Epitaxial lift off stack having a pre-curved handle and methods thereof
View Patent ↗Embodiments of the invention generally relate to epitaxial lift off (ELO) thin films and devices and methods used to form such films and devices. In one embodiment, a method for forming an ELO thin film is provided which includes depositing an epitaxial material over a sacrificial layer on a substrate, adhering a flattened, pre-curved support handle onto the epitaxial material, and removing the sacrificial layer during an etching process. The etching process includes bending the pre-curved support handle to have substantial curvature while peeling the epitaxial material from the substrate and forming an etch crevice therebetween. Compression is maintained within the epitaxial material during the etching process. The flattened, pre-curved support handle may be formed by flattening a pre-curved support material.
1. A thin film stack material for at least one device selected from a group consisting of a solar device, a semiconductor device, and an electronic device, said thin film stack material comprising:
a sacrificial layer disposed on a substrate;
an epitaxial material disposed over the sacrificial layer;
a pre-curved support material configured to be flattened; and
a flattened, pre-curved support handle comprising the pre-curved support material disposed over the epitaxial material, wherein the flattened, pre-curved support handle is under tension while the epitaxial material is under compression, and wherein said flattened, pre-curved support handle is operable to bend said epitaxial material responsive to an etching of said sacrificial layer.
2. The thin film stack material of claim 1 , wherein the flattened, pre-curved support handle comprises a material selected from the group consisting of wax, polyethylene, polyester, polyolefin, polyethylene terephthalate polyester, rubber, derivatives thereof, and combinations thereof.
3. The thin film stack material of claim 1 , wherein the flattened, pre-curved support handle comprises a first layer comprising wax and a second layer comprising a polymer disposed over the first layer.
4. The thin film stack material of claim 1 , wherein an adhesive is disposed between the flattened, pre-curved support handle and the epitaxial material, and the adhesive is selected from the group consisting of pressure sensitive adhesive, hot melt adhesive, UV curing adhesive, natural adhesive, synthetic adhesive, derivatives thereof, and combinations thereof.
5. The thin film stack material of claim 4 , wherein the epitaxial material comprises a material selected from the group consisting of gallium arsenide, aluminum gallium arsenide, indium gallium phosphide, alloys thereof, derivatives thereof, and combinations thereof.
6. The thin film stack material of claim 1 , wherein the epitaxial material comprises a cell structure containing multiple layers comprising at least one material selected from the group consisting of gallium arsenide, n-doped gallium arsenide, p-doped gallium arsenide, aluminum gallium arsenide, n-doped aluminum gallium arsenide, p-doped aluminum gallium arsenide, indium gallium phosphide, alloys thereof, derivatives thereof, and combinations thereof.
7. The thin film stack material of claim 1 , wherein the sacrificial layer comprises a material selected from the group consisting of aluminum arsenide, alloys thereof, derivatives thereof, and combinations thereof.
8. The thin film stack material of claim 1 , wherein the substrate comprises gallium arsenide, n-doped gallium arsenide, p-doped gallium arsenide, or derivatives thereof.