The routine “on demand” fabrication of features smaller than 10 nm opens up new possibilities for the realization of many devices. Driven by the thermally actuated piezoresistive cantilever technology, we have developed a prototype of a scanning probe lithography (SPL) platform which is able to image, inspect, align, and pattern features down to the single digit nanoregime. Here, we present examples of practical applications of the previously published electric-field based current-controlled scanning probe lithography. In particular, individual patterning tests are carried out on calixarene by using our developed table–top SPL system. We have demonstrated the application of a step-and-repeat SPL method including optical as well as atomic force microscopy-based navigation and alignment. The closed-loop lithography scheme was applied to sequentially write positive and negative tone features. Due to the integrated unique combination of read–write cycling, each single feature is aligned separately with the highest precision and inspected after patterning. This routine was applied to create a pattern step by step. Finally, we have demonstrated the patterning over larger areas, over existing topography, and the practical applicability of the SPL processes for lithography down to 13-nm pitch patterns. To enhance the throughput capability variable beam diameter electric field, current-controlled SPL is briefly discussed.
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.
The conventional optical lever detection technique involves optical components and its precise mechanical alignment.
An additional technical limit is the weight of the optical system, in case a top-scanner is used in high speed and high
precision metrology. An alternative represents the application of self-actuated AFM cantilevers with integrated 2DEG
piezoresistive deflection sensors. A significant improvement in performance of such cantilevers with respect to
deflection sensitivity and temperature stability has been achieved by using an integrated Wheatstone bridge
configuration. Due to employing effective cross-talk isolation and temperature drift compensation the performance of
these cantilevers was significantly improved. In order to enhance the speed of AFM measurements we are presenting a
fast cantilever-approach technology, Q-factor-control and novel adaptive scanning speed procedure. Examples of AFM
measurements with high scanning speed (up to 200 lines/s) committed to advanced lithography process development are
The routine “on demand” fabrication of features smaller than 10 nm opens up new possibilities for the realization of
many novel nanoelectronic, NEMS, optical and bio-nanotechnology-based devices. Based on the thermally actuated,
piezoresistive cantilever technology we have developed a first prototype of a scanning probe lithography (SPL) platform
able to image, inspect, align and pattern features down to single digit nano regime. The direct, mask-less patterning of
molecular resists using active scanning probes represents a promising path circumventing the problems in today’s
radiation-based lithography. Here, we present examples of practical applications of the previously published electric field
based, current-controlled scanning probe lithography on molecular glass resist calixarene by using the developed tabletop
SPL system. We demonstrate the application of a step-and-repeat scanning probe lithography scheme including
optical as well as AFM based alignment and navigation. In addition, sequential read-write cycle patterning combining
positive and negative tone lithography is shown. We are presenting patterning over larger areas (80 x 80 μm) and feature
the practical applicability of the lithographic processes.
Within last two years, we have shown the positive-tone, development-less patterning of calixarene molecular glass resists using highly confined electric field, current-controlled scanning probe lithography scheme. Herein, we give a more detailed view insight describing the applied Scanning Probe Lithography (SPL) technology platform applying selfactuating, self-sensing cantilever. The experimental results are supported by first preliminary simulation results estimating the local electric field strength, the electron trajectories, and the current density distribution at the sample surface. In addition, the diameter of Fowler-Nordheim electron beam, emitted from SPL-tip, was calculated as function of the bias voltage for different current set-points and tip radii. In experimental part we show the reproducible writing of meander line patterns as well as the patterning of individual features using specially developed pattern generator software tool.
The presented work deals with molecular glass resist materials based on (i) calixresorcinarene 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.
Going “beyond the CMOS information-processing era,” taking advantage of quantum effects occurring at sub-10-nm level, requires novel device concepts and associated fabrication technologies able to produce promising features at acceptable cost levels. Herein, the challenge affecting the lithographic technologies comprises the marriage of down-scaling the device-relevant feature size towards single-nanometer resolution with a simultaneous increase of the throughput capabilities. Mix-and-match lithographic strategies are one promising path to break through this trade-off. Proof-of-concept combining electron beam lithography (EBL) with the outstanding capabilities of closed-loop electric field current-controlled scanning probe nanolithography (SPL) is demonstrated. This combination, whereby also extreme ultraviolet lithography (EUVL) is possible instead of EBL, enables more: improved patterning resolution and reproducibility in combination with excellent overlay and placement accuracy. Furthermore, the symbiosis between EBL (EUVL) and SPL expands the process window of EBL (EUVL) beyond the state of the art, allowing SPL-based pre- and post-patterning of EBL (EUVL) written features at critical dimension levels with scanning probe microscopy-based pattern overlay alignment capability. Moreover, we are able to modify the EBL (EUVL) pattern even after the development step. The ultra-high resolution mix-and-match lithography experiments are performed on the molecular glass resist calixarene using a Gaussian e-beam lithography system operating at 10 keV and a home-developed SPL setup.
