Differential Thermal Analysis of Glass Mixtures Containing SiO2, GeO2,  B 2 O 3, and  P 2 O 5

Abstract

Present isolation technology in microelectronic applications uses chemical mechanical polishing (CMP) in order to achieve planar surfaces for dielectric films used in trench isolation and interlayer dielectric structures, among others. Reflowed glasses have not played an important role in planarization because of the high temperatures required to achieve a planarized glass layer. 1 However, germanosilicate glasses (combinations of SiO 2 and GeO 2 ) with or without B 2 O 3 and/or P 2 O 5 dopants have shown promise for reduced reflow temperatures as compared to traditional borophosphosilicate glasses. [2][3][4][5] The purpose of the present work is to examine bulk glasses comprised of SiO 2 , GeO 2 , B 2 O 3 , and/or P 2 O 5 via differential thermal analysis (DTA).Glasses experience a substantial change in properties when passing through a specific temperature region, sometimes referred to as the "anomalous" region for the particular glass. The temperature at which the effects begin is dubbed the glass transition temperature, T g . 6,7 Several properties of a glass change nonlinearly near the glass transition temperature, including thermal coefficient of expansion (TCE), 7 specific heat, 7,8 electrical conductivity, elastic modulus, 7 and dielectric constant. 8 Perhaps the most important change at T g with respect to reflow is the reduction in the glass viscosity upon heating up to and beyond T g . 8 Since glass viscosity is reduced markedly at the glass transition temperature, reflow should occur at lower temperature for glasses that have lower glass transition temperatures.According to the literature, DTA can be used to determine glass transition temperatures. 6,[9][10][11][12][13] The present work utilizes DTA in order to examine the thermal behavior of glass formers, namely, SiO 2 , GeO 2 , B 2 O 3 , and P 2 O 5 , as well as several pseudo-binary, pseudoternary, and pseudo-quaternary mixtures of these materials. Such information may provide guidelines for choosing compositions and anneal temperatures when attempting reflow of doped or undoped germanosilicate glasses. O 5 as well as selected pseudo-binary, pseudo-ternary, and pseudo-quaternary compositions of these compounds have been examined for glass transitions by differential thermal analysis (DTA) in the context of reflow of doped germanosilicate glasses. SiO 2 does not exhibit a glass transition to temperatures above 1135ЊC. GeO 2 appears to exhibit a glass transition around 578ЊC, while B 2 O 3 appears to exhibit a glass transition in the range of 257-268ЊC. Although the glass transition temperature of P 2 O 5 could not be determined, the transition and melting behavior of the H, O, and OЈ phases have been reevaluated. Moreover, a new mechanism for conversion from H phase to O phase is presented. Namely, the melting of H phase followed by the spontaneous recrystallization of the resulting liquid to form the O phase was observed by DTA. Germanosilicate mixtures exhibited no glass transition, but the germanoborates' glass transition temperatures increased ...

para-Octaiodophenylsilsesquioxane, [p-IC6H4SiO1.5]8, a Nearly Perfect Nano-Building Block

“…As we will report elsewhere, the alkyne systems polymerize to give 3-D carbon networks that are air stable to temperatures >550 °C and may not completely oxidize in the time frame of the thermogravimetric analysis (TGA), as evidenced by dark residues after the TGA runs rather than white SiO 2 . The phosphonate system can be expected to decompose to give phosphosilicate glasses that encapsulate residual carbon, leading to the much higher CYs than expected . Finally, the carbazole system, which has the poorest conversion, retains the highest aryl iodide content, and the decomposition process(es) may lead to more char that also limits oxidation at the heating rates used for our standard TGA runs.…”

“…All of these materials are highly soluble and offer oxidative stabilities >400 °C (TGA), especially the alkyne complexes, as noted above . Of particular interest are the cyano and 4-vinylpyridine moieties, which offer the potential for 3-D dative bonding . The 2-vinylpyridine system may provide access to octairidium systems that are of potential use in light-emitting diodes, light harvesting, and novel photovoltaics. – Finally, while the UV–vis absorptions of the stilbene derivatives are essentially the same as those of the parent organic molecules, the emission characteristics of the derivatives are very different, being red-shifted up to 80 nm (~0.75 eV), as will be discussed elsewhere [M. Neurock, J.-S. Filhol, C.-Y.…”

“…68 The phosphonate system can be expected to decompose to give phosphosilicate glasses that encapsulate residual carbon, leading to the much higher CYs than expected. 74 Finally, the carbazole system, which has the poorest conversion, retains the highest aryl iodide content, and the decomposition process(es) may lead to more char that also limits oxidation at the heating rates used for our standard TGA runs.…”

Heat capacity and glass transition in P2O5–H2O solutions: support for Mishima's conjecture on solvent water at low temperature

“…2. The glass transition of the P 2 O 5 -water system P 2 O 5 , one of the three primary ''glass former'' oxides (along with SiO 2 and B 2 O 3 ), is used as a major component, 7 or as a dopant, 8 in the preparation of many glasses. Mixtures of P 2 O 5 with 3d-transition metal oxides have also received considerable attention because of their semiconducting and optical properties and potential applications.…”

“…In spite of their practical relevance, the glass transition temperatures, T g , of P 2 O 5 and its mixtures with water remain very uncertain. Thus, T g for pure P 2 O 5 remains elusive, probably because of its polymorphism 8,14,15 and its sensitivity to traces of water that are extremely difficult to remove. The first reported glass transition temperature (T g = 535 K) of pure P 2 O 5 was indirectly obtained by Sakka and McKenzie, 16 by extrapolating viscosity data obtained over a higher temperature range.…”