Inedible cellulose-based biomass resist material amenable to water-based processing for use in electron beam lithography

T-Gate fabrication processes for InP-based High electron mobility transistors (HEMTs) are described using PMMA/Al/UVIII. The single-step and two-step Electron beam lithography (EBL) methods are proposed contrastively without dielectric support layer. The opti- mal gate-foot length is 196nm for 50nm geometry path by single-step EBL technique. Since the gate-foot and gate-head are defined independently, the two-step EBL process minimizes forward scattering and enables smaller gate-foot length, which improves to be 141nm for 50nm geometry path and also 88nm for 30nm geometry path. Both EBL methods have been incorporated into InP- based HEMTs fabrication. With the gate-foot length de- creases from 196nm to 141nm, the current-gain cutoff fre- quency (fT) is improved from 125GHz to 164GHz, and also the maximum oscillation frequency (fmax )i ncreases from 305GHz to 375GHz.

Since the photoelectric response and charge carriers transport can be influenced greatly by the density and spacing of the ZnO nanorod arrays, controlling of these geometric parameters precisely is highly desirable but rather challenging in practice. Here, we fabricated patterned ZnO nanorod arrays with different densities and spacing distances on silicon (Si) substrate by electron beam lithography (EBL) method combined with the subsequent hydrothermal reaction process. By using the EBL method, patterned ZnO seed layers with different areas and spacing distances were obtained firstly. ZnO nanorod arrays with different densities and various morphologies were obtained by the subsequent hydrothermal growth process. The combination of EBL and hydrothermal growth process was very attractive and could make us control the geometric parameters of ZnO nanorod arrays expediently. Finally, the vertical transport properties of the patterned ZnO nanorod arrays were investigated through the microprobe station equipment, and the I-V measurement results indicated that the back-to-back Schottky contacts with different barrier heights were formed in dark conditions. Under UV light illumination, the patterned ZnO nanorod arrays showed a high UV light sensitivity, and the response ratio was about 104. The controllable fabrication of patterned ZnO nanorod arrays and understanding their photoelectric transport properties were helpful to improve the performance of nanodevices based on them.

ABSTRACTOrdered arrays of crystalline complex oxides nanostructures were synthesized onto single crystal insulating substrates using aqueous polyvinyl alcohol based electron beam resist precursors. The irradiated zones are insoluble in water (negative-tone resist) due to the electron induced cross linking of polyvinyl alcohol. The subsequent high temperature treatment of the developed precursor samples leads to the formation of ordered arrays of nanodots for low irradiation doses. For high irradiation dosages, epitaxially and oriented nanowires are obtained. These same precursors were shown to be nanoimprintable on single crystal substrates. This allows for future dual processing of a single precursor film gaining nano-structuration from both electron beam and nanoimprint lithography methods.

The “top‐down” approach is used to fabricate Silicon Nanowires using Scanning Electron Microscope (SEM) based Electron Beam Lithography (EBL) method. Silicon Nanowires or one dimensional nanowires are widely recognized as important elements in development of certain advance nanoscale devices. The Silicon Nanowires with line‐width of 50 nm are successfully fabricated at our clean room using this approach. The approach used includes SEM based EBL method, followed by size reduction using Inductively Coupled Plasma—Reactive Ion Etching (ICP—RIE). In addition, the diameter and the length of the Silicon Nanowires can be precisely controlled. In this paper, the Silicon Nanowires formation which includes the EBL system and fabrication processes have been reviewed and discussed. High Power Microscope (HPM), SEM and Atomic Force Microscopy (AFM) were used to characterize the Silicon Nanowires.

A three-dimensional (3D) seamless roll mold is difficult to fabricate because of its cylindrical shape. However, seamless 3D nanoscale patterns are in great demand for optical film applications and printed electronics. The authors have therefore developed a method for producing a 3D seamless roll mold by direct electron-beam (EB) writing onto a layer of resist material coated on a cylindrical substrate that is rotating in a vacuum. In addition, the 3D shape is produced by using the EB dose change method and the controlled-acceleration-voltage electron beam lithography (CAV-EBL) method developed by the authors. In the case of the EB dose change method, hydrogen silsesquioxane (HSQ), which is a negative-type EB resist, was used for the 3D roll mold. In the case of CAV-EBL, spin on glass, which is a positive-type EB resist, was used for the 3D roll mold. As a result, the developed HSQ height can be controlled by changing the EB dose; however, the dose change also causes a line width change. On the other hand, in the CAV-EBL method, the EB dose and acceleration voltage can be used to control the line width and depth independently; therefore, this method can successfully fabricate the coveted 3D roll mold.

