The present state of the art for microstructuring and/or nanostructuring of surfaces primarily comprises photolithography and different embossing techniques. Embossing techniques work either with hard or soft dies. In recent times, embossing lithography techniques have predominated and have eclipsed conventional photolithography techniques. Among embossing lithography techniques, primarily the use of so-called soft dies, is becoming more and more popular. The reason lies in the easy production of the dies, efficient embossing processes, very good surface properties of the respective die materials, the low costs, the reproducibility of the embossing product, and in the possibility of the elastic deformation of the die during demolding. In soft lithography, a die that is comprised of an elastomer with a microstructured or nanostructured surface is used in order to produce structures in the range of 20 nm up to >1,000 μm. Embossing lithography techniques can be roughly divided into hot embossing, nanoimprint lithography, and nanocontact or microcontact embossing. During hot embossing, the die is pressed mainly with application of force in a (heated) embossing material. In nanoimprint lithography, a very finely structured die is brought into contact with the embossing material. Although forces are also used in this method, the receiving of embossing material into nanometer- or micrometer-sized structures by capillary action is a driving force of the embossing process. With microcontact embossing, the structured die is not pressed by force into an embossing material but rather transfers a substance located on the surface of its structures onto another surface.
There are six known microcontact embossing methods:                Microcontact and/or nanocontact pressing (μ/nCP)        Replica casting (REM)        Microtransfer molding (μTM) or nanoimprint lithography (NIL),        Microforming in capillaries (MIMIC)        Solvent-supported microforms (SAMIM), and        Phase shift lithography.        
Elastomer structural dies are produced as negatives of a master. A master die is a hard die made of metal or ceramic, which is produced at one time by correspondingly expensive processes. Any number of elastomer dies can then be produced from the master. The elastomer dies make possible a conformable, uniform contact across large surfaces. They are easy to separate from their rigid master die as well as from the embossing products. In addition, elastomer dies have a low surface tension for an easy and simple separation from die and substrate. The material combinations of the structural die and the embossing material cause technical problems, whereby the important factors are, i.a., a long service life or extended usability of the structural die and an exact transfer of the microstructures and/or nanostructures.
An advantage of this invention is a microcontact embossing method with which a long-lived structural die is indicated, which is suitable for an exact transfer of the microstructures and/or nanostructures to large surfaces.
This advantage is achieved with the features of the claims. Advantageous further developments of the invention are indicated in the subclaims. All combinations that comprise at least two of the features indicated in the specification, the claims and/or the figures also fall within the scope of the invention. In the indicated ranges of values, values as boundary values that lie within the above-mentioned limits are also to be considered as disclosed and can be claimed in any combination.
USPTO Backgrounds
USPTO Backgrounds