A microelectronic device includes a metal layer on a first dielectric layer. An etch stop layer is disposed over the metal layer and on the dielectric layer directly adjacent to the metal layer. The etch stop layer includes a metal oxide, and is less than 10 nanometers thick. A second dielectric layer is disposed over the etch stop layer. The second dielectric layer is removed from an etched region which extends down to the etch stop layer. The etched region extends at least partially over the metal layer. In one version of the microelectronic device, the etch stop layer may extend over the metal layer in the etched region. In another version, the etch stop layer may be removed in the etched region. The microelectronic device is formed by etching the second dielectric layer using a plasma etch process, stopping on the etch stop layer.