Insulating block in a semiconductor trench
A semiconductor device is produced by: creating an opening in a mask formed on a semiconductor body; creating, underneath the opening, a trench in the semiconductor body which has a side wall and a trench bottom; creating, while the mask is on the semiconductor body, an insulating layer covering the trench bottom and the side wall; depositing a spacer layer including a first electrode material on the insulating layer; removing the spacer layer from at least a portion of the insulating layer that covers the trench bottom; filling at least a portion of the trench with an insulating material; removing the part of the insulating material laterally confined by the spacer layer so as to leave an insulating block in the trench; and filling at least a portion of the trench with a second electrode material so as to form an electrode within the trench.
1. A method of producing a semiconductor device, the method comprising:
providing a semiconductor body having a front side;
forming a mask on the front side;
creating at least one opening in the mask, the opening exposing a portion of the front side;
creating, underneath the at least one opening, at least one trench extending into the semiconductor body, the trench having at least one side wall and a trench bottom;
creating, while the mask is arranged on the front side, an insulating layer that covers the trench bottom and the at least one side wall, wherein creating the insulating layer comprises growing a thermal oxide on the trench bottom and on the at least one side wall;
depositing a spacer layer on the insulating layer, the spacer layer comprising a first electrode material;
removing the spacer layer from at least a portion of the insulating layer that covers the trench bottom;
filling at least a portion of the trench with an insulating material;
removing only a part of the insulating material that is laterally confined by the spacer layer so as to leave an insulating block in the trench; and
filling at least a portion of the trench with a second electrode material so as to form an electrode within the trench.
2. The method of claim 1 , wherein removing the insulating material comprises a wet etch process.
3. The method of claim 1 , wherein the mask comprises the same material as the insulating layer.
4. The method of claim 1 , wherein forming the mask comprises depositing at least one of silicon dioxide and silicon nitride.
5. The method of claim 1 , wherein removing the spacer layer from the portion of the insulating layer comprises an anisotropic etch process.
6. The method of claim 1 , wherein filling the portion of the trench with the insulating material comprises depositing silicon dioxide.
7. The method of claim 1 , wherein removing the insulating material comprises an anisotropic etch process.
8. The method of claim 1 , wherein the first electrode material and the second electrode material each comprise at least one of polysilicon, metal, and a metal silicide.
9. The method of claim 1 , wherein an electric conductivity of the second electrode material is higher than an electric conductivity of the first electrode material.
10. The method of claim 1 , further comprising: removing portions of the second electrode material, of the mask, of the spacer layer, of the insulating layer, and of the semiconductor body, by at least one of an etch process, a polishing process, and a chemical-mechanical planarization process carried out after the filling of at least the portion of the trench with the second electrode material.