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Thermal silicon probes have demonstrated their potential to investigate the thermal properties of various materials at high resolution. However, a thorough assessment of the achievable resolution is missing. Here, we present a probe-based thermal-imaging technique capable of providing sub-10 nm lateral resolution at a sub-10 ms pixel rate. We demonstrate the resolution by resolving microphase-separated PS-b-PMMA block copolymers that self-assemble in 11 to 19 nm half-period lamellar structures. We resolve an asymmetry in the heat flux signal at submolecular dimensions and assess the ratio of heat flux into both polymers in various geometries. These observations are quantitatively compared with coarse-grained molecular simulations of energy transport that reveal an enhancement of transport along the macromolecular backbone and a Kapitza resistance at the internal interfaces of the self-assembled structure. This comparison discloses a tip-sample contact radius of a ≈ 4 nm and identifies combinations of enhanced intramolecular transport and Kapitza resistance.

Diffusion relates the flux of particles to the local gradient of the particle density in a deterministic way. The question arises as to what happens when the particle density is so low that the local gradient becomes an ill-defined concept. The dilemma was resolved early last century by analyzing the average motion of particles subject to random forces whose magnitude is such that the particles are always in thermal equilibrium with their environment. The diffusion dynamics is now described in terms of the probability density of finding a particle at some position and time and the probabilistic flux density, which is proportional to the gradient of the probability density. In a time average sense, the system thus behaves exactly like the ensemble average. Here, we report on an experimental method and test this fundamental equivalence principle in statistical physics. In the experiment, we study the flux distribution of 20 nm radius polystyrene particles impinging on a circular sink of micrometer dimensions. The particle concentration in the water suspension is approximately 1 particle in a volume element of the dimension of the sink. We demonstrate that the measured flux density is exactly described by the solution of the diffusion equation of an infinite system, and the flux statistics obeys a Poissonian distribution as expected for a Markov process governing the random walk of noninteracting particles. We also rigorously show that a finite system behaves like an infinite system for very long times despite the fact that a finite system converges to a zero flux empty state.

High-resolution lithography often involves thin resist layers which pose a challenge for pattern characterization. Direct evidence that the pattern was well-defined and can be used for device fabrication is provided if a successful pattern transfer is demonstrated. In the case of thermal scanning probe lithography (t-SPL), highest resolutions are achieved for shallow patterns. In this work, we study the transfer reliability and the achievable resolution as a function of applied temperature and force. Pattern transfer was reliable if a pattern depth of more than 3 nm was reached and the walls between the patterned lines were slightly elevated. Using this geometry as a benchmark, we studied the formation of 10-20 nm half-pitch dense lines as a function of the applied force and temperature. We found that the best pattern geometry is obtained at a heater temperature of ∼600 °C, which is below or close to the transition from mechanical indentation to thermal evaporation. At this temperature, there still is considerable plastic deformation of the resist, which leads to a reduction of the pattern depth at tight pitch and therefore limits the achievable resolution. By optimizing patterning conditions, we achieved 11 nm half-pitch dense lines in the HM8006 transfer layer and 14 nm half-pitch dense lines and L-lines in silicon. For the 14 nm half-pitch lines in silicon, we measured a line edge roughness of 2.6 nm (3σ) and a feature size of the patterned walls of 7 nm.

Thermal scanning probe lithography (t-SPL) is a direct-write patterning method that creates high-resolution features with a heated scanning probe tip in an organic resist material. It is able to produce dense high-resolution patterns with sub-20 nm half-pitch at ambient conditions which can be transferred into silicon substrates using a hard-mask patterning stack and reactive ion etching (RIE). Feature sizes of transferred lines can be as small as 7 nm. Linear write speeds of up to 20 mm/s can be achieved. Different from e-beam lithography (EBL), in t-SPL proximity effects are absent and substrate damage of sensitive materials caused by high energy electrons is avoided. A direct inspection of the patterned area is provided during the writing process. Overlay patterning without additional alignment marks onto pre-existing structures is another feature of the t-SPL method. Existing device structures can be located precisely under a resist stack with the local probe tip and the additional target structures can then be generated with $\lt 5$ nm-precise overlay alignment. One further strength of tSPL is the capability of producing 3D patterns. The process can be controlled to produce 3D structures with $\approx 1$ nm $(1 \sigma)$ depth accuracy. Examples of unique devices fabricated by tSPL will be discussed.

