Vertical channel transistor and method of fabricating the same
A vertical channel transistor includes a plurality of active pillar patterns extending perpendicularly from the top surface of the substrate toward an upper part. A gate insulating layer is deposited on the side wall of the active pillar pattern and serves as an ion diffusion barrier between the pillar patterns and surrounding lower gate electrodes. The resultant pillar pattern structure is encapsulated with a metal. The resultant pillar pattern is surrounded on all sides by a specified height by a sacrificial layer of Spin-On Dielectric (SOD). The metal layer is etched-back to the height of the sacrificial layer, thus forming the lower gate electrodes. A spacer layer of an insulating mater is deposited surrounding the upper part of the pillar patterns and the sacrificial layer is removed exposing a part of the lower gate electrodes. The exposed gate electrode is etched to facilitate semiconductor integration.
1. A vertical channel transistor, comprising:
a plurality of active pillar patterns extending perpendicularly from a top surface of the substrate toward an upper part, each of the active pillar patterns having an upper part and a lower part;
a plurality of metal gate electrodes formed by interposing gate insulating layers on sidewalls of the active pillar patterns;
a hard mask pattern formed above the upper parts of the active pillar patterns; and
spacers formed surrounding the sidewalls of the hard mask pattern and the active pillar patterns.
2. The vertical channel transistor of claim 1 , wherein
each of the active pillar patterns includes a channel active pillar pattern unit in the lower part and a drain active pillar pattern unit in the upper part, and
the metal gate electrodes are formed surrounding sidewalls of the channel active pillar pattern units.
3. The vertical channel transistor of claim 2 , wherein the channel active pillar pattern unit and the drain active pillar pattern unit have a substantially uniform line width, and the active pillar pattern has a straight cylindrical shape.
4. The vertical channel transistor of claim 2 , wherein a line width of the channel active pillar pattern unit is formed narrower than a line width of the drain active pillar pattern unit.
5. The vertical channel transistor of claim 3 , wherein the hard mask pattern is formed above an upper part of the drain active pillar pattern unit.
6. The vertical channel transistor of claim 5 , wherein the spacers are formed surrounding the sidewalls of the hard mask pattern and the drain active pillar pattern unit.
7. The vertical channel transistor of claim 1 , wherein each of the metal gate electrodes includes a barrier metal formed in contact with the gate insulating layer.
8. The vertical channel transistor of claim 1 , wherein the metal gate electrode is formed of any material selected from the group consisting of Ta, Ti, TiN, TiB 2 , TaN and TaSiN and a combination thereof.