The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
Uli Lemmer - One of the best experts on this subject based on the ideXlab platform.
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Hybrid lithography: Combining UV-exposure and two photon direct laser writing
Optics Express, 2013Co-Authors: Carsten Eschenbaum, Daniel Großmann, Katja Dopf, Siegfried Kettlitz, Tobias Bocksrocker, Sebastian Valouch, Uli LemmerAbstract:We demonstrate a method for the combination of UV-lithography and direct laser writing using two-photon polymerization (2PP-DLW). First a dye doped Photoresist is used for UV-lithography. Adding an undoped Photoresist on top of the developed structures enables three-dimensional alignment of the 2PP-DLW structures by detecting the spatially varying fluorescence of the two Photoresists. Using this approach we show three dimensional alignment by adding 3D structures made by 2PP-DLW to a previously UV-exposed structure. Furthermore, a fluidic system with an integrated total internal reflection mirror to observe particles in a microfluidic channel is demonstrated. OCIS codes: (110.6895) Three-dimensional lithography; (110.3960) Microlithography; (220.3740) Lithography; (220.4000) Microstructure fabrication. References and links 1. M. J. Madou, Manufacturing Techniques for Microfabrication and Nanotechnology (CRC, 2012). 2. C. M. Waits, A. Modafe, and R. Ghodssi, " Investigation of gray-scale technology for large area 3D silicon MEMS structures, " J. Micromech. Microeng. 13(2), 170–177 (2003). 3. W. Ehrfeld, " Recent developments in deep x-ray lithography, " J. Vac. Sci. Technol. B 16(6), 3526 (1998). 4. A. Neumeister, " Properties of three-dimensional precision objects fabricated by using laser based micro stereo lithography, " J. Laser Micro. Nanoeng. 3(2), 67–72 (2008). 5. A. Bertsch, P. Bernhard, C. Vogt, and P. Renaud, " Rapid prototyping of small size objects, " Rapid Prototyping J. 6(4), 259–266 (2000). 6. A. Bertsch, H. Lorenz, and P. Renaud, " 3D microfabrication by combining microstereolithography and thick resist UV lithography, " Sens. Actuators A 73(1–2), 14–23 (1999).
Warren W. Flack - One of the best experts on this subject based on the ideXlab platform.
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Process improvements for ultrathick Photoresist using a broadband stepper
Optical Microlithography XIV, 2001Co-Authors: Warren W. Flack, Ha-ai Nguyen, Elliott CapsutoAbstract:There are a number of new lithographic applications that require the use of ultra-thick Photoresists. Extremely large structure heights and high aspect ratios are often necessary for electroplating processes. In this situation it is important for the height of the patterned Photoresist to exceed the plating height. Two of the main applications for thick Photoresist are micromachining and advanced packaging. Ultra-thick Photoresists are used in packaging to define the size and location of the bonds for bump bonding, while in micromachining the Photoresist is used to define fluidic chambers and electroforming molds. At Photoresist thickness greater than 15 microns, standard lithographic techniques become difficult in terms of performance and productivity. The bake, exposure and develop times increase dramatically as the Photoresist thickness climbs. The estimated total process time for a 15 micron Photoresist is approximately three times greater than that of a 1 micron Photoresist. For thick films the develop time on the wafer track becomes the throughput limiter for the entire lithography cell. Therefore, reducing develop time for thick Photoresist processes is critical to enhancing the lithography cell cost of ownership. In this paper we will focus on the developer chemistry and process to improve both performance and productivity for a 15 micron thick Photoresist. We evaluate process changes in both normality and surfactant level of the developer. Cross sectional analysis, contrast curves, process linearity and process windows are used to establish the lithographic capabilities. It is clear that a developer and process for a thin Photoresist is not necessarily optimum for a thick Photoresist process. The implementation of an ultra-thick Photoresist becomes more feasible in a manufacturing environment after optimizing developer chemistry and process conditions.
