A high silica content substrate, such as for a device, is provided. The substrate has a high silica content and is thin. The substrate may include a surface with a topography or profile that facilitates bonding with a conductive metal layer, such as a metal layer for a circuit or antenna. The substrate may be flexible, have high temperature resistance, very low CTE, high strength and/or be non-reactive. The substrate may be suitable for use in circuits intended for use in high temperature environments, low temperature environments, reactive environments, or other harsh environments. The substrate may be suitable for high frequency antenna applications.