In this paper, we report, for the first time, the statistical distribution of thin-gate-oxide breakdown characterized by using conductive atomic force microscopy (C-AFM) in conjuncdion with the semiconductor parameter analyzer Agilent 4156C. Nanoscaled constant-voltage stress (CVS) and constant-current stress (CCS) were applied to the samples, and the time-to-breakdown Tbd Weibull plots were obtained as a function of stress condition as well as oxide thickness. A different trend in TBD Weibull distribution dependence on the oxide thickness was found for the case of nanoscaled CVS and CCS. By examining the pre- and post-breakdown I-V characteristics as well as their curve fittings, we found that different degradation mechanisms are involved in the oxides subjected to CVS and CCS. For oxides subjected to nanoscaled CVS, the degradation follows the percolation model, whereas for those subjected to nanoscaled CCS, the degradation obeys the trap-assisted tunneling model. The Weibull slope beta value obtained in this paper is found to be consistent with those in the conventional oxide-breakdown tests.

This paper investigates the nanoscale breakdown characteristics of thin silicon dioxide (SiO₂) films subjected to mechanical strain. A uniaxial compressive strain or a tensile strain was applied to the oxide samples using a homemade bending tool followed by the application of a ramped voltage stress (RVS) or a constant voltage stress to the oxide samples by means of a conductive atomic force microscope tip. The nanoscale current versus voltage (I-V) characteristics and the cumulative failure distributions of the oxide breakdown voltage for the RVS as well as the nanoscale current versus time (I-t) characteristics and cumulative failure distributions of time to breakdown at various surface positions along the strain axis were determined. The nanoscale breakdown characteristics of the strained oxide samples after Co-60 γ-ray irradiation were also investigated. It was found that the central region of both the preand postirradiated strained samples always exhibited a higher oxide leakage current, a lower oxide breakdown voltage, and a shorter time to breakdown than the side regions, regardless if they were under compressive or tensile strain. Our experimental results also showed that interfacial strain release as well as the nanoscale bias-annealing effect increased the Weibull slope β and 63%T_BR in the center region of the postirradiated strained oxide samples, compared to the preirradiated ones.

This report investigates the sensing characteristics of polysilicon wire (PSW) glucose biosensors, including thickness characteristics and line-width effects on detection limits, linear range and interference immunity with membranes coated by micropipette/spin-coating and focus-ion-beam (FIB) processed capillary atomic-force-microscopy (C-AFM) tip scan/coating methods. The PSW surface was modified with a mixture of 3-aminopropyl-triethoxysilane (γ-APTES) and polydimethylsiloxane (PDMS)-treated hydrophobic fumed silica nanoparticles (NPs). We found that the thickness of the γ-APTES+NPs nonocomposite could be controlled well at about 22 nm with small relative standard deviation (RSD) with repeated C-AFM tip scan/coatings. The detection limit increased and linear range decreased with the line width of the PSW through the tip-coating process. Interestingly, the interference immunity ability improves as the line width increases. For a 500 nm-wide PSW, the percentage changes of the channel current density changes (ΔJ) caused by acetaminophen (AP) can be kept below 3.5% at an ultra-high AP-to-glucose concentration ratio of 600:1. Simulation results showed that the line width dependence of interference immunity was strongly correlated with the channel electrical field of the PSW biosensor.

In this paper, we report the use of polysilicon (poly-Si) wire for label-free DNA sequence detection. Both single-strained (ss) homopolymers, polyadenine [poly(A)], polythymine [poly(T)], polycytosine [poly(C)], and polyguanine [poly(G)], and double-stranded (ds) heteropolymers (one homopolymer with its complement homopolymer), (A-T) [poly(A-T)] and (C-G) [poly(C-G)], were detected. These polymers, with different lengths and concentrations, were dropped onto the poly-Si wire surface, and then the currents flowing through the poly-Si wire channel were determined. The absolute value of the amount of current change <mml:math display="inline"><mml:mrow><mml:mi>Δ</mml:mi><mml:mi>I</mml:mi></mml:mrow></mml:math>ΔI in the channel for ss homopolymers with fixed length and fixed concentration is as follows: <mml:math display="inline"><mml:mrow><mml:mtext>poly</mml:mtext><mml:mrow><mml:mo>(</mml:mo><mml:mi mathvariant="normal">T</mml:mi><mml:mo>)</mml:mo></mml:mrow><mml:mo></mml:mo><mml:mtext>poly</mml:mtext><mml:mrow><mml:mo>(</mml:mo><mml:mi mathvariant="normal">C</mml:mi><mml:mo>)</mml:mo></mml:mrow><mml:mo></mml:mo><mml:mtext>poly</mml:mtext><mml:mrow><mml:mo>(</mml:mo><mml:mi mathvariant="normal">G</mml:mi><mml:mo>)</mml:mo></mml:mrow><mml:mo></mml:mo><mml:mtext>poly</mml:mtext><mml:mrow><mml:mo>(</mml:mo><mml:mi mathvariant="normal">A</mml:mi><mml:mo>)</mml:mo></mml:mrow></mml:mrow></mml:math>poly(T)poly(C)poly(G)poly(A) . For ds heteropolymers, it was observed that poly(A-T) has a <mml:math display="inline"><mml:mrow><mml:mi>Δ</mml:mi><mml:mi>I</mml:mi></mml:mrow></mml:math>ΔI that is higher than that of poly(C-G). This study also showed that the poly-Si wire is useful for detecting single- and multiple-base changes in the ss homopolymers as well as single- and multiple-matched-pair changes in ds heteropolymers. A single-pair mismatch in ds poly(C-G) was also investigated in this work.

This paper investigated the reliability of thin silicon dioxide (SiO₂) subjected to irradiation followed by stress, using conductive atomic force microscopy (C-AFM). The I-V characteristics of localized spots on thin oxide films were measured before and after Co⁶⁰gamma-ray irradiation. The oxide films were then subjected to a ramped voltage stress simultaneously during the I-V measurements. By taking advantage of a small contact area, we report for the first time the nanoscale postirradiation bias-annealing effect in thin SiO₂ film using C-AFM. Based on the number of fluctuating current peaks appearing in the I-V curves of the pre- and posttreatment oxide films, as well as the calculated effective barrier height from the Fowler-Nordheim tunneling theory, we found that the trapped charge in the oxide films, but not the charge at the interface caused by Co⁶⁰gamma-ray irradiation, can be effectively annealed out by a postirradiation ramped voltage.