Semiconductor devices

A semiconductor device, comprising:

• a substrate having an active region;
• an interlayer insulating layer on the substrate;
• a contact structure in the interlayer insulating layer and electrically connected to the active region;
• a first insulating layer on the interlayer insulating layer;
• a via contact in the first insulating layer and electrically connected to the contact structure;
• a second insulating layer on the first insulating layer;
• an interconnection line in the second insulating layer and electrically connected to the via contact;
• and
• an etch stop layer between the first insulating layer and the second insulating layer, the etch stop layer including an upper layer region, a lower layer region and an intermediate film between the upper layer region and the lower layer region, each of the upper layer region and the lower layer region including a compound that includes a first element, and the intermediate film including a second element intermixed with the first element.

A semiconductor device, comprising:

• a substrate having an active region
• a first insulating layer on the substrate;
• a second insulating layer on the first insulating layer;
• a via contact in the first insulating layer and electrically connected to the active region;
• an interconnection structure in the second insulating layer and electrically connected to the via contact;
• and
• an etch stop layer between the first insulating layer and the second insulating layer, the etch stop layer including an upper layer region, a lower layer region and an intermediate film between the upper layer region and the lower layer region, each of the upper layer region and the lower layer region including a compound that includes aluminum, and the intermediate film including a silicon atomic layer,
• wherein the upper layer region has a thickness greater than a thickness of the lower layer region.