Epitaxial substrate, method of making same and method of making a semiconductor chip
View Patent ↗Proposed is an epitaxial substrate, particularly for making thin-film semiconductor chips based on III-V semiconductors, comprising a sacrificial layer that is applied to a wafer substrate and whose band gap is smaller than the band gap of the surrounding substrate, and a method of making the epitaxial substrate. Further described is a method of making a thin-film semiconductor chip, particularly an LED, wherein an epitaxial substrate is prepared, wherein at least one LED structure is grown on said epitaxial substrate and the LED structure is bonded to an acceptor substrate, and wherein the semiconductor wafer is released by at least partially destroying the sacrificial layer, and the at least one LED structure is singulated.
1. A III-V-semiconductor-containing epitaxial substrate comprising:
a wafer substrate comprising gallium arsenide;
a sacrificial layer comprising at least one of Ge, GaAsN, GaAsSb and InGaAs, applied to the wafer substrate, and having a band gap smaller than the band gap of the wafer substrate;
an epitaxial layer structure configured to emit radiation and applied to the sacrificial layer opposite to the wafer substrate;
a first etch-stop layer between the wafer substrate and the sacrificial layer;
a second etch-stop layer between the sacrificial layer and the epitaxial layer structure;
a first lattice-match layer between the first etch-stop layer and the sacrificial layer; and
a second lattice-match layer between the sacrificial layer and the second etch-stop layer, such that said lattice-match layers eliminate or reduce the occurrence of lattice defects in the epitaxial layer structure.
2. The epitaxial substrate as in claim 1 , wherein a band gap of at least one epitaxial layer of the epitaxial layer structure is larger than the band gap of said sacrificial layer.
3. The epitaxial substrate as in claim 1 , characterized in that said epitaxial substrate comprises at least one lattice-match layer.
4. The epitaxial substrate as in claim 1 , characterized in that said sacrificial layer contains superlattices.
5. The epitaxial substrate as in claim 1 , characterized in that said sacrificial layer has a direct band gap.
6. The epitaxial substrate as in claim 1 , characterized in that the lattice structure of said sacrificial layer is matched to the lattice structure of said wafer.
7. The epitaxial substrate as in claim 1 , characterized in that disposed on the growth side of said epitaxial substrate are trenches or depressions which extend in depth at least to said sacrificial layer.
8. The epitaxial substrate as in claim 1 , characterized in that at least one light-emitting diode structure is disposed on said epitaxial substrate.
9. The epitaxial substrate as in claim 8 , characterized in that disposed on said at least one LED structure is a bonding layer, particularly for bonding to an acceptor substrate.
10. An LED thin-film chip fabricated by means of an epitaxial substrate as in claim 1 .
11. The epitaxial substrate of claim 1 , wherein the epitaxial layer structure comprises a light emitting diode structure, a laser structure, or an infra red diode structure.
12. A III-V-semiconductor-containing epitaxial substrate comprising:
a wafer substrate comprising gallium arsenide;
a sacrificial layer comprising at least one of Ge, GaAsN, and GaAsSb, applied to the wafer substrate, and having a band gap smaller than the band gap of the wafer substrate;
an epitaxial layer structure configured to emit radiation and applied to the sacrificial layer opposite to the wafer substrate;
a first etch-stop layer between the wafer substrate and the sacrificial layer;
a second etch-stop layer between the sacrificial layer and the epitaxial layer structure;
a first lattice-match layer between the first etch-stop layer and the sacrificial layer; and
a second lattice-match layer between the sacrificial layer and the second etch-stop layer, such that said lattice-match layers eliminate or reduce the occurrence of lattice defects in the epitaxial layer structure.
13. A III-V semiconductor-containing epitaxial substrate comprising:
a wafer substrate comprising gallium arsenide;
a sacrificial layer comprising at least one of Ge and GaAsSb, applied to the wafer substrate, and having a band gap smaller than the band gap of the wafer substrate;
an epitaxial layer structure configured to emit radiation and applied to the sacrificial layer opposite to the wafer substrate;
a first etch-stop layer between the wafer substrate and the sacrificial layer;
a second etch-stop layer between the sacrificial layer and the epitaxial layer structure;
a first lattice-match layer between the first etch-stop layer and the sacrificial layer; and
a second lattice-match layer between the sacrificial layer and the second etch-stop layer, wherein said lattice-match layers eliminate or reduce the occurrence of lattice defects in the epitaxial layer structure.