Germanium-containing release layer for transfer of a silicon layer to a substrate
View Patent ↗A germanium-containing layer is deposited on a single crystalline bulk silicon substrate in an ambient including a level of oxygen partial pressure sufficient to incorporate 1%-50% of oxygen in atomic concentration. The thickness of the germanium-containing layer is preferably limited to maintain some degree of epitaxial alignment with the underlying silicon substrate. Optionally, a graded germanium-containing layer can be grown on, or replace, the germanium-containing layer. An at least partially crystalline silicon layer is subsequently deposited on the germanium-containing layer. A handle substrate is bonded to the at least partially crystalline silicon layer. The assembly of the bulk silicon substrate, the germanium-containing layer, the at least partially crystalline silicon layer, and the handle substrate is cleaved within the germanium-containing layer to provide a composite substrate including the handle substrate and the at least partially crystalline silicon layer. Any remaining germanium-containing layer on the composite substrate is removed.
1. A semiconductor structure comprising a material stack, said material stack including:
a single crystalline silicon substrate;
a germanium-containing layer contacting said single crystalline silicon substrate, said germanium-containing layer comprising a plurality of cavities;
an at least partially crystalline silicon layer located on and directly contacting said germanium-containing layer; and
a handle substrate bonded to said at least partially crystalline silicon layer.
2. The semiconductor structure of claim 1 , wherein said germanium-containing layer includes oxygen at an atomic concentration between 1% and 50%.
3. The semiconductor structure of claim 1 , wherein said germanium-containing layer consists essentially of germanium and oxygen, wherein a sum of an atomic concentration of germanium and an atomic concentration of oxygen is greater than 99%.
4. The semiconductor structure of claim 1 , wherein said germanium-containing layer has a substantially constant germanium concentration at an atomic concentration from 30% to 99%.
5. The semiconductor structure of claim 1 , wherein said germanium-containing layer includes oxygen at an atomic concentration between 1% and 50%.
6. The semiconductor structure of claim 5 , wherein said germanium-containing layer includes oxygen at an atomic concentration between 2% and 20%.
7. The semiconductor structure of claim 5 , wherein oxygen incorporated in said at least partially crystalline silicon layer 30 is below 5% in atomic concentration.
8. The semiconductor structure of claim 1 , wherein said germanium-containing layer is a single crystalline layer having an epitaxial alignment with said single crystalline silicon substrate at an atomic level.
9. The semiconductor structure of claim 1 , wherein said at least partially crystalline silicon layer is another single crystalline layer having a complete epitaxial alignment with said germanium-containing layer at an atomic level.
10. The semiconductor structure of claim 1 , wherein said germanium-containing layer is a textured crystalline layer in which grains are predominantly oriented in a direction providing epitaxial alignment with a single crystalline structure of said single crystalline silicon substrate at an atomic level.
11. The semiconductor structure of claim 10 , wherein said at least partially crystalline silicon layer is another textured crystalline layer in which grains are predominantly oriented in a direction providing epitaxial alignment with said single crystalline structure of said germanium-containing layer at an atomic level.
12. The semiconductor structure of claim 1 , wherein a predominant portion of grains of said germanium-containing layer has the same set of crystallographic orientations as said single crystalline silicon substrate.
13. The semiconductor structure of claim 12 , wherein a predominant portion of grains of said at least partially crystalline silicon layer has the same set of crystallographic orientations as said germanium-containing layer.
14. The semiconductor structure of claim 1 , wherein said germanium-containing layer is polycrystalline.
15. The semiconductor structure of claim 1 , wherein said germanium-containing layer is aligned to said single crystalline silicon substrate with at least some degree of epitaxial alignment.
16. A semiconductor structure comprising a material stack, said material stack including:
a single crystalline silicon substrate;
a germanium-containing layer contacting said single crystalline silicon substrate;
a graded germanium-containing layer located on and directly contacting said germanium-containing layer, wherein said graded germanium-containing layer is epitaxially aligned to said germanium-containing layer or a predominant portion of grains of said graded germanium-containing layer is along a predominant grain orientation in said germanium-containing layer,
an at least partially crystalline silicon layer located on and directly contacting said graded germanium-containing layer; and
a handle substrate bonded to said at least partially crystalline silicon layer.
17. The semiconductor structure of claim 16 , wherein said graded germanium-containing layer includes silicon, germanium, and oxygen, and an atomic concentration of germanium decreases in said graded germanium-containing layer with a distance from said germanium-containing layer.
18. The semiconductor structure of claim 1 , further comprising a bonding material layer in contact with said handle substrate.
19. The semiconductor structure of claim 1 , wherein a surface normal of a planar top surface of said single crystalline silicon substrate has a set of Miller indices, wherein at least one Miller index in said set of Miller indices has an absolute value that exceeds 6.