| 1. |
- Forsen, E, et al.
(författare)
-
Dry release of suspended nanostructures
- 2004
-
Ingår i: Microelectronic Engineering. - 1873-5568. ; 73-74, s. 487-490
-
Tidskriftsartikel (refereegranskat)abstract
- A dry release method for fabrication of suspended nanostructures is presented. The technique has been combined with an anti-stiction treatment for fabrication of nanocantilever based nanoelectromechanical systems (NEMS). The process combines a dry release method, using a supporting layer of photoresist which is removed using oxygen ashing in a reactive ion etcher (RIE), with CHF3 plasma induced deposition of an fluorocarbon (FC) film acting as an antistiction coating. All in a single RIE sequence. The dry release process is contamination free and batch process compatible. Furthermore, the technique enables long time storage and transportation of produced devices without the risk of stiction. By combining the dry release method with a plasma deposited anti-stiction coating both fabrication induced stiction, which is mainly caused by capillary forces originating from the dehydration of meniscuses formed between suspended structures and the substrate during processing, as well as in-use stiction, occurring during mechanical operation of the system, are avoided. (C) 2004 Elsevier B.V. All rights reserved.
|
|
| 2. |
|
|
| 3. |
- Forsen, E, et al.
(författare)
-
Fabrication of cantilever based mass sensors integrated with CMOS using direct write laser lithography on resist
- 2004
-
Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 15:10, s. 628-633
-
Tidskriftsartikel (refereegranskat)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.
|
|
| 4. |
|
|
| 5. |
- Forsen, E, et al.
(författare)
-
Laser lithography on resist bi-layer for nanoelectromechanical systems prototyping
- 2004
-
Ingår i: Microelectronic Engineering. - 1873-5568. ; 73-74, s. 491-495
-
Tidskriftsartikel (refereegranskat)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.
|
|
| 6. |
- Forsen, E, et al.
(författare)
-
Ultrasensitive mass sensor fully integrated with complementary metal-oxide-semiconductor circuitry
- 2005
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 87:4
-
Tidskriftsartikel (refereegranskat)abstract
- Nanomechanical resonators have been monolithically integrated on preprocessed complementary metal-oxide-semiconductor (CMOS) chips. Fabricated resonator systems have been designed to have resonance frequencies up to 1.5 MHz. The systems have been characterized in ambient air and vacuum conditions and display ultrasensitive mass detection in air. A mass sensitivity of 4 ag/Hz has been determined in air by placing a single glycerine drop, having a measured weight of 57 fg, at the apex of a cantilever and subsequently measuring a frequency shift of 14.8 kHz. CMOS integration enables electrostatic excitation, capacitive detection, and amplification of the resonance signal directly on the chip.
|
|
| 7. |
- Ghatnekar-Nilsson, Sara, et al.
(författare)
-
Resonators with integrated CMOS circuitry for mass sensing applications, fabricated by electron beam lithography
- 2005
-
Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 16:1, s. 98-102
-
Tidskriftsartikel (refereegranskat)abstract
- A resonator system has been fabricated directly on a pre-processed CMOS chip. The system is to be used for high sensitivity mass sensing applications in air and vacuum. The resonator system, corresponding of a cantilever and structures for electrostatic actuation and capacitive read-out, have been defined by electron beam lithography on top of a charge and radiation sensitive CMOS layer in predefined areas as a post-process step. This has been accomplished without affecting the electronic properties of the pre-processed CMOS circuits. The subsequent etching steps to fully release the cantilevers have been obtained without stiction of the cantilevers to the substrate. Cantilevers are driven at their mechanical resonance in a lateral mode, and the frequency is monitored by capacitive read-out on the chip. CMOS integration enables signal detection directly on the chip, which radically decreases the parasitic capacitances. Consequently, low-noise electrical measurements with a very high mass sensitivity are obtained. Fabricated resonator systems were characterized to have resonance frequencies of approximately 1.49 MHz, which is in good agreement with a theoretical estimation of 1.41 MHz. The theoretical mass resolution, partial derivativem/partial derivativef, is approximately 17 ag Hz(-1) using a Young modulus value of 160 GPa.
|
|
| 8. |
- Ling, TGI, et al.
(författare)
-
Fa-brication and characterization of a molecular adhesive layer for micro- and nanofabricated electrochemical electrodes
- 2003
-
Ingår i: Microelectronic Engineering. - 1873-5568. ; 67-8, s. 887-892
-
Tidskriftsartikel (refereegranskat)abstract
- In the microelectronics industry, gold electrodes on silicon dioxide are produced using an adhesive layer of chromium or titanium. This method is applicable whenever a dry environment is present. However, when such an electrode is exposed to an electrolyte a galvanic cell is formed and the less noble metal will dissolve and eventually destroy the electrode. We describe here how a monolayer of mercaptopropyl-trimethoxysilane (MPTS) can be used as an adhesive. The layer can be structured lithographically making gold electrodes in the micro- and nano-range applicable for use in electrochemistry. The properties of the MPTS layer were investigated with photoelectron microscopy, atomic force microscopy and the electrochemical performance of the gold electrodes was determined by cyclic voltammetry. (C) 2003 Elsevier Science B.V. All rights reserved.
|
|
