Neon Ion Beam Lithography (NIBL).

Existing techniques for electron- and ion-beam lithography, routinely employed for nanoscale device fabrication and mask/mold prototyping, do not simultaneously achieve efficient (low fluence) exposure and high resolution. We report lithography using neon ions with fluence <1 ion/nm(2), ∼1000× more efficient than using 30 keV electrons, and resolution down to 7 nm half-pitch. This combination of resolution and exposure efficiency is expected to impact a wide array of fields that are dependent on beam-based lithography.

Defect Localization and Nanofabrication for Conductive Structures with Voltage Contrast in Helium Ion Microscopy.

As the dimensions of feature sizes in electronic devices decrease to nanoscale, an easy method for failure analysis and evaluation of processing steps is required. Gallium-focused ion beam (Ga-FIB) or scanning electron microscope is an efficient approach to detect voltage contrast for addressing failure analysis in semiconductor devices and processing. However, Ga-FIB may cause damage or implantation to the surface of the analyzed area, and its resolution is low. Helium ion microscopy (HIM) uses a light ion beam (helium or neon) for imaging and fabrication at nanoscale. With passive voltage contrast (PVC) in HIM images, the defect localization for failure of conductive structures can be rapidly and easily detected with a sufficient voltage contrast. Furthermore, a defect gap as narrow as sub-10 nm can be investigated with HIM imaging. PVC with HIM is an efficient method for defect localization at nanoscale with a minimal damage to the analyzed area. For circuit edit and failure analysis, it may be necessary to intentionally cut the conductive connection. In this circumstance, final results can be easily verified using PVC imaging with HIM. With XeF2 gas assistance, both helium and neon ion beams can be used to perform nanofabrication for metal disconnection. XeF2 gas plays an important role in preventing deposition of conductive materials on etching region and enhancing material removal rates to achieve electrically isolated structures. The etching rate with a neon ion beam is much faster than that of a helium ion beam. PVC in HIM images with controllable operation and dimensions using a helium ion beam with XeF2 gas assistance could also be used to localize a hidden defect for a single-location-defect situation. With neon ion beam irradiation on a defective location, PVC can be used to find the defect locations in the case of a series of defects.

Rapid fabrication of solid-state nanopores with high reproducibility over a large area using a helium ion microscope.

The fabrication of solid-state nanopores in an insulating membrane has attracted much attention for biomolecule analysis such as DNA sequencing and detection in recent years. For practical applications and device integration, the challenges include precise size control for sub 10 nm nanopores, excellent repeatability and rapid fabrication over a large area to reduce the cost for mass production. A helium ion beam could provide an effective fabrication approach to produce such solid-state nanopores. It is easy to control the nanopore size and reach sub 10 nm pore size with a simple change in the milling time with an appropriate ion beam current. Here we report new results in a set of experiments demonstrating that with a small range of stage automatized motions and equal mill times one can obtain good fabrication reproducibility in nanopore sizes (<10% variation in size). The automation in the stage motion and milling time opens a door for the rapid mass production of nanopore chips over a wafer size of several inches.

The prospects of a subnanometer focused neon ion beam.

The success of the helium ion microscope has encouraged extensions of this technology to produce beams of other ion species. A review of the various candidate ion beams and their technical prospects suggest that a neon beam might be the most readily achieved. Such a neon beam would provide a sputtering yield that exceeds helium by an order of magnitude while still offering a theoretical probe size less than 1-nm. This article outlines the motivation for a neon gas field ion source, the expected performance through simulations, and provides an update of our experimental progress.