Process of fabricating a precision microcontact printing stamp

#1. Field of the Invention

#The present invention is directed to a formation of a microcontact printing stamp employed in the creation of microcircuitry where dimensional integrity and registration must be maintained at the micron level over very large distances that may be as long as half a meter. More particularly, the present invention is directed to a process of preparing a high precision microcontact printing stamp wherein monomeric shrinkage is compensated for by low temperature curing.

#2. Background of the Prior Art

#The present invention may be better understood by reference to the accompanying drawings of which:

#FIG. 1 is a sectional elevation view of a mold housing prior to introduction of an elastomeric monomer;

#FIG. 2 is a sectional elevation view of a mold housing after the introduction of an elastomeric monomer;

#The recently developed process of microcontact printing, often called “soft-lithography,” requires the preparation of a very fine pitch pattern on the surface of a rubber stamp. It is to the preparation of such a stamp that the present invention is directed. The process of preparing a very fine pitch pattern on the surface of rubber stamp occurs in a molding operation. In this molding operation a mold housing 1, in which a flexible stamp backplane 4, usually formed of a rubber-like material, such as polydimethylsiloxane, natural rubber, vulcanized rubber, butadiene rubber, polyurethane rubber, polyepoxy rubber, acrylic rubber, polyphosphazine rubber and the like, is predisposed, is utilized. The flexible backplane 4 is disposed on a temporary substrate 5 Temporary substrate 5 may be any metal, ceramic, glass or plastic which does not react with the monomer or oligomer disposed in the mold and which maintains the backplane 4 flat and rigid. Of the materials employed as the temporary substrate 5, a glass plane is particularly preferred.

#In addition to the predisposition of the backplane 4 in mold housing 1, a photoresist master 3, expressing a microcircuit in negative relief, disposed on a substrate 2, is also predisposed in the mold housing 1 above the backplane 4. Substrate 2 is any smooth metal, plastic, ceramic or glass. In a preferred embodiment, the substrate 2 is a glass plane.

#A liquid elastomeric monomer or oligomer 6, which is curable to a solid elastomeric, is introduced into the mold housing 1. In a particularly preferred embodiment the elastomeric monomer or oligomer, which is thereupon crosslinked, is dimethylsiloxane or an oligomer thereof so that the product elastomer is silicone rubber, another name for polydimethylsiloxane (PDMS). This is not to say that other monomer and oligomer precursors of elastomeric materials cannot be employed in the process of the present invention.