Nanoimprint lithography (NIL) is one of the most promising technology platforms for replication of nanometer and micrometer scale 3D topographies with extremely high resolution and throughput, as needed for e.g. photonic or optical applications. One of the remaining challenges of 3D NIL, however, is the fabrication of high quality 3D master originals – the initial patterns that are replicated multiple times in the NIL process. Here, we demonstrate a joint solution for 3D NIL where NanoFrazor thermal scanning probe lithography (t-SPL) is used to pattern the master templates with singlenanometer accurate 3D topographies. 3D topographies from polymer resist master templates are replicated using a HERCULES NIL system with SmartNIL technology. Furthermore, 3D patterns are transferred from the resist into a silicon substrate via reactive ion etching (RIE) and the resulting silicon master template is used for producing polymeric working stamps into OrmoStamp and, finally, replicas into optical grade OrmoClearFX material. Both replication strategies result in very high-quality replicas of the original patterns.

Using friction to guide fabrication Ultralow friction found in certain layered materials such as graphite is important in the construction of nanomechanical devices. Koren et al. combined measurements and modeling to characterize the interaction of sliding graphite planes (see the Perspective by Liechti). This helped them to make small graphite devices that featured rotational pivots and multiple locking positions. Science , this issue p. 679

Thermal scanning probe lithography (t-SPL) has demonstrated unique capabilities for maskless lithography. A heated atomic force microscope tip is used to locally remove a thermally sensitive resist. This process is able to fabricate precise 3D patterns and high resolution structures without the use of charged particles, such as electrons, which have been implicated in substrate damage. Here we outline our work to improve the throughput of t-SPL via integration with a laser writer for the patterning of large features and the development of independently addressable cantilever arrays.

Detection and precise localization of nano-scale structures buried beneath spin coated films are highly valuable additions to nano-fabrication technology. In principle, the topography of the final film contains information about the location of the buried features. However, it is generally believed that the relation is masked by flow effects, which lead to an upstream shift of the dry film's topography and render precise localization impossible. Here we demonstrate, theoretically and experimentally, that the flow-shift paradigm does not apply at the sub-micron scale. Specifically, we show that the resist topography is accurately obtained from a convolution operation with a symmetric Gaussian Kernel whose parameters solely depend on the resist characteristics. We exploit this finding for a 3 nm precise overlay fabrication of metal contacts to an InAs nanowire with a diameter of 27 nm using thermal scanning probe lithography., 23 pages, 5 figures

The thermo-electrical properties of a complex silicon cantilever structure used in thermal scanning probe lithography are modeled based on well established empirical laws for the thermal conductivity in silicon, the electrical conductivity in the degenerate silicon support structure, and a comprehensive physical model of the electrical conductivity in the low-doped heater structure. The model calculations are performed using a set of physically well defined material parameters and finite element methods to solve the coupled thermal and electrical diffusion equations in the cantilever. The material parameters are determined from a non-linear regression fit of the numerical results to corresponding measured data which also includes Raman measurements of the heater temperature. Excellent agreement between predicted and measured data in the absence of air cooling is obtained if a tapered doping profile in the heater is used. The heat loss through the surrounding air is also studied in a parameter free three-dimensional simulation. The simulation reveals that the heater temperature can be accurately predicted from the electrical power supplied to the cantilever via a global scaling of the power in the power-temperature correlation function which can be determined from the vacuum simulation., Comment: 24 pages, 10 figures

Thermal scanning probe lithography combines high-resolution patterning capabilities with the ability to read topography without causing resist exposure. As such, it is an ideal candidate for the implementation of markerless pattern overlay. This approach eliminates errors arising from marker degradation and inconsistencies in the positioning hardware used for reading and writing. Here, we outline our implementation and characterization of a markerless lithography process. We demonstrate theoretically and experimentally that alignment errors below 5 nm are possible for micron-sized features having an amplitude of just 4 nm. Further, we show that following proper calibration, a limiting overlay accuracy of 1.1 nm per axis is achievable.

