Nano and Micro Technology
Inductively Coupled Plasma Reactive Ion Etching (ICP-RIE) Technology
- High aspect ratio anisotropic silicon etching
Linewidth = 2 µm, Etching depth = 43 µm, aspect ratio = 21 (Figure.a). Etching depth=80 µm, aspect ratio=21 (Figure.b). - Isotropic silicon etching
Isotropic silicon etching can fabricate sealed micro channel (Figure.c) and suspension microstructures (Figure.d). - Smooth sidewall silicon etchingRipple is disappear after ICP etching, the sidewall roughness Rms ~ 10 nm, Ra ~ 8 nm. (Figure.e)
Dry-SCREAM fabrication process
A novel fabrication process to etch, to passivate, and to release single-crystal silicon structures totally in just only one process by inductively coupled plasma reactive ion etching (ICP-RIE) has been presented. We call this technique is Dry-SCREAM process. Several kinds of movable actuators such as relay, comb-drive, and capacitance (Figure.a~c) with thickness of 30 µm have been fabricated successfully to demonstrate this fabrication process.
Different materials such as silicon dioxide, photoresist, nitride and metal could be chosen as etching masks. In this way, bi-level (Figure.d) or multi-level movable structures have been successfully fabricated in Dry-SCREAM process.
Micro Total Analysis system (µ-TAS)
Micro Total Analysis System (µ-TAS) (Figure.a) is becoming very popular nowadays. The µ-TAS can do the function for the reagent and sample such as transportation, extraction, purification, mixing, separation, chromatography, detection. It will have innovation for biomedical, chemical and environmental field.
The purpose of project is design and fabrication µ-TAS. A lateral concave grating as a detection light source and micro channel are fabricated on a bio-chip.
Micro concave grating (Figure.b) used for the wave division demultiplexing of fiber communication with 81 channels about 0.181 nm FWHM, and less than 0.39 nm channel spacing (Figure.c) has been successfully carried out. This micro-concave-grating for DWDM was fabricated by ICP-RIE advanced silicon etching (ASE) technique with a sidewall perpendicularity of 90±1° and an average surface roughness of less than 5 nm.
BioMEMS
Nanotechnology has a number of attributes in Biomedical Research. The BioMEMS group in Precision Instrument Development Center (PIDC) organizes professionals from ME, EE, Physics, Biology and Medicine working on bio-related aspects. The prospective research directs toward the development in:
Lab-on-a-chip
Build up the chip-based detection system to fulfill the spirit of µ-TAS (micro-Total Analysis System).Nano structure
Nanoimprint lithography offers the ability to control the molecular structure of surface and patterns the complex molecules relevant to biology. The ability is important for biosensor technology, tissue engineering, and fundamental studies of cell biology, oncology, and neural network.Single molecular detection
Develop a novel tool for single molecular detection. This design can be structurally and chemically modified to provide a high throughput molecular sequencing based on real-time detection.
Nanostructuring Technology
Electron Beam Lithography (EBL)
Electron beam lithography is one of the most powerful methods for nanostructure forming. It uses high voltage electrons (1 kV – 100 kV) to transfer nanopatterns into resist (ex. PMMA) on the substrate by directly writing. Very high resolution achieved several 10 nm can be obtained by this method. Base on this technology, many nanostructure forming processes can be developed, like nano lift-off process for nano metal wires, and nanoimprint lithography (NIL) for high throughput.
Focus Ion Beam (FIB)
Focused ion beam (FIB) systems have been produced commercially for approximately ten years, primarily for large semiconductor manufactures. FIB systems operate in a similar fashion to a scanning electron microscope (SEM) except, rather than a beam of electrons and as the name implies, FIB systems use a finely focused beam of gallium ions that can be operated at low beam currents for imaging or high beam current for site specific sputtering or milling.
At low beam currents, very little material is sputtering; modem FIB system can achieve 5 nm imaging resolution. If you raise the beam current, the gallium ions will bombard samples then you can observe the cross section to analysis the composites or the defects of the samples. Furthermore, with the gas assisted systems, it's allowable to deposit or etch the materials such as Pt, W, and oxide directly in the same time.
Recently, the overwhelming usage of FIB has been in the semiconductor industry. Such applications as defect analysis, circuit modification, mask repair, and transmission electron microscope sample preparation have become commonplace procedures. Currently, the nano research group in PIDC devotes to combine this powerful tool with MEMS technology to fabricate some 2D or 3D nanostructures applied in the field of bio and optical.
Nano Optical Device and Element (NODE)
Two of the most important subjects are photonic crystal and sub-wavelength optical element. The photonic crystal is one kind of artificial crystal, these band-gaps nano structures can be applied to guide the light path with higher efficient (lower loss) than waveguide. Sub-wavelength elements, like grating and diffraction lens, can be applied to ultra-high density optical communication network by high resolution and efficient.
NanoFluidics and Nanoimprint
Nanoimprint lithography will be used to form nanoscale texture on fluidic channel surface for the purpose of controlling the fixed amount, transmission, sorting, mixing of bio-droplets. The nanotexture will change the surface energy and can be used to form a super hydrophobic surface, and the ultimate goal is to let liquid form a spherical droplet on these texture zones. The critical point of the fabrication process is to obtain a super hydrophobic surface, and both nano-surface texture and polymer material are used in the process. E-beam lithography is for direct exposure on photoresist for processing nanoscale structures. Super hydrophobic surface is then achieved after depositing a layer of polymer material. Nanoimprint lithography technique is also employed for high-throughput manufacturing.
By integrating the techniques mentioned above and micro optical device techniques, bio-droplet ingredient analysis is able to be accomplished. And integrating all the components into a single chip is aimed for complete automation, efficiency and compact Lab-on-a-chip.
