University of Michigan

Agency for Science, Technology and Research

Stella W Pang

Albert F Yee

Yen Peng Kong

Li Tan

Jason W Weigold

Lingjie Jay Guo

Hong Yee Low

Edward T Zellers

Wei-Cheng Tian

Lirong Bao

Xudong Huang

Yen-Peng Kong

The present invention is directed to micro- and nano-scale imprinting methods and the use of such methods to fabricate supported and/or free-standing 3-D micro- and/or nano-structures of polymeric, ceramic, and/or metallic materials. In some embodiments, a duo-mold approach is employed in the fabrication of these structures. In such methods, surface treatments are employed to impart differential surface energies to different molds and/or different parts of the mold(s). Such surface treatments permit the formation of three-dimensional (3-D) structures through imprinting and the transfer of such structures to a substrate. In some or other embodiments, such surface treatments and variation in glass transition temperature of the polymers used can facilitate separation of the 3-D structures from the molds to form free-standing micro- and/or nano-structures individually and/or in a film. In some or other embodiments, a 'latch-on' assembly technique is utilized to form supported and/or free-standing stacked micro- and/or nano-structures that enable the assembly of polymers without a glass transition temperature and eliminate the heating required to assemble thermoplastic polymers.

Imprinting of supported and free-standing 3-D micro- or nano-structures

A method of applying a pattern on a topography includes first applying a polymer film to an elastomer member, such as PDMS, to form a pad. The pad is then applied to a substrate having a varying topography under pressure. The polymer film is transferred to the substrate due to the plastic deformation of the polymer film under pressure compared to the elastic deformation of the PDMS member. Thus, upon removal of the pad from the substrate, the PDMS member pulls away from the polymer layer, thereby depositing the polymer layer upon the substrate.

Imprinting polymer film on patterned substrate

A microelectromechanical heating apparatus and fluid preconcentrator device utilizing same wherein heating elements of the apparatus are sized and spaced to substantially uniformly heat a heating chamber within a heater of the apparatus. Tall, thermally-isolated heating elements are fabricated in Si using high aspect ratio etching technology. These tall heating elements have large surface area to provide large adsorbent capacity needed for high efficiency preconcentrators in a micro gas chromatography system (&#x3bc;GC). The tall heating elements are surrounded by air gaps to provide good thermal isolation, which is important for a low power preconcentrator in the &#x3bc;GC system.

Microelectromechanical heating apparatus and fluid preconcentrator device utilizing same

Methods of creating patterns on substrates are presented, and articles of manufacture resulting therefrom. One method comprises applying a first surface energy modifier to an applicator to form a coating on the applicator; contacting the coating with a receiving member, the receiving member having a topography, the coating only contacting and remaining on at least some protrusions; exposing the first modified receiving member to a second surface energy modifier, thereby forming a second modified receiving member having surface modified recesses; applying a composition comprising a polymeric material to the second modified receiving member, the composition substantially conforming to the topography of the surface modified protrusions and the surface modified recesses; and contacting the composition-coated, surface modified protrusions with a substrate for a time and under conditions sufficient to transfer the polymeric material on protrusions to the substrate. Because the surface energy of the sidewalls is lower than that on the protrusions, polymer dewetting from the sidewalls is promoted, which makes the polymer film discontinuous along the edges of patterns. Therefore, inked polymer patterns from the protrusions of the mold show very smooth edges and smaller dimensions compared to that of the mold.

Methods of creating patterns on substrates and articles of manufacture resulting therefrom

A monolithic sensor including a doped mechanical structure is movably supported by but electrically isolated from a single crystal semiconductor substrate of the sensor through a relatively simple process. The sensor is preferably made from a single crystal silicon substrate using front-side release etch-diffusion. Thick single crystal Si micromechanical devices are combined with a conventional bipolar complimentary metal oxide semiconductor (BiCMOS) integrated circuit process. This merged process allows the integration of Si mechanical resonators as thick as 15 &mgr;m thick or more with any conventional integrated circuit process with the addition of only a single masking step. The process does not require the use of Si on insulator wafers or any type of wafer bonding. The Si resonators are etched in an inductively coupled plasma source which allows deep trenches to be fabricated with high aspect ratios and smooth sidewall surfaces. Clamped-clamped beam Si resonators 500 &mgr;m long, 5 &mgr;m wide, and 11 &mgr;m thick are disclosed. A typical resonator had a resonance frequency of 28.9 kHz and an amplitude of vibration at resonance of 4.6 &mgr;m in air. Working NMOS transistors are fabricated on the same chip as the resonator with measured threshold voltages of 0.6 V and an output conductance of 2.0&times;10 &OHgr; for a gage voltage of 4 V.

Method of making a micromechanical device from a single crystal semiconductor substrate and monolithic sensor formed thereby

A monolithic sensor including a doped mechanical structure is movably supported by but electrically isolated from a single crystal semiconductor substrate of the sensor through a relatively simple process. The sensor is preferably made from a single crystal silicon substrate using front-side release etch-diffusion. Thick single crystal Si micromechanical devices are combined with a conventional bipolar complimentary metal oxide semiconductor (BiCMOS) integrated circuit process. This merged process allows the integration of Si mechanical resonators as thick as 15 .mu.m thick or more with any conventional integrated circuit process with the addition of only a single masking step. The process does not require the use of Si on insulator wafers or any type of wafer bonding. The Si resonators are etched in an inductively coupled plasma source which allows deep trenches to be fabricated with high aspect ratios and smooth sidewall surfaces. Clamped-clamped beam Si resonators 500 .mu.m long, 5 .mu.m wide, and 11 .mu.m thick are disclosed. A typical resonator had a resonance frequency of 28.9 kHz and an amplitude of vibration at resonance of 4.6 .mu.m in air. Working NMOS transistors are fabricated on the same chip as the resonator with measured threshold voltages of 0.6 V and an output conductance of 2.0.times.10.sup.-5 .OMEGA..sup.-1 for a gage voltage of 4 V.

Growing community of inventors

Ann Arbor, MI, United States of America

Stella W Pang