Decal Transfer Microlithography:  A New Soft-Lithographic Patterning Method

Abstract

A new soft-lithographic method for micropatterning polymeric resists, Decal Transfer Microlithography (DTM), is described. This technique is based on the transfer of elastomeric decal patterns via the engineered adhesion and release properties of a compliant poly(dimethylsiloxane) (PDMS) patterning tool. An important feature of the DTM method is the exceptionally broad spectrum of design rules that it embraces. This procedure is capable of transferring micron to submicron-sized features with high fidelity over large substrate areas and potentially simplifies to a significant degree the requirements for effecting multiple levels of registration. The DTM method offers some potential advantages over other soft-lithographic patterning methods in that it is amenable to transferring resist patterns with both open and closed forms, negative and positive image contrasts, and does so for a wide variety of aspect ratios and a significant range of pattern pitches that can be accommodated without degradation due to mechanical distortions of the pattern transfer tool. The most significant advance embodied in the DTM method, however, is that it offers useful new capabilities for the design and fabrication of advanced planar and 3D microfluidic assemblies and microreactors.

Micron and submicron patterning of polydimethylsiloxane resists on electronic materials by decal transfer lithography and reactive ion-beam etching: Application to the fabrication of high-mobility, thin-film transistors

“…30 Briefly, PDMS prepolymer ͑Dow Corning Sylgard 184͒ was spun cast onto a master bearing micron-and submicron-sized features ͑i.e., photoresist patterned silicon wafer͒ and cured at 70°C. After curing, the PDMS coated master was exposed to UV/ozone ͑UVO͒ ͑mercury lamp from BHK, 173 W/cm 2 ͒ and tridecafluoro-1,1,2,2-tetrahydrooctyl trichlorosilane ͑"no stick," Gelest͒.…”

“…The key feature of this method consists of the development of a latent image of a resist pattern, one embedded within a closed-form decal. 30 As shown in Fig. 1͑a͒, the irreversible bonding of a composite PDMS stamp to a substrate is followed by a mechanical debonding procedure to generate the nascent substrate-bonded decal.…”

“…30 The conventional DTL process appears to be most useful for delivering micron-sized PDMS patterns ͑ones that can be used as resists for subsequent processing͒ to flat or curved large area electronic materials such as silicon ͑Si͒, silicon dioxide ͑SiO 2 ͒, and other metal and metal-oxide thin films with high fidelity and low defect densities. 30,31 Submicron-sized patterns, however, are more difficult to transfer with high fidelity and low defect densities due to the limitations of the mechanical properties of the PDMS structures used to form the decal. To overcome this limitation, a second variant of the DTL technique was developed.…”

Sub-Micrometer Patterning Using Soft Lithography

“…It is also possible to pick up thin films from a donor substrate followed by transfer to an appropriate receiver using a patterned or planar stamp as an intermediate vehicle [115,116]. Decal transfer lithography (DTL) is a technique that involves printing of PDMS microstructures, which can be achieved through fracture of PDMS features [117] or by selective release of a thin film of PDMS being cast onto a stamp [118].…”

Fabrication and transfer of fragile 3D PDMS microstructures

“…Manual handling of fragile structures, such as thin membranes, results in low device yield since even low levels of strain will rupture or deform the membranes. Several transfer processes [8][9][10] utilize a carrier to provide protection and control of spatial positions, which could be used to minimize handling of fragile structures and thus increase device yield. However, carrier transfer methods normally require a stepwise increase of bond strength between the polymer and mould, polymer and transfer carrier, and polymer and destination substrate [11].…”