Semiconductor device and method of manufacturing the same

A method of manufacturing a semiconductor device, comprising:

• forming a lower substrate that includes a lower interconnect layer including a plurality of lower interconnects, and a plurality of lower pads provided on the lower interconnects;
• forming an upper substrate that includes an upper interconnect layer including a plurality of upper interconnects, and a plurality of upper pads provided on the upper interconnects;
• and
• bonding the upper substrate and the lower substrate such that the upper pads are provided on the lower pads and are in contact with the lower pads,
• wherein
• the lower pads are formed to include a plurality of first pads and a plurality of second pads, and
• the upper pads are formed to include a plurality of third pads provided on the second pads and a plurality of fourth pads provided on the first pads after the bonding, a lower face of each third pad after the bonding being larger in area than an upper face of each second pad, a lower face of each fourth pad after the bonding being smaller in area than an upper face of each first pad.