claim 1 , further comprises focusing the illumination beam onto the diffraction target using a microelectromechanical system-based actuator.

5 . A lithographic apparatus comprising:

an illumination system configured to illuminate a patterning device;

a projection system configured to project an image of the patterning device onto a substrate; and

a sensor apparatus configured to measure a characteristic of a diffraction target on the substrate, the sensor apparatus comprising:

a sensor chip comprising a first side and a second side opposite the first side;

a second illumination system disposed on the sensor chip and configured to transmit an illumination beam along an illumination path;

a first optical system disposed on the sensor chip and comprising a first integrated optic configuration to configure and transmit the illumination beam toward the diffraction target on the substrate, disposed adjacent to the sensor chip, and generate a signal beam comprising diffraction order sub-beams generated from the diffraction target;

a second optical system coupled to the sensor chip and comprising a second integrated optic configuration to collect and transmit the signal beam from the first side to the second side of the sensor chip; and

a detector system configured to measure the characteristic of the diffraction target based on the signal beam transmitted by the second optical system.

6 . The lithographic apparatus of claim 5 , wherein the characteristic of the diffraction target is an overlay measurement.

7 . The lithographic apparatus of claim 5 , wherein an area of the first side of the sensor chip is no greater than about 5 mm by about 5 mm.

8 . The lithographic apparatus of claim 5 , wherein the sensor apparatus comprises a plurality of sensors arranged symmetrically relative to each other and disposed above a plurality of diffraction targets on the substrate.

9 . The lithographic apparatus of claim 5 , wherein the illumination system comprises a photonic crystal fiber disposed on the sensor chip and coupled to the first optical system.

10 . The lithographic apparatus of claim 5 , wherein the first integrated optic configuration comprises a mirror and a photonic crystal waveguide disposed on the first side of the sensor chip.

11 . The lithographic apparatus of claim 10 , wherein the mirror comprises a microelectromechanical system-based actuator configured to focus the illumination beam onto the diffraction target.

12 . The lithographic apparatus of claim 10 , wherein:

the photonic crystal waveguide comprises the same bandgap as the photonic crystal fiber; and

the illumination beam wavelength is about 400 nm to about 2000 nm.

13 . The lithographic apparatus of claim 5 , wherein the illumination system comprises a plurality of photonic crystal fibers disposed on the sensor chip and coupled to the first optical system comprising a plurality of photonic crystal waveguides.

14 . The lithographic apparatus of claim 13 , wherein the plurality of photonic crystal fibers and the plurality of photonic crystal waveguides are arranged symmetrically relative to each other and configured to focus the illumination beam onto the diffraction target.

15 . The lithographic apparatus of claim 5 , wherein the second integrated optic configuration comprises a negative lens, a positive lens, a meta lens, or a through-hole.

16 . The lithographic apparatus of claim 15 , wherein the meta lens is a flat Fresnel lens.

17 . The lithographic apparatus of claim 15 , wherein the meta lens is a nanostructured surface lens.

18 . The lithographic apparatus of claim 5 , wherein the detector system comprises a first detector, a second detector, a wavelength filter, and a focusing optic.

19 . The lithographic apparatus of claim 5 , wherein the first detector is configured to detect an infrared range of the signal beam from about 700 nm to about 2000 nm and the second detector is configured to detect an ultraviolet-visible range of the signal beam from about 10 nm to about 700 nm.

20 . The lithographic apparatus of claim 5 , wherein the illumination system, the first optical system, and the second optical system are integrated on the sensor chip.