Helium ion microscopy (HIM) was used for direct nano-patterning of single-layer graphene (SLG) on SiO2/Si substrates. This technique involves irradiation of the sample with accelerated helium ions (He+). Doses of 2.0 × 1016 He+ cm−2 from a 30 kV beam induced a metal-insulator transition in the SLG. The resolution of HIM patterning on SLG was investigated by fabricating nanoribbons and nanostructures. Analysis of scanning capacitance microscopy measurements revealed that the spatial resolution of HIM patterning depended on the dosage of He+ in a non-monotonic fashion. Increasing the dose from 2.0 × 1016 to 5.0 × 1016 He+ cm−2 improved the spatial resolution to several tens of nanometers. However, doses greater than 1.0 × 1017 He+ cm−2 degraded the patterning characteristics. Direct patterning using HIM is a versatile approach to graphene fabrication and can be applied to graphene-based devices.

We studied the oxide charges and traps within nitrided Hf-silicate (HfSiON)∕SiO2 gate stacks processed with high-temperature annealing with a spectroscopic technique by using high spatial resolution scanning capacitance microscopy. Spectroscopy was performed by detecting the static capacitance (dC∕dZ) between a conductive probe and the sample while sweeping the sample bias. The dC∕dZ image and spatially resolved dC∕dZ-V spectrum revealed the existence of positive fixed charges within HfSiON and interface trap charges between the SiO2 underlayer and Si substrate. We also observed a transient electron trap process from the conductive probe to the HfSiON film as abrupt discontinuities in the dC∕dZ-V spectrum and with bias-induced topography change of the HfSiON surface. These oxide charges and trap sites distribute inhomogeneously within HfSiON∕SiO2 gate stacks, and the origin of these charged defects is ascribable to phase separation induced by high-temperature postdeposition annealing.

The scanning capacitance microscope (SCM) reported here uses a frequency modulation (FM) technique to control the distance between the sample and an all-metal probe. The probe was attached to a quartz tuning fork in a configuration minimizing the perturbation due to the probe. The FM-SCM yields two images of ∂C∕∂V and ∂C∕∂Z signals, where C is capacitance sensed by the probe, Z the probe–sample distance, and V a bias voltage, respectively. On a cross section of a field effect transistor, the two-dimensional p–n junction locus was observed with a spatial resolution better than 5nm in the ∂C∕∂V image. The ∂C∕∂Z images of polysilicon gate electrodes and highly doped source/drain regions have higher contrast than the ∂C∕∂V images.

Irradiation of a single-layer graphene (SLG) with accelerated helium ions (He+) controllably generates defect distributions, which create a charge carrier scattering source within the SLG. We report direct experimental observation of metal-insulator transition in SLG on SiO2/Si substrates induced by Anderson localization. This transition was investigated using scanning capacitance microscopy by monitoring the He+ dose conditions on the SLG. The experimental data show that a defect density of more than ∼1.2% induced Anderson localization. We also investigated the localization length by determining patterned placement of the defects and estimated the length to be several dozen nanometers. These findings provide valuable insight for patterning and designing graphene-based nanostructures using helium ion microscopy.

Scanning capacitance microscopy using a self-sensing probe has been applied to the quantification of local dielectric properties in Hf-based high-k films grown by an atomic layer deposition method. Local capacitance spectroscopy revealed distinctive contrasts in dC∕dV and dC∕dZ images originating from the spatial distribution of fixed charges in the films. We also found that the HfSiON film shows better performance than HfSiO and HfO2, in terms of flat-band voltage (VFB) shift and spatial fluctuation. In every sample, the spatial fluctuations of gate capacitance (COX) are less than 3%. Considering VFB shift and COX fluctuations, HfSiON was found to be a promising candidate for gate dielectric applications.