A dielectric stack and method of depositing the stack to a substrate using a single step deposition process. The dielectric stack includes a dense layer and a porous layer of the same elemental compound with different compositional atomic percentage, density, and porosity. The stack enhances mechanical modulus strength and enhances oxidation and copper diffusion barrier properties. The dielectric stack has inorganic or hybrid inorganic-organic random three-dimensional covalent bonding throughout the network, which contain different regions of different chemical compositions such as a cap component adjacent to a low-k component of the same type of material but with higher porosity.