Stress analysis in tungsten and Si3N4 coated silicon wafers

A paper by G. Gerald Stoney [Gerald Stoney, The Tension of Metallic Films Deposited by Electrolysis, Proc. R. Soc. Lond. A 82 (1909) 172–175], entitled “The Tension of Metallic Films deposited by Electrolysis,” was presented to the Royal Society of London by the Hon. C. A. Parsons. It was well known at that time that films deposited electrolytically were liable to peel off when exceeding a certain thickness. After examining many thin Steel rules of thickness d which have a thin, t, deposit of Nickel, which curved the Rule to a radius r. Taking the moments about the point b for the steel, Stoney then arrived at the following equation where the integral must be equal to zero;

(1)

From the solution of Eq. (1), we obtain the important fact that the neutral plane is at 2/3 the thickness of the rule from film surface. This also implies that the absolute value of the stress on the film side is twice that on the opposite side of the steel rule. The important point is that if the absolute stress in the silicon on the film side is twice that on the opposite side then the position of the neutral plane must be at 2/3 d. The purpose of this paper is to show that the neutral plane in silicon wafers, which have a thin film (~ 3 μm) of tungsten or Si₃N₄ is indeed at 2/3 the thickness of the wafer.     

Electron spin resonance studies of group IV organometallic radical anions : I. Organometal-substituted benzenes

Electron spin resonance spectra have been measured under uniform conditions for a series of trimethylsilyl-substituted benzene anion radicals. These ESR results have been used to derive a general set of Hückel molecular orbital parameters by treating the organosilyl substituent as a pseudo-heteroatom. ESR data for radical anions of organosilyl-substituted benzenes, biphenyls and naphthalenes are reproduced accurately by MO calculations employing h_Si = –2.0 and k_CSi = 0.7. For these series of compounds, the silicon-methyl proton ESR splittings, while not related to the π electron density on silicon alone or to the density on the aromatic carbon to which silicon is bonded, may be related to a combination of the π spin densities by a semiempirical relation:

     

ESR study of weak exchange interactions in binuclear copper(ii) complexes with acyldihydrazones of fluorinated β-diketones

A series of binuclear copper(ii) complexes with acyldihydrazones of aliphatic dicarboxylic acids (from malonic to adipic) and fluorinated -diketones (trifluoro- and hexafluoroacetylacetone) of composition Cu₂L·2Py (H₄L is acyldihydrazone) were studied by ESR spectroscopy. The ESR spectra of solutions of complexes with trifluoroacetylacetone acyldihydrazones have an isotropic signal with a seven-line hyperfine structure from two equivalent copper nuclei (g = 2.112, a _Cu = (39—40)·10^–4 cm^–1), which is indicative of weak exchange interactions between the paramagnetic centers due to spin density delocalization through a chain of the -bonds of the polymethylene bridge. On going to hexafluoroacetylacetone derivatives, the coupling is suppressed and the ESR spectra of solutions of such complexes show a signal with a four-line hyperfine structure (g = 2.121—2.131, a _Cu = (55—63)·10^–4 cm^–1) typical of mononuclear copper complexes.     

Thermodynamique de composes azotes III. Etude Thermochimique de la glycine et de la l-α-alanine

The enthalpies of formation of glycine and L-α-alanine are determined by two complementary techniques: combustion calorimetry and change of state (sublimation) calorimetry.

Full-size image (2K)

Full-size image (2K)

The values of the experimental and theoretical energy of conjugation of these two molecules (partially conjugated) and the energetical value of the C---N bond in Laidler's scheme, derived from the experimental enthalpy of atomization, are also given.

