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- Forsen, E, et al.
(author)
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Fabrication of cantilever based mass sensors integrated with CMOS using direct write laser lithography on resist
- 2004
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In: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 15:10, s. 628-633
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Journal article (peer-reviewed)abstract
- A CMOS compatible direct write laser lithography technique has been developed for cantilever fabrication on pre-fabricated standard CMOS. We have developed cantilever based sensors for mass measurements in vacuum and air. The cantilever is actuated into lateral vibration by electrostatic excitation and the resonant frequency is detected by capacitive readout. The device is integrated on standard CMOS circuitry. In the work a new direct write laser lithography (DWL) technique is introduced. This laser lithography technique is based on direct laser writing on substrates coated with a resist bi-layer consisting of poly(methyl methacrylate) (PMMA) on lift-off resist (LOR). Laser writing evaporates the PMMA, exposing the LOR. A resist solvent is used to transfer the pattern down to the substrate. Metal lift-off followed by reactive ion etching is used for patterning the structural poly-Si layer in the CMOS. The developed laser lithography technique is compatible with resist exposure techniques such as electron beam lithography. We demonstrate the fabrication of sub-micrometre wide suspended cantilevers as well as metal lift-off with feature line widths down to approximately 500 nm.
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- Forsen, E, et al.
(author)
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Laser lithography on resist bi-layer for nanoelectromechanical systems prototyping
- 2004
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In: Microelectronic Engineering. - 1873-5568. ; 73-74, s. 491-495
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Journal article (peer-reviewed)abstract
- We present a laser lithography technique based on lift-off, for fast and flexible prototyping of micro and nanoelectromechanical systems (MEMS/NEMS). The technique is based on direct laser writing on substrates coated with a resist bi-layer consisting of polymethyl methacrylate (PMMA) on lift-off resist (LOR). Laser writing melts and evaporates the PMMA exposing the LOR. Oxygen ashing removes PMMA residues within the lithography pattern. A resist solvent is used to transfer the pattern down to the substrate. The LOR is dissolved isotropically while the PMMA is unaffected by the solvent, hence creating an undercut profile. After metal evaporation a two-step lift-off process prevents metal flakes from adhering to the surface. First, warm acetone dissolves the PMMA and lifts off the metal layer, then warm Remover PG removes the LOR and any remaining metal. Metal structures with line widths down to 600 nm and dots with 600 mn diameters are presented. (C) 2004 Elsevier B.V. All rights reserved.
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