Nano-imprint lithography (NIL) is an emerging high-resolution parallel patterning method, mainly aimed towards fields in which high-end photolithography methods are costly and do not provide sufficient resolution at reasonable throughput. High resolution stamp patterning can currently be performed by electron and ion dual beam system. By scanning the focused electron beam (or ion beam) while injecting a suitable organometallic precursor gas around the location of e-beam (or ion beam) and just above the stamp substrate, a high-density and high-uniformity hard mask for subsequent etching without use proximity-effect correction techniques. Furthermore, this technique can also directly deposit a metal pattern for interconnect or a dielectric pattern on NIL stamp without the need for separate metal or dielectric deposition, photoresist etch-mask, and etching processes. FEI Helios Nano Lab™ 1200 and Nova Nano Lab™ 600 dual beam system are used in this work for NIL stamp inspection and fabrication.
Nano-imprinting lithography (NIL) technology, as one of the most promising fabrication technologies, has been demonstrated to be a powerful tool for large-area replication up to wafer-level, with features down to nanometer scale. The cost of resists used for NIL is important for wafer-level large-area replication. This study aims to develop capabilities in patterning larger area structure using thermal NIL. The commercial available Poly (Methyl Methacrylate) (PMMA) and Polystyrene (PS) polymers possess a variety of characteristics desirable for NIL, such as low material cost, low bulkvolumetric shrinkage, high spin coating thickness uniformity, high process stability, and acceptable dry-etch resistance. PMMA materials have been utilized for positive electron beam lithography for many years, offering high resolution capability and wide process latitude. In addition, it is preferable to have a negative resist like PMMA, which is a simple polymer with low cost and practically unlimited shelf life, and can be dissolved easily using commercial available Propylene glycol methyl ether acetate (PGMEA) safer solvent to give the preferred film thickness. PS is such a resist, as it undergoes crosslinking when exposed to deep UV light or an electron beam and can be used for NIL. The result is a cost effective patterning larger area structure using thermal nano-imprint lithography (NIL) by using commercial available PMMA and PS ploymers as NIL resists.
Nano-imprinting technology, as one of the most promising fabrication technologies, has been
demonstrated to be a powerful tool for large-area replication up to wafer-level, with features down to
nanometer scale. This study aims to develop capabilities in patterning nano structure using thermal
nano-imprint lithography (NIL). 30nm Si molds are patterned by electron-beam lithography (EBL)
using NEB22 A2 negative e-beam resist. The NEB22 A2 negative e-beam resist possess a variety of
characteristics desirable for NIL, such as low viscosity, low bulk-volumetric shrinkage, high
Young's modulus, high thermal stability, and excellent dry-etch resistance. The excellent oxygenetch
resistance of the barrier material enables a final transfer pattern that is about three times higher
than that of the original NIL mold. Based on these imprint on negative electron beam resist approach
is used for pattern transfer into silicon substrates. The result is a high-resolution pattern with feature
sizes in the range of nanometer to several microns.
Novel wafer stepper by using contact or proximity printing will be developed, using violet LED light source to replace Hg Arc. lamp or laser. Mirror, filter and condenser lens for Hg Arc. Lamp or laser and reduction lens for projection printing can be discarded. Reliability and manufacturing cost of wafer stepper can be improved. Exposure result by using IP3600 resist and wafer stepper with violet LED light source (wave-length 360nm to 410 nm) will be obtained. This novel wafer stepper can be used for 3DIC, MEMS and bio-chip lithography application by using thin and thick resist with sub-micron to 100 micron thickness.
Nano-pillars pattern on PDMS were fabricated by using highly ordered and density nano-pore arrays of anodic aluminum
oxide film as template. We used cyclohexane to dilute polydimethylsiloxane then filled it to template, the pillars
diameters range from 100 to 200 nm, pillars height about 3 to 5 μm. The morphologies of template membrane and nanopillars
arrays were investigated by scanning electron microscopy and atomic force microscopy. This process offered a
cheaper and easier method to develop a large area and highly ordered nanostructure mold, this mold can be used in a
broad range applications such as, optoelectronic devices, semiconductor devices, bio devices, field emission displays,
data storage and so on.
Gray level 3D resist process were developed by using negative e-beam resist and multiple coating
multiple electron beam wafer direct write alignment, and are now going into be used to create
complex 3D structures in thick resist. Gray level resist process to create 3D structure in thick resist
can be used as mold for manufacturing Fly's-eye lens array, Fresnel lens, Prism, Flat prism and
Light guiding plate. Such optical devices can be used for TFT LCD display, solar concentrator and
Highly ordered and highly density nanopore arrays of anodic aluminum oxide template was prepared by a two-step
anodization method and with the assistance of ultrasonic. Well-aligned nanopore arrays were obtained perpendicular
to the surface of aluminum. The first step anodization was carried out under 0.4 M oxalic acid for one hour, and the
anodized film was removed by chemical etching, than the sample was anodized again for 40 minute under the same
conditions as the first anodization and with ultrasonic. The results of aluminum oxide films were characterized by
scanning electron microscopy, and the microstructure of the anodic aluminum oxide membrane indicating that the
nanochannel arrays prepared with the assistance of ultrasonic are better than those in ordinary way related to the pore
aligned and pore density.
