In the manufacture of photovoltaic cells, among other things, it may be desirable to transfer a lamina that, in some aspects, may be less than 100 microns thick to a receiver element. As an example, the process of transferring the lamina to the receiver element may include exfoliating the lamina from a donor wafer such as a monocrystalline silicon wafer with a thickness of from about 300 microns to about 1000 microns and bonding the lamina to the receiver element, which may be composed of metal, glass, semiconductor material, polymer, or other suitable material. The usual transfer process includes implanting hydrogen ions within the donor wafer to form a cleave plane within the donor wafer, followed by bonding the donor wafer to the receiver element at ambient temperature, and then subsequently heating the donor wafer and the receiver element to a higher temperature to induce exfoliation of the lamina from the donor wafer along the cleave plane.
However, a bond between materials with dissimilar thermal expansion such as the bond between the donor wafer and receiver element may fail during the bonding and the lamina transfer process. Accordingly, there is a need for improved methods for transferring a lamina to a receiver element where the donor wafer and the receiver element have dissimilar thermal expansion properties.
USPTO Backgrounds
USPTO Backgrounds