With the continuous trend of electronic component miniaturization, process control technologies must keep up with component size reduction. Defects that were so far negligible, are now posing critical operation obstacles, and are more difficult to identify as scales are reduced to <10 nm. This new technology developed by a group of researchers from the Weizmann Institute of Science is a carbon nanotube (CNT)-based single-electron transistor (SET), enabling noninvasive, simultaneous visualization of currents and potentials of flowing electrons at the single-electron level. In addition, it can be used to detect defects in buried structures, a key challenge in semiconductor process control. This state-of-the-art noninvasive instrument exhibits sensitivity up to X1000 higher than that of characterization technologies currently in use. This technology can serve as a valuable tool for the semiconductor manufacturing industry, ensuring retention of both yield and high quality standard production.
- Advanced non-contact inspection method for the semiconductor production line
- CNT-based nanoscale transistor
- AFM-like inspection tool with high sensitivity for multiple applications
- Simultaneous imaging of potentials and current flow
- Non-invasive and no-contact method
- Up to x1000 higher sensitivity, both on the surface and in buried structures, even below an insulating layer
- Does not entail global measurement of the magnetic field
- Detects changes at the single-electron level
The method takes advantage of the high voltage sensitivity of the scanning SET. It operates by applying a small AC bias voltage across a device of interest. The SET is used to isolate and image the potentials of the flowing electrons induced by the bias voltage. This can be done with a voltage imaging sensitivity of ~2uV/sqrt(Hz), three orders of magnitude (x1000) higher than that of the Kelvin probe technology, and can thus accurately map the potentials of flowing electrons. The current imaging sensitivity is ~10nA/um/sqrt(Hz) for semiconductors, which is X100 higher than that of SQUID-like techniques or scanning NV centers. As no charge is directly transferred between the SET and the device under study (unlike tunneling-based techniques), this method is ideally suited for high-sensitivity imaging potentials of flowing electrons in buried structures, which are increasingly prevalent. By applying a weak magnetic field perpendicular to the plane of the device, the SET can be used to map the local Hall voltage produced by flowing electrons, enabling imaging of the local current density. Unlike existing approaches, this method requires only local voltage measurements (instead of the global magnetic field), and is, therefore, less prone to artifacts. Imaging both the potential and current of flowing electrons relies on local voltage measurements, and can, therefore, be performed simultaneously, instead of requiring two separate apparatus/imaging tools.
A schematic presentation of the arrangement of the carbon nanotube on the SET detection arm. The nanotube is connected to source and drain electrodes (yellow) and suspended above multiple gates (blue). The CNT structure is designed to scan the device of interest with no charge directly transferred between the probe and the inspected area.