In the presented work solvent-free film preparation from molecular glass resists, the evaluation of the patterning performance using thermal scanning probe lithography (tSPL) and an efficient etch transfer process are demonstrated. As the presented materials have a high tendency to crystallize and thus form crystalline films of bad quality when processed by solution casting, two component mixtures prepared by coevaporation were investigated. Stable amorphous films were obtained by selecting compatible material pairs for the coevaporation. One optimized material pair is based on trissubstituted, twisted resist materials with a distinct difference in molecular design. Here a high resolution tSPL prepared pattern of 18 nm half pitch in a 10 nm thick film is demonstrated. A further optimization is reported for “small” cubic silsequioxane molecules. Again single component films show independent to applied film preparation techniques bad film forming properties due to the high crystallinity of the symmetric cubic silsequioxane molecules. But coevaporation of the phenyl substituted octaphenylsilsequioxane combined with the fully aromatic 2,2',7,7'-tetraphenyl-9,9'-spirobi[fluorene] results in stable amorphous thin films. tSPL investigations demonstrate the patternability by writing high resolution line features of 20 nm half pitch. An important advantage of such a silicon rich resist material is that it can be directly converted to SiO2, yielding to a patterned hardmask of SiO2. This proof of principle is demonstrated and an efficient pattern transfer of 60 nm half pitch line into the underlying HM8006 is reported.

In the presented work solvent-free film preparation from tailored molecular glass resists, their thermal analysis, the characterization of etch resistance for plasma etching transfer processes, and the evaluation of the patterning performance using scanning probe lithography (SPL) tools, in particular electric field and thermal based SPL, are demonstrated. Therefore a series of fully aromatic spiro-based and tris-substituted twisted resist materials were systematically investigated. The materials feature very high glass transition temperatures of up to 173 °C, which allows solvent-free thin film preparation by physical vapor deposition (PVD) due to their high thermal stability. The PVD prepared films offer distinct advantages compared to spin coated films such as no pinholes, defects, or residual solvent domains, which can locally affect the film properties. In addition, PVD prepared films do not need a post apply bake (PAB) and can be precisely prepared in the nanometer range layer thickness. An observed sufficient plasma etching resistance is promising for an efficient pattern transfer even by utilizing only 10 nm thin resist films. Their lithographic resolution potential is demonstrated by a positive and a negative tone patterning using electric field, current controlled scanning probe lithography (EF-CC-SPL) at the Technical University of Ilmenau or thermal scanning probe lithography (tSPL) investigations at the IBM Research - Zurich. High resolution tSPL prepared patterns of 11 nm half pitch and at 4 nm patterning depth are demonstrated.

A novel alternative to E-beam lithography, in particular for plasmonic and nanophotonic devices, is presented. Patterning resolution and speed are similar; however, the novel technique enables direct 3D lithography and markerless overlay with sub-5 nm accuracy.

