Zig-zag trench structure to prevent aspect ratio trapping defect escape
A semiconductor structure including: trench-defining layer; an epitaxial layer; and a set of defect-blocking member(s). The trench-defining layer includes a trench surface which defines an elongated interior space called the “trench.” The epitaxial layer is grown epitaxially in the interior space of the trench. Each defect blocking member of the set of defect blocking members: (i) extends from a portion of trench surface into the interior space of the trench; and (ii) is located below a top surface of the epitaxial layer. The defect blocking member(s) are designed to arrest the propagation of generally-longitudinal defects in the epitaxial layer, as it is grown, where the generally-longitudinal defects are defects that propagate at least generally in the elongation direction of the trench.
1. A semiconductor structure comprising:
a trench-defining layer;
an epitaxial layer; and
a pair of defect-blocking members; wherein:
the trench-defining layer includes a trench surface which defines an elongated trench interior space having a bottom surface and opposing sidewalls;
the epitaxial layer is formed by epitaxial growth on the bottom surface within the opposing sidewalls of the elongated trench interior space;
each defect-blocking member of the pair of defect-blocking members extends upwardly from the bottom surface of the trench into the trench interior space;
the pair of defect-blocking members includes a first defect-blocking member laterally contacting one of the opposing sidewalls of the elongated trench interior space, and a second defect-blocking member laterally contacting the other of the opposing sidewalls of the elongated trench interior space, wherein the first and second defect-blocking members form a zig-zag pattern; and
the epitaxial layer is located in the portions of the trench interior space not occupied by the pair of defect-blocking members.
2. The semiconductor structure of claim 1 wherein the pair of defect blocking members is sized, shaped and/or located to prevent lattice mismatch defects from propagating through the epitaxial layer generally in the direction of elongation of the trench.
3. The semiconductor device of claim 1 wherein:
the trench-defining layer includes a base sub-layer and a lateral wall sub-layer;
the base sub-layer includes a top surface that defines the bottom surface of the trench;
the lateral wall sub-layer includes two lateral surfaces that define the opposing sidewalls of the trench; and
the base sub-layer and lateral sub-layer are made from different materials.
4. The semiconductor structure of claim 3 wherein:
the material of the base sub-layer allows therefrom epitaxial growth of the material of the epitaxial layer; and
the material of the lateral wall sub-layer does not allow therefrom epitaxial growth of the material of the epitaxial layer.
5. The semiconductor structure of claim 3 wherein each of the pair of defect-blocking members is made from the same material as, and is unitary with the lateral wall sub-layer.
6. The semiconductor structure of claim 3 wherein:
the base sub-laver is made from one of the following materials: silicon, SiGe (silicon germanium) or germanium; and
the lateral wall sub-layer is made from a dielectric material.
7. The semiconductor structure of claim 1 wherein the epitaxial layer is made of a III-V semiconductor material.
8. The semiconductor structure of claim 1 wherein a top surface of the epitaxial layer and a top surface of the trench-defining layer together form a flat, planar surface.
9. The semiconductor structure of claim 1 wherein:
each defect-blocking members member of the pair of defect-blocking includes a top surface;
the epitaxial growth layer has a top surface; and
the top surfaces of the pair of defect-blocking members are all below the top surface of the epitaxial layer.
10. The semiconductor structure of claim 1 wherein the trench includes: an upper tier that is free of the defect blocking members.
11. The semiconductor structure of claim 1 wherein more of the pair of defect-blocking members each alternately extending from opposing lateral walls of the trench.
12. The semiconductor structure of claim 11 wherein the defect blocking members are shaped as rectangular prisms.
13. A field-effect transistor (FET) device comprising:
a FET components set including a first gate and a first contact; trench-defining layer;
an epitaxial layer; and
a pair of defect-blocking members; wherein:
the trench-defining layer includes a trench surface which defines an elongated trench interior space having a bottom surface and opposing sidewalls;
the epitaxial layer is formed by epitaxial growth;
each defect-blocking member of the pair of defect-blocking members extends upwardly from the bottom surface of the trench into the trench interior space;
the epitaxial layer is located in portions of the trench interior space not occupied by the pair of defect blocking members;
the pair of defect-blocking members includes a first defect-blocking member laterally contacting only one of the opposing sidewalls of the elongated trench interior space, and a second defect-blocking member laterally contacting only the other of the opposing sidewalls of the elongated trench interior space, wherein the first and second defect-blocking members define a lateral space therebetween; and
the FET components set are located at least partially on top of a top surface of the epitaxial layer.