Method of forming vertical channel devices
The disclosed technology generally relates semiconductor devices and more particularly to vertical channel devices and methods of forming the vertical channel devices. According to one aspect, a method of forming a vertical channel device includes forming on a semiconductor substrate a plurality of vertical channel structures. The method additionally includes forming gates, where each of the gates wraps around one of the vertical channel structures. The method additionally includes embedding the gates in a first dielectric layer and exposing top portions of the vertical channel structures. The method additionally includes forming top electrodes on corresponding top portions of the vertical channel structures. The method additionally includes forming sidewall etch barriers on sidewalls of each of the top electrodes. The method additionally includes forming a second dielectric layer covering the first dielectric layer and the top electrodes. The method additionally includes etching a set of vertically extending gate contact holes through the first and second dielectric layers and selectively against the sidewall etch barriers, where each of the gate contact holes exposes one of the gates adjacent to one of the top electrodes. The method further includes filling the set of gate contact holes with a conductive material. A vertical channel device fabricated using the method is also disclosed according another aspect.
1. A method of forming a vertical channel semiconductor device, the method comprising:
forming on a semiconductor substrate a plurality of vertical channel structures;
forming gates, each of the gates wrapping around one of the vertical channel structures;
embedding the gates in a first dielectric layer and exposing top portions of the vertical channel structures;
forming top electrodes on corresponding top portions of the vertical channel structures;
forming sidewall etch barriers on sidewalls of each of the top electrodes;
forming a second dielectric layer covering the first dielectric layer and the top electrodes;
forming a set of gate contact holes, comprising:
forming a gate contact mask layer on the second dielectric layer,
forming openings in the gate contact mask layer, the openings defining locations of the gate contact holes, and
etching using the gate contact mask layer a set of vertically extending gate contact holes through the first and second dielectric layers and selectively against the sidewall etch barriers, wherein each of the gate contact holes exposes one of the gates adjacent to one of the top electrodes; and
filling the set of gate contact holes with a conductive material.
2. The method according to claim 1 , wherein a width of at least one of the openings is such that etching the at least one of the openings exposes a corresponding sidewall etch barrier layer.
3. The method according to claim 1 , wherein forming the sidewall etch barriers includes:
forming a conformal etch barrier layer covering the first dielectric layer and the top electrodes; and
anisotropically etching the etch barrier layer such that the etch barrier layer is removed from the first dielectric layer while remaining on the sidewalls of the top electrodes.
4. The method according claim 1 , further comprising forming upper etch barriers on an upper surface of each of the top electrodes, wherein etching the set of vertically extending gate contact holes through the first and second dielectric layers comprises selectively etching against both the sidewall etch barriers and the upper etch barriers.
5. The method according to claim 1 , wherein forming the top electrodes comprises:
forming a top electrode layer including at least a first conductive layer that covers the first dielectric layer and the top portions of the vertical channel structures; and
using a top electrode pattern as an etch mask to pattern the top electrode layer, thereby forming the top electrodes.
6. The method according to claim 5 , wherein patterning the top electrode layer includes:
forming a top electrode mask layer on the top electrode layer;
forming the top electrode pattern in the top electrode mask layer, the top electrode pattern including a set of discrete mask portions, each mask portion of the pattern overlapping at least one top portion along a vertical direction; and
etching the top electrode layer in regions exposed by the mask portions of the top electrode pattern such that a set of discrete top electrodes are formed.
7. The method according to claim 1 , wherein the first and the second dielectric layers are formed of the same material.
8. A method of forming a vertical channel semiconductor device, the method comprising:
forming on a semiconductor substrate a plurality of vertical channel structures;
forming gates, each of the gates wrapping around one of the vertical channel structures;
embedding the gates in a first dielectric layer and exposing top portions of the vertical channel structures;
forming top electrodes on corresponding top portions of the vertical channel structures, wherein forming the top electrodes comprises:
forming a top electrode layer including at least a first conductive layer that covers the first dielectric layer and the top portions of the vertical channel structures;
forming an etch barrier layer covering the top electrode layer; and
using a top electrode pattern as an etch mask to pattern the etch barrier layer and the top electrode layer, thereby forming the top electrodes and upper etch barriers;
forming sidewall etch barriers on sidewalls of each of the top electrodes;
forming a second dielectric layer covering the first dielectric layer and the top electrodes;
etching a set of vertically extending gate contact holes through the first and second dielectric layers and selectively against the sidewall etch barriers, wherein each of the gate contact holes exposes one of the gates adjacent to one of the top electrodes; and
filling the set of gate contact holes with a conductive material.
9. The method according to claim 8 , wherein the top electrode layer further includes a second conductive layer formed on the first conductive layer, wherein at least the first conductive layer is formed as a conformal layer on the first dielectric layer and the top portions of the vertical channel structures.
10. A method of forming a vertical channel semiconductor device, the method comprising:
forming on a semiconductor substrate a plurality of vertical channel structures;
forming gates, each of the gates wrapping around one of the vertical channel structures;
embedding the gates in a first dielectric layer and exposing top portions of the vertical channel structures;
forming top electrodes on corresponding top portions of the vertical channel structures;
forming sidewall etch barriers on sidewalls of each of the top electrodes;
forming a second dielectric layer covering the first dielectric layer and the top electrodes;
etching a set of vertically extending gate contact holes through the first and second dielectric layers and selectively against the sidewall etch barriers, wherein each of the gate contact holes exposes one of the gates adjacent to one of the top electrodes;
etching a set of vertically extending top contact holes through the second dielectric layer, each of the top contact holes exposing a corresponding one of the top electrodes; and
filling the set of gate contact holes and the set of top contact holes with a conductive material by forming a conductive material layer covering the second dielectric layer and filling the set of gate contact holes and the set of top contact holes.
11. The method according to claim 10 , further using a contact pattern as an etch mask to pattern the conductive material layer into a set of discrete contacts including gate contacts connected to gates below the set of gate contact holes and top contacts connected to top electrodes below the set of contact holes.