Aluminoborophosphosilicate glasses for microelectronics packaging

Abstract

Glasses are used in microelectronic packaging for insulation and passivation purposes. To optimize the performance of these packages, it is necessary to investigate new glasses or improve on properties of the glasses in use. The insulating glass should have low dielectric constant, low dissipation factor, low glass transition temperature, high chemical resistivity, and a thermal expansion coefficient matching the substrate. In this study, various aluminoborophosphosilicate glasses containing Ca(Mg)O, Ca(Mg)F₂, and AlF₃ as flux were investigated. Processing temperatures for these glasses range from 1300°C to 1500°C. The coefficients of thermal expansion range from 4.52 μ/°C to 9.39 μ/°C. The dielectric constant as a function of frequency and composition is in the range of 4.1 to 5.2. The index of refraction for these glasses is in the range of 1.52 to 1.58. Glass transition and softening temperatures as low as 538°C and 622°C, respective, were found. Results of this investigation are discussed in terms of the possible use of aluminoborophosphosilicate glasses in microelectronic packaging.