Method for manufacturing a composite wafer having a graphite core, and composite wafer having a graphite core
According to an embodiment, a composite wafer includes a carrier substrate having a graphite core and a monocrystalline semiconductor layer attached to the carrier substrate.
1. A method for manufacturing a composite wafer, comprising:
providing a monocrystalline semiconductor wafer comprising a first side and a second side arranged opposite the first side;
depositing a moulding composition comprising at least one of carbon powder and pitch on the second side of the semiconductor wafer; and
annealing the deposited moulding composition to form a graphite carrier attached to the semiconductor wafer.
2. A method according to claim 1 , wherein the moulding composition further comprises a binder.
3. A method according to claim 1 , wherein depositing a moulding composition comprises at least one of injection moulding and compression moulding.
4. A method according to claim 1 , wherein annealing the deposited moulding composition comprises a first annealing process in a first temperature range and a subsequent second annealing process in a second temperature range different than the first temperature range.
5. A method according to claim 1 , further comprising:
forming a first protective layer at least on the first side of the monocrystalline semiconductor wafer prior to depositing the moulding composition.
6. A method according to claim 5 , further comprising:
removing the first protective layer from the monocrystalline semiconductor wafer after depositing the moulding composition or after annealing the deposited moulding composition.
7. A method according to claim 1 , further comprising:
forming a second protective layer at least on the graphite carrier.
8. A method according to claim 1 , further comprising:
forming an intermediate layer on the second side of the monocrystalline semiconductor wafer; and
depositing the moulding composition on the intermediate layer.
9. A method according to claim 1 , further comprising:
forming a recess in the second side of the monocrystalline semiconductor wafer; and
depositing the moulding composition into the recess.
10. A method according to claim 9 , wherein forming a recess comprises:
grinding the second side of the monocrystalline semiconductor wafer; and
etching the monocrystalline semiconductor wafer at the second side.
11. A method according to claim 1 , further comprising:
forming a doping region at the first side of the monocrystalline semiconductor wafer, the doping region forming an etch stop layer;
forming an epitaxial semiconductor layer on the first side of the monocrystalline semiconductor wafer; and
etching the material of the monocrystalline semiconductor wafer at the second side selectively with respect to the etch stop layer.
12. A method according to claim 11 , further comprising:
grinding the second side of the monocrystalline semiconductor wafer after forming the epitaxial semiconductor layer.
13. A method according to claim 1 , further comprising:
reducing the thickness of the monocrystalline semiconductor wafer by removing semiconductor material at the first side of the monocrystalline semiconductor wafer.
14. A method for manufacturing a composite wafer, comprising:
providing a monocrystalline semiconductor wafer comprising a first side and a second side arranged opposite the first side;
implanting gas ions into the first side of the monocrystalline semiconductor wafer to form a delamination layer at a predefined depth in the monocrystalline semiconductor wafer;
depositing a moulding composition comprising at least one of carbon powder and pitch on the first side of the monocrystalline semiconductor wafer; and
subjecting the monocrystalline semiconductor wafer and the moulding composition to at least one heat treatment to form a graphite carrier attached to the first side of the semiconductor wafer and split the monocrystalline semiconductor wafer along the delamination layer.
15. A method according to claim 14 , wherein the gas ions are implanted into the first side of the monocrystalline semiconductor wafer using implantation energy of no more than 150 keV.
16. A method according to claim 14 , wherein splitting of the monocrystalline semiconductor wafer results in the formation of a monocrystalline semiconductor layer which remains attached to the graphite carrier, the monocrystalline semiconductor layer comprising an exposed side, the method further comprising:
forming an epitaxial semiconductor layer on the exposed side of the monocrystalline semiconductor layer.