Strain and kinetics control during separation phase of imprint process
Systems and methods for improving robust layer separation during the separation process of an imprint lithography process are described. Included are methods of matching strains between a substrate to be imprinted and the template, varying or modifying the forces applied to the template and/or the substrate during separation, or varying or modifying the kinetics of the separation process.
1. An imprint lithography method comprising:
positioning an imprint lithography template and substrate to define a volume therebetween, wherein the imprint lithography template is connected to a chuck;
filling the volume with a polymerizable material;
contacting the polymerizable liquid with the imprint lithography template;
solidifying the polymerizable material, thereby forming a solidified patterned layer on the substrate; and
separating the imprint lithography template and the solidified patterned layer, wherein the separating comprises:
applying, by an imprint head connected to the chuck, a separation force to the imprint lithography template normal to the solidified patterned layer to initiate separation of the imprint lithography template from the solidified patterned layer;
monitoring the separation force applied by the imprint head;
monitoring stress forces caused by bending of the imprint lithography template, wherein monitoring the stress forces comprises imaging motion of a contact line between the imprint lithography template and the solidified patterned layer with an imaging system; and
based on the motion of the contact line, reducing the pressure applied by the chuck to the imprint lithography template such that the stress forces caused by the bending of the imprint lithography template are balanced by the separation force.
2. The imprint lithography method of claim 1 , wherein monitoring the separation force comprises monitoring the peak separation force.
3. The imprint lithography method of claim 1 , further comprising, after solidifying the polymerizable material but prior to initiating separation of the imprint lithography template from the solidified patterned layer, applying a predetermined pressure to the imprint lithography template.
4. The imprint lithography method of claim 1 , further comprising applying a predetermined pressure to the template prior to initiating separation.
5. The imprint lithography method of claim 1 , wherein the separating comprises maintaining a constant pulling stress.
6. The imprint lithography method of claim 1 , wherein the separating further comprises applying a partial vacuum pressure to the imprint lithography template to achieve final separation of the imprint lithography template from the solidified patterned layer.
7. The imprint lithography method of claim 6 , further comprising reducing motion of the imprint head in the direction normal to the solidified patterned layer during the final separation of imprint lithography template from the solidified patterned layer.
8. The imprint lithography method of claim 7 , wherein the imprint head is stationary in the direction normal to the solidified patterned layer at the final separation of the imprint lithography template from the solidified patterned layer.
9. The imprint lithography method of claim 6 , wherein applying the partial vacuum pressure minimizes deflection of the imprint lithography template at the final separation of the imprint lithography template from the solidified patterned layer.
10. The imprint lithography method of claim 1 , wherein monitoring the stress forces comprises monitoring an amount of curvature of the contact line.