The field of invention relates generally to micro-fabrication of structures. More particularly, the present invention is directed to a polymerization technique suited for use in imprint lithography.
Micro-fabrication involves the fabrication of very small structures, e.g., having features on the order of micro-meters or smaller. One area in which micro-fabrication has had a sizeable impact is in the processing of integrated circuits. As the semiconductor processing industry continues to strive for larger production yields while increasing the circuits per unit area formed on a substrate, micro-fabrication becomes increasingly important. Micro-fabrication provides greater process control while allowing increased reduction of the minimum feature dimension of the structures formed. Other areas of development in which micro-fabrication has been employed include biotechnology, optical technology, mechanical systems and the like.
An exemplary micro-fabrication technique is commonly referred to as imprint lithography and is described in detail in numerous publications, such as United States published patent applications no. 2004/0065976 entitled METHOD AND A MOLD TO ARRANGE FEATURES ON A SUBSTRATE TO REPLICATE FEATURES HAVING MINIMAL DIMENSIONAL VARIABILITY; no. 2004/0065252, entitled METHOD OF FORMING A LAYER ON A SUBSTRATE TO FACILITATE FABRICATION OF METROLOGY STANDARDS; and No. 2004/0046271, entitled METHOD AND A MOLD TO ARRANGE FEATURES ON A SUBSTRATE TO REPLICATE FEATURES HAVING MINIMAL DIMENSIONAL VARIABILITY, all of which are assigned to the assignee of the present invention. The fundamental imprint lithography technique as shown in each of the aforementioned published patent applications includes formation of a relief pattern in a polymerizable layer and transferring the relief image into an underlying substrate forming a relief image in a structure. To that end, a template is employed spaced-apart from a substrate, with a formable liquid present between the template and the substrate. The liquid is solidified forming a solidified layer that has a pattern recorded therein that is conforming to a shape of the surface of the template in contact with the liquid. The substrate and the solidified layer are then subjected to processes to transfer, into the substrate, a relief structure that corresponds to the pattern in the solidified layer.
One manner in which the polymerizable liquid is located between the template and the substrate is by depositing a plurality of droplets of liquid on the substrate. Thereafter, contact is made with the polymerizable liquid by the template to spread the polymerizable liquid over the surface of the substrate and subsequently record a pattern therein. It is highly desirable to avoid trapping of gases, such as air, when the polymerizable liquid spreads over the substrate.
It is desired, therefore, to provide a method for forming a fluid layer on a substrate while minimizing the trapping of gases therein.