Uniform exposed raised structures for non-planar semiconductor devices
The use of two different materials for shallow trench isolation and deep structural trenches with a dielectric material therein (e.g., flowable oxide and a HARP oxide, respectively) causes non-uniform heights of exposed portions of raised semiconductor structures for non-planar semiconductor devices, due to the different etch rates of the materials. Non-uniform openings adjacent the exposed portions of the raised structures from recessing the isolation and dielectric materials are filled with additional dielectric material to create a uniform top layer of one material (the dielectric material), which can then be uniformly recessed to expose uniform portions of the raised structures.
1. A non-planar semiconductor structure, comprising:
a semiconductor substrate;
a plurality of raised semiconductor structures coupled to the substrate, a non-uniform layer of isolation material surrounding bottom portions of the plurality of raised semiconductor structures;
at least one trench through the non-planar structure and into the substrate, the at least one trench filled with only a dielectric material different from the isolation material and having a different etch rate than the isolation material for a given etch; and
wherein a top layer of the dielectric material is situated above the non-uniform layer of isolation material and in the at least one trench, and wherein a top surface of the top layer has a uniform height below uniform exposed portions of the plurality of raised semiconductor structures.
2. The non-planar semiconductor structure of claim 1 , wherein a height of the uniform exposed portions is about 40 nm to about 60 nm.
3. The non-planar semiconductor structure of claim 1 , wherein the isolation material comprises flowable oxide, and wherein the dielectric material comprises a HARP oxide.
4. The non-planar semiconductor structure of claim 1 , wherein the top layer of the dielectric material is wider in cross-section taken through the plurality of raised semiconductor structures, than a remainder of the dielectric material therebelow.