A recent breakthrough in nanotechnology provides a great extent in sensor fabrication and application. The technology has emerged as a powerful technique to minimize the size of devices; amount of materials, energy and time consumption. Nanogap based sensor is one of the sensor that capable of characterizing and quantifying molecules selectively and sensitively with good electrical behavior. In this manuscript, we present a collaboration work between UniMAP, MARDI and UPM in the process development of 40 nm silicon nanogap for sensor application. The process consists of a combination of electron beam lithography (EBL) method and conventional photolithography method. Both methods were for nanogap and electrodes pattern respectively. Silicon on insulator (SOI) substrate was used to fabricate the nanogap structure and gold was used for the electrode. The ability of EBL system to fabricate a gap in nanometer scale with direct lithography technique on SOI substrate gives advantages in this development work. The developed silicon nanogap device was physically characterized with scanning electron microscope (SEM). The sensor application was accomplished by testing the device with different level of pH solutions using a dielectric analyzer.

Optical lithography is the unrivalled mainstream patterning method that allows for costefficient, high-volume fabrication of microand nanoelectronic devices. Current optical photolithography allows for structures with a reproducible resolution below 32 nm. Nevertheless, alternative lithography methods coexist and excel in all cases where the requirement for a photomask is a disadvantage. Especially for low-volume fabrication of microdevices, the need for a photomask is inefficient and restricts a fast structuring, such as required for prototype device development and for the modification and repair of devices. The necessity of high-resolution masks with a price well above €10k is too cost intensive for the fabrication of single test devices. For this reason ‘direct-write’ approaches have emerged that are popular for several niche applications, such as mask repair and chip repair. Optical direct-write lithography and electron beam lithography are among the most prominent techniques of direct-write lithography. Less known, but highly versatile and powerful, is the ion beam lithography (IBL) method. Optical direct-write lithography uses laser beam writers with a programmable spatial light modulator (SLM). With 500 mm2/minute write speed and advanced 3D lithography capabilities, optical direct-write lithography is also suitable for commercial microchip fabrication. However, with a resolution of 0.6-μm minimum feature size of the photoresist pattern, optical direct-write lithography cannot be considered a nanopatterning method. Electron beam lithography uses a focused electron beam to expose an electron beam resist. Gaussian beam tools operate with electron beams with a diameter below 1 nm so that true nanofabrication of structures is feasible. A resolution of 10 nm minimum feature size of the e-beam resist pattern has been successfully demonstrated with this method. However, special resists are required for e-beam lithography, that are compatible with the high energy of forward scattered, back-scattered and secondary electrons. A common resist for sub-50nm resolution is polymethylmetacrylate (PMMA) requiring an exposure dose above 0.2 μC/μm2. For highest resolution (below 20 nm) inorganic resists such as hydrogen silsesquioxane (HSQ) or aluminium fluoride (AlF3) are used, which unfortunately require a high electron exposure dose. Hence, high-resolution electron beam lithography (EBL) is linked to long exposure times which, in combination with a single scanning beam, results in slow processing times. Therefore, this high-resolution method is only used for writing photomasks for optical projection lithography and for a limited number of high-end applications. A resolution to this dilemma may be the use of multi-beam electron tools, as are currently under development. Also electron projection lithography has been under

Organic contaminants adsorbed on the surface of a silicon stencil mask in a high-vacuum chamber in an electron-beam exposure lithography system have been analyzed and identified using thermal-desorption gas chromatography/mass spectrometry (TD-GC/MS), X-ray photoelectron spectrometry (XPS), and electron energy loss spectroscopy (EELS). The major organic compound adsorbed onto the surface of the silicon stencil mask in the high vacuum chamber has been found to be di-2-ethylhexyl phthalate (DOP). The amount of DOP adsorbed onto the silicon surface in high vacuum is much larger than that adsorbed in ambient air. A relatively high molar ratio and long mean free path of organic molecules with a low vapor pressure, such as DOP, in high vacuum is considered to enable them to be easily adsorbed onto the silicon surface in high vacuum. On the other hand, organic volatiles with higher vapor pressure are not adsorbed on the silicon surface in high vacuum. It has been found by XPS and EELS that the organic contaminants adsorbed on the surface of the silicon stencil mask are transformed into graphite-like carbon by electron beam irradiation during the exposure process.

