Three-Dimensional in Situ Electron-Beam Lithography Using Water Ice

Electron beam lithography on nonplanar and irregular surfaces

E-beam lithography is a powerful tool for generating nanostructures and fabricating nanodevices with fine features approaching a few nanometers in size. However, alternative approaches to conventional spin coating and development processes are required to optimize the lithography procedure on irregular surfaces. In this review, we summarize the state of the art in nanofabrication on irregular substrates using e-beam lithography. To overcome these challenges, unconventional methods have been developed. For instance, polymeric and nonpolymeric materials can be sprayed or evaporated to form uniform layers of electron-sensitive materials on irregular substrates. Moreover, chemical bonds can be applied to help form polymer brushes or self-assembled monolayers on these surfaces. In addition, thermal oxides can serve as resists, as the etching rate in solution changes after e-beam exposure. Furthermore, e-beam lithography tools can be combined with cryostages, evaporation systems, and metal deposition chambers for sample development and lift-off while maintaining low temperatures. Metallic nanopyramids can be fabricated on an AFM tip by utilizing ice as a positive resistor. Additionally, Ti/Au caps can be patterned around a carbon nanotube. Moreover, 3D nanostructures can be formed on irregular surfaces by exposing layers of anisole on organic ice surfaces with a focused e-beam. These advances in e-beam lithography on irregular substrates, including uniform film coating, instrumentation improvement, and new pattern transferring method development, substantially extend its capabilities in the fabrication and application of nanoscale structures.

Out-of-Plane Electronics on Flexible Substrates Using Inorganic Nanowires Grown on High-Aspect-Ratio Printed Gold Micropillars

Out-of-plane or 3D electronics on flexible substrates are an interesting direction that can enable novel solutions such as efficient bioelectricity generation and artificial retina. However, the development of devices with such architectures is limited by the lack of suitable fabrication techniques. Additive manufacturing (AM) can but often fail to provide high-resolution, sub-micrometer 3D architectures. Herein, the optimization of a drop-on-demand (DoD), high-resolution electrohydrodynamic (EHD)-based jet printing method for generating 3D gold (Au) micropillars is reported. Libraries of Au micropillar electrode arrays (MEAs) reaching a maximum height of 196 µm and a maximum aspect ratio of 52 are printed. Further, by combining AM with the hydrothermal growth method, a seedless synthesis of zinc oxide (ZnO) nanowires (NWs) on the printed Au MEAs is demonstrated. The developed hybrid approach leads to hierarchical light-sensitive NW-connected networks exhibiting favorable ultraviolet (UV) sensing as demonstrated via fabricating flexible photodetectors (PDs). The 3D PDs exhibit an excellent omnidirectional light-absorption ability and thus, maintain high photocurrents over wide light incidence angles (±90°). Lastly, the PDs are tested under both concave and convex bending at 40 mm, showing excellent mechanical flexibility.

All-Water Etching-Free Electron Beam Lithography for On-Chip Nanomaterials

Electron beam lithography uses an accelerated electron beam to fabricate patterning on an electron-beam-sensitive resist but requires complex dry etching or lift-off processes to transfer the pattern to the substrate or film on the substrate. In this study, etching-free electron beam lithography is developed to directly write a pattern of various materials in all-water processes, achieving the desired semiconductor nanopatterns on a silicon wafer. Introduced sugars are copolymerized with metal ions-coordinated polyethylenimine under the action of electron beams. The all-water process and thermal treatment result in nanomaterials with satisfactory electronic properties, indicating that diverse on-chip semiconductors (e.g., metal oxides, sulfides, and nitrides) can be directly printed on-chip by an aqueous solution system. As a demonstration, zinc oxide patterns can be achieved with a line width of 18 nm and a mobility of 3.94 cm² V^-1 s^-1. This etching-free electron beam lithography strategy provides an efficient alternative for micro/nanofabrication and chip manufacturing.

Production and Patterning of Fluorescent Quantum Dots by Cryogenic Electron-Beam Writing

Graphene quantum dots (GQDs) have emerged as a promising type of functional material with distinguished properties. Although tremendous effort was devoted to the preparation of GQDs, their applications are still limited due to a lack of methods for processing GQDs from synthesis to patterning smoothly. Here, we demonstrate that aromatic molecules, e.g., anisole, can be directly converted into GQD-containing nanostructures by cryogenic electron-beam writing. Such an electron-beam irradiation product exhibits evenly red fluorescence emission under laser excitation at 473 nm, and its photoluminescence intensity can be easily tuned with the electron-beam exposure dose. Experimental characterizations on the chemical composition of the product reveal that anisole undergoes a carbonization and further graphitization process during e-beam irradiation. With conformal coating of anisole, our approach can create arbitrary fluorescent patterns on both planar and curved surfaces for concealing information or anticounterfeiting applications. This study provides a one-step method for production and patterning of GQDs, facilitating their applications in highly integrated and compact optoelectronic devices.