Full-size image (3K)

Full-size image (3K)

Résumé

Les enthalpies de combustion à létat condensé de la glycine et de la L-α-alanine ont été déterminées à d'un calorìmetre isopéribolique à bombe rotative. Leurs valeurs à l'état standard à 298,15 K sont: δH°_c = −(972,98±0,19) kJ mol⁻¹ pour la glycine et ΔHδ_c = −(1621,45 − 0,48) kJ mol^-1 pour la L-α-alanine. Les enthalpies de sublimation à l'état standard à 298,15 K ont été obtenues par calori-     

Preparation and structural study of a novel nonlinear molecular material: the -histidinum dihydrogenarsenate orthoarsenic acid crystal

-Histidinium dihydrogenarsenate orthoarsenic acid (LHA) crystal ;

Full-size image

belongs to P2₁ space group of the monoclinic system, Z=2, a=9.264(2) Å, b=8.929(2) Å, c=8.874(2) Å, β=108.61(3)°. The crystal is isomorphous to

Full-size image

(LHP) crystal. The H₂AsO₄⁻ anions and H₃AsO₄ molecules are joined into layers parallel to the (100) crystallographic planes by the O–HO type hydrogen bonds. The histidinium cations occupy the space between the layers. The histidinium cation posses the carboxylic COO⁻ group. The positive charges appear in the ring (the proton is attached to the =N(3)– nitrogen) and in the ammonium group. The differential scanning calorimetric (DSC) diagram does not show any phase transition till 100 K. The infrared spectrum fully confirms the X-ray crystal structure. The LHA crystal is a good second harmonic generator (0.46 relative to KDP)     

Reaktionen kationischer η-phosphinocarben-komplexe des wolframs mit anionischen nukleophilen

η²-Phosphinocarbebe complexes of tungsten show a different behaviour towards anionic nucleophiles. The cationic η²-phosphinocarbene complex

Full-size image

reacts with the thiophenolate anion PhS⁻ via carbonyl substitution, whereas the corresponding trimethylphosphine substituted carbene complex

Full-size image

adds the cyclopentadienyl anion at the carbene carbon atom. A third reaction pathway is observed on treating

Full-size image

with lithium diethylamide, providing a neutral η²-phosphinovinyl complex.

Zusammenfassung

Kationische η²-Phosphinocarbenkomplexe des Wolframs zeigen ein differenziertes Verhalten gegenüber anionischen Nukleophilen, Während sich das Cyclopentadienyl-Anion am elektrophilen Carbenkohlenstoffatom in

Full-size image

] addiert, setzt sich das Thiophenolat-Ion mit dem Dicarbonyl-substituierten Homologen

Full-size image

unter Carbonyl-Substitution um. In Gegenwart on Lithiumdiethylamid wird eine vergleichbare Additions- oder Substitutionsreaktion nicht beobachtet. Vielmehr findet beim Komplex

Full-size image

eine Deprotonierung der C_Carben-Methylgruppe unter Ausbildung eines neutralen Metalla-phospha-cyclopropan-Ringes mit exocyclischer Doppelbinding statt.     

CaO solubility and activity coefficient in molten salts CaCl2–x (x = 0, NaCl, KCl, SrCl2, BaCl2 and LiCl)

CaO solubility in equimolar molten salts CaCl₂–x (x = 0, NaCl, KCl, SrCl₂, BaCl₂ and LiCl) was determined at 873–1223 K and activity coefficient calculated. CaO solubility in the binary salts is less than in CaCl₂, and the activity coefficient is greater than one. With increasing temperature CaO solubility increases and the activity coefficient decreases. The dependency of CaO activity coefficient on temperature in equimolar molten salts CaCl₂–x is

CaCl2	RTln γCaO = 6961 + 5.06 T (K)	1123–1223 K
CaCl2–NaCl	RTln γCaO = 3985 + 17.67 T (K)	923–1123 K
CaCl2–KCl	RTln γCaO = 2384 + 22.72 T (K)	1073–1223 K
CaCl2–SrCl2	RTln γCaO = 27245–1.13 T (K)	1073–1223 K
CaCl2–BaCl2	RTln γCaO = 17068 + 10.19 T (K)	1223–1273 K
CaCl2–LiCl	RTln γCaO = 14724 + 0.72 T (K)	923–1073 K

Full-size table