Semiconductor wafer and process for its production
View Patent ↗A layered semiconductor wafer contains the following layers in the given order: a monocrystalline substrate wafer ( 1 ) containing substantially silicon, a first amorphous intermediate layer ( 2 ) of an electrically insulating material having a thickness of 2 nm to 100 nm, a monocrystalline first oxide layer ( 3 ) having a cubic Ia-3 crystal structure, a composition of (M 1 2 O 3 ) 1-x (M 2 2 O 3 ) x wherein each of M 1 and M 2 is a metal and wherein 0≦x≦1, and a lattice constant which differs from the lattice constant of the material of the substrate wafer by 0% to 5%. The invention also relates to a process for manufacturing such semiconductor wafers by epitaxial deposition.
1. A semiconductor wafer comprising the following layers in the given order:
a) a monocrystalline substrate wafer ( 1 ) consisting essentially of silicon,
b) a first amorphous intermediate layer ( 2 ) comprising an electrically insulating material and having a thickness of 2 nm to 100 nm,
c) a monocrystalline first oxide layer ( 3 ) having a cubic Ia-3 crystal structure, a composition of (M 1 2 O 3 ) 1-x (M 2 2 O 3 ) x wherein each of M 1 and M 2 is a metal and wherein 0≦x≦1, and a lattice constant which differs from the lattice constant of the material of the substrate wafer by 0% to 5%, and
a monocrystalline second oxide layer ( 4 ) adjacent to the first oxide layer ( 3 ), the second oxide layer ( 4 ) having a cubic Ia-3 crystal structure, a composition of (M 3 2 O 3 ) 1-y (M 4 2 O 3 ) y wherein each of M 3 and M 4 is a metal and wherein 0≦y≦1, y starting with a value y 1 at the boundary to the first oxide layer ( 3 ), varying across the thickness of the second oxide layer ( 4 ) in order to achieve a variation in the lattice constant of the material of the second oxide layer ( 4 ) across its thickness, and ending with a value y 2 at the surface of the second oxide layer ( 4 ), the value y 1 being selected such that the lattice constant of the second oxide layer ( 4 ) at its boundary to the first oxide layer ( 3 ) differs from the lattice constant of the material of the first oxide layer ( 3 ) by 0% to 2%.
2. The semiconductor wafer of claim 1 , wherein the substrate wafer ( 1 ) contains 90% to 100% silicon.
3. The semiconductor wafer of claim 1 , wherein the electrically insulating material of the first amorphous intermediate layer ( 2 ) comprises a silicon oxide, a metal silicate, or a mixture thereof.
4. The semiconductor wafer of claim 1 , wherein each of M 1 and M 2 is a rare earth metal or a transition metal.
5. The semiconductor wafer of claim 4 wherein M 1 is praseodymium and M 2 is yttrium.
6. The semiconductor wafer of claim 1 , wherein the first oxide layer ( 3 ) has a uniform lattice constant across its entire thickness.
7. The semiconductor wafer of claim 1 , wherein the thickness of the first amorphous intermediate layer is between 3 nm and 10 nm.
8. The semiconductor wafer of claim 1 , wherein each of M 3 and M 4 is a rare earth metal or a transition metal.
9. The semiconductor wafer of claim 8 , wherein M 3 is praseodymium and M 4 is yttrium.
10. The semiconductor wafer of claim 1 , further comprising a superficial layer ( 8 ) comprising a monocrystalline semiconductor material.
11. The semiconductor wafer of claim 10 , further comprising a second amorphous intermediate layer ( 7 ) comprising an electrically insulating material and being located adjacent to the superficial layer ( 8 ) comprising a monocrystalline semiconductor material.
12. The semiconductor wafer of claim 1 , further comprising a monocrystalline third oxide layer ( 51 ) of M 5 2 O w , wherein M 5 is a metal and wherein 3<w≦4.