Looking into a crystal ball: printing and patterning self-assembled peptide nanostructures

The solution processability of organic semiconductors and conjugated polymers along with the advent of nanomaterials as conducting inks have revolutionized next-generation flexible consumer electronics. Another equally important class of nanomaterials, self-assembled peptides, heralded as next-generation materials for bioelectronics, have a lot of potential in printed technology. In this minireview, we address the self-assembly process in dipeptides, their application in electronics, and recent progress in three-dimensional printing. The prospect of a generalizable path for nanopatterning self-assembled peptides using ice lithography and its challenges are further discussed.

Freeform 3D Ice Printing (3D-ICE) at the Micro Scale

Water is one of the most important elements for life on earth. Water's rapid phase-change ability along with its environmental and biological compatibility also makes it a unique structural material for 3D printing of ice structures reproducibly and accurately. This work introduces the freeform 3D ice printing (3D-ICE) process for high-speed and reproducible fabrication of ice structures with micro-scale resolution. Drop-on-demand deposition of water onto a -35 °C platform rapidly transforms water into ice. The dimension and geometry of the structures are critically controlled by droplet ejection frequency modulation and stage motions. The freeform approach obviates layer-by-layer construction and support structures, even for overhang geometries. Complex and overhang geometries, branched hierarchical structures with smooth transitions, circular cross-sections, smooth surfaces, and micro-scale features (as small as 50 µm) are demonstrated. As a sample application, the ice templates are used as sacrificial geometries to produce resin parts with well-defined internal features. This approach could bring exciting opportunities for microfluidics, biomedical devices, soft electronics, and art.

Evolution in Lithography Techniques: Microlithography to Nanolithography

In this era, electronic devices such as mobile phones, computers, laptops, sensors, and many more have become a necessity in healthcare, for a pleasant lifestyle, and for carrying out tasks quickly and easily. Different types of temperature sensors, biosensors, photosensors, etc., have been developed to meet the necessities of people. All these devices have chips inside them fabricated using diodes, transistors, logic gates, and ICs. The patterning of the substrate which is used for the further development of these devices is done with the help of a technique known as lithography. In the present work, we have carried out a review on different types of lithographic techniques such as optical lithography, extreme ultraviolet lithography, electron beam lithography, X-ray lithography, and ion beam lithography. The evolution of these techniques with time and their application in device fabrication are discussed. The different exposure tools developed in the past decade to enhance the resolution of these devices are also discussed. Chemically amplified and non-chemically amplified resists with their bonding and thickness are discussed. Mask and maskless lithography techniques are discussed along with their merits and demerits. Device fabrication at micro and nano scale has been discussed. Advancements that can be made to improve the performance of these techniques are also suggested.

In Situ Time-of-Flight Mass Spectrometry of Ionic Fragments Induced by Focused Electron Beam Irradiation: Investigation of Electron Driven Surface Chemistry inside an SEM under High Vacuum

Recent developments in nanoprinting using focused electron beams have created a need to develop analysis methods for the products of electron-induced fragmentation of different metalorganic compounds. The original approach used here is termed focused-electron-beam-induced mass spectrometry (FEBiMS). FEBiMS enables the investigation of the fragmentation of electron-sensitive materials during irradiation within the typical primary electron beam energy range of a scanning electron microscope (0.5 to 30 keV) and high vacuum range. The method combines a typical scanning electron microscope with an ion-extractor-coupled mass spectrometer setup collecting the charged fragments generated by the focused electron beam when impinging on the substrate material. The FEBiMS of fragments obtained during 10 keV electron irradiation of grains of silver and copper carboxylates and shows that the carboxylate ligand dissociates into many smaller volatile fragments. Furthermore, in situ FEBiMS was performed on carbonyls of ruthenium (solid) and during electron-beam-induced deposition, using tungsten carbonyl (inserted via a gas injection system). Loss of carbonyl ligands was identified as the main channel of dissociation for electron irradiation of these carbonyl compounds. The presented results clearly indicate that FEBiMS analysis can be expanded to organic, inorganic, and metal organic materials used in resist lithography, ice (cryo-)lithography, and focused-electron-beam-induced deposition and becomes, thus, a valuable versatile analysis tool to study both fundamental and process parameters in these nanotechnology fields.

