Semiconductor device including contact plug and associated methods

A semiconductor device, comprising:

• a semiconductor layer including a first region and a second region;
• a first contact plug disposed on the semiconductor layer and electrically connected to the first region;
• a second contact plug disposed on the semiconductor layer and electrically connected to the second region;
• a conductive layer electrically connected to the first contact plug, the conductive layer having a side surface and a bottom surface;
• and
• an insulating layer disposed between the conductive layer and the second contact plug so as to insulate the conductive layer from the second contact plug, the insulating layer facing the side surface and a portion of the bottom surface of the conductive layer,
• wherein:
• the second contact plug includes a lower portion and an upper portion, the lower portion being between the upper portion and a surface of the semiconductor layer, and
• a cross-sectional area of the lower portion of the second contact plug is greater than a cross-sectional area of the upper portion of the second contact plug.