SixNy/Ni thin film green mask blanks were developed , and are now going to be used to replace general chromium film used for binary mask as well as to replace molydium silicide embedded material for AttPSM for I-line (365 nm), KrF (248 nm), ArF (193 nm) and Contact/Proximity lithography. A bilayer structure of a 1 nm thick opaque, conductive nickel layer and a SixNy layer is proposed for binary and phase-shifting mask. With the good controlling of plasma CVD of SixNy under silane (50 sccm), ammonia (5 sccm) and nitrogen (100 sccm), the pressure is 250 mTorr. and RF frequency 13.56 MHz and power 50 W. SixNy has enough deposition latitude to meet the requirements as an embedded layer for required phase shift 180 degree, and the T% in 193, 248 and 365 nm can be adjusted between 2% to 20% for binary and phase shifting mask usage. Ni can be deposited by E-gun, its sheet resistance Rs is less than 1.435 kΩ/square. Jeol e-beam system and I-line stepper are used to evaluate these thin film green mask blanks, feature size less than 200 nm half pitch pattern and 0.558 μm pitch contact hole can be printed. Transmission spectrums of various thickness of SixNy film are inspected by using UV spectrometer and FTIR. Optical constants of the SixNy film are measured by n & k meter and surface roughness is inspected by using Atomic Force Microscope (AFM).
Nanoimprint technology is placed on the ITRS 04 for the 32nm and 22nm technology node (half pitch of metal 1 layer for DRAM) competing technologies, which can also reach the throughput requirements of SEMI: EUV, DUV, X-ray and Electron projection lithography. Nanoimprint technology can be used for mainstream IC, nanoelectronics, polymer electronics, optics (wave guides, switches, lenses), data storage, biochemistry, life science (DNA), μTAS and
microfluidics. However, the technology key of nanoimprint is stamp fabrication. In this paper, high resolution electron beam resist ZEP520 is used for the fabrication of 32 and 22nm nanoimprint stamp, PDMS material for nanoimprint is evaluated and the applications of nanoimprint technology using PDMS stamp for semiconductor, optoelectronics and biotechnology are presented.
Anodic aluminum oxide (AAO) mask was fabricated by a two-step aluminum anodizing process. Highly ordered through-holes porous anodic alumina film was obtained by oxidation of aluminum in the solution of oxalic or sulfuric acid, that were used as electrolytes. AAO mask possess hexagonally ordered porous structures with narrow size distributions of pore diameters and inter-pore space, we can control the dimensions of the AAO structure such as pore diameter, pore length, and pore density by changing the procedures and conditions of the fabrication process. In this paper, we change the etching condition, such as different kinds of etching solution, concentration of etching solution, and etching time. We hope to find out the adequate conditions to get a suitable pore size of AAO mask for different requirement. AAO mask offers a cheaper and easier method to apply to a large area and highly ordered nanostructure, such as nano-dot arrays, and nano-wire arrays with high aspect ratio, which is quite difficult to be formed by using electron beam lithography and track etching technique.
The oldest lithography technique contact/proximity printing are widely used for research activity, most MEMS, Bio-Chip and Optical Electro devices can be fabricated by this method. In this paper, deep submicron 1x mask can be fabricated easily by using e-beam exposure, chemically amplified resist (CAR) and Cr dry etching, a chemical shrink method using dry/wet etching technology was proposed for nanofabrication by using Cr film as hard mask. Micro channel for biochip as well as micro lens for Optical Electro devices can easily be fabricated on glass and quartz substrates by this method.
In this paper, the deep submicron complementary metal-oxide- semiconductor (CMOS) devices were fabricated. A conducting poly(aniline-co-N-propanesulfonic acid aniline) (PAPSAH) as charge dissipation layer for e-beam lithography is used for direct writing the critical polysilicon gate level. Most of the specification of the designed CMOS parameters are met. The optimum conditions for submicron to 0.15 micrometers line/space of polysilicon gate using PAPSAH as charge dissipation layer for e-beam lithography are also established.
Lithography is one of the most important techniques in the IC fabrication and has been extensively used in processing. The high resolution and accuracy of electron beam lithography is most appropriate for making mask of optical and X-ray lithography as well as direct writing on wafer. Two types of resist, ZEP-520 positive resist and SAL-601 negative resist, were prepared for used in the electron beam lithography. Three different patterns, which include isolated line, contact hole and line and space patterns were exposed on the tungsten, oxide, and metal substrates, respectively. The 0.15 micrometers resolution of lithography patterns was achieved. For the etching of polysilicon and oxide, well defined profile of polysilicon gate with 0.1 micrometers width and well-defined tapered profiles of oxide contact hole have been obtained successfully.
