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 ...
