STRUCTURE WITH UPPER FEATURES OF ADJACENT METAL STRUCTURES WITH SIDEWALL SPACERS PROVIDING VOID-FREE DIELECTRIC FILLING

A structure includes a first metal structure including a first upper metal feature having a first sidewall spacer thereabout, and a first lower metal feature under the first upper metal feature. The first lower metal feature includes a sidewall devoid of the first sidewall spacer. The structure also includes a second metal structure spaced from the first metal structure. The second metal structure includes a second upper metal feature having a second sidewall spacer thereabout, and a second lower metal feature under the first upper metal feature. The second lower metal feature includes a sidewall devoid of the second sidewall spacer. A dielectric is between the first metal structure and the second metal structure. The dielectric is devoid of any voids therein, and the opening it fills has a high aspect ratio. A related method is also provided.