The reversed intrinsic curve and voltage dependence for ultra-low k dielectrics

Author(s):  
Wei-Ting Kary Chien ◽  
Atman Yong Zhao ◽  
Liwen Zhang ◽  
Flora Cheng
Keyword(s):  
2005 ◽  
Vol 125 (6) ◽  
pp. 619-629 ◽  
Author(s):  
Jill Thompson ◽  
Ted Begenisich

We have examined the voltage dependence of external TEA block of Shaker K+ channels over a range of internal K+ concentrations from 2 to 135 mM. We found that the concentration dependence of external TEA block in low internal K+ solutions could not be described by a single TEA binding affinity. The deviation from a single TEA binding isotherm was increased at more depolarized membrane voltages. The data were well described by a two-component binding scheme representing two, relatively stable populations of conducting channels that differ in their affinity for external TEA. The relative proportion of these two populations was not much affected by membrane voltage but did depend on the internal K+ concentration. Low internal K+ promoted an increase in the fraction of channels with a low TEA affinity. The voltage dependence of the apparent high-affinity TEA binding constant depended on the internal K+ concentration, becoming almost voltage independent in 5 mM. The K+ sensitivity of these low- and high-affinity TEA states suggests that they may represent one- and two-ion occupancy states of the selectivity filter, consistent with recent crystallographic results from the bacterial KcsA K+ channel. We therefore analyzed these data in terms of such a model and found a large (almost 14-fold) difference between the intrinsic TEA affinity of the one-ion and two-ion modes. According to this analysis, the single ion in the one-ion mode (at 0 mV) prefers the inner end of the selectivity filter twofold more than the outer end. This distribution does not change with internal K+. The two ions in the two-ion mode prefer to occupy the inner end of the selectivity filter at low K+, but high internal K+ promotes increased occupancy of the outer sites. Our analysis further suggests that the four K+ sites in the selectivity filter are spaced between 20 and 25% of the membrane electric field.


Author(s):  
Avril V. Somlyo ◽  
H. Shuman ◽  
A.P. Somlyo

This is a preliminary report of electron probe analysis of rabbit portal-anterior mesenteric vein (PAMV) smooth muscle cryosectioned without fixation or cryoprotection. The instrumentation and method of electron probe quantitation used (1) and our initial results with cardiac (2) and skeletal (3) muscle have been presented elsewhere.In preparations depolarized with high K (K2SO4) solution, significant calcium peaks were detected over the sarcoplasmic reticulum (Fig 1 and 2) and the continuous perinuclear space. In some of the fibers there were also significant (up to 200 mM/kg dry wt) calcium peaks over the mitochondria. However, in smooth muscle that was not depolarized, high mitochondrial Ca was found in fibers that also contained elevated Na and low K (Fig 3). Therefore, the possibility that these Ca-loaded mitochondria are indicative of cell damage remains to be ruled out.


2010 ◽  
Vol 130 (4) ◽  
pp. 319-324
Author(s):  
Kouichiro Mizuno ◽  
Hirotake Sugawara ◽  
Akihiro Murayama
Keyword(s):  

2002 ◽  
Vol 715 ◽  
Author(s):  
P. Louro ◽  
A. Fantoni ◽  
Yu. Vygranenko ◽  
M. Fernandes ◽  
M. Vieira

AbstractThe bias voltage dependent spectral response (with and without steady state bias light) and the current voltage dependence has been simulated and compared to experimentally obtained values. Results show that in the heterostructures the bias voltage influences differently the field and the diffusion part of the photocurrent. The interchange between primary and secondary photocurrent (i. e. between generator and load device operation) is explained by the interaction of the field and the diffusion components of the photocurrent. A field reversal that depends on the light bias conditions (wavelength and intensity) explains the photocurrent reversal. The field reversal leads to the collapse of the diode regime (primary photocurrent) launches surface recombination at the p-i and i-n interfaces which is responsible for a double-injection regime (secondary photocurrent). Considerations about conduction band offsets, electrical field profiles and inversion layers will be taken into account to explain the optical and voltage bias dependence of the spectral response.


2003 ◽  
Vol 766 ◽  
Author(s):  
Ahila Krishnamoorthy ◽  
N.Y. Huang ◽  
Shu-Yunn Chong

AbstractBlack DiamondTM. (BD) is one of the primary candidates for use in copper-low k integration. Although BD is SiO2 based, it is vastly different from oxide in terms of dielectric strength and reliability. One of the main reliability concerns is the drift of copper ions under electric field to the surrounding dielectric layer and this is evaluated by voltage ramp (V-ramp) and time dependent dielectric breakdown (TDDB). Metal 1 and Metal 2 intralevel comb structures with different metal widths and spaces were chosen for dielectric breakdown studies. Breakdown field of individual test structures were obtained from V-ramp tests in the temperature range of 30 to 150°C. TDDB was performed in the field range 0.5 – 2 MV/cm. From the leakage between combs at the same level (either metal 1 or metal 2) Cu drift through SiC/BD or SiN/BD interface was characterized. It was found that Cu/barrier and barrier/low k interfaces functioned as easy paths for copper drift thereby shorting the lines. Cu/SiC was found to provide a better interface than Cu/SiN.


2011 ◽  
Vol E94-C (6) ◽  
pp. 1072-1075
Author(s):  
Tadashi YASUFUKU ◽  
Yasumi NAKAMURA ◽  
Zhe PIAO ◽  
Makoto TAKAMIYA ◽  
Takayasu SAKURAI

Author(s):  
Dongmei Meng ◽  
Laura Buck ◽  
James Cargo

Abstract Cu needs a higher level of ultrasound combined with bonding force to be bonded to the Al pad properly, not just because Cu is harder than Au, but it is also harder to initiate intermetallic compounds (IMC) formation during bonding. This increases the chances of damaging the metal/low k stack under the bondpad. This paper presents a fundamental study of IMC as well as one example of a failure mode of Cu/Al bonded devices, all based on detailed analysis using scanning electron microscopy, scanning transmission electron microscopy, energy dispersive spectrometers, and transmission electron microscopy. It presents a case study showing a corrosion mechanism of Cu/Al ballbond after 168hr UHAST stress. It is observed that all Cu9Al4 was consumed, while very little copper aluminide remained after 168 hours of UHAST stressing.


Sign in / Sign up

Export Citation Format

Share Document