Nanometer-scale resolution of calixarene negative resist in electron beam lithography October 21, 2020 Electron Beam Lithography, Photomask / Direct Write Lithography 0 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. 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-28.pdf 399.08 KB Related Articles 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. 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-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. Nanometer-Scale Patterning of Polystyrene Resists in Low-Voltage Electron Beam Lithography We studied nanometer-scale patterning using a polystyrene negative resist in electron beam lithography. We found that the use of a low-molecular-weight polystyrene enables 10-nm-level patterning at low-acceleration voltage. We also found that the spot dose of such ultrasmall patterns formed at a 5kV acceleration voltage was one-tenth of that formed at 50kV. Low-voltage electron beam lithography is a suitable technique for organic resist nanopatterning. The Charlesby theory can still be applied to nanodot formation, and we can therefore estimate the dot sensitivity for various polystyrene molecular weights. We suppose that an exposure model is based on polymer aggregation to explain the formation of a 10-nm-level pattern with a height of 40 nm can be formed by using a small molecule, not a large one. 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. Intra-Level Mix-and-Match Lithography Process for Fabricating Sub-100-nm Complementary Metal-Oxide-Semiconductor Devices using the JBX-9300FS Point-Electron-Beam System To increase the throughput of electron beam lithography used to fabricate sub- 100-nm patterns, we developed an electron beam and deep UV intra-level mix-and-match lithography process, that uses the JBX-9300FS point-electron-beam system and a conventional KrF stepper. Pattern data preparation was improved for sub- 100-nm patterns. To reduce the effect of line width variation caused by post-exposure delay on complementary metal-oxide-semiconductor (CMOS) devices, we first exposed KrF patterns and then added another post-exposure bake before the electron beam (EB) exposure. We have used this technique to expose the gate layer of sub- 100-nm CMOS devices. When we set the threshold size between EB and KrF patterns at 0.16 µm, the throughput of electron beam lithography was about threefold that of the full exposure by the electron beam lithography process. Sub-50-nm CMOS devices with high drive current were successfully fabricated. Showing 0 Comment Comments are closed.