Misalignment management
View Patent ↗A method of determining overlay error between a template and a substrate using placement of template features and placement of substrate features in one or more images. Estimated distortion of the template and/or substrate may be determined using the overlay error. One or more forces acting on the template and/or substrate may be varied based on the estimated distortion for subsequent nano-lithography imprinting. Additionally, bias may be introduced in subsequent imprinting steps based on overlay performance.
1. A method, comprising:
providing an imprint lithography template having a patterning surface with at least one template feature;
providing a first image of the imprint lithography template;
for each field of two consecutive fields of a first substrate:
imprinting a patterned layer on the first substrate using the imprint lithography template, the template subjected to a plurality of balanced forces arrayed around the perimeter of the template,
providing a second image of the first substrate having at least two substrate features defined by the imprinted patterned layer,
determining a placement of the template feature using the first image,
determining a placement of the substrate features using the second image,
determining an overlay error between the template and the first substrate using the placement of the template feature and the placement of the substrate features, the overlay error comprising a magnification, trapezoidal and orthogonal overlay error;
calculating distortion {right arrow over (D)} of the template according to a relationship ∂{right arrow over (D)}(F)/∂F={[{right arrow over (O)} i+1 (x,y)−{right arrow over (O)} i (x,y)+[{right arrow over (W)} i+1 (x,y)−{right arrow over (W)} i (x,y)]}/δF i , where ∂{right arrow over (D)}(F)/∂F is determined using a Least Square Estimation, O i+1 is the overlay error associated with a second field of the two consecutive fields, O i is the overlay error associated with a first field of the two consecutive fields, W i+1 is the placement of the substrate features associated with the second field, W i is the placement of the substrate features associated with the first field, and F i are the plurality of balanced forces;
varying one or more of the arrayed perimeter forces applied to the template based on the distortion of the template so as to reduce template distortion and thereby reduce the magnification, trapezoidal and orthogonal overlay error; and,
imprinting a subsequent patterned layer on a field on a second substrate using the template while subjected to the varied force.
2. The method of claim 1 , wherein the first substrate and the second substrate are the same substrate.
3. The method of claim 1 , wherein the force applied to the template is increased during alignment of the second substrate and the template.
4. The method of claim 1 , wherein the force applied to the template is decreased during alignment of the second substrate and the template.
5. The method of claim 1 , further comprising:
determining a second estimated distortion of the first substrate using the overlay error; and,
varying at least one force applied to the second substrate based on the second estimated distortion.
6. The method of claim 1 , wherein the first image and the second image include substantially similar features.
7. The method of claim 1 , wherein the first image and the second image are different images.
8. The method of claim 1 , wherein at least one image is provided using a magnification optical system.
9. The method of claim 1 , wherein at least one image is provided using an interferometer stage.
10. The method of claim 1 , wherein the first image is a compilation of images.
11. The method of claim 1 , wherein the second image is a compilation of images.