Pillar-structured 3D inlets fabricated by dose-modulated e-beam lithography and nanoimprinting for DNA analysis in passive, clogging-free, nanofluidic devices

We present the fabrication of three-dimensional inlets with gradually decreasing widths and depths and with nanopillars on the slope, all defined in just one lithography step. In addition, as an application, we show how these micro- and nanostructures can be used for micro- and nanofluidics and lab-on-a-chip devices to facilitate the flow and analyze single molecules of DNA. For the fabrication of 3D inlets in a single layer process, dose-modulated electron beam lithography was used, producing depths between 750 nm and 50 nm along a 30 μm long inlet, which is additionally structured with nanometer-scale pillars randomly distributed on top, as a result of incomplete exposure and underdevelopment of the resist. The fabrication conditions affect the slope of the inlet, the nanopillar density and coverage. The key parameters are the dose used for the electron beam exposure and the development conditions, like the developer's dilution, stirring and development time. The 3D inlets with nanostructured pillars were integrated into fluidic devices, acting as a transition between micro and nanofluidic structures for pre-stretching and unfolding DNA molecules, avoiding the intrusion of folded molecules and clogging the analysis channel. After patterning these structures in silicon, they can be replicated in polymer by UV nanoimprinting. We show here how the inlets with pillars slow down the molecules before they enter the nanochannels, resulting in a 3-fold decrease in speed, which would translate to an improvement in the resolution for DNA optical mapping.

Theoretical modeling of ice lithography on amorphous solid water

Due to the perfection of the nanofabrication in nanotechnology and nanoscience, ice lithography (IL) by patterning ice thin-films with a focused electron beam, as a significant derivative technology of electron beam lithography (EBL), is attracting growing attention, evoked by its advantages over traditional EBL with respects of in situ-fabrication, high efficiency, high accuracy, limited proximity effect, three-dimensional (3D) profiling capability, etc. However, theoretical modeling of ice lithography for replicated profiles on the ice resist (amorphous solid water, ASW) has rarely been reported so far. As the result, the development of ice lithography still stays at the experimental stage. The shortage of modeling methods limits our insight into the ice lithography capability, as well as theoretical anticipations for future developments of this emerging technique. In this work, an e-beam induced etching ice model based on the Monte Carlo algorithm for point/line spread functions is established to calculate the replicated profiles of the resist by ice lithography. To testify the fidelity of the modeling method, systematic simulations of the ice lithography property under the processing parameters of the resist thickness, electron accelerating voltage and actual patterns are performed. Theoretical comparisons between the IL on ASW and the conventional EBL on polymethyl methacrylate (PMMA) show superior properties of IL over EBL in terms of the minimum feature size, the highest aspect ratio, 3D nanostructure/devices, etc. The success in developing a modeling method for ice lithography, as reported in this paper, offers a powerful tool in characterizing ice lithography up to the theoretical level and down to molecular scales.

Gentle Patterning Approaches toward Compatibility with Bio-Organic Materials and Their Environmental Aspects

Advances in material science, bioelectronic, and implantable medicine combined with recent requests for eco-friendly materials and technologies inevitably formulate new challenges for nano- and micropatterning techniques. Overall, the importance of creating micro- and nanostructures is motivated by a large manifold of fundamental and applied properties accessible only at the nanoscale. Lithography is a crucial family of fabrication methods to create prototypes and produce devices on an industrial scale. The pure trend in the miniaturization of critical electronic semiconducting components has been recently enhanced by implementing bio-organic systems in electronics. So far, significant efforts have been made to find novel lithographic approaches and develop old ones to reach compatibility with delicate bio-organic systems and minimize the impact on the environment. Herein, such delicate materials and sophisticated patterning techniques are briefly reviewed.