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Optimization and characterization of ultrathick Photoresist films
Advances in Resist Technology and Processing XV, 1998Co-Authors: Warren W. Flack, Sylvia WhiteAbstract:There are in increasing number of advanced lithographic technologies that require Photoresist film thickness in excess of twenty microns. For example, suppliers of microprocessors are migrating to flip chip packaging because of bond pad limitations. The flip chip application can require Photoresist materials as thick as 125 micrometers for the bump-bonding step. Another application that requires ultra- thick Photoresist films is micromachining. Extremely large structure heights are frequently required for micro- electrodeposition of the mechanical components such as coils, cantilevers and valves. These applications can require Photoresist in excess of a hundred microns thickness. The patterning of high aspect ratio structures in these ultra-thick Photoresist films is extremely challenging. The aspect ratios easily exceed those encountered in submicron lithography for standard integrated circuit (IC) manufacturing. In addition, the specific Photoresist optical properties and develop characteristics degrade the critical dimension control for these ultra-thick films. The bulk absorption effect of the Photoresist reduces the effective dose at the bottom of the film. This effect is exacerbated by the isotropic wet development process which produces sloped profiles. Unlike thin Photoresist for IC manufacturing, lithography modeling and characterization are not readily available for ultra-thick Photoresist films. The performance of several commercially available positive and negative ultra-thick Photoresists is examined over a thickness range of 20 to 100 micrometers . This paper is primarily focused on the 25 micrometers film thickness using both high throughput i-line and gh-line lithography systems optimized for thick film processing. The various Photoresists used in this study were selected to represent the full range of available chemistries from multiple suppliers. Basic Photoresist characterization techniques for thin films are applied to the ultra-thick Photoresist films. The cross sectional SEM analysis and Bossung plots were used to establish relative lithographic capabilities of each Photoresist. The trade-offs between the various Photoresist chemistries is reviewed and compared with the process requirements for the various applications. A future paper will discus the capabilities of these same Photoresists at both 50 and 100 micrometers film thicknesses.
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The optimization and characterization of ultra-thick Photoresist films
1998Co-Authors: Warren W. Flack, Sylvia WhiteAbstract:There are an increasing number of advanced lithographic technologies that require Photoresist film thickness in excess of twenty microns. For example, suppliers of microprocessors are migrating to flip chip packaging because of bond pad limitations. The flip chip application can require Photoresist materials as thick as 125 jim for the bump-bonding step. Another application that requires ultra-thick Photoresist films is micromachining (MEMS). Extremely large structure heights are frequently required for micro-electrodeposition of the mechanical components such as coils, cantilevers and valves. These applications can require Photoresist in excess of a hundred microns thickness. The patterning of high aspect ratio structures in these ultra-thick Photoresist films is extremely challenging. The aspect ratios easily exceed those encountered in submicron lithography for standard integrated circuit (IC) manufacturing. In addition, the specific Photoresist optical properties and develop characteristics degrade the critical dimension (CD) control for these ultra-thick films. The bulk absorption effect of the Photoresist reduces the effective dose at the bottom of the film. This effect is exacerbated by the isotropic wet development process which produces sloped profiles. Unlike thin Photoresist for IC manufacturing, lithography modeling and characterization are not readily available for ultra-thick Photoresist films. The performance of several commercially available positive and negative ultra-thick Photoresists is examined over a thickness range of 20 to 100 μm. This paper is primarily focused on the 25 μm film thickness using both high throughout i-line and gh-line lithography systems optimized for thick film processing. The various Photoresists used in this study were selected to represent the full range of available chemistries from multiple suppliers. Basic Photoresist characterization techniques for thin films are applied to the ultra-thick Photoresist films. The cross sectional SEM analysis and Bossung plots were used to establish relative lithographic capabilities of each Photoresist. The trade-offs between the various Photoresist chemistries is reviewed and compared with the process requirements for the various applications. A future paper will discuss the capabilities of these same Photoresists at both 50 and 100 μm film thicknesses.
William D Hinsberg - One of the best experts on this subject based on the ideXlab platform.
