Wojciech Majstrzyk

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.

Design, technology, and application of integrated piezoresistive scanning thermal microscopy (SThM) microcantilever

In this article we describe a novel piezoresistive cantilever technology The described cantilever can be also applied in the investigations of the thermal surface properties in all Scanning Thermal Microscopy (SThM) techniques. Batch lithography/etch patterning process combined with focused ion beam (FIB) modification allows to manufacture thermally active, resistive tips with a nanometer radius of curvature. This design makes the proposed nanoprobes especially attractive for their application in the measurement of the thermal behavior of micro- and nanoelectronic devices. Developed microcantilever is equipped with piezoresistive deflection sensor. The proposed architecture of the cantilever probe enables easy its easy integration with micro- and nanomanipulators and scanning electron microscopes.In order to approach very precisely the microcantilever near to the location to be characterized, it is mounted on a compact nanomanipulator based on a novel mobile technology. This technology allows very stable positioning, with a nanometric resolution over several centimeters which is for example useful for large samples investigations. Moreover, thanks to the vacuum-compatibility, the experiments can be carried out inside scanning electron microscopes.

Metrology of electromagnetic static actuation of MEMS microbridge using atomic force microscopy.

The objective of this paper is to describe application of atomic force microscopy (AFM) for characterization and calibration of static deflection of electromagnetically and/or thermally actuated micro-electromechanical (MEMS) bridge. The investigated MEMS structure is formed by a silicon nitride bridge and a thin film metal path enabling electromagnetic and/or thermal deflection actuation. We present how static microbridge deflection can be measured using contact mode AFM technology with resolution of 0.05nm in the range of up to tens of nm. We also analyze, for very small structure deflections and under defined and controlled load force varied in the range up to ca. 32nN, properties of thermal and electromagnetical microbridge deflection actuation schemes.

Magnetoelectric versus thermal actuation characteristics of shear force AFM probes with piezoresistive detection

In this paper the authors compare methods used for piezoresistive microcantilevers actuation for the atomic force microscopy (AFM) imaging in the dynamic shear force mode. The piezoresistive detection is an attractive technique comparing the optical beam detection of deflection. The principal advantage is that no external alignment of optical source and detector are needed. When the microcantilever is deflected, the stress is transferred into a change of resistivity of piezoresistors. The integration of piezoresistive read-out provides a promising solution in realizing a compact non-contact AFM. Resolution of piezoresistive read-out is limited by three main noise sources: Johnson, 1/f and thermomechanical noise. In the dynamic shear force mode measurement the method used for cantilever actuation will also affect the recorded noise in the piezoresistive detection circuit. This is the result of a crosstalk between an aluminium path (current loop used for actuation) and piezoresistors located near the base of the beam. In this paper authors described an elaborated in ITE (Institute of Electron Technology) technology of fabrication cantilevers with piezoresistive detection of deflection and compared efficiency of two methods used for cantilever actuation.

New approach for a multi-cantilever arrays sensor system with advanced MOEMS readout

Currently available sensor systems relying on multi-cantilever deflection detection by optical means are generally limited in their functionality by complexity and cost. Several laser sources as well as big sized detectors are needed to record the signal from each cantilever separately. In the frame of the ENIAC Joint Undertaking project Lab4MEMS II our group is currently developing a novel device capable of sensing large cantilever arrays using only a single laser source and a small sized position sensitive detector (PSD). The device is a closely packed highly integrated Micro-Opto-Electro-Mechanical-System (MOEMS) featuring dedicated optics, electronics and software combined with a micro-mirror. The system is being developed to become a lightweight and compact portable device, capable of determining measurement positions across the cantilever array providing self-adjustment automatically. The flexibility of the system makes it interesting for use in several fields ranging from research to industrial application. In this paper we show a general sensor system overview and examples of representative results of measurements performed on multi-cantilever arrays in which several vibrational modes are recorded for each cantilever.

Innovative multi-cantilever array sensor system with MOEMS read-out

Cantilever based sensor system are a well-established sensor family exploited in several every-day life applications as well as in high-end research areas. The very high sensitivity of such systems and the possibility to design and functionalize the cantilevers to create purpose built and highly selective sensors have increased the interest of the scientific community and the industry in further exploiting this promising sensors type. Optical deflection detection systems for cantilever sensors provide a reliable, flexible method for reading information from cantilevers with the highest sensitivity. However the need of using multi-cantilever arrays in several fields of application such as medicine, biology or safety related areas, make the optical method less suitable due to its structural complexity. Working in the frame of a the Joint Undertaking project Lab4MEMS II our group proposes a novel and innovative approach to solve this issue, by integrating a Micro-Opto-Electro-Mechanical-System (MOEMS) with dedicated optics, electronics and software with a MOEMS micro-mirror, ultimately developed in the frame of Lab4MEMSII. In this way we are able to present a closely packed, lightweight solution combining the advantages of standard optical read-out systems with the possibility of recording multiple read-outs from large cantilever arrays quasi simultaneously.

Quality factor and resonant frequency measurement by ARMA process identification of randomly excited MEMS/NEMS cantilever

Microcantilever based sensors are very promising devices for biochemical applications. They usually operate in two modes. In the first one a microcantilever static bending induced by the surface stress is observed, while in the second mode, resonant frequency shift caused by mass loading is measured. In the paper, the real-time noise analysis (RTNA) technique is presented. It is based on ARMA process modeling. The estimated model parameters are used for the calculation of the eigenfrequency and quality factor of a given vibration mode. The description of the entire procedure is presented as well as the results of an analysis of stochastic response of an electromagnetically excited cantilever. These results confirm validity of the proposed ARMA model and show the expected estimation errors. The proposed solution is an interesting option, especially, if the simplicity and the cost of the measurement system are important issues.