13. The semiconductor wafer of claim 12 , wherein M 5 is a rare earth metal or a transition metal.
14. The semiconductor wafer of claim 13 , wherein M 5 is praseodymium.
15. The semiconductor wafer of claim 12 , further comprising a monocrystalline fourth oxide layer ( 6 ) adjacent to the third oxide layer ( 51 ), the fourth oxide layer ( 6 ) having a cubic Ia-3 crystal structure, a composition of (M 6 2 O 3 ) 1-z (M 7 2 O 3 ) z wherein each of M 6 and M 7 is a metal and wherein 0≦z≦1, z starting with a value z 1 at the boundary to the third oxide layer ( 51 ), varying across the thickness of the fourth oxide layer ( 6 ) in order to achieve a variation in the lattice constant of the material of the fourth oxide layer ( 6 ) across its thickness, and ending with a value z 2 at the surface of the fourth oxide layer ( 6 ).
16. The semiconductor wafer of claim 15 , further comprising a superficial layer ( 8 ) of a monocrystalline semiconductor material.
17. The semiconductor wafer of claim 1 , further comprising:
d) a monocrystalline third oxide layer ( 52 ) adjacent to the second oxide layer ( 4 ), the third oxide layer having a cubic Ia-3 crystal structure and a composition of M 5 2 O 3 , wherein M 5 is a metal which is also capable of forming oxides having a composition of M 5 2 O w with 3<w≦4,
e) a monocrystalline fourth oxide layer ( 6 ) adjacent to the third oxide layer ( 52 ), the fourth oxide layer ( 6 ) having a cubic Ia-3 crystal structure, a composition of (M 6 2 O 3 ) 1-z (M 7 2 O 3 ) z wherein each of M 6 and M 7 is a metal and wherein 0≦z≦1, z starting with a value z 1 at the boundary to the third oxide layer ( 52 ), varying across the thickness of the fourth oxide layer ( 6 ) in order to achieve a variation in the lattice constant of the material of the fourth oxide layer ( 6 ) across its thickness, and ending with a value z 2 at the surface of the fourth oxide layer ( 6 ),
f) a second amorphous intermediate layer ( 7 ) adjacent to the fourth oxide layer ( 6 ), the second amorphous intermediate layer ( 7 ) comprising an electrically insulating material and having a thickness of 0.5 nm to 100 nm, and
g) a superficial layer ( 8 ) consisting of a monocrystalline semiconductor material.
18. The semiconductor wafer of claim 10 , wherein the semiconductor material of the superficial layer ( 8 ) comprises silicon (Si), germanium (Ge), silicon-germanium (Si 1-a Ge a , 0<a<1), silicon carbide (SiC), gallium phosphide (GaP), aluminium phosphide (AlP), gallium nitride (GaN), gallium arsenide (GaAs), aluminium arsenide (AlAs), indium arsenide (InAs), indium nitride (InN), indium phosphide (InP), gallium indium phosphide (Ga 0.51 In 0.49 P), indium arsenic phosphide (In 0.51 As 0.49 P), zinc sulphide (ZnS) or zinc oxide (ZnO).
19. The semiconductor wafer of claim 16 , wherein the semiconductor material of the superficial layer ( 8 ) comprises silicon (Si), germanium (Ge), silicon-germanium (Si 1-a Ge a , 0<a<1), silicon carbide (SiC), gallium phosphide (GaP), aluminium phosphide (AlP), gallium nitride (GaN), gallium arsenide (GaAs), aluminium arsenide (AlAs), indium arsenide (InAs), indium nitride (InN), indium phosphide (InP), gallium indium phosphide (Ga 0.51 In 0.49 P), indium arsenic phosphide (In 0.51 As 0.49 P), zinc sulphide (ZnS) or zinc oxide (ZnO).
20. The semiconductor wafer of claim 17 , wherein the semiconductor material of the superficial layer ( 8 ) comprises silicon (Si), germanium (Ge), silicon-germanium (Si 1-a Ge a , 0<a<1), silicon carbide (SiC), gallium phosphide (GaP), aluminium phosphide (AlP), gallium nitride (GaN), gallium arsenide (GaAs), aluminium arsenide (AlAs), indium arsenide (InAs), indium nitride (InN), indium phosphide (InP), gallium indium phosphide (Ga 0.51 In 0.49 P), indium arsenic phosphide (In 0.51 As 0.49 P), zinc sulphide (ZnS) or zinc oxide (ZnO).