Ice-assisted electron-beam lithography for MoS2 transistors with extremely low-energy electrons

Ice-assisted electron-beam lithography (iEBL) by patterning ice with a focused electron-beam has emerged as a green nanofabrication technique for building nanostructures on diverse substrates. However, materials like atomically thin molybdenum disulfide (MoS2), can be easily damaged by electron irradiation. To ensure the performance of devices based on sensitive materials, it is critical to control electron-beam induced radiolysis in iEBL processes. In this paper, we demonstrate that electron-beam patterning with extremely low-energy electrons followed by a heating process can significantly reduce the damage to substrate materials. A thin film of water ice not only acts as a sacrificial layer for patterning but also becomes a protecting layer for the underlying materials. As a result, MoS2 field effect transistors with back-gate configuration and ohmic contacts have been successfully fabricated. Moreover, the presence or absence of such a protecting layer can lead to the retention or destruction of the underlying MoS2, which provides a flexible method for creating electrical insulation or connection on 2D materials.

3D Nanoprinting by Electron-Beam with an Ice Resist

Following the general trend in the miniaturization of electronic devices, techniques that enable 3D printing at the nanometer scale are gaining momentum. As a widely used planar processing method, electron-beam lithography (EBL) can be employed to create 3D nanostructures in a layer-by-layer fashion. However, compared with other 3D printing techniques, EBL is limited by the stringent requirement of a range of fabrication equipment and complex fabrication processes. Here, we have demonstrated that EBL can be developed to a controllable 3D nanoprinting technology with the aid of ice resists. With carefully selected accelerating voltage, electron dose, and ice thickness, 3D objects can be efficiently printed in a single vacuum system through an iterative process of ice deposition and e-beam exposure. Mixed ice resists containing solid anisole and water are also introduced into the printing process, which offer a flexible control of the thickness of printed layers. Apart from carbonaceous objects obtained with our method, 3D printing of metals is also promising by employing organometallic compounds as ice resists. This study provides a fresh perspective in EBL-based nanofabrication and expands the spectrum of modern additive manufacturing.

MEMS inductor fabrication and emerging applications in power electronics and neurotechnologies

MEMS inductors are used in a wide range of applications in micro- and nanotechnology, including RF MEMS, sensors, power electronics, and Bio-MEMS. Fabrication technologies set the boundary conditions for inductor design and their electrical and mechanical performance. This review provides a comprehensive overview of state-of-the-art MEMS technologies for inductor fabrication, presents recent advances in 3D additive fabrication technologies, and discusses the challenges and opportunities of MEMS inductors for two emerging applications, namely, integrated power electronics and neurotechnologies. Among the four top-down MEMS fabrication approaches, 3D surface micromachining and through-substrate-via (TSV) fabrication technology have been intensively studied to fabricate 3D inductors such as solenoid and toroid in-substrate TSV inductors. While 3D inductors are preferred for their high-quality factor, high power density, and low parasitic capacitance, in-substrate TSV inductors offer an additional unique advantage for 3D system integration and efficient thermal dissipation. These features make in-substrate TSV inductors promising to achieve the ultimate goal of monolithically integrated power converters. From another perspective, 3D bottom-up additive techniques such as ice lithography have great potential for fabricating inductors with geometries and specifications that are very challenging to achieve with established MEMS technologies. Finally, we discuss inspiring and emerging research opportunities for MEMS inductors.

Room Temperature Direct Electron Beam Lithography in a Condensed Copper Carboxylate

High-resolution metallic nanostructures can be fabricated with multistep processes, such as electron beam lithography or ice lithography. The gas-assisted direct-write technique known as focused electron beam induced deposition (FEBID) is more versatile than the other candidates. However, it suffers from low throughput. This work presents the combined approach of FEBID and the above-mentioned lithography techniques: direct electron beam lithography (D-EBL). A low-volatility copper precursor is locally condensed onto a room temperature substrate and acts as a positive tone resist. A focused electron beam then directly irradiates the desired patterns, leading to local molecule dissociation. By rinsing or sublimation, the non-irradiated precursor is removed, leaving copper-containing structures. Deposits were formed with drastically enhanced growth rates than FEBID, and their composition was found to be comparable to gas-assisted FEBID structures. The influence of electron scattering within the substrate as well as implementing a post-purification protocol were studied. The latter led to the agglomeration of high-purity copper crystals. We present this as a new approach to electron beam-induced fabrication of metallic nanostructures without the need for cryogenic or hot substrates. D-EBL promises fast and easy fabrication results.

