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 dielectric layer over a silicon containing crystalline substrate;
forming an angled trench through the dielectric material to expose a portion of the silicon containing crystalline substrate at a bottom of the angled trench, wherein an angle between sidewalls of the angled trench and a top surface of the silicon containing crystalline substrate is less than
tan
-
1
h
w
,
h represents a Height of the dielectric layer, and w represents a width of the angled trench along the top surface of the silicon containing crystalline substrate;
etching the exposed silicon containing crystalline substrate at the bottom of the angled trench to produce a surface along (111) crystal plane direction; and
forming a crystalline material comprising a Group III element and a Group V element in the angled trench by epitaxial growth.
2. The method of claim 1 , wherein forming the angled trench comprises:
generating a plasma over the substrate; and
modifying a sheath of the plasma to generate an angled ion stream from the sheath and directing the angled ion stream toward the substrate.
3. The method of claim 1 , wherein the etching the exposed silicon containing substrate at the bottom of the angled trench is a wet etching.
4. The method of claim 1 , wherein the height of the angled trench is less than or equal to 100 nanometers.
5. The method of claim 1 , wherein the width of the angled trench is between about 20 nanometers and about 40 nanometers.
6. The method of claim 1 , wherein the angle of the angled trench is between about 11 degrees and about 45 degrees.
7. The method of claim 1 , wherein the angle of the angled trench is about 30 degrees.
8. A method for forming a semiconductor device, comprising:
forming a dielectric layer over a silicon containing crystalline substrate;
forming an angled trench through the dielectric material by generating a plasma over the substrate, modifying a sheath of the plasma to generate an angled ion stream from the sheath, and directing the angled ion stream toward the substrate to expose a portion of the silicon containing crystalline substrate at a bottom of the angled trench, wherein an angle between sidewalls of the angled trench and a top surface of the silicon containing crystalline substrate is less than
tan
-
1
h
w
,
h represents a height of the dielectric layer, and w represents a width of the angled trench along the top surface of the silicon containing crystalline substrate;
wet etching the exposed silicon containing crystalline substrate at the bottom of the angled trench to produce a surface along (111) crystal plane direction; and
forming a crystalline material comprising a Group III element and a Group V element in the angled trench by epitaxial growth.
9. The method of claim 8 , wherein the height of the angled trench is less than or equal to 100 nanometers.
10. The method of claim 8 , wherein the width of the angled trench is between about 20 nanometers and about 40 nanometers.
11. The method of claim 8 , wherein the angle of the angled trench is between about 11 degrees and about 45 degrees.
12. The method of claim 8 , wherein the angle of the angled trench is about 30 degrees.