Thermal Scanning Probe Lithography [1] (tSPL) utilises a heated AFM tip to locally evaporate a polymer layer. Using tSPL nanometer precise 3D profiles can be formed in this polymer layer [2]. tSPL offers a resolution and linear scan speed that is competitive [3] with the current state of the art maskless technique, Gaussian electron beam lithography. A recently developed pattern transfer technique allows for the subsequent transfer of these patterns into the substrate [4]. Pattern alignment or overlay is a key challenge both in device fabrication and the investigation of novel nanostructures. tSPL has a pair of unique capabilities for meeting this challenge. Firstly it can read topography with sub-nanometer sensitivity and secondly reading the surface does not lead to resist exposure. This removes the need for dedicated alignment marks which in turn removes difficulties associated with marker degradation and inconsistencies in the positioning hardware used for read and write. Here we describe our efforts to implement and assess a markerless overlay process. In particular we investigate the two sources of error in the overlay process. The first are errors arising in the determination of the position of the existing pattern. We demonstrate theoretically that for our tSPL patterning stack the detection error may be some 200 times smaller than the 1μm feature size present in patterns produced using optical lithography. The second source of error is in the writing of the overlay pattern. We outline the practical steps including feed forward scanner control, on-the-fly drift correction and 3D patterning required to achieve nanometer accuracy in the pattern placement.

The presented work deals with molecular glass resist materials based on (i) calix[4]resorcinarene resist systems, (ii) twisted fully aromatic biscarbazole-biphenyl materials, and (iii) fully aromatic spiro resist materials as new promising materials for Scanning Probe Lithography (SPL). Because of the non-chemically amplified resist nature and the absence of corresponding material diffusion, the novel SPL resists have the potential to increase the patterning resolution capabilities at a simultaneous reduction of the edge roughness (LER). In addition, these low molecular weight molecular glasses offer the advantage of solvent-free film preparation by physical vapor deposition (PVD). The PVD prepared films offer a number of advantages compared to spin coated ones such as no more pinholes, defects, or residual solvent domains, which can locally affect the film properties. These high-quality PVD films are ideal candidates for the direct patterning by SPL tools. Presented highlights are the thermal scanning probe lithography (tSPL) investigations at IBM Research - Zurich and the patterning by using electric field, current controlled scanning probe lithography (EF-CC-SPL) at the Technical University of Ilmenau. Further investigations on film forming behavior, etch resistance, and etch transfer are presented. Owing to the high-resolution probe based patterning capability in combination with their improved etch selectivity compared to reference polymeric resists the presented molecular glass resists are highly promising candidates for lithography at the single nanometer digit level.

Thermal Scanning Probe Lithography (tSPL) is an AFM based patterning technique, which uses heated tips to locally evaporate organic resists such as molecular glasses [1] or thermally sensitive polymers.[2][3] Organic resists offer the versatility of the lithography process known from the CMOS environment and simultaneously ensure a highly stable and low wear tip-sample contact due to the soft nature of the resists. Patterning quality is excellent up to a resolution of sub 15 nm,[1] at linear speeds of up to 20 mm/s and pixel rates of up to 500 kHz.[4] The patterning depth is proportional to the applied force which allows for the creation of 3-D profiles in a single patterning run.[2] In addition, non-destructive imaging can be done at pixel rates of more than 500 kHz.[4] If the thermal stimulus for writing the pattern is switched off the same tip can be used to record the written topography with Angstrom depth resolution. We utilize this unique feature of SPL to implement an efficient control system for reliable patterning at high speed and high resolution. We combine the writing and imaging process in a single raster scan of the surface. In this closed loop lithography (CLL) approach, we use the acquired data to optimize the writing parameters on the fly. Excellent control is in particular important for an accurate reproduction of complex 3D patterns. These novel patterning capabilities are equally important for a high quality transfer of two-dimensional patterns into the underlying substrate. We utilize an only 3-4 nm thick SiOx hardmask to amplify the 8±0.5 nm deep patterns created by tSPL into a 50 nm thick transfer polymer. The structures in the transfer polymer can be used to create metallic lines by a lift-off process or to further process the pattern into the substrate. Here we demonstrate the fabrication of 27 nm wide lines and trenches 60 nm deep into the Silicon substrate.[5] In addition, the combined read and write approach ensures that the lateral offset between read and write field is minimized. Thus we achieve high precision in marker-less stitching of patterning fields. A 2D cross-correlation technique is used to determine the offset of a neighboring patterning field relative to a previously written field with an accuracy of about 1 nm. We demonstrate stitching of 1 μm2 fields with ~5 nm accuracy and stitching of larger 10x10 μm2 fields with 10 nm accuracy.[6]

