The feature dimensions of integrated circuits are becoming smaller and the fabrication, metrology and inspection is becoming harder to be fulfilled. Fast-writing of long respectively large nano-features with Scanning-ProbeLithography and their inspection with an Atomic Force Microscope (AFM) is a challenge, for the accomplishment of which the Nanofabrication Machine (NFM-100) can serve as a beneficial experimental platform for basic research in the field of scale-spanning nanomeasuring and nanofabrication. The NFM-100 has an integrated tipbased system, which can be used as an AFM as well as for Field-Emission Scanning Probe Lithography (FESPL). The combination of both systems offers the possibility to fabricate and analyze micro- and nanostructures with high resolution and precision down to a single nanometre over a large area of 100 mm in diameter in a single configuration without tool or sensor change. Thus, in contrast to conventional optical inspection and alignment systems, the NFM-100 offers the potential for full lithographic and metrological automation. For FESPL, the implemented active probes enable an in-situ inspection capability, a quantitative mapping at unprecedented resolution, as well as an integrated overlay alignment system. In this paper, the basic set-up of the NFM-100 as well as the capability of the system for long range AFM scans and FESPL is demonstrated.
This paper focuses on a new Nano Fabrication Machine 100 (NFM-100) with a working range up to 100 mm in diameter and its integrated tip-based system, which can be used as an Atomic Force Microscope (AFM) as well as for Field-Emission-Scanning-Probe-Lithography (FESPL). The combination of both systems offers the possibility to fabricate and analyze micro- and nanostructures with high resolution and precision down to a single nanometer over a large area in one single configuration without tool or sensor change. After the description of the basic machine structure of the NFM-100, the demonstration of long range and large area AFM scans in combination with the NFM-100 will be shown. Additionally, the basic functionality of the FESPL manufacturing process is presented.
KEYWORDS: Scanning electron microscopy, Atomic force microscope, Electron microscopes, Metrology, Electron beams, Nanofabrication, Diamond, Scanning probe lithography, Microscopy, Overlay metrology
An integration of atomic force microscopy (AFM) and scanning electron microscopy (SEM) within a single system is opening new capabilities for correlative microscopy and tip-induced nanoscale interactions. Here, the performance of an AFM-integration into a high resolution scanning electron microscope and focused ion beam (FIB) system for nanoscale characterization and nanofabrication is presented. Combining the six-axis degree of freedom (DOF) of the AFM system with the DOF of the SEM stage system, the total number of independent degree of freedom of the configuration becomes eleven. The AFM system is using piezoresistive thermomechanically transduced cantilevers (active cantilevers). The AFM integrated into SEM is using active cantilevers that can characterize and generate nanostructures all in situ without the need to break vacuum or contaminate the sample. The developed AFM-integration is described and its performance is demonstrated. The benefit of the active cantilever prevents the use of heavy and complex optical cantilever detection technique and makes the AFM integration into a SEM very simple and convenient. Results from combined examinations applying fast AFM-methods and SEM-image fusion, AFM-SEM combined metrology verification, and tip-based nanofabrication are shown. Simultaneous operation of SEM and AFM provides a fast navigation combined with sub-nm topographic image acquisition. The combination of two or more different types of techniques like SEM, energy dispersive x-ray spectroscopy, and AFM is called correlative microscopy because analytical information from the same place of the sample can be obtained and correlated [1]. We introduced to the SEM/FIB tool correlative nanofabrication methods like field-emission scanning probe lithography, tip-based electron beam induced deposition, and nanomachining/nanoidentation.
Atomic Force Microscopes are capable to provide non-destructive high resolution, CD-metrology and precise defect analysis. However, a conventional AFM has not enough throughput for today’s large scale semiconductor manufacturing. The primary point remains the increase of the scanning area in case of large wafers, masks, displays or dies. Cantilever array-based AFMs are intended to increase the imaging throughput by parallelizing the work of many AFM probes that may be practiced by parallel AFM systems that are capable to operate autonomously. An active cantilever scheme makes it possible to sense electronically the deflection and individually to control the actuation of every cantilever in the array. Each cantilever in the array represents a self-sustaining AFM-hardware system for metrology and imaging. In that, the multiple parallel probes are forming many AFMs capable to work independently.
KEYWORDS: Metrology, Atomic force microscopy, Inspection, Semiconducting wafers, Actuators, Photomasks, Silicon, Digital signal processing, Field programmable gate arrays, Imaging systems
Atomic Force Microscopy (AFM) is a capable to provide high resolution CD-metrology and precise defects analysis on large wafers, masks or displays. However, AFM is not enough productive for high-throughput industrial uses. Standard single probe AFMs are showing low throughput as a serial imaging tools. The use of an array of four cantilevers as a Quattro-Array results in effective speed of 6 to 10 mm/s. An image size of 0.5mm x 0.2mm is achieved employing a piezoelectric positioner with a scan range of 200μm x 200μm and a resolution of 0.25nm (x,y) and 0.2nm (z), respectively. These capabilities are qualifying the Quattro-cantilever array system as fastest tool for. In this paper we present new results obtained with our Quattro-AFM high-throughput parallel SPM system that exhibits two key advances that are required for a successful deployment of SPM in time-efficient metrology, defect analysis and mask inspection.
Cost-effective generation of single-digit nano-lithographic features could be the way by which novel nanoelectronic devices, as single electron transistors combined with sophisticated CMOS integrated circuits, can be obtained. The capabilities of Field-Emission Scanning Probe Lithography (FE-SPL) and reactive ion etching (RIE) at cryogenic temperature open up a route to overcome the fundamental size limitations in nanofabrication. FE-SPL employs Fowler-Nordheim electron emission from the tip of a scanning probe in ambient conditions. The energy of the emitted electrons (<100 eV) is close to the lithographically relevant chemical excitations of the resist, thus strongly reducing proximity effects. The use of active, i.e. self-sensing and self-actuated, cantilevers as probes for FE-SPL leads to several promising performance benefits. These include: (1) Closed-loop lithography including pre-imaging, overlay alignment, exposure, and post-imaging for feature inspection; (2) Sub-5-nm lithographic resolution with sub-nm line edge roughness; (3) High overlay alignment accuracy; (4) Relatively low costs of ownership, since no vacuum is needed, and ease-of-use. Thus, FE-SPL is a promising tool for rapid nanoscale prototyping and fabrication of high resolution nanoimprint lithography templates. To demonstrate its capabilities we applied FE-SPL and RIE to fabricate single electron transistors (SET) targeted to operate at room temperature. Electrical characterization of these SET confirmed that the smallest functional structures had a diameter of only 1.8 nanometers. Devices at single digit nano-dimensions contain only a few dopant atoms and thus, these might be used to store and process quantum information by employing the states of individual atoms.
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