Solid assemblies having a composite dielectric spacer and processes for fabricating the solid assemblies are provided. The composite dielectric spacer can include, in some embodiments, a first dielectric layer and a second dielectric layer having a mutual interface. The composite dielectric spacer can separate a contact member from a conductive interconnect member, thus reducing the capacitance between such members with respect to solid assemblies that include one of first dielectric layer or the second dielectric layer. The composite dielectric spacer can permit maintaining the real estate of an interface between the conductive interconnect and a trench contact member that has an interface with a carrier-doped epitaxial layer embodying or constituting a source contact region or a drain contact region of a field effect transistor. The trench contact member can form another interface with the conductive interconnect member, providing a satisfactory contact resistance therebetween.