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simple and versatile methods to integrate directed self assembly with optical lithography using a polarity switched Photoresist
ACS Nano, 2010Co-Authors: Joy Cheng, Daniel P Sanders, Hoa D Truong, Stefan Harrer, Alexander Friz, Steven J Holmes, Matthew E Colburn, William D HinsbergAbstract:We report novel strategies to integrate block copolymer self-assembly with 193 nm water immersion lithography. These strategies employ commercially available positive tone chemically amplified Photoresists to spatially encode directing information into precise topographical or chemical prepatterns for the directed self-assembly of block copolymers. Each of these methods exploits the advantageous solubility and thermal properties of polarity-switched positive tone Photoresist materials. Precisely registered, sublithographic self-assembled structures are fabricated using these versatile integration schemes which are fully compatible with current optical lithography patterning materials, processes, and tooling.
Sylvia White - One of the best experts on this subject based on the ideXlab platform.
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Optimization and characterization of ultrathick Photoresist films
Advances in Resist Technology and Processing XV, 1998Co-Authors: Warren W. Flack, Sylvia WhiteAbstract:There are in increasing number of advanced lithographic technologies that require Photoresist film thickness in excess of twenty microns. For example, suppliers of microprocessors are migrating to flip chip packaging because of bond pad limitations. The flip chip application can require Photoresist materials as thick as 125 micrometers for the bump-bonding step. Another application that requires ultra- thick Photoresist films is micromachining. Extremely large structure heights are frequently required for micro- electrodeposition of the mechanical components such as coils, cantilevers and valves. These applications can require Photoresist in excess of a hundred microns thickness. The patterning of high aspect ratio structures in these ultra-thick Photoresist films is extremely challenging. The aspect ratios easily exceed those encountered in submicron lithography for standard integrated circuit (IC) manufacturing. In addition, the specific Photoresist optical properties and develop characteristics degrade the critical dimension control for these ultra-thick films. The bulk absorption effect of the Photoresist reduces the effective dose at the bottom of the film. This effect is exacerbated by the isotropic wet development process which produces sloped profiles. Unlike thin Photoresist for IC manufacturing, lithography modeling and characterization are not readily available for ultra-thick Photoresist films. The performance of several commercially available positive and negative ultra-thick Photoresists is examined over a thickness range of 20 to 100 micrometers . This paper is primarily focused on the 25 micrometers film thickness using both high throughput i-line and gh-line lithography systems optimized for thick film processing. The various Photoresists used in this study were selected to represent the full range of available chemistries from multiple suppliers. Basic Photoresist characterization techniques for thin films are applied to the ultra-thick Photoresist films. The cross sectional SEM analysis and Bossung plots were used to establish relative lithographic capabilities of each Photoresist. The trade-offs between the various Photoresist chemistries is reviewed and compared with the process requirements for the various applications. A future paper will discus the capabilities of these same Photoresists at both 50 and 100 micrometers film thicknesses.
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The optimization and characterization of ultra-thick Photoresist films
1998Co-Authors: Warren W. Flack, Sylvia WhiteAbstract:There are an increasing number of advanced lithographic technologies that require Photoresist film thickness in excess of twenty microns. For example, suppliers of microprocessors are migrating to flip chip packaging because of bond pad limitations. The flip chip application can require Photoresist materials as thick as 125 jim for the bump-bonding step. Another application that requires ultra-thick Photoresist films is micromachining (MEMS). Extremely large structure heights are frequently required for micro-electrodeposition of the mechanical components such as coils, cantilevers and valves. These applications can require Photoresist in excess of a hundred microns thickness. The patterning of high aspect ratio structures in these ultra-thick Photoresist films is extremely challenging. The aspect ratios easily exceed those encountered in submicron lithography for standard integrated circuit (IC) manufacturing. In addition, the specific Photoresist optical properties and develop characteristics degrade the critical dimension (CD) control for these ultra-thick films. The bulk absorption effect of the Photoresist reduces the effective dose at the bottom of the film. This effect is exacerbated by the isotropic wet development process which produces sloped profiles. Unlike thin Photoresist for IC manufacturing, lithography modeling and characterization are not readily available for ultra-thick Photoresist films. The performance of several commercially available positive and negative ultra-thick Photoresists is examined over a thickness range of 20 to 100 μm. This paper is primarily focused on the 25 μm film thickness using both high throughout i-line and gh-line lithography systems optimized for thick film processing. The various Photoresists used in this study were selected to represent the full range of available chemistries from multiple suppliers. Basic Photoresist characterization techniques for thin films are applied to the ultra-thick Photoresist films. The cross sectional SEM analysis and Bossung plots were used to establish relative lithographic capabilities of each Photoresist. The trade-offs between the various Photoresist chemistries is reviewed and compared with the process requirements for the various applications. A future paper will discuss the capabilities of these same Photoresists at both 50 and 100 μm film thicknesses.