Functionality of superconducting thin-film devices such as superconducting nanowire single photon detectors stems from the geometric effects that take place at the nanoscale. The engineering of these technologies requires high-resolution patterning, often achieved with electron beam lithography. Common lithography processes using hydrogen silsesquioxane (HSQ) as the electron beam resist rely on tetramethylammonium hydroxide (TMAH) as both a developer and a resist adhesion promoter. Despite the strong role played by TMAH in the fabrication of superconducting devices, its potential influence on the superconducting films themselves has not yet been reported. In this work, the authors demonstrate that a 25% TMAH developer damages niobium nitride (NbN) thin films by modifying the surface chemistry and creating an etch contaminant that slows reactive ion etching in CF4. They also show how the identity of the contaminant may be revealed through characterization including measurement of the superconducting film properties and Fourier transform infrared spectroscopy. Although workarounds may be available, the results reveal that processes using 25% TMAH as an adhesion promoter are not preferred for NbN films and that changes to the typical HSQ fabrication procedure will need to be made in order to prevent damage of NbN nanoscale devices.

In order to achieve the use of pure water in the developable process of extreme-ultraviolet and electron beam lithography, instead of conventionally used tetramethylammonium hydroxide and organic solvents, a water developable resist material was designed and developed. The water-developable resist material was derived from woody biomass with beta-linked disaccharide unit for environmental affair, safety, easiness of handling, and health of the working people. 80 nm dense line patterning images with exposure dose of 22 μC/cm² and CF₄ etching selectivity of 1.8 with hardmask layer were provided by specific process conditions. The approach of our water-developable resist material will be one of the most promising technologies ready to be investigated into production of medical device applications.

Electron beam lithography is one of the enabling methods in advanced nanoresearch. Electron beam lithography is a maskless lithography technique which is therefore very flexible. Electron beam lithography provides very high resolution. This is the main reason of its wide use in nanoresearch [1]. Electron beam lithography tools are in use in all engineering and basic science disciplines. Raith manufactures a variety of electron and ion beam lithography systems for research and development applications designed to meet the needs of researchers, designers, and engineers in both university and industry environment. Furthermore, Raith develops ultrahigh precision stages and navigation packages for failure analysis applications.

Atomic force microscopy characterization of the chemical contrast of nanoscale patterns fabricated by electron beam lithography on polyethylene glycol oxide thin films

The application of natural linear polysaccharide to green resist polymers was demonstrated for electron beam (EB) and extreme-ultraviolet (EUV) lithography using organic-solvent-free water spin-coating and tetramethylammonium hydroxide (TMAH)-free water-developable techniques. The water spin-coating and water-developable processes in a green resist material were carried out on wafers because of the water solubility of natural polysaccharides for an environmentally friendly manufacturing process for next-generation electronic devices. The developed green resist material with a weight-average molecular weight of 83,000 and 70 mol % hydroxyl groups as a water-developable feature was found to have acceptable properties such as spin-coat ability on 200 mm wafers, prediction sensitivity to EUV at the wavelengths of 6.7 and 13.5 nm, a high contrast of the water dissolution rate before and after EB irradiation, pillar patterns of 100–400 nm with a high EB sensitivity of 10 µC/cm2, and etch selectivity with a silicon-based middle layer in CF4 plasma treatment.

Quantum optical lithography from 1nm resolution to pattern transfer on silicon wafer

A major problem in the optical lithography was the diffraction limit. Here, we report and demonstrate a lithography method, Quantum Optical Lithography [1,2], able to attain 1 nm resolution by optical means using new materials (fluorescent photosensitive glass-ceramics and QMC-5 resist). The performance is several times better than that described for any optical or Electron Beam Lithography (EBL) methods. In Fig. 1 we present TEM images of 1 nm lines recorded at 9.6 m/s. a) b) Fig. 1 TEM images of: a) multiple 1 nm lines written in a fluorescent photosensitive glass-ceramics sample; b) single 1 nm line written in QMC-5 resist.