The most direct definition of a patterning process' resolution is the smallest half-pitch feature it is capable of transferring onto the substrate. Here we demonstrate that thermal Scanning Probe Lithography (t-SPL) is capable of fabricating dense line patterns in silicon and metal lift-off features at sub 20 nm feature size. The dense silicon lines were written at a half pitch of 18.3 nm to a depth of 5 nm into a 9 nm polyphthalaldehyde thermal imaging layer by t-SPL. For processing we used a three-layer stack comprising an evaporated SiO2 hardmask which is just 2-3 nm thick. The hardmask is used to amplify the pattern into a 50 nm thick polymeric transfer layer. The transfer layer subsequently serves as an etch mask for transfer into silicon to a nominal depth of 60 nm. The line edge roughness (3 sigma) was evaluated to be less than 3 nm both in the transfer layer and in silicon. We also demonstrate that a similar three-layer stack can be used for metal lift-off of high resolution patterns. A device application is demonstrated by fabricating 50 nm half pitch dense nickel contacts to an InAs nanowire., Comment: 7 pages, 5 figures, to be published in JVST B

Nanomagnetic structures have the potential to surpass silicon's scaling limitations both as elements in hybrid CMOS logic and as novel computational elements. Magnetic force microscopy (MFM) offers a convenient characterization technique for use in the design of such nanomagnetic structures. MFM measures the magnetic field and not the sample's magnetization. As such the question of the uniqueness of the relationship between an external magnetic field and a magnetization distribution is a relevant one. To study this problem we present a simple algorithm which searches for magnetization distributions consistent with an external magnetic field and solutions to the micromagnetic equations' qualitative features. The algorithm is not computationally intensive and is found to be effective for our test cases. On the basis of our results we propose a systematic approach for interpreting MFM measurements.

The measurement of cantilever parameters is an essential part of performing a calibrated measurement with an atomic force microscope (AFM). The thermal motion method is a widely used technique for calibrating the spring constant of an AFM cantilever, which can be applied to non-rectangular cantilevers. Given the trend towards high frequency scanning, calibration of non-rectangular cantilevers is of increasing importance. This paper presents two results relevant to cantilever calibration via the thermal motion method. We demonstrate the possibility of using the AFM's phase signal to acquire the thermal motion. This avoids the challenges associated with connecting the raw photodiode signal to a separate spectrum analyser. We also describe how numerical calculations may be used to calculate the parameters needed in a thermal motion calibration of a non-rectangular cantilever. Only accurate knowledge of the relative size of the in-plane dimensions of the cantilever is needed in this computation. We use this pair of results in the calibration of a variety of rectangular and non-rectangular cantilevers. We observe an average difference between the Sader and thermal motion values of cantilever stiffness of 10%.

We have extended our previous work (Rawlings et al 2010 Phys. Rev. B 82 085404) on simulating magnetic force microscopy (MFM) images for magnetically soft samples to include an accurate representation of coated MFM tips. We used an array of square 500 nm nanomagnets to evaluate our improved MFM model. A quantitative comparison between model and experiment was performed for lift heights ranging from 20 to 100 nm. No fitting parameters were used in our comparison. For all lift heights the qualitative agreement between model and experiment was significantly improved. At low lift heights, where the magnetic signal was strong, the difference between theory and experiment was less than 30%.