In this paper, TiSix as a new material suitable for using as an embedded layer for an attenuated phase shift mask (APSM) is presented. TiSix thin film was formed by plasma sputtering under Ar gas of 26 sccm. The related characteristics of TiSix at 365 nm (i-line) wavelength are as follows: n (refractive index) approximately 3.6; k (extinction coefficient) approximately 1.2; R percent (reflection) approximately 36, (rho) (resistivity 1.0 approximately 8.3 (mu) (Omega) -cm (depends on substrate). For required phase shift degree (theta) equals 180 degrees, calculated thickness d180 is 3.6 which is suitable for APSM. T percent under visible wavelength at thickness d180 is 14 approximately 17 which is suitable for mask's alignment by laser beam. TiSix film has good electrical conductivity, therefore, suitable for e-beam direct-write in patterning mask. TiSix film is also highly resistant to strong acid, suitable for fabrication of mask.
This work describes the mix-and-match lithography technology for 0.1 micrometer device fabrication including a resist patterning process using a G-line stepper and an e-beam lithography system on 6 inch wafers, device pattern layout and device fabrication. A high resolution positive type e-beam resist combined with a high throughput G-line stepper is found to be ideally suitable for fabricating a device with nanometer scale.
In this paper, a metrology for micro- and nanofabrication process has been implemented using an atomic force microscope (AFM). Deep submicron patterning on wafer and chromium photomask were done using well established e-beam direct write technology and evaluated using AFM. A fine pitch control method was proposed to fabricate grating pitch mask for the pitch measurement of AFM. It can finely control the grating pitch to 1 nm, less than the most pattern data unit (5 nm) used in electron beam lithography. AFM is a powerful metrology tool for deep submicron process. AFM was employed as an inspection tool for the evidence of the existence of quantum dots on the GaAs substrate, the quantum dots or islands can be inspected clearly. Good performance is obtained.
This paper reports the simulation study of a new phase-shifting mask (PSM), quartz-etch halftone-rim, applied on one and two dimensional patterns, such as contact hole, line/space and polylayer using positive- tone resist (optical parameters focused mainly on (lambda) equals 365 nm, NA equals 0.5, sigma equals 0.6, halftone chrome T equals 4%). When apply this halftone-rim PSM on 0.35 micrometers dense contact holes, the simulations indicated that optimized rim width is 0.15 (lambda) /NA (0.11 micrometers ). Optimized single side width for biased contact is 0.1 micrometers (0.9 X optimized rim width). Optimized biased contact is 0.55 micrometers (0.35 + 0.1 + 0.1 micrometers ) which is 1.57 times larger of 0.35 micrometers design rule. Exposure latitude is 9.9%. Total depth of focus (DOF) is about 1.2 micrometers . Compared with sized-rim PSM (chrome T equals 0%), this halftone-rim PSM has lower operation exposure dose; higher exposure latitude and larger DOF. When apply it on the 0.35 micrometers dense and isolated line/space, optimized rim width is 0.12 (lambda) /NA (0.09 micrometers ). Optimized single side width for biased space is 0.08 micrometers (0.9 X optimized rim width). The total DOF is about 1.0 micrometers for line/space. By using combination of halftone-rim PSM and off-axis illumination (OAI), the total DOF will reach 1.2-1.5 micrometers for 0.35 micrometers dense line/space. However, the improvement for line/space is insignificant if compared with sized-rim PSM. Halftone-rim PSM has advantages on patterning of contact holes but not on line/space in this study.
In this paper, a very simple data processing system for deep submicron nanofabrication was developed on a popular 80486 based personal computer using commercially available softwares: AutoCAD and ASM3500. Each personal computer can communicate with the control computer (Micro Vax 3900) in the JBX-5DII electron-beam system using the Telnet and FTP software. Deep submicron patterning on wafer and chromium photomask were done using well established electron-beam direct write technology and evaluated using AFM and SEM. Although most electron-beam systems supply text editing program, it is hard to use even for compact pattern data and cannot inspect the overlaying of the patterns. This system can be of great cost-effective value in researching applications for nanofabrication too.
In this paper we report a new type of phase shifting mask (PSM), namely, halftone-rim, which is a combination of rim and halftone. Based on our simulation study using DEPICT-2 simulation tool, the aerial image of halftone-rim PSM in i-line for 0.35 micrometers contact hole pattern has better contrast and larger total depth of focus (DOF) than other mask techniques, such as conventional, subresolution, rim, and attenuated (halftone). Except attenuated mask, halftone-rim also has higher aerial image intensity among these masks. The preliminary contact hole pattern transfer studies using this new type PSM indicate a resolution down to 0.31 micrometers and a total DOF of 0.9 micrometers for contact holes by 5X i-line stepper (NA: 0.5, coherence: 0.6). Further experimental works on optimization of lithographic processes, especially in reactive ion etching of shifter layer and wet etching of halftone chrome, are needed to improve both resolution and total DOF.