Film thickness measurements of SiO 2 by XPS

Journal of Molecular Structure

et al. 1999

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

XPS investigation of thin SiOx and SiOxNy overlayers

Birer

Sayan

Journal of Molecular Structure

et al. 1999

“…Some components of the total current can easily be controlled by application of a small (0-10 V) external voltage bias, both in the form of d.c. and/or a.c. pulses, as it has been reported recently [17][18][19][20][21][22][23][24][25][26][27][28][29][30]. The effect of this applied voltage-bias can then be assessed in the measured line positions.…”

Section: Introductionmentioning

confidence: 95%

Methods for probing charging properties of polymeric materials using XPS

Sezen

Ertaş

Journal of Electron Spectroscopy and Related Phenomena

2010

a b s t r a c tVarious thin polystyrene, PS, and poly(methyl methacrylate), PMMA and PS + PMMA blend films have been examined using the technique of recording X-ray photoelectron spectrum while the sample is subjected to ±10 V d.c. bias, and three different forms of (square-wave (SQW), sinusoidal (SIN) and triangular (TRG)), a.c. pulses. All films exhibit charging shifts as observed in the position of the corresponding C1s peak under d.c. bias. The a.c. pulses convert the single C1s peak to twinned peaks in the case of the square-wave form, and distort severely in the cases of the SIN, and TRG forms, and all three of them exhibit strong frequency dependence. In order to mimic and better understand the behavior of these polymeric materials, an artificial dielectric system consisting of a clean Si-wafer coupled to an external 1 M resistor and 56 nF capacitor is created, and its response to different forms of voltage stimuli, is examined in detail. A simple electrical circuit model is also developed treating the system as consisting of a parallel resistor and a series capacitor. With the help of the model, the response of the artificial system is successfully calculated as judged by comparison with the experimental data. Using one high frequency SQW measurements, the off-set in the charging shift due to the extra low-energy neutralizing electrons is estimated. After correcting the corresponding off-set shifts, the XPS spectra of the three different PS films, one PMMA, and one PS + PMMA blend film are re-examined. As a result of these detailed analysis, there emerges a clear relationship between the thicknesses of the PS films with their charging abilities. In the blend film, PS and PMMA domains are electrically separated, and exhibit different charging shifts, however, the presence of one is felt by the other. Hence, the PS component shifts are larger in the blend, due to the presence of PMMA domains, which has intrinsically a larger R eff , and conversely the PMMA component shifts are smaller due to the presence of PS domains.

“…Thickness of the overlayer was estimated from the angular dependency of the XPS data. 38 A Kratos ES300 electron spectrometer with MgKR X-rays (nonmonochromatic) was used for XPS measurements. In the standard geometry, the sample accepts X-rays at 45°and ejects photoelectrons at 90°with respect to the surface plane.…”

mentioning

confidence: 99%

X-ray Photoemission for Probing Charging/Discharging Dynamics

Dâna

2006

J. Phys. Chem. B

A novel technique is introduced for probing charging/discharging dynamics of dielectric materials in which X-ray photoemission data is recorded while the sample rod is subjected to (10.0 V square-wave pulses with varying frequencies in the range of 10 -3 to 10 3 Hz. For a clean silicon sample, the Si2p(Si 0 ) peak appears at correspondingly -10.0 eV and +10.0 eV binding energy positions (20.0 eV difference) with no frequency dependence. However, the corresponding peak of the oxide (Si 4+ ) appears with less than 20.0 eV difference and exhibits a strong frequency dependence due to charging of the oxide layer, which is faithfully reproduced by a theoretical model. In the simplest application of this technique, we show that the two O1s components can be assigned to SiO x and TiO y moeties by correlating their dynamical shifts to those of the Si2p and Ti2p peaks in a composite sample. Our pulsing technique turns the powerful X-ray photoemission into an even more powerful impedance spectrometer with an added advantage of chemical resolution and specificity.Charge accumulation and dissipation (charging/discharging) in dielectric materials are vital processes for design and function of various devices and sensors. 1 This is especially important for SiO 2 , as the thickness of the dielectric layer is expected to shrink down to few atomic layers for the next generation of metal oxide semiconductor (MOS) devices. 2 Charge accumulation in the oxide layer occurs via various trapping mechanisms and is normally probed by electrical current-voltage and/or current-capacitance measurements. [3][4][5][6] Photoemission utilizing UV, X-rays, and lasers has also been employed for probing very fast (<10 -9 s) charging dynamics. 7-9 Core-level X-ray photoemission, XPS, is especially attractive, since additional chemical information can also be derived from the line positions of the corresponding peaks. However, the measured line positions are severely altered by local potentials developed due to the uncompensated charges resulting from photoelectron emission, especially for poorly conducting samples or regions (layers or domains) within such samples. [10][11][12][13][14][15][16] Various methods of charge compensation have been developed using low-energy electrons, ions, and/or photons. 17,18 On the other hand, one can also utilize XPS for understanding the mechanisms leading to and/or controlling of the charging/ discharging processes in materials which offer great possibilities for researchers in all fields. 19 Several applications have been reported, which utilize the charging, called controlled surface charging, for extracting chemical, physical, structural, and electrical parameters of various surface species. 20-26 Using a slightly different strategy and by applying voltage stress to the sample rod while recording XPS spectra, we have shown that the extent of charging can be controlled and various analytical and electrical information can be extracted. [27][28][29][30][31][32] In addition to static information derived from applic...