Nano Crystal Memory Devices Characterization Using the Charge Pumping Technique

In this paper the authors proposed a new method to estimate ¿V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> from floating gate NAND flash memory, using charge pumping method to a cell string. Although any cells in a string are selected, this method could be roughly applied to extract ¿V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> . After P/E cycling, the charge pumping method also estimated ¿V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> with moderate pulse amplitude (in this work, at 4.5 V or 5 V). By using our proposed method, not only it is simply possible to estimate ¿V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> of NAND flash memory, but also measurement time can be reduced so much.

The interfacial density of states (Dit) distribution of high-κ dielectric Ga2O3(Gd2O3) [GGO] directly deposited on n-type Ge(100) without invoking any interfacial passivation layer (IPL) was established using conductance measurements and charge pumping (CP) technique. The conductance measurements yielded Dit values in the range of (1–4)×1011 cm-2 eV-1 from the mid-gap energy to the conduction band edge within the Ge band gap, which are consistent with the mean Dit value of ∼2×1011 cm-2 eV-1 near the mid-gap obtained independently by the CP method. The flat Dit distribution at the conduction band edge compares favorably with those attained using IPLs such as SiO2/Si-cap and GeO2.

A novel charge pumping technique is proposed for measuring the spatial distribution of interface state density N/sub it/ in MOSFETs. Instead of connecting the source and the drain together as is usually done, different reverse bias voltages are applied to the source and the drain separately. The method makes it possible to measure the distribution of N/sub it/ without making any assumptions about it. With this method, one can determine N/sub it/ distribution near the source and the drain of the channel independently. Results show that the interface state distribution of a virgin MOSFET is not constant along the channel. >

Traditional charge pumping (CP) technique relies on trap-assisted recombination from the source/drain to the body contact to characterize interface trap density (Nit) of classical bulk MOSFETs. A variant of the technique called single pulse CP (SPCP) allows interface trap characterization even if the bulk contact is absent, as in silicon-on-insulator (SOI) MOSFET. Unfortunately, neither technique is useful for devices with source-body-tied (SBT) and inhomogeneous channel doping profile, as in lateral diffused MOS (LDMOS) power transistors. Here, we propose a generalization of the CP/SPCP techniques, called Super SPCP (S2PCP), to extract position-resolved localized degradations (ΔNit) in an SBT LDMOS. Careful TCAD modeling and experimental characterizations demonstrate the effectiveness of the proposed approach. Our analysis provides deep insights into the physics of the SPCP technique, demonstrating that the approach can be used to characterize a variety of transistors with nontraditional doping profiles and contact configurations.

Instead, the classical consideration that the geometric component in charge pumping method (CP) is parasitic component, in this work we demonstrate that this component can be used to estimate the negative bias temperature (NBTI) induced mobility degradation using the charge pumping based method such as on- the-fly interface trap (OTFIT).

Trench DMOS interface trap characterization by three-terminal charge pumping measurement

Charge-pumping (CP) technique is proposed to simultaneously measure the border traps and interface-trap density <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(D_ it)$</tex> . The charge pumped per cycle <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(Q_ cp)$</tex> versus high level <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(V_h)$</tex> of gate pulse for various frequencies was used to observe the behavior of the bulk traps close to the interface as a function of the CP frequency. Evolution on <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$Q_ cp$</tex> as a function of frequency was successfully used to determine the depth profile of border-trap density near the high- <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$kappa$</tex> gate dielectric/Si interface. The influence of border trap in high- <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$kappa$</tex> dielectric on the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$D_ it$</tex> measurement can be prevented by an appropriate selection of gate frequency in CP technique.

In this work, a charge pumping characterization has been carried out on 4H-SiC nMOSFETs built with different SiC doping processes. Because charge pumping (CP) measurements on SiC are complex to implement, three different CP methods have been used for Dit characterization. The impact of geometrical and electrical parameters on each method is studied. Finally, it is detailed the full measurement flow chosen for a deeper and more accurate understanding of Dit electrical characterization.

Explores the MOS interface-trap charge-pump as an ultralow constant-current generator for analog CMOS applications. Charge pumping techniques in general are more suitable than conventional continuous-time techniques for ultralow current generation because the linear controllability of current by frequency is maintained regardless of the level of current. An interface-trap pump has the same property but the minimum charge it puts out per cycle is at least two orders of magnitude smaller than that of a switched-capacitor charge pump. This helps generate the same current more accurately at a much higher frequency with a much smaller filter capacitance. The paper presents a simplified model of the terminal characteristics of the interface-trap pump and an evaluation of its performance as a stand-alone current generator. Cascoding and complementary pumping are introduced as measures of performance improvement. Temperature sensitivity, pulse feedthrough, controllability, matching, reliability, and trimming issues are addressed. Transconductor circuits built with the charge pump are presented and experimentally evaluated.

A semi-analytical-model is proposed to predict the geometric component in charge pumping (CP) measurements for transistors. It is based on contributing of active CP-area and low-level voltage (V L ) of the gate signal, thermal diffusion, drift field, and self-induced drift field. The calculated I CP -V L characteristics with geometric component model are found in good correlation with the experimental I CP -V L data and are more accurate than the calculated CP without geometric component. This modeling approach can be extended for MOSFET stress reliability evaluation such as negative bias temperature instability (NBTI) and radiation degradations.

A high inversion channel mobility is a key parameter of normally off Silicon-Carbide MOS field effect power transistors. The mobility is limited by scattering centers at the interface between the semiconductor and the gate-oxide. In this work we investigate the mobility of lateral normally-off MOSFETs with different p-doping concentrations in the channel. Additionally the effect of a shallow counter n-doping at the interface on the mobility was determined and, finally, the properties of interface traps with the charge pumping method were examined. A lower p-doping in the cannel reduces the threshold voltage and increases the mobility simultaneously. A shallow counter n-doping shows a similar effect, but differences in the behavior of the charge pumping current can be observed, indicating that the nitrogen has a significant effect on the electrical properties of the interface, too.

We made systematic measurements of the maximum charge pumping current from single MOS interface traps, and found that two energy levels are formed per trap, and the current shows various values of 0∼2fq (ƒ: the gate pulse frequency, q: the electron charge), depending upon the two energy levels. Moreover, we demonstrated fundamental trap counting, and found that the variability in the actual number of traps is quite large.

Charge pumping current from single Si/SiO₂ interface traps: Direct observation of <i>P</i>_b centers and fundamental trap-counting by the charge pumping method

We carried out a unique and systematic characterization of single Si/SiO2 interface traps using the charge pumping (CP) method, and observed for the first time that two energy levels participate in electron capture/emission processes in a single trap, and the maximum CP current (I CPMAX) from a single trap is in the range of 0≤I CPMAX≤2fq, where f is the gate pulse frequency, and q is the electron charge. Although it is widely believed that I CPMAX is given by fqN, where N is the total number of traps contributing to the CP current, we experimentally clarified that this belief is basically incorrect. Based on the systematic characterization of the single traps, we estimated the distribution of the two energy levels of the single traps for the first time. By considering the essential nature of the traps, we corrected a widely held misconception and introduced a fundamental refinement of the CP theory.

Charge pumping technique is investigated to identify biomolecular charge polarity using a nanogap-embedded biotransistor. Biomolecules immobilized in a nanogap provide additional charges in the gate dielectric. They give rise to a change in the charge pumping current, as detected by applying a designed pulse waveform. The measured results are analyzed with the aid of numerical simulations. The proposed charge pumping technique represents an insightful method of investigating the electrical properties of biomolecules beyond biosensing.