The electrical properties of metal-oxide-semiconductor (MOS) capacitors composed of atomic-layer-deposited (ALD) hafnium-dioxide (HfO2) dielectrics and plasma-synthesized interface layers were investigated. MOS capacitor with oxynitride interface layer shows negative flatband voltage (Vfb) shift from the ideal value. Hafnium-alkylamide ALD process performed on a plasma nitrided silicon surface causes negative Vfb shift. Germanium MOS capacitors show additional negative Vfb shift (−0.5V). X-ray photoelectron spectroscopy shows evidence of germanium diffusion into the HfO2 layer. Germanium MOS capacitor with tantalum-oxynitride (TaON) interface layer shows superior electrical properties. These results indicate that the selection of the interface layer strongly influences germanium MOS capacitor electrical properties.

This paper presents a glitchy-clock generator integrated in FPGA for evaluating fault injection attacks and their countermeasures on cryptographic modules. The proposed generator exploits clock management capabilities, which are common in modern FPGAs, to generate clock signal with temporal voltage spike. The shape and timing of the glitchy-clock cycle are configurable at run time. The proposed generator can be embedded in a single FPGA without any external instrument (e.g., a pulse generator and a variable power supply). Such integration enables reliable and reproducible fault injection experiments. In this paper, we examine the characteristics of the proposed generator through experiments on Side-channel Attack Standard Evaluation Board (SASEBO). The result shows that the timing of the glitches can be controlled at the step of about 0.17 ns. We also demonstrate its application to the safe-error attack against an RSA processor.

Abstract.A successful detection of the stealthy dopant-level circuit (trojan), proposed by Becker et al. at CHES 2013 [1], is reported. Contrary to an assumption made by Becker et al., dopant types in active region are visible with either scanning electron microscopy (SEM) or focused ion beam (FIB) imaging. The successful measurement is explained by an LSI failure analysis technique called the passive voltage contrast [2]. The experiments are conducted by measuring a dedicated chip. The chip uses the diffusion programmable device [3]: an anti-reverse-engineering technique by the same principle as the stealthy dopant-level trojan. The chip is delayered down to the contact layer, and images are taken with (1) an optical microscope, (2) SEM, and (3) FIB. As a result, the four possible dopant-well combinations, namely (i) p+/n-well, (ii) p+/p-well, (iii) n+/n-well and (iv) n+/p-well are distinguishable in the SEM images. Partial but sufficient detection is also achieved with FIB. Although the stealthy dopant-level circuits are visible, however, they potentially make a detection harder. That is because the contact layer should be measured. We show that imaging the contact layer is at most 16-times expensive than that of a metal layer in terms of the number of images 3 .

Correlations among interface properties and chemical bonding characteristics in HfnormalO2∕GenormalOxnormalNy∕Ge metal–insulator–semiconductor stacks were investigated using in situ remote nitridation of the Ge(100) surface prior to HfnormalO2 atomic layer deposition. Ultrathin (∼1.1nm) , thermally stable, and aqueous etch-resistant GenormalOxnormalNy interface layers that exhibited Ge core-level photoelectron spectra similar to stoichiometric normalGe3normalN4 were synthesized. To evaluate GenormalOxnormalNy∕Ge interface defects, the density of interface states (Dit) was extracted by the conductance method across the bandgap. Forming gas annealed (FGA) samples exhibited substantially lower Dit (∼1×1012cm−2eV−1) than did high-vacuum-annealed and inert gas anneal samples (∼1×1013cm−2eV−1) . Germanium core-level photoelectron spectra from similar FGA-treated samples detected out-diffusion of germanium oxide to the HfnormalO2 film surface and apparent modification of chemical bonding at the GenormalOxnormalNy∕Ge interface which is related to the reduced Dit .

Tantalum nitride thin films were deposited at 400°C by plasma enhanced atomic layer deposition using an amido-based metal organic tantalum precursor. An Ar/ N 2 /H 2 mixture was flowed upstream of a remote plasma system to produce the reactive species used for the nitridation process. The as-deposited film was amorphous and contained 15 at. % oxygen in the bulk of the film. High resolution photoelectron spectroscopy studies of the Ta 4f feature were consistent with the presence of the semiconducting Ta 3 N 5 phase in the as-deposited films. Electron diffraction studies were carried out by annealing the Ta 3 N 5 film in situ in a transmission electron microscope. The high resistivity Ta 3 N 5 phase crystallized into the cubic TaN phase at 850°C. This transformation appeared to coincide with outdiffusion of excess nitrogen from the Ta 3 N 5 film during the anneal. The resistivity of the crystallized film was estimated to be 600 ⍀ cm from four point probe measurements.

No abstract

Flame-resistant clothing or fabrics against thermal exposure is a crucial requirement in order to ensure people survivability and to protect the structure. A model-based method was developed to evaluate the thermal performance of flame-resistant fabrics used in protective clothing. The skin simulant sensor is used to determine the heat flux at the skin simulant surface from the elevation of temperature of the skin simulant surface. The heat flux is then applied to a newly developed skin thermal wave model (STWM) instead of Pennes' model, which inherits some questionable physical and physiological aspects, and the Henriques burn integral is incorporated into the new model to predict the level of skin injury. Results of tolerance time from the Stoll criterion method are also compared with those from the Henriques method with two skin models (Pennes' model and STWM) by a thermal protective performance calorimeter. Deviations between the STWM and the traditional Pennes' equation imply that the STWM, which accounts for finite thermal wave propagation, may provide realistic predictions on burn evaluation. The comparison measurements show that the test results by the STWM correlated well with those obtained from the Henriques method with Pennes' model. Therefore, this test method provides a new technique to accurately and precisely characterize the thermal performance of flame-resistant fabrics.

Virtual field‐programmable gate array (FPGA) is an emerging technology to put multiple users in the same FPGA fabric with logical isolation. Security researchers have studied new threats in virtual FPGA and proposed attacks on the logical isolation by exploiting analogue natures of FPGA. These attacks use an oscillator comprising a combinatorial loop to have access to the analogue domain using digital components only. Interestingly, the system in the field prohibits a combinatorial loop by a design rule check. In this Letter, the authors study if prohibiting a combinatorial loop is sufficient to thwart the conventional attacks. They negatively answer the question by showing oscillators without a combinatorial loop. They also show how to detect and reject the proposed oscillators by a design rule check.