Fabrication of 2D silicon nano-mold by side etch lift-off method

Nano-imprint technology is a method of nano-pattern reproduction, has the characteristics of high resolution, high throughput, and low-cost. It can reduce the complexity and cost of the equipment while improving the resolution, which considered a promising industrial production technology. The key to nanoimprinting lies in the mold, and the quality of the mold directly determines the quality of the imprinted graphics. Here, a method for fabricating sub-100 nm concave 2D silicon nano-mold by side etch lift-off is proposed. The effects of different wet etching time and the metal deposition angle on the width of nanochannels were studied. The measurement result of dry etching shows that on the entire 4 inch silicon wafer, the width of the nanochannel varies by 4% and the depth by 2%. The width of the nanochannel between chips varies by 0.7%, and the depth variation is 1%. With this new method, high-precision and large-scale silicon nano-mold can be produced, which has great potential for realizing high-precision and low-cost manufacturing of nano devices.

Solvent-Free Nanofabrication Based on Ice-Assisted Electron-Beam Lithography

Advances in electron-beam lithography (EBL) have fostered the prominent development of functional micro/nanodevices. Nonetheless, traditional EBL is predominantly applicable to large-area planar substrates and often suffers from chemical contamination and complex processes for handling resists. This paper reports a streamlined and ecofriendly approach to implement e-beam patterning on arbitrary shaped substrates, exemplified by solvent-free nanofabrication on optical fibers. The procedure starts with the vapor deposition of water ice as an electron resist and ends in the sublimation of the ice followed by a "blow-off" process. Without damage and contamination from chemical solvents, delicate nanostructures and quasi-3D structures are easily created. A refractive index sensor is further demonstrated by decorating plasmonic nanodisk arrays on the end face of a single-mode fiber. Our study provides a fresh perspective in EBL-based processing, and more exciting research exceeding the limits of traditional approaches is expected.

Direct electron-beam patterning of monolayer MoS2 with ice

Two-dimensional transition metal dichalcogenides (TMDCs) are considered strong competitors for next generation semiconductor materials. In this paper, we propose direct electron-beam patterning of monolayer MoS2 inspired by an emerging ice lithography technique. Compared to conventional resist-based nanofabrication, ice-assisted patterning is free of contaminations from polymer resist and allows in situ processing of MoS2. The effects of electron beam dose and energy are investigated and nanoribbons with width below 30 nm are attainable. This method is expected to be applicable also to other TMDCs, providing a promising alternative for nanofabrication of 2D material devices.

Tuning Surface Morphology of Fluorescent Hydrogels Using a Vortex Fluidic Device

In recent decades, microfluidic techniques have been extensively used to advance hydrogel design and control the architectural features on the micro- and nanoscale. The major challenges with the microfluidic approach are clogging and limited architectural features: notably, the creation of the sphere, core-shell, and fibers. Implementation of batch production is almost impossible with the relatively lengthy time of production, which is another disadvantage. This minireview aims to introduce a new microfluidic platform, a vortex fluidic device (VFD), for one-step fabrication of hydrogels with different architectural features and properties. The application of a VFD in the fabrication of physically crosslinked hydrogels with different surface morphologies, the creation of fluorescent hydrogels with excellent photostability and fluorescence properties, and tuning of the structure-property relationship in hydrogels are discussed. We conceive, on the basis of this minireview, that future studies will provide new opportunities to develop hydrogel nanocomposites with superior properties for different biomedical and engineering applications.

Photo-induced electrodeposition of metallic nanostructures on graphene

Graphene, a single atomic layer of sp2 hybridized carbon, is a promising material for future devices due to its excellent optical and electrical properties. Nevertheless, for practical applications, it is essential to deposit patterned metals on graphene in the micro and nano-meter scale in order to inject electrodes or modify the 2D film electrical properties. However, conventional methods for depositing patterned metals such as lift-off or etching leave behind contamination. This contamination has been demonstrated to deteriorate the interesting properties of graphene such as its carrier mobility. Therefore, to fully exploit the unique properties of graphene, the controlled and nano-patterned deposition of metals on graphene films without the use of a sacrificial resist is of significant importance for graphene film functionalization and contact deposition. In this work, we demonstrate a practical and low-cost optical technique of direct deposition of metal nano-patterned structures without the need for a sacrificial lift-off resist. The technique relies on the laser induced reduction of metal ions on a graphene film. We demonstrate that this deposition is optically driven, and the resolution is limited only by the diffraction limit of the light source being used. Patterned metal features as small as 270 nm in diameter are deposited using light with a wavelength of 532 nm and a numerical aperture of 1.25. Deposition of different metals such as Au, Ag, Pd, Pb and Pt is shown. Additionally, change in the Fermi level of the graphene film through the nano-patterned metal is demonstrated through the electrical characterization of four probe field effect transistors.

