Semiconductor device with cap element
A semiconductor device structure is provided. The semiconductor device structure includes an epitaxial structure over a substrate and a cap element over the epitaxial structure. The cap element has a first thickness measured between a top surface of the cap element and a top surface of the epitaxial structure. The cap element has a second thickness measured between a side surface of the cap element and a side surface of the epitaxial structure. The first thickness and the second thickness are different from each other.
1 . A semiconductor device structure, comprising:
an epitaxial structure over a substrate; and
a cap element over the epitaxial structure, wherein:
the cap element has a first thickness measured between a top surface of the cap element and a top surface of the epitaxial structure,
the cap element has a second thickness measured between a side surface of the cap element and a side surface of the epitaxial structure, and
the first thickness and the second thickness are different from each other.
2 . The semiconductor device structure as claimed in claim 1 , wherein the top surface of the cap element is wider than the top surface of the epitaxial structure.
3 . The semiconductor device structure as claimed in claim 2 , wherein the top surface of the cap element is substantially parallel to the top surface of the epitaxial structure.
4 . The semiconductor device structure as claimed in claim 2 , wherein a surface orientation of the top surface of the cap element and a surface orientation of the side surface of the cap element are different from each other, and the surface orientation of the side surface of the cap element is {111}.
5 . The semiconductor device structure as claimed in claim 4 , wherein the surface orientation of the top surface of the cap element is {311}.
6 . The semiconductor device structure as claimed in claim 1 , wherein the epitaxial structure has a first atomic concentration of germanium, the cap element has a second atomic concentration of germanium, and the first atomic concentration of germanium is higher than the second atomic concentration of germanium.
7 . The semiconductor device structure as claimed in claim 1 , wherein the epitaxial structure is in direct contact with the cap element.
8 . The semiconductor device structure as claimed in claim 1 , further comprising:
a second epitaxial structure over the substrate; and
a second cap element over the second epitaxial structure, wherein the second cap element and the cap element are spaced apart from each other.
9 . The semiconductor device structure as claimed in claim 8 , wherein a shortest distance between the cap element and the second cap element is smaller than a width of the top surface of the cap element.
10 . The semiconductor device structure as claimed in claim 9 , wherein a ratio of the shortest distance to the width of the top surface of the cap element is in a range from about 0.6 to about 0.8.
11 . A semiconductor device structure, comprising:
a first epitaxial structure over a substrate;
a first cap element over the first epitaxial structure, wherein the first epitaxial structure is a portion of a first transistor;
a second epitaxial structure laterally spaced apart from the first epitaxial structure; and
a second cap element over the second epitaxial structure, wherein the second epitaxial structure is a portion of a second transistor, wherein a shortest distance between the cap element and the second cap element is smaller than a width of a top surface of the first cap element.
12 . The semiconductor device structure as claimed in claim 11 , wherein a ratio of the shortest distance to the width of the top surface of the first cap element is in a range from about 0.6 to about 0.8.
13 . The semiconductor device structure as claimed in claim 11 , further comprising:
a first metal-semiconductor compound structure on the first cap element; and
a second metal-semiconductor compound structure on the second cap element, wherein a shortest distance between the first metal-semiconductor compound structure and the second metal-semiconductor compound structure is smaller than the width of the top surface of the first cap element.
14 . The semiconductor device structure as claimed in claim 11 , further comprising:
an isolation feature surrounded by the substrate, wherein a top surface of the isolation feature is higher than a bottom surface of the first epitaxial structure and lower than the top surface of the first epitaxial structure.
15 . The semiconductor device structure as claimed in claim 11 , wherein the first cap element and the second cap element contain no germanium.
16 . A semiconductor device structure, comprising:
a first epitaxial structure over a substrate;
a first cap element over the first epitaxial structure;
a first metal-semiconductor compound structure on the first cap element;
a second epitaxial structure laterally spaced apart from the first epitaxial structure;
a second cap element over the second epitaxial structure; and
a second metal-semiconductor compound structure on the second cap element, wherein a shortest distance between the first metal-semiconductor compound structure and the second metal-semiconductor compound structure is smaller than a width of a top surface of the first cap element.
17 . The semiconductor device structure as claimed in claim 16 , wherein:
the first cap element has a first thickness measured between the top surface of the first cap element and a top surface of the first epitaxial structure,
the first cap element has a second thickness measured between a side surface of the first cap element and a side surface of the first epitaxial structure, and
the first thickness and the second thickness are different from each other.
18 . The semiconductor device structure as claimed in claim 16 , wherein:
the first cap element has a first thickness measured between the top surface of the first cap element and a top surface of the first epitaxial structure,
the first cap element has a second thickness measured between a side surface of the first cap element and a side surface of the first epitaxial structure, and
a ratio of the first thickness to the second thickness is in a range from about 0.8 to about 1.2.
19 . The semiconductor device structure as claimed in claim 18 , wherein a width ratio of the top surface of the first cap element to the side surface of the first cap element is in a range from about 0.125 to about 1.
20 . The semiconductor device structure as claimed in claim 16 , wherein the first epitaxial structure has a higher atomic concentration of germanium than that of the second cap element.