Semiconductor device having wafer-to-wafer bonding structure and manufacturing method thereof

A semiconductor device comprising:

• a lower wafer including a first substrate, a first dielectric layer that is defined on the first substrate, and a first wiring line that is defined in the first dielectric layer;
• an upper wafer including a second substrate, an isolation layer that is defined in an upper surface of the second substrate, a through hole that extends from a lower surface of the second substrate towards the upper surface to expose a lower surface of the isolation layer, a second dielectric layer that fills the through hole, covers the lower surface of the second substrate and is bonded to an upper surface of the first dielectric layer, a third dielectric layer that is defined on the upper surface of the second substrate, and a second wiring line that is defined on the third dielectric layer;
• and
• a through via passing through, under the second wiring line, the third dielectric layer, the isolation layer, the second dielectric layer under the isolation layer and the first dielectric layer, and coupling the second wiring line and the first wiring line.

A method for manufacturing a semiconductor device, comprising:

• forming isolation layers in a front surface of an upper wafer substrate;
• forming a through hole that exposes one of the isolation layers, through the upper wafer substrate from a back surface of the upper wafer substrate facing away from the front surface;
• forming a first dielectric layer that fills the through hole and covers the back surface;
• defining a lower wafer including a lower wafer substrate, a second dielectric layer defined on the lower wafer substrate, and a first wiring line disposed in the second dielectric layer;
• bonding a top surface of the second dielectric layer of the lower wafer and a bottom surface of the first dielectric layer;
• forming a third dielectric layer on the front surface of the upper wafer substrate;
• forming a through via that passes through the third dielectric layer, the one isolation layer, the first dielectric layer under the one isolation layer and the second dielectric layer, and couples to the first wiring line;
• and
• forming, on the third dielectric layer, a second wiring line that is coupled to the through via.