Elshad Guliyev

Scanning probes in nanostructure fabrication

Scanning probes have enabled modern nanoscience and are still the backbone of todays nanotechnology. Within the technological development of AFM systems, the cantilever evolved from a simple passive deflection element to a complex microelectromechanical system through integration of functional groups, such as piezoresistive detection sensors and bimaterial based actuators. Herein, the authors show actual trends and developments of miniaturization efforts of both types of cantilevers, passive and active. The results go toward the reduction of dimensions. For example, the authors have fabricated passive cantilever with a width of 4 μm, a length of 6 μm and thickness of 50–100 nm, showing one order of magnitude lower noise levels. By using active cantilevers, direct patterning on calixarene is demonstrated employing a direct, development-less phenomena triggered by tip emitted low energy (<50 eV) electrons. The scanning probes are not only applied for lithography, but also for imaging and probing of the sur...

Quasi-monolithic integration of silicon-MEMS with piezoelectric actuators for high-speed non-contact atomic force microscopy

High-speed atomic force microscopy (AFM) is actually a functional tool for the studies of dynamical phenomena of biological and chemical objects on a sub-second timescale. In order to increase the imaging speed, all dynamic components of AFM have to be optimized. This paper presents advancement in the development of a novel x?y scanner for high-speed non-contact AFM. We have developed a quasi-monolithic integration of a silicon parallel kinematic mechanism with piezoelectric actuators. Decoupling of motion in x?y directions is realized due to novel ?-shaped flexures. For the control of the stage motion, we employed piezoresistive sensors integrated into silicon L-shaped guidance features. Due to the use of a push?pull actuation principle, we obtained a large scanning frequency and a 6???6??m2 scanning area. The resonance frequency of the stage is about 26?kHz. The silicon stage facilitates fast quantitative imaging with high lateral resolution.

Pattern-generation and pattern-transfer for single-digit nano devices

Single-electron devices operating at room temperature require sub-5 nm quantum dots having tunnel junctions of comparable dimensions. Further development in nanoelectronics depends on the capability to generate mesoscopic structures and interfacing these with complementary metal–oxide–semiconductor devices in a single system. The authors employ a combination of two novel methods of fabricating room temperature silicon single-electron transistors (SETs), Fowler–Nordheim scanning probe lithography (F-N SPL) with active cantilevers and cryogenic reactive ion etching followed by pattern-dependent oxidation. The F-N SPL employs a low energy electron exposure of 5–10 nm thick high-resolution molecular resist (Calixarene) resulting in single nanodigit lithographic performance [Rangelow et al., Proc. SPIE 7637, 76370V (2010)]. The followed step of pattern transfer into silicon becomes very challenging because of the extremely low resist thickness, which limits the etching depth. The authors developed a computer simulation code to simulate the reactive ion etching at cryogenic temperatures (−120 °C). In this article, the authors present the alliance of all these technologies used for the manufacturing of SETs capable to operate at room temperatures.

0.1-nanometer resolution positioning stage for sub-10 nm scanning probe lithography

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.

Scanning probe lithography approach for beyond CMOS devices

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.

Self-actuated, self-sensing cantilever for fast CD measurement

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 shown.

Improved single ion implantation with scanning probe alignment

Single dopant atoms can affect transport properties in scaled semiconductor devices and coherent control of spin and charge degrees of freedom of single dopant atoms promises to enable quantum computing. The authors report on an improved technique for deterministic placement of single dopant atoms by single ion implantation with scanning probe alignment. Ions are generated in a microwave driven ion source, mass analyzed in a Wien filter, and impinge on spin readout devices after alignment of the ion beam to regions of interest with a noncontact scanning force microscope.

Electric field scanning probe lithography on molecular glass resists using self-actuating, self-sensing cantilever

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.

Six-axis AFM in SEM with self-sensing and self-transduced cantilever for high speed analysis and nanolithography

Merging two state-of-the-art surface research techniques, in particular, atomic force microscopy (AFM) and scanning electron microscopy (SEM), within a single system is providing novel capabilities like direct visual feedback and life-monitoring of tip-induced nanoscale interactions. In addition, the combination of AFM and SEM accelerates nanoscale characterization and metrology development. Here, the concept and first results of a novel AFM-integration into a high resolution scanning electron microscope and focused ion beam system for nanoscale characterization is presented. In this context, a six-axis AFM system using self-sensing thermomechanically transduced active cantilever was developed and integrated. The design of the developed AFM-integration is described and its performance is demonstrated. Results from combined examinations applying fast AFM-methods and SEM-image fusion, AFM-SEM combined metrology verification, and three dimensional-visualization are shown. Simultaneous operation of SEM and AF...

Large area fast-AFM scanning with active “Quattro” cantilever arrays

In this work, the fabrication and operation of an active parallel cantilever device integrating four self-sensing and self-actuating probes in an array is presented. The so called “Quattro” cantilever system is controlled by a multichannel field programmable gate array (FPGA) controller. The integrated cantilever devices are fabricated on the basis of a silicon-on-insulator wafer using surface micromachining and gas chopping plasma-etching processes [I. W. Rangelow, J. Vac. Sci. Technol., A 21, 1550 (2003)]. The unique design of the active cantilever probes provides both patterning and readout capabilities [Kaestner et al., J. Micro-Nanolithogr. MEMS 14, 031202 (2015)]. The thermomechanical actuation allows the individually operation of each cantilever in static and dynamic modes. This enables a simultaneous atomic force microscopy operation of all cantilevers in an array, while the piezoresistive read-out of the cantilever bending routinely ensures atomic resolution at a high imaging speed. The scanning ...