Semiconductor devices including buried gate electrodes and isolation layers and methods of forming semiconductor devices including buried gate electrodes and isolation layers using self aligned double patterning
A semiconductor device, including a semiconductor substrate including isolations defining active regions of the semiconductor substrate, and a plurality of buried gate electrodes between a pair of the isolations, wherein each of the buried gate electrodes and the isolations includes a conductive layer and a capping layer.
1. A method of forming a semiconductor device, comprising:
forming and patterning a plurality of layers on a semiconductor substrate to form a patterned structure;
simultaneously forming isolation trenches and buried gate trenches in the semiconductor substrate by selectively removing portions of the patterned structure, the isolation trenches defining active regions of the semiconductor substrate;
forming a conductive pattern in the isolation trenches and the buried gate trenches; and
forming a capping layer on the conductive patterns in the isolation trenches and the buried gate trenches,
wherein forming and patterning the plurality of layers to form the patterned structure includes:
forming a first insulation layer on the semiconductor substrate;
forming a patterning layer on the first insulation layer;
forming a pattern by patterning the patterning layer to expose portions of the first insulation layer and define trenches in the pattern;
forming a first layer on the portions of the first insulation layer exposed by the pattern to partially fill the trenches defined by the pattern;
forming a second layer on the first insulation layer, the second layer filling the partially filled trenches defined by the pattern;
performing a planarization process to expose upper surfaces of the pattern, the first layer, and the second layer;
removing the pattern to expose sidewalls of the first layer;
forming spacers on the sidewalls of the first layer; and
removing a portion of the first insulation layer to expose portions of the semiconductor substrate.
2. A method of forming a semiconductor device, comprising:
forming and patterning a plurality of layers on a semiconductor substrate to form a patterned structure that includes a first layer having a different etch rate from a second layer;
simultaneously forming isolation trenches and buried gate trenches in the semiconductor substrate, the isolation trenches defining active regions of the semiconductor substrate, the isolation trenches being formed by selectively removing portions of the semiconductor substrate, and the buried gate trenches being formed by selectively removing portions of the patterned structure to remove a part of the first layer covering lateral sides of the second layer such that another part of the first layer under a lower side of the second layer remains;
forming a conductive pattern in the isolation trenches and the buried gate trenches; and
forming a capping layer on the conductive patterns in the isolation trenches and the buried gate trenches, wherein forming and patterning the plurality of layers to form the patterned structure includes:
forming a first insulation layer on the semiconductor substrate;
forming a patterning layer on the first insulation layer;
forming a pattern by patterning the patterning layer to expose portions of the first insulation layer and define trenches in the pattern;
forming the first layer on the portions of the first insulation layer exposed by the pattern to partially fill the trenches defined by the pattern;
forming the second layer on the first insulation layer, the second layer filling the partially filled trenches defined by the pattern;
performing a planarization process to expose upper surfaces of the pattern, the first layer and the second layer;
removing the pattern to expose sidewalls of the first layer;
forming spacers on the sidewalls of the first layer; and
removing a portion of the first insulation layer to expose portions of the semiconductor substrate.
3. The method as claimed in claim 2 , further comprising:
forming a gate insulating layer in the isolation trenches and the buried gate trenches.
4. The method of forming a semiconductor device as claimed in claim 2 , wherein:
forming the conductive patterns includes forming the conductive patterns such that an upper surface of the conductive pattern is below an upper surface of the semiconductor substrate,
forming the capping layers includes covering exposed surfaces of the conductive patterns, and
an upper surface of the capping layer is substantially and/or completely aligned with the upper surface of the semiconductor substrate.
5. The method of forming a semiconductor device as claimed in claim 2 , wherein simultaneously forming isolation trenches and buried gate trenches in the semiconductor substrate includes etching portions of the semiconductor substrate exposed by the first insulation layer and portions of the semiconductor substrate below exposed portions of the first layer.
6. The method of forming a semiconductor device as claimed in claim 2 , wherein a material of the spacers and a material of the second layer are same.
7. The method of forming a semiconductor device as claimed in claim 2 , wherein a distance between adjacent ones of the spacers is greater than a distance between facing wall portions of a respective one of the spacers and the second layer.
8. The method of forming a semiconductor device as claimed in claim 2 , wherein forming the conductive pattern includes depositing a same conductive material in the isolation trenches and the buried gate trenches.
9. The method of forming a semiconductor device as claimed in claim 2 , wherein forming the capping layer includes depositing a same capping material on the conductive patterns in the isolation trenches and the buried gate trenches.
10. The method of forming a semiconductor device as claimed in claim 2 , wherein:
the semiconductor substrate includes a cell region and a peripheral region,
simultaneously forming isolation trenches and buried gate trenches in the semiconductor substrate includes simultaneously forming the isolation trenches and the gate trenches on the cell region of the semiconductor substrate, and
the method further includes forming peripheral isolations in the peripheral region independently of forming the isolation trenches and the buried gate trenches in the cell region.
11. The method of forming a semiconductor device as claimed in claim 2 , further comprising forming a conductive line that electrically connects the conductive patterns of the isolations trenches together.
12. The method of forming a semiconductor device as claimed in claim 2 , wherein the patterned structure is formed such that an upper side of the second layer and an upper side of the first layer are exposed, and the first layer covers the lateral sides and the lower side of the second layer.