Trench isolation having a self-adjusting surface seal and method for producing one such trench isolation
View Patent ↗The invention relates to a trench isolation with a self-aligning surface sealing and a fabrication method for said surface sealing. In this case, the surface sealing may have an overlap region of the substrate surface or a receded region into which extends an electrically conductive layer formed on the substrate surface.
1. A semiconductor structure having a trench isolation in a semiconductor substrate comprising:
an isolation trench having a first and a second insulator layer,
the second insulator layer extending from a level below a surface of the semiconductor substrate as far as a level above a surface of the semiconductor substrate and being essentially planar with respect to the first insulator layer,
the isolation trench and the first and second insulator layers having essentially parallel side walls,
the second insulator layer having a higher resistance to removing and/or modifying methods than the first insulator layer, and
the second insulator layer having, along the periphery of the isolation trench, a collar region directly on the surface of the semiconductor substrate with a defined lateral extent.
2. The semiconductor structure as claimed in claim 1 , the collar region of the second insulator layer being formed in stepped fashion or in lamellar fashion.
3. The semiconductor structure as claimed in claim 1 , the collar region of the second insulator layer having a lateral extent of 3 nm to 100 nm.
4. A semiconductor structure having a trench isolation in a semiconductor substrate,
an isolation trench having a first and a second insulator layer,
the second insulator layer extending from a level below a surface of the semiconductor substrate as far as a level above a surface of the semiconductor substrate and being essentially planar with respect to the first insulator layer,
the isolation trench and the first and second insulator layers having essentially parallel side walls,
the second insulator layer having a higher resistance to removing and/or modifying methods than the first insulator layer,
the second insulator layer having a cross-section in a lower region and a second cross-section in the upper region, the first cross-section being a cross-section of the isolation trench, the second cross-section being narrower than the first cross-section,
an electrically conductive layer being formed directly on the surface of the semiconductor substrate as far as a level below a surface of the second insulator layer, and
the electrically conductive layer enclosing the upper region of the second insulator layer.
5. The semiconductor structure as claimed in claim 4 , the upper region of the second insulator layer with the reduced cross section extending essentially as far as the level of the surface of the semiconductor substrate.
6. The semiconductor structure as claimed in claim 4 , the upper region of the second insulator layer with the reduced cross section extending as far as a level below a surface of the semiconductor substrate, the electrically conductive layer filling the gap between the upper region of the second insulator layer and the isolation trench.
7. The semiconductor structure as claimed in claim 4 , the electrically conductive layer being a semiconductor layer produced epitaxially.
8. A semiconductor structure having a trench isolation in a semiconductor substrate,
an isolation trench having a first and a second insulator layer,
the second insulator layer extending from a level below a surface of the semiconductor substrate as far as a level above a surface of the semiconductor substrate and being essentially planar with respect to the first insulator layer,
the isolation trench and the first and second insulator layers having essentially parallel side walls,
the second insulator layer having a higher resistance to removing and/or modifying methods than the first insulator layer,
the second insulator layer having a reduced cross section in an upper region,
an electrically conductive layer being formed directly on the surface of the semiconductor substrate as far as a level below a surface of the second insulator layer, and
the electrically conductive layer enclosing the upper region of the second insulator layer, wherein
the upper region of the second insulator layer with the reduced cross section extends as far as a level below a surface of the semiconductor substrate, and
the electrically conductive layer fills the gap between the upper region of the second insulator layer and the isolation trench.