We have used the scanning probe technique, magnetic force microscopy (MFM), to study the magnetization distribution in a system of indented rectangles made from permalloy. An accurate linear approximation to the micromagnetic equations was implemented in commercial finite element software. This model was used to study the important effect of tip-sample interaction on our MFM measurements. Comparison between experiment and our model confirmed that even for large indents the nanomagnets adopted vortex ground states. A qualitative relationship between the sample's magnetization, in the absence of the MFM tip's magnetic field, and the induced contrast was identified. The optimum ratio of charge contrast to induced contrast when observing vortex states was found to be proportional to the tip moment raised to the power of 0.4. This was subject to the limitations imposed by resolution and thermal noise. It occurred for large separation between tip and sample.

Inefficient and inconsistent use of codes and standards can hamper effective delivery of infrastructure projects. Steven Wilson of BSI, Bill Grose of High Speed Two (HS2) and Colin Rawlings of CH2MHill/HS2 outline initiatives on the HS2 project to deliver successful standards.

Superconductors, such as YBCO bulks, have extremely high potential magnetic flux densities, comparing to rare earth magnets. Therefore, the magnetization of superconductors has attracted broad attention and contribution from both academic research and industry. In this paper, a novel technique is proposed to magnetize superconductors. Unusually, instead of using high magnetic fields and pulses, repeatedly magnetic waves with strength of as low as rare earth magnets are applied. These magnetic waves, generated by thermally controlling a Gadolinium (Gd) bulk with a rare earth magnet underneath, travel over the flat surface of a YBCO bulk and get trapped little by little. Thus, a very small magnetic field can be used to build up a very large magnetic field. In this paper, the modelling results of thermally actuated magnetic waves are presented showing how to transfer sequentially applied thermal pulses into magnetic waves. The experiment results of the magnetization of YBCO bulk are also presented to demonstrate how superconductors are progressively magnetized by small magnetic field

Abstract Among the possible reasons for leakage from reservoirs in the Barents Sea are spill due to tilting, expulsion caused by gas expansion and cap rock failure. All mechanisms have been related to the pronounced Cenozoic uplift of the Barents Shelf. This paper focuses on how the uplift has influenced the cap rock seal. The simulations presented comprised Late Jurassic rifting at shallow burial, post-rifting sedimentation followed by two phases of Tertiary uplift/erosion with subsequent compression and extension at different depths of burial. The two main results from these simulations are:that cap rock failure may occur due to the build up of deviatoric stresses during uplift, andthat minimal strain is required to initiate fracturing during extensional or compressional tectonics. By combining the map of total erosion with the results of the fracture modelling study presented, uplift could be identified as a critical factor in structurally high areas. Fracture initiation in cap rocks is less likely in basinal areas. As a result exploration can be concentrated on the most promising areas. Introduction Wells drilled on the Barents Shelf (Norway) have in several cases proven traces of hydrocarbons and underfilled reservoirs. The results have been interpreted to indicate that the reservoirs were once filled to spill point, but that the hydrocarbons escaped at a later stage. Among the possible reasons for leakage from the reservoirs are spill due to tilting, expulsion caused by gas expansion and cap rock failure. All mechanisms have been related to the pronounced Cenozoic uplift of the Barents Shelf. The work presented focuses on how the uplift has influenced the cap rock seal. Central aspects of this problem are the mechanical properties of the cap rock, uplift history, stress field variation through time, pore pressure development and fracture mechanisms. This paper presents results from the rock mechanical testing program and numerical simulation of the Hekkingen Formation cap rock behaviour during the geological history. The discontinuous modelling approach applied has been developed for simulation of fractured rock mass behaviour and was applied to the problem described. The applicability of discontinuum modelling to problems related to major stress variations is shown. A sophisticated fracture behaviour model is included in the applied modelling approach which permits tracking of fracture aperture variations. The execution of tasks is illustrated by the flow diagram shown in Figure 1. Numerical simulation of fractured rock masses A two-dimensional distinct element program was used to simulate fracture initiation and fracture behaviour in the cap rock due to changes of boundary stresses and pore pressure. Short description of UDEC-BB The distinct element method is a discontinuum modelling approach for simulating the behaviour of fractured rock masses. The method has three features which makes it well suited for discontinuum modelling: P. 821^