High Performance Single Nanometer Lithography (SNL) is an enabling technology for beyond CMOS and future
nanoelectronics. To keep on with scaling down nanoelectronic components, novel instrumentation for nanometer precise
placement, overlay alignment and measurement are an essential pre-requirement to realize Next Generation Lithography
(NGL) systems. In particular, scanning probe based methods for surface modification and lithography are an emerging
method for producing sub-10 nm features. In this study, we demonstrate nano-scale lithography using a scanning probe
based method in combination with a Nanopositioning and Nanomeasuring Machine. The latter one has a measuring
range of 25 mm x 25 mm x 5 mm, 0.1 nanometer resolution and outstanding nanometer accuracy. The basic concept
consists of a special arrangement allowing Abbe error free measurements in all axes over the total scan range.
Furthermore, the Nanopositioning and Nanomeasuring Machine is able to store the exact location that can be found again
with an accuracy of less than 2.5 nanometers. This system is also predestinated for critical dimension, quality and
overlay control. The integrated scanning probe lithography is based on electric-field-induced patterning of calixarene. As
a result, repeated step response tests are presented in this paper.
The prosperous demonstration of a technique able to produce features with single nanometer (SN) resolution could guide
the semiconductor industry into the desired beyond CMOS era. In the lithographic community immense efforts are being
made to develop extreme ultra-violet lithography (EUVL) and multiple-e-beam direct-write systems as possible
successor for next generation lithography (NGL). However, patterning below 20 nm resolution and sub-10 nm overlay
alignment accuracy becomes an extremely challenging quest. Herein, the combination of electron beam lithography
(EBL) or EUVL with the outstanding capabilities of closed-loop scanning proximal probe nanolithography (SPL) reveals
a promising way to improve both patterning resolution and reproducibility in combination with excellent overlay and
placement accuracy. In particular, the imaging and lithographic resolution capabilities provided by scanning probe
microscopy (SPM) methods touches the atomic level, which expresses the theoretical limit of constructing
nanoelectronic devices. Furthermore, the symbiosis between EBL (EUVL) and SPL expands the process window of EBL
(EUVL) far beyond state-of-the-art allowing SPL-based pre- and post-patterning of EBL (EUVL) written features at
critical dimension level with theoretically nanometer precise pattern overlay alignment. Moreover, we can modify the
EBL (EUVL) pattern before as well as after the development step. In this paper we demonstrate proof of concept using
the ultra-high resolution molecular glass resist calixarene. Therefor we applied Gaussian E-beam lithography system
operating at 10 keV and a home-developed SPL set-up. The introduced Mix and Match lithography strategy enables a
powerful use of our SPL set-up especially as post-patterning tool for inspection and repair functions below the sub-10
nm critical dimension level.
As present CMOS devices approach technological and physical limits at the sub-10 nm scale, a ‘beyond CMOS’
information-processing technology is necessary for timescales beyond the semiconductor technology roadmap. This
requires new approaches to logic and memory devices, and to associated lithographic processes. At the sub-5 nm scale, a
technology platform based on a combination of high-resolution scanning probe lithography (SPL) and nano-imprint
lithography (NIL) is regarded as a promising candidate for both resolution and high throughput production. The practical
application of quantum-effect devices, such as room temperature single-electron and quantum-dot devices, then becomes
feasible. This paper considers lithographic and device approaches to such a ‘single nanometer manufacturing’
technology. We consider the application of scanning probes, capable of imaging, probing of material properties and
lithography at the single nanometer scale. Modified scanning probes are used to pattern molecular glass based resist
materials, where the small particle size (<1 nm) and mono-disperse nature leads to more uniform and smaller
lithographic pixel size. We also review the current status of single-electron and quantum dot devices capable of room-temperature operation, and discuss the requirements for these devices with regards to practical application.
To keep on with scaling down of nanoelectronic components novel lithographic approaches are required. The direct, positive-tone lithography of calixarene molecular resists by scanning probe techniques represents a promising alternative for ease-of-use sub-10 nm mask-less lithography. Herein, we demonstrate a closed loop tip-based nanolithography using the same nanoprobe for: (i) AFM pre-imaging for pattern overlay alignment; (ii) direct writing of features into calixarene molecular resist applying a highly confined, development-less removal process; and (iii) AFM post-imaging as final in-situ inspection. In addition, we demonstrate parallel writing capabilities by employing multi nano-tip probes. By using these methods we can drastically enhance the attractiveness of calixarene molecular resist as development-less, high resolution resist material for Scanning Probe Lithography (SPL).