Strain and kinetics control during separation phase of imprint process
View Patent ↗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. A method of patterning a substrate with a template, the template having a first relief pattern, and separating the template from the substrate, the method comprising:
transferring a second relief pattern to the substrate corresponding to the first relief pattern on the template, the transferring comprising forming the second relief pattern in a formable liquid between the substrate and the template corresponding to the first relief pattern on the template, the formable liquid forming a solidified layer deposited on the substrate;
applying a predetermined pressure to the template;
applying a separation force normal to the solidified layer to initiate separation of the template from the solidified layer;
monitoring a velocity of a separation crack formed between the template and the solidified layer during separation of said template from said solidified layer, wherein the separation crack forms and propagates at least in the x-y horizontal plane defined by the template/substrate interface;
reducing the pressure applied to the template during separation; and
controlling the magnitude of the applied separation force to maintain a steady separation crack velocity as the template separates from the solidified layer.
2. The method of claim 1 further comprising applying a predetermined pressure and/or vacuum to the substrate prior to applying the separation force.
3. The method of 1 further comprising monitoring the separation crack velocity using an imaging system.
4. The method of claim 3 wherein the imaging system tracks the motion of the separation crack between the template and the solidified layer during separation.
5. The method of claim 4 wherein the controlling the magnitude of the separation force further comprises analyzing the motion of the separation crack and, based on the analysis, adjusting the applied separation force to maintain the steady separation crack velocity.
6. The method of claim 1 wherein controlling the magnitude of the separation force further comprises adjusting the applied separation force based on the feature density of the first relief pattern in the region of separation.