Accurate deposition of nanoparticles at defined positions on a substrate is still a challenging task, because it requires simultaneously stable long-range transport and attraction to the target site and precise short-range orientation and deposition. Here we present a method based on geometry-induced energy landscapes in a nanofluidic slit for particle manipulation: Brownian motors or electro-osmotic flows are used for particle delivery to the target area. At the target site, electrostatic trapping localizes and orients the particles. Finally, reducing the gap distance of the slit leads sequentially to a focusing of the particle position and a jump into adhesive contact by several nanometers. For 60 nm gold spheres, we obtain a placement accuracy of 8 nm. The versatility of the method is demonstrated further by a stacked assembly of nanorods and the directed deposition of InAs nanowires., 7 pages, 5 figures

Applications for high resolution 3D profiles, so-called grayscale lithography, exist in diverse fields such as optics, nanofluidics and tribology. All of them require the fabrication of patterns with reliable absolute patterning depth independent of the substrate location and target materials. Here we present a complete patterning and pattern-transfer solution based on thermal scanning probe lithography (t-SPL) and dry etching. We demonstrate the fabrication of 3D profiles in silicon and silicon oxide with nanometer scale accuracy of absolute depth levels. An accuracy of less than 1nm standard deviation in t-SPL is achieved by providing an accurate physical model of the writing process to a model-based implementation of a closed-loop lithography process. For transfering the pattern to a target substrate we optimized the etch process and demonstrate linear amplification of grayscale patterns into silicon and silicon oxide with amplification ratios of ∼6 and ∼1, respectively. The performance of the entire process is demonstrated by manufacturing photonic molecules of desired interaction strength. Excellent agreement of fabricated and simulated structures has been achieved.

The fabrication of high-performance solid-state silicon quantum-devices requires high resolution patterning with minimal substrate damage. We have fabricated room temperature single-electron transistors (SETs) based on point-contact tunnel junctions using a hybrid lithography tool capable of both high resolution thermal scanning probe lithography and high throughput direct laser writing. The best focal z-position and the offset of the tip- and the laser-writing positions were determined in-situ with the scanning probe. We demonstrate < 100 nm precision in the registration between the high resolution and high throughput lithographies. The SET devices were fabricated on degenerately doped n-type > 1020/cm3 silicon on insulator (SOI) chips using a CMOS compatible geometric oxidation process. The characteristics of the three devices investigated were dominated by the presence of Si nanocrystals or phosphorous atoms embedded within the SiO2, forming quantum dots (QDs). The small size and strong localisation of electrons on the QDs facilitated SET operation even at room temperature. Temperature measurements showed that in the range 300 K > T > ~100 K, the current flow was thermally activated but at < 100 K, it was dominated by tunnelling.

Thermal scanning probe lithography (t-SPL) is applied to the fabrication of chemical guiding patterns for directed self-assembly (DSA) of block copolymers (BCP). The two key steps of the overall process are the accurate patterning of a poly(phthalaldehyde) resist layer of only 3.5 nm thickness, and the subsequent oxygen-plasma functionalization of an underlying neutral poly(styrene-random-methyl methacrylate) brush layer. We demonstrate that this method allows one to obtain aligned line/space patterns of poly(styrene-block-methyl methacrylate) BCP of 18.5 and 11.7 nm half-pitch. Defect-free alignment has been demonstrated over areas of tens of square micrometres. The main advantages of t-SPL are the absence of proximity effects, which enables the realization of patterns with 10 nm resolution, and its compatibility with standard DSA methods. In the brush activation step by oxygen-plasma exposure, we observe swelling of the brush. This effect is discussed in terms of the chemical reactions occurring in the exposed areas. Our results show that t-SPL can be a suitable method for research activities in the field of DSA, in particular for low-pitch, high-χ BCP to achieve sub-10 nm line/space patterns.