Semiconductor structure and method of manufacturing the same
Provided are a semiconductor structure and a method of manufacturing the same. The semiconductor structure includes a substrate, a membrane bridge that defines, with the substrate, a plurality of cavities, and a nitride semiconductor layer arranged on the membrane bridge. The membrane bridge and the substrate have the same crystal structure. The membrane bridge has an upper surface with a constant height with respect to a surface of the substrate.
1. A method of manufacturing a semiconductor structure, the method comprising:
forming, on a substrate, a sacrificial layer pattern comprising a plurality of sacrificial layers spaced apart from each other;
forming, on the sacrificial layer pattern, a membrane bridge that covers the plurality of sacrificial layers and comprises an upper surface with a constant height with respect to a surface of the substrate, the upper surface being at the constant height over an entire length of the sacrificial layer pattern comprising the plurality of sacrificial layers;
removing the sacrificial layer pattern from the substrate to form a plurality of cavities defined by the substrate and the membrane bridge;
crystallizing the membrane bridge such that the membrane bridge and the substrate have a same crystallographic direction; and
growing a nitride semiconductor layer on the crystallized membrane bridge wherein the membrane bridge comprises alumina (A2O3).
2. The method of claim 1 , wherein a gap between adjacent sacrificial layers of the plurality of sacrificial layers is less than a width of each of the plurality of sacrificial layers.
3. The method of claim 1 , wherein a gap between adjacent sacrificial layers of the plurality of sacrificial layers is less than or equal to half of a width of each of the plurality of sacrificial layers.
4. The method of claim 1 , wherein a gap between adjacent sacrificial layers of the plurality of sacrificial layers is about 500 nm or less.
5. The method of claim 1 , wherein the plurality of cavities are in contact with the substrate.
6. The method of claim 1 , wherein the membrane bridge comprises:
a plurality of first regions wherein each of the plurality of first regions overlaps a respective sacrificial layer of the plurality of sacrificial layers in a thickness direction of the substrate; and
a plurality of second regions that do not overlap any of the plurality of sacrificial layers in the thickness direction of the substrate.
7. The method of claim 6 , wherein each of the plurality of second regions fills a respective space between adjacent sacrificial layers of the plurality of sacrificial layers.
8. The method of claim 6 , wherein a width of each of the plurality of second regions is less than a thickness of the plurality of first regions.
9. The method of claim 6 , wherein a width of the plurality of first regions is about 1 μm or less.
10. The method of claim 6 , wherein each of the plurality of second regions comprises a first sub-region and a second sub-region,
wherein a first end of the first sub-region is spaced apart from a first end of the second sub-region,
wherein the first end of the first sub-region and the first end of the second sub-region are in contact with the substrate, and
wherein a second end of the first sub-region is in contact with a second end of the second sub-region.
11. The method of claim 10 , wherein for each second region of the plurality of second regions, a second cavity is formed between the first sub-region and the second sub-region.
12. The method of claim 11 , wherein for each first region of the plurality of first regions, a width of a corresponding cavity of the plurality of cavities decreases from the first region toward the substrate.
13. The method of claim 11 , wherein a size of each of the plurality of second cavities is less than a size of each of the plurality of cavities.