In this study, the glass transition temperature Tg is determined from thermal expansion measurements in a series of glass compositions prepared by bulk fusion of a phosphosilicate matrix to which oxides of boron, germanium, or arsenic are added. On a per-molar basis, addition of boron was observed to be the most effective in lowering the glass transition temperature of the phosphosilicate matrix, as compared to arsenic or germanium, which is found to be the least effective. For borophosphosilicate glass with concentrations of B2O3 less than 13 m/o, values of Tg are observed to be reduced by increasing the P2O5 content. Near 13 m/o B2O3 the temperatures become independent of P2O5 while at a still higher B2O3 content they are actually raised upon increasing the P2O5 concentration. For the germanophosphosilicate glass, no such reversal is noted as values of Tg decrease slightly with P2O5 additions at all GeO2 concentrations. Glass compositions with potential VLSI applications can, thus, have the P2O5 content reduced to the minimum value required to provide gettering without significantly affecting the glass transition or associated viscous flow parameters. From a comparison of the measured values of Tg in bulk glasses with reported values of the flow temperature Tf for films with corresponding compositions, a correlation factor relating those two parameters is established. Thus, the relatively simple thermal expansion technique can now be used to survey for glass compositions with promising flow characteristics without the rigorous and time consuming effort of conducting the more difficult bulk viscosity experiments or developing deposition processes for films with possibly unsuitable viscous characteristics.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Materials Chemistry
- Surfaces, Coatings and Films
- Renewable Energy, Sustainability and the Environment