| CPC H01L 21/7682 (2013.01) [H01L 21/76831 (2013.01); H01L 21/76834 (2013.01); H01L 21/7684 (2013.01); H01L 21/76843 (2013.01); H01L 21/7685 (2013.01); H01L 21/76852 (2013.01); H01L 21/7688 (2013.01); H01L 21/76885 (2013.01); H01L 23/5222 (2013.01); H01L 23/53295 (2013.01); H10D 64/251 (2025.01)] | 20 Claims |

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1. A semiconductor structure, comprising:
a via structure disposed in a first dielectric layer;
a first etch stop layer (ESL) over the first dielectric layer;
a second dielectric layer over the first ESL;
a diffusion barrier layer extending through the second dielectric layer and the first ESL to contact the via structure;
a metal feature disposed over the diffusion barrier layer;
a protecting layer disposed between the second dielectric layer and the diffusion barrier layer;
a capping layer disposed on top surfaces of the diffusion barrier layer and the metal feature; and
a second ESL over and interfacing the capping layer, the protecting layer and the second dielectric layer,
wherein the second dielectric layer comprises an air gap,
wherein the protecting layer partially extends into the first ESL.
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