Vertical mos transistor

A device, comprising:

• a substrate;
• a metal line over the substrate;
• a semiconductor pillar over the metal line;
• a gate dielectric layer surrounding the semiconductor pillar;
• a metal gate surrounding the gate dielectric layer;
• and
• a gate electrode tapering toward and in contact with a sidewall of the metal gate.

A device, comprising:

• a substrate;
• a metal line over the substrate;
• a semiconductor pillar over the metal line;
• a gate dielectric layer surrounding the semiconductor pillar;
• a metal gate surrounding the gate dielectric layer;
• a conductive pillar over the metal line;
• and
• a contact over the conductive pillar, wherein the contact has a convex top surface.