CSAR 62 as negative-tone resist for high-contrast e-beam lithography at temperatures between 4 K and room temperature

Abstract

The temperature dependence of the electron-beam sensitive resist CSAR 62 is investigated in its negative-tone regime. The writing temperatures span a wide range from 4 K to room temperature with the focus on the liquid helium temperature regime. The importance of low temperature studies is motivated by the application of CSAR 62 for deterministic nanophotonic device processing by means of in-situ electron-beam lithography. At low temperature, CSAR 62 exhibits a high contrast of 10.5 and a resolution of 49 nm. The etch stability is almost temperature independent and it is found that CSAR 62 does not suffer from peeling which limits the low temperature application of the standard electron-beam resist PMMA. As such, CSAR 62 is a very promising negative-tone resist for in-situ electron-beam lithography of high quality nanostructures at low temperature.

Quantum Dot Single-Photon Emission Coupled into Single-Mode Fibers with 3D Printed Micro-Objectives

“…With the help of the numerical optimization of the microlens design, it is possible to achieve outcoupling efficiencies of almost 30% for an NA of 0.4. 31,41 For the fabrication of the QD-microlenses, a 80 nm thick electron-sensitive CSAR62 resist film 42 is first spin-coated onto the sample, and then a specially modified electron scanning microscope is used to record cathodoluminescence maps at T = 10 K. Suitable QDs are selected based on the emission wavelength and the emission intensity of the excitonic lines, and a lenticular dose profile is then introduced into the resist at the positions of selected QDs. In the later anisotropic, plasma-enhanced reactive ion etching step, the electron-sensitive resist remaining on the sample surface after exposure and development acts as an etching mask so that the introduced lens profile is transferred into the semiconductor material, resulting in the monolithic QD microlenses.…”

Single Quantum Dot with Microlens and 3D-Printed Micro-objective as Integrated Bright Single-Photon Source

“…The process includes low-temperature cathodoluminescence spectroscopy to identify suitable QDs in combination with 3D low-temperature EBL to write lens-shaped structures into AR-P 6200 (CSAR 62) as low-temperature electron-beam resist. 28 In the final step, the lens shapes are transferred into the 420 nm thick GaAs capping layer by inductively coupled plasma reactive-ion etching. A scanning-electron microscopy image of a microlens is shown in Figure 2 a.…”

Enhanced photon-extraction efficiency from InGaAs/GaAs quantum dots in deterministic photonic structures at 1.3 μm fabricated by in-situ electron-beam lithography

“…Due to a relatively high QD spatial density of a few times 10 9 /cm 2 ( Fig. 1 (a)) mesas of diameters in the range of (500 -2500) nm were fabricated deterministically over the selected QDs with respect to the brightness and spectral range, to assure that only a single QD is embedded within the mesa structure via the lowtemperature in-situ EBL approach [Kaganskiy (2015), , Gschrey (2013)] utilizing CSAR62 [Kaganskiy (2016)] electron-beam sensitive resist. As it has recently been proven theoretically, the main photon losses are related to the in-plane propagation [Schneider (2018)] which can be limited by forming even relatively simple disc-shaped mesa structures.…”