Semiconductor device having stacked structure and method for manufacturing the same

A method for manufacturing a semiconductor device comprising:

• forming a first stacked structure in which a first interconnect layer having a first bonding pad is formed over a first front surface of a first substrate, a second stacked structure in which a second interconnect layer having a second bonding pad and an electrode pad is formed over a second front surface of a second substrate, and a third stacked structure in which a third interconnect layer having a third bonding pad is formed over a third front surface of a third substrate;
• disposing the first stacked structure over the second stacked structure such that the first bonding pad and the second bonding pad are directly bonded to each other;
• forming an interconnection via structure that penetrates the second substrate and contacts the electrode pad by etching the second substrate and the second interconnect layer;
• disposing the third stacked structure over the second stacked structure such that the interconnection via structure and the third bonding pad are directly bonded to each other;
• and
• forming a pad open region exposing the electrode pad by etching the first substrate, the first interconnect layer, and the second interconnect layer.