25 nm pitch GaInAs/InP buried structure: Improvement by calixarene as an electron beam resist and tertiarybutylphosphine as a P source in organometallic vapor phase epitaxy regrowth October 21, 2020 Electron Beam Lithography, Photomask / Direct Write Lithography 0 To achieve a fine periodic semiconductor structure by electron beam (EB) lithography, calixarene was used as an EB resist. A 25 nm pitch InP pattern was formed successfully and 40 nm pitch InP structures were achieved with good reproducibility. A shorter developing time, precise stage motion, accurate control of the widths of lines and spaces, and slight O2 ashing were important to obtain a fine InP pattern by a two-step wet chemical etching process. Furthermore, the fabricated periodic InP pattern was buried in a GaInAs structure by organometallic vapor phase epitaxy. The introduction of tertiarybutylphosphine as the phosphorous source prevented the fine structure from deforming when the temperature was raised and a 25 nm pitch periodic structure was buried successfully. For full details: Attached files often contain the full content of the item you are viewing. Be sure and view any attachments. resources_se/Nanotech-23.pdf 545.12 KB Related Articles Nanometer-scale resolution of calixarene negative resist in electron beam lithography New nonpolymer materials, calixarene derivatives were tested as high-resolution negative resists for use in electron beam lithography. Arrays of 12-nm-diam dots with a 25 nm pitch were fabricated easily. The sensitivity of calixarene in terms of area dose ranged from 700 to 7000 µC/em2, and the required dose for dot fabrication was about 105 electrons/dot. The standard area dose for calixarene is almost 20 times higher than that for polymethyl methacrylate (PMMA), but the electron spot dose for dot fabrication by calixarene is almost the same as that for PMMA and other highly sensitive resists such as SAL (chemically amplified negative resist for electron beam made by Shipley). The electron spot dose for such extremely small dots does not seem to depend on standard area dose, but any resist tends to require the same dose under exposure in a 50 keV electron beam writing system. We propose a qualitative exposure model that suggests a tradeoff of dose and dot size. The calixarene seems to be promising material for nanofabrication. Calixarene Electron Beam Resist for Nan0-Lithography New electron beam (EB) resists made of calixarene resists are introduced. Typical sensitivities of calixarene resists range from 700 µC/cm2 to 7 mC/cm2. High-density dot arrays with 15 µm diameter constructed using calixarene resist were easily delineated using a point EB lithography system. Our results suggest that the resolution limit of calixarene resists is dominated by a development process such as adhesion to a substrate rather than by the EB profile. Calixarene resists are resistant to etching by halide plasma. We also demonstrated nanoscale devices processed by using calixarene resists. Calixarene resists are promising materials for nanofabrication. High-purity, ultrahigh-resolution calixarene electron-beam negative resist Calixarene is a promising high-resolution negative electron-beam resist having a resolution of the order of 10 nm because of its low molecular weight. We have made a purified calixarene resist containing metal contaminants whose concentrations are measured in parts per billion and which therefore do not degrade the performance of silicon-based electron devices. The purity of the calixarene itself was also improved and we obtained high-purity calixarene and high-purity calixarene, both of which contain the main component, which is more than 95% of all the calixarene present. The resolution of both purified calixarene resists is almost the same as that of the unpurified calixarene, but the sensitivity of calixarene is higher than that of calixarene because its molecular weight is higher. Nanobeam process system: An ultrahigh vacuum electron beam lithography system with 3 nm probe size We have constructed a "nanobeam process system" which is applicable to high resolution electron beam lithography using inorganic resists and is also compatible with electron beam induced surface reaction. It is a 50 kV electron beam lithography system with a gas introducible ultrahigh vacuum sample chamber using a double chamber stage system which isolates stage mechanisms from the sample chamber. The probe size measured with a knife edge method was 2.8 nm, where the probe current was 127 pA. The base pressure of the sample chamber was 3.5X10-7 Pa after baking. The pressure of the gun chamber did not vary at all and the pressure rise of the mechanism chamber was 3X10-6 Pa when the pressure of the sample chamber increased to 1X10-3 Pa during N2 gas introduction. Standard deviations of stitching and overlay accuracy were 14 and 18 nm, respectively. Line patterns with a width of about 5 nm and a pitch of 15 nm were delineated in SiO2 when used as a high resolution resist. High-Resolution Electron-Beam Lithography and Its Application to MOS Devices A point electron-beam lithography system using a thermal field emitter (TFE) allows us to use a nanometer-level fine electron beam to investigate nano-fabrication techniques and minute devices. We developed an organic negative resist, called calixarene, which has low molecular weight of 972 and almost monodispersity. This resist shows a high resolution of about 10 nm when it is exposed to an electron-beam system of 50 kV using TFE. The newly developed resist has been applied in order to fabricate an EJ-MOSFET (electrically variable shallow junction metal-oxide-semiconductor field effect transistor). A 14-nm-gate-length EJ-MOSFET was fabricated by using a calixarene resist and an electron-beam exposure system, and showed MOS device performance. Double electron layer tunneling transistors by dual-side electron beam lithography We describe the first demonstration of small-area double electron layer tunneling transistors (DELTTs) fabricated by dual-side electron beam lithography. The DELTT is a planar quantum device which operates by modulating the two-dimensional (2D)-to-2I) tunneling between two coupled quantum wells. The fabrication technique utilizes the epoxy-bond and stop-etch process to remove the substrate material which allows the backside gates to be placed in close proximity (less than 1 µm) to the frontside gates. The use of electron beam lithography provides precise alignment of the front and back features to each other, We have applied this technique to the fabrication of DELTTs on coupled AlGaAs/GaAs double quantum wells. Low temperature electrical characterization yields source-drain current voltage curves that exhibit negative differential resistance with peak-to-valley ratios of up to 8:1. The height and position of the resonant peak varies strongly with gate bias, demonstrating transistor action. Showing 0 Comment Comments are closed.