Microcontact printing is a technique for forming patterns of organic monolayers with micron and submicron lateral dimensions. It offers experimental simplicity and flexibility in forming certain types of patterns. In the prior art, microcontact printing was used with self-assembled monolayers of long-chain alkanethiolates to form organic structures on gold and other metals. These patterns acted as nanometer resists by protecting the supporting metal from corrosion by appropriately formulated etchants, or, allowed for the selective placement of fluids on hydrophilic regions of the pattern. In general, patterns of self-assembled monolayers having dimensions that can be less than 1 micron are formed by using the alkanethiol as an "ink", and by printing them on the metal support using an elastomeric "stamp". The stamp is fabricated by molding a silicone elastomer using a master prepared by optical or X-ray microlithography or by other techniques. (See U.S. patent application Ser. Nos. 08/654,993; 08/769,594; 08/821,464; 08/707,456 and 08/768,449 which are incorporated herein in their entirety by reference)
Microcontact printing brings to microfabrication a number of new capabilities. Microcontact printing makes it possible to form patterns that are distinguished only by their constituent functional groups; this capability permits the control of surface properties such as interfacial free energies with great precision. In the prior art microcontact printing relies on molecular self-assembly. Using self-assembling monolayers, a system is generated that is (at least locally) close to a thermodynamic minimum and is intrinsically defect-rejecting and self-healing. Simple procedures, with minimal protection against surface contamination by adsorbed materials or by particles, can lead to surprisingly low levels of defects in the final structures. The procedure using self-assembling monolayers can be conducted at atmospheric pressure, in an unprotected laboratory atmosphere. Thus, microcontact printing that uses self-assembling monolayers is useful in laboratories that do not have routine access to the equipment normally used in microfabrication, or for which the capital cost of equipment is a serious concern. The patterned self-assembled monolayers can be designed to act as resists with a number of wet-chemical etchants.
Also in the prior art, a gold film 5 to 2000 nanometers thick is typically supported on a titanium-primed Si/SiO.sub.2 wafer or glass sheet. The titanium serves as an adhesion promoter between gold and the support. However, the silicon wafer is rigid, brittle, and cannot transmit light. These silicon wafers are also not suitable for a large-scale, continuous printing process, such as in letterpress, gravure, offset, and screen printing (see Printing Fundamentals, A. Glassman, Ed. (Tappi Press Atlanta, Ga. 1981); Encyclopedia Britannica, vol. 26, pp. 76-92, 110-111 (Encyclopedia Brittanica, Inc. 1991)). In addition, silicon must be treated in a separate step with an adhesion promoter such as Cr or Ti, or Au will not adequately adhere, preventing formation of a stable and well-ordered monolayer. Finally, silicon is opaque to visible light, so any diffraction pattern obtained must be created with reflected, not transmitted light.
What is needed is an easy, efficient and simple method of contact printing a patterned receptor on an optically transparent, flexible substrate, that is amenable to continuous processing and does not use self-assembling monolayers. Such a method and the device resulting from such a method is simpler, not restricted to the limitations of self-assembling monolayers and is easier to manufacture.