Electron-Beam Patterning of Vapor-Deposited Solid Anisole

The emerging ice lithography (IL) nanofabrication technology differs from conventional electron-beam lithography by working at cryogenic temperatures and using vapor-deposited organic molecules, such as solid water and alkanes, as e-beam resists. In this paper, we systematically investigate e-beam patterning of frozen anisole and assess its performance as an e-beam resist in IL. Dose curves reveal that anisole has a very low contrast of ∼1, with a very weak dependence on primary beam energy in the investigated range of 5-20 keV. The minimum line width of 60 nm is attainable at 20 keV, limited by stage vibration in our apparatus. Notably, various solid states of anisole have been observed and we can control the deposited anisole from crystalline to amorphous state by decreasing the deposition temperature. The critical temperature for forming an amorphous film is 130 K in the vacuum of a microscope chamber. Smooth patterns with a surface roughness of ∼0.7 nm are achieved in the as-deposited amorphous solid anisole. As a proof of principle of 3D fabrication, we finally fabricate nanoscale patterns on exotic silicon micropillars with a high aspect ratio using this resist.

Wide-Angle Polarization-Independent Ultra-Broadband Absorber from Visible to Infrared

We theoretically proposed and numerically analyzed a polarization-independent, wide-angle, and ultra-broadband absorber based on a multi-layer metasurface. The numerical simulation results showed that the average absorption rates were more than 97.2% covering the broad wavelength of 400~6000 nm (from visible light to mid-infrared light) and an absorption peak was 99.99%, whatever the polarization angle was changed from 0° to 90°. Also, as the incidence angle was swept from 0° to 55°, the absorption performance had no apparent change over the wavelength ranges of 400 to 6000 nm. We proved that the proposed metasurface structure was obviously advantageous to achieve impedance matching between the absorber and the free space as compared with conventionally continuous planar-film structures. The broadband and high absorption resulted from the strong localized surface plasmon resonance and superposition of resonant frequencies. As expectable the proposed absorber structure will hold great potential in plasmonic light harvesting, photodetector applications, thermal emitters and infrared cloaking.

Ice lithography for 3D nanofabrication

Nanotechnology and nanoscience are enabled by nanofabrication. Electron-beam lithography, which makes 2D patterns down to a few nanometers, is one of the fundamental pillars of nanofabrication. Recently, significant progress in 3D electron-beam-based nanofabrication has been made, such as the emerging ice lithography technology, in which ice thin-films are patterned by a focused electron-beam. Here, we review the history and progress of ice lithography, and focus on its applications in efficient 3D nanofabrication and additive manufacturing or nanoscale 3D printing. The finest linewidth made using frozen octane is below 5 nm, and nanostructures can be fabricated in selected areas on non-planar surfaces such as freely suspended nanotubes or nanowires. As developing custom instruments is required to advance this emerging technology, we discuss the evolution of ice lithography instruments and highlight major instrumentation advances. Finally, we present the perspectives of 3D printing of functional materials using organic ices. We believe that we barely scratched the surface of this new and exciting research area, and we hope that this review will stimulate cutting-edge and interdisciplinary research that exploits the undiscovered potentials of ice lithography for 3D photonics, electronics and 3D nanodevices for biology and medicine.

Effect of Molecular Weight on the Feature Size in Organic Ice Resists

The feature size of patterns obtained by electron-beam lithography (EBL) depends critically on resist properties, beam parameters, development process, and instrument limitations. Frozen layers of simple organic molecules such as n-alkanes behave as negative-tone resists for EBL. With the unique advantage of an in situ thermal treatment replacing chemical development, the entire lithographic process can be performed within a single instrument, thus removing the influence of chemical developers on the feature size. By using an environmental transmission electron microscope, we can also minimize the influence of instrumental limitations and explore the fundamental link between resist characteristics and feature size. Our results reveal that the onset dose of organic ice resists correlates with the inverse molecular weight and that in the thermal development the role of change in solubility of polymers is mirrored in a shift in the solid/vapor critical temperature of organic ices. With a 0.4 pA beam current, we obtained 4.5, 5.5, and 8.5 nm lines with frozen octane, undecane, and tetradecane, respectively, consistent with the predictions of a model we developed that links beam profile and feature size. The knowledge acquired on the response of small organic molecules to electron irradiation, combined with the flexibility and operational advantages of using them as qualified EBL resists, provides us with new opportunities for the design and production of nanodevices and broadens the reach of EBL especially toward biological applications.