Semiconductor device having storage nodes and its method of fabrication
Embodiments of a semiconductor device having storage nodes include an interlayer insulating layer disposed on a semiconductor substrate; a conductive pad disposed in the interlayer insulating layer to contact with a predetermined portion of the substrate, an upper portion of the conductive pad protruding above the interlayer insulating layer; an etch stop layer disposed on the conductive pad and the interlayer insulating layer; and storage nodes penetrating the etch stop layer and disposed on the conductive pad. A penetration path of wet etchant is completely blocked during the wet etch process that removes the mold oxide layer. Therefore, inadvertent etching of the insulating layer due to penetration of wet etchant is prevented, resulting in a stronger, more stable, storage node structure.
1. A method of fabricating a semiconductor device, the method comprising:
forming an interlayer insulating layer on a semiconductor substrate;
forming a conductive pad in the interlayer insulating layer;
selectively etching the interlayer insulating layer so that an upper portion of the conductive pad protrudes above the interlayer insulating layer;
sequentially forming an etch stop layer and a mold oxide layer on the interlayer insulating layer and the protruded conductive pad;
etching the mold oxide layer and the etch stop layer to expose an upper surface of the conductive pad; and
forming a storage node on the exposed upper surface of the conductive pad.
2. The method according to claim 1 , wherein selectively etching the interlayer insulating layer is performed so that an upper portion of the conductive pad protrudes above the interlayer insulating layer by about 300 to 2000 .
3. The method according to claim 1 , wherein selectively etching the interlayer insulating layer uses an etchant containing fluorine.
4. The method according to claim 1 , wherein forming the interlayer insulating layer comprises sequentially forming a lower insulating layer and an upper insulating layer.
5. The method according to claim 4 , wherein forming the conductive pad comprises:
selectively etching the upper insulating layer to form a trench;
selectively etching the lower insulating layer exposed by the trench to form a via hole that exposes a portion of the substrate;
forming a conductive layer on the substrate having the via hole; and
planarizing the conductive layer to fill the trench and the via hole.
6. The method according to claim 5 , wherein the conductive layer includes one of a polycrystalline silicon layer and a metal layer.
7. The method according to claim 5 , wherein planarizing the conductive layer is performed using one of an etch back process and a chemical mechanical polishing (CMP) process.
8. The method according to claim 4 , wherein forming the conductive pad comprises:
forming a buried contact plug in the lower insulating layer to be in contact with a portion of the substrate; and
forming a buffer conductive layer pattern covering at least a portion of the buried contact plug in the upper insulating layer, and extending along one direction beyond an edge of the buried contact plug.
9. The method according to claim 8 , wherein the buffer conductive layer pattern is formed with a thickness of about 1500 to 2500 .
10. The method according to claim 8 , after forming the buried contact plug, further comprising selectively etching the lower insulating layer so that an upper portion of the buried contact plug protrudes above the lower insulating layer.
11. The method according to claim 10 , wherein selectively etching the lower insulating layer is performed so that an upper portion of the buried contact plug protrudes above the lower insulating layer by about 1500 to 2500 .
12. The method according to claim 1 , wherein the etch stop layer includes silicon nitride.
13. The method according to claim 1 , wherein the storage node includes one of a polycrystalline silicon layer and a metal layer.
14. The method according to claim 1 , after forming the storage node, further comprising removing the remaining mold oxide layer.
15. The method according to claim 14 , wherein removing the mold oxide layer is performed using a wet etch process.
16. The method according to claim 15 , wherein the wet etch process uses one HF and BOE as an etchant.