Nancy L. Allbritton - One of the best experts on this subject based on the ideXlab platform.
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Transparent magnetic Photoresists for bioanalytical applications
Biomaterials, 2010Co-Authors: Philip C. Gach, Christopher E. Sims, Nancy L. AllbrittonAbstract:Abstract Microfabricated devices possessing magnetic properties are of great utility in bioanalytical microdevices due to their controlled manipulation with external magnets. Current methods for creating magnetic microdevices yield a low-transparency material preventing light microscopy-based inspection of biological specimens on the structures. Uniformly transparent magnetic Photoresists were developed for microdevices that require high transparency as well as consistent magnetism across the structure. Colloidal formation of 10 nm maghemite particles was minimized during addition to the negative Photoresists SU-8 and 1002F through organic capping of the nanoparticles and utilization of solvent-based dispersion techniques. Photoresists with maghemite concentrations of 0.01–1% had a high transparency due to the even dispersal of maghemite nanoparticles within the polymer as observed with transmission electron microscopy (TEM). These magnetic Photoresists were used to fabricate microstructures with aspect ratios up to 4:1 and a resolution of 3 μm. Various cell lines showed excellent adhesion and viability on the magnetic Photoresists. An inspection of cells cultured on the magnetic Photoresists with TEM showed cellular uptake of magnetic nanoparticles leeched from the Photoresists. Cellular contamination by magnetic nanoparticles was eliminated by capping the magnetic Photoresist surface with native 1002F Photoresist or by removing the top layer of the magnetic Photoresist through surface roughening. The utility of these magnetic Photoresists was demonstrated by sorting single cells (HeLa, RBL and 3T3 cells) cultured on arrays of releasable magnetic micropallets. 100% of magnetic micropallets with attached cells were collected following release from the array. 85–92% of the collected cells expanded into colonies. The polymeric magnetic materials should find wide use in the fabrication of microstructures for bioanalytical technologies.
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Photoresist with low fluorescence for bioanalytical applications
Analytical Chemistry, 2007Co-Authors: Yuli Wang, Christopher E. Sims, Gina To A Salazar, Mark Bachman, Guannpyng Li, Nancy L. AllbrittonAbstract:The negative Photoresist SU-8 has found widespread use as a material in the fabrication of microelectrical−mechanical systems (MEMS). Although SU-8 has been utilized as a structural material for biological MEMS, a number of SU-8 properties limit its application in these bioanalytical devices. These attributes include its brittleness, nonspecific adsorption of biomolecules, and high fluorescence in the visible wavelengths. In addition, native SU-8 is a poor substrate for cellular adhesion. Photoresists composed of resins with epoxide side groups and photoacids were screened for their ability to serve as a low-fluorescence Photoresist with sufficient resolution to generate microstructures with dimensions of 5−10 μm. The fluorescence of structures formed from 1002F Photoresist (1002F resin combined with triarylsulfonium hexafluoroantimonate salts) was as much as 10 times less fluorescent than similar SU-8 microstructures. The absorbance of 1002F in the visible wavelengths was also substantially lower than th...
