Utilization of angled trench for effective aspect ratio trapping of defects in strain-relaxed heteroepitaxy of semiconductor films
Embodiments of the present disclosure relate to reducing dislocation density in a heteroepitaxial growth film and devices including heteroepitaxial films with reduced dislocation density. According to embodiments of the present disclosure, sidewalls of high aspect ratio trenches may be tilted or angled to allow defects in crystalline material formed in the high aspect ratio trenches to be terminated in the tilted sidewalls, including defects propagating along the length of the high aspect ratio trenches. Embodiments of the present disclosure may be used to reduce defects in heteroepitaxial growth on silicon (Si) for microelectronic applications, such as high mobility channels using Group III-V elements in field effect transistors.
1. A method for forming a semiconductor device, comprising:
forming a non-crystalline layer over a first crystalline material;
forming an angled trench through the non-crystalline layer to expose a portion of the first crystalline material at a bottom of the angled trench; and
forming a second crystalline material from the bottom of the angled trench by epitaxial growth to fill the angled trench, wherein the first and second crystalline materials have mismatched lattice dimensions and depositing a third crystalline material in a vertical narrow trench over the second crystalline material.
2. The method of claim 1 , wherein an angle between sidewalls of the angled trench and a top surface of the first crystalline material is less than
tan
-
1
h
w
,
h represents a height of the non-crystalline layer, and w represents a width of the angled trench along the top surface of the first crystalline material.
3. The method of claim 1 , wherein forming the angled trench comprises:
generating a plasma over the non-crystalline material; and
modifying a sheath of the plasma to generate an angled ion stream from the sheath and directing the angled ion stream toward the non-crystalline material.
4. The method of claim 1 , wherein forming the angled trench comprises:
directing an ion beam toward the non-crystalline material at an angle.
5. The method of claim 2 , wherein the height of the angled trench is less than or equal to 100 nanometers.
6. The method of claim 2 , wherein the width of the angled trench is between about 20 nanometers and about 40 nanometers.
7. The method of claim 2 , wherein the angle of the angled trench is between about 11 degrees and about 45 degrees.
8. A method for forming a semiconductor device, comprising:
forming a non-crystalline layer over a first crystalline material;
forming an angled trench through the non-crystalline layer to expose a portion of the first crystalline material at a bottom of the angled trench;
forming a second crystalline material from the bottom of the angled trench by epitaxial growth to fill the angled trench, wherein the first and second crystalline materials have mismatched lattice dimensions; and
forming a functional structure narrower than the angled trench by etching an upper portion of the second crystalline material.
9. The method of claim 8 , wherein an angle between sidewalls of the angled trench and a top surface of the first crystalline material is less than
tan
-
1
h
w
,
h represents a height of the non-crystalline layer, and w represents a width of the angled trench along the top surface of the first crystalline material.
10. The method of claim 8 , wherein forming the angled trench comprises:
generating a plasma over the non-crystalline material; and
modifying a sheath of the plasma to generate an angled ion stream from the sheath and directing the angled ion stream toward the non-crystalline material.
11. The method of claim 8 , wherein forming the angled trench comprises:
directing an ion beam toward the non-crystalline material at an angle.
12. The method of claim 9 , wherein the height of the angled trench is less than or equal to 100 nanometers.
13. The method of claim 9 , wherein the width of the angled trench is between about 20